[RFC PATCH 00/25] migration: Cleanup early connection code

[RFC PATCH 00/25] migration: Cleanup early connection code

[Fabiano Rosas]

Based-on: <20251223142959.1460293-1-peterx@redhat.com>

[PULL 00/31] Next patches
https://lore.kernel.org/r/20251223142959.1460293-1-peterx@redhat.com
--

Address some of the issues that make the early connection code a bit
too idiosyncratic. By "early connection" I mean from
qmp_migrate[_incoming] until the start of the migration
thread|coroutine.

(IOW, the whole dance of going into socket code, starting an async
routine, calling back to migration code, checking TLS, going back
again, coming back once more, etc. All while passing an error_in and
hostname string that eventually gets (maybe) ignored in tls code,
along with some is_resume checks along the way)

This series is mostly inspired by the work Markus and Peter did
recently in organizing some of the error handling code. The new
migration_connect_error_propagate() function seems like a good place
to centralize the error handling and call migration_cleanup() during
this early connection phase when everything is still fairly
linear. (apologies if I'm dirtying your design =)

Aside from the initial patches that are a bit disruptive, most of the
series is just refactoring to make the code easier to navigate, names
more consistent and some general cleanups.

- patches 1-8:

General cleanups, could be applied standalone, although they are
prerequisites for the rest of the series.

- patches 9-12:

Changes to allow calling migration_cleanup() from
migration_connect_error_propagate().

The idea here is to make sure error propagation and cleanup happen
when the error is detected, without calling into non-error-path
functions.

This is the more risky change because it will cause cleanup to run in
places where it didn't before.

- patch 13 & 19:

The main change of this series, simplifying the
qmp-migrate --> migration_connect path. Stops calling the connection
functions when an error happens in the transport code, adds
clarification around which paths have asynchronous completion and
makes the synchronous path return to their caller to start the
migration instead of initiating it themselves.

- patches 14-18, 20-22:

Moves code out of migration.c and into channel.c. Now that the code is
more compartmentalized, move it to a more appropriate source file.

- patches 23-25:

BONUS CONTENT, wrap the uri/channels parsing and move it to channel.c
as well.

- future work?

I think we could move all QMP command functions to a QAPI-specific
file, but I don't see any standardization in the tree, there's
block/qapi.c, various instances of foo-qmp-cmds.c and many more just
laying along with the rest of the code. So I left this for another
moment.

CI run: https://gitlab.com/farosas/qemu/-/pipelines/2233810778

Fabiano Rosas (25):
  migration: Remove redundant state change
  migration: Fix state change at migration_channel_process_incoming
  migration/tls: Remove unused parameter
  migration: Move multifd_recv_setup call
  migration: Cleanup TLS handshake hostname passing
  migration: Move postcopy_try_recover into migration_incoming_process
  migration: Use migrate_mode() to query for cpr-transfer
  migration: Free the error earlier in the resume case
  migration: Move error reporting out of migration_cleanup
  migration: Expand migration_connect_error_propagate to cover
    cancelling
  migration: yank: Move register instance earlier
  migration: Fold migration_cleanup() into
    migration_connect_error_propagate()
  migration: Handle error in the early async paths
  migration: Remove QEMUFile from channel.c
  migration/channel: Rename migration_channel_connect
  migration: Rename instances of start
  migration: Move channel code to channel.c
  migration: Move transport connection code into channel.c
  migration/channel: Make synchronous calls evident
  migration/channel: Use switch statements in outgoing code
  migration/channel: Cleanup early passing of MigrationState
  migration/channel: Merge both sides of the connection initiation code
  migration: Move channel parsing to channel.c
  migration: Move URI parsing to channel.c
  migration: Remove qmp_migrate_finish

 migration/channel.c      | 410 +++++++++++++++++++++++++----
 migration/channel.h      |  36 ++-
 migration/exec.c         |  10 +-
 migration/exec.h         |   7 +-
 migration/fd.c           |  14 +-
 migration/fd.h           |   8 +-
 migration/file.c         |  19 +-
 migration/file.h         |   6 +-
 migration/migration.c    | 540 ++++++++++-----------------------------
 migration/migration.h    |  11 +-
 migration/multifd.c      |  16 +-
 migration/multifd.h      |   2 +-
 migration/options.c      |   5 +
 migration/postcopy-ram.c |   2 +-
 migration/rdma.c         |  52 ++--
 migration/rdma.h         |   5 +-
 migration/socket.c       |  54 ++--
 migration/socket.h       |   5 +-
 migration/tls.c          |  39 +--
 migration/tls.h          |  10 +-
 migration/trace-events   |  20 +-
 21 files changed, 654 insertions(+), 617 deletions(-)

-- 
2.51.0

[RFC PATCH 01/25] migration: Remove redundant state change

[Fabiano Rosas]

If local_err is set, migration_connect_error_propagate() will be
called and that function already has a state transtion from SETUP to
FAILED.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/migration.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 635851fe8c..71efe945f6 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2326,8 +2326,6 @@ static void qmp_migrate_finish(MigrationAddress *addr, bool resume_requested,
         file_start_outgoing_migration(s, &addr->u.file, &local_err);
     } else {
         error_setg(&local_err, "uri is not a valid migration protocol");
-        migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
-                          MIGRATION_STATUS_FAILED);
     }
 
     if (local_err) {
-- 
2.51.0

[RFC PATCH 02/25] migration: Fix state change at migration_channel_process_incoming

[Fabiano Rosas]

When the incoming migration fails during the channel connection phase,
the state transition to FAILED is currently being done in the
MigrationState->state, but the MigrationIncomingState->state is the
one that should be used.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/migration/channel.c b/migration/channel.c
index 92435fa7f7..4768c71455 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -48,7 +48,7 @@ void migration_channel_process_incoming(QIOChannel *ioc)
 
     if (local_err) {
         error_report_err(local_err);
-        migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED);
+        migrate_set_state(&mis->state, mis->state, MIGRATION_STATUS_FAILED);
         if (mis->exit_on_error) {
             exit(EXIT_FAILURE);
         }
-- 
2.51.0

[RFC PATCH 03/25] migration/tls: Remove unused parameter

[Fabiano Rosas]

MigrationState is not used at migration_tls_channel_process_incoming().

The last usage was removed by commit 3f461a0c0b ("migration: Drop
unused parameter for migration_tls_get_creds()")

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c | 3 +--
 migration/tls.c     | 4 +---
 migration/tls.h     | 4 +---
 3 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index 4768c71455..b4ab676048 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -32,7 +32,6 @@
  */
 void migration_channel_process_incoming(QIOChannel *ioc)
 {
-    MigrationState *s = migrate_get_current();
     MigrationIncomingState *mis = migration_incoming_get_current();
     Error *local_err = NULL;
 
@@ -40,7 +39,7 @@ void migration_channel_process_incoming(QIOChannel *ioc)
         ioc, object_get_typename(OBJECT(ioc)));
 
     if (migrate_channel_requires_tls_upgrade(ioc)) {
-        migration_tls_channel_process_incoming(s, ioc, &local_err);
+        migration_tls_channel_process_incoming(ioc, &local_err);
     } else {
         migration_ioc_register_yank(ioc);
         migration_ioc_process_incoming(ioc, &local_err);
diff --git a/migration/tls.c b/migration/tls.c
index 56b5d1cc90..1df31bdcbb 100644
--- a/migration/tls.c
+++ b/migration/tls.c
@@ -71,9 +71,7 @@ static void migration_tls_incoming_handshake(QIOTask *task,
     object_unref(OBJECT(ioc));
 }
 
-void migration_tls_channel_process_incoming(MigrationState *s,
-                                            QIOChannel *ioc,
-                                            Error **errp)
+void migration_tls_channel_process_incoming(QIOChannel *ioc, Error **errp)
 {
     QCryptoTLSCreds *creds;
     QIOChannelTLS *tioc;
diff --git a/migration/tls.h b/migration/tls.h
index 58b25e1228..7607cfe803 100644
--- a/migration/tls.h
+++ b/migration/tls.h
@@ -24,9 +24,7 @@
 #include "io/channel.h"
 #include "io/channel-tls.h"
 
-void migration_tls_channel_process_incoming(MigrationState *s,
-                                            QIOChannel *ioc,
-                                            Error **errp);
+void migration_tls_channel_process_incoming(QIOChannel *ioc, Error **errp);
 
 QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
                                            const char *hostname,
-- 
2.51.0

[RFC PATCH 04/25] migration: Move multifd_recv_setup call

[Fabiano Rosas]

The multifd_recv_setup() call is currently in a place where it will be
called for every channel that appears. That doesn't make much
sense.

It seems it was moved when the channel discovery mechanism was added
back at commit 6720c2b327 (migration: check magic value for deciding
the mapping of channels, 2022-12-20). The original place was
migration_incoming_setup() which would run for just the main channel,
but it was discovered that the main channel might arrive after a
multifd channel.

Move the call back to a place where it will be called only once.

With respect to cleanup, this new location at
qemu_start_incoming_migration() has the same issue as the previous
callsite at migration_ioc_process_incoming(): no cleanup ever happens.

The error message goes from being emitted via error_report_err(), to
being returned to the qmp_migrate_incoming() incoming command, which
is arguably better, since this is setup code.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/migration.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 71efe945f6..974313944c 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -786,6 +786,10 @@ static void qemu_start_incoming_migration(const char *uri, bool has_channels,
         return;
     }
 
+    if (multifd_recv_setup(errp) != 0) {
+        return;
+    }
+
     if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
         SocketAddress *saddr = &addr->u.socket;
         if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
@@ -1065,10 +1069,6 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
         channel = CH_POSTCOPY;
     }
 
-    if (multifd_recv_setup(errp) != 0) {
-        return;
-    }
-
     if (channel == CH_MAIN) {
         f = qemu_file_new_input(ioc);
         migration_incoming_setup(f);
-- 
2.51.0

[RFC PATCH 05/25] migration: Cleanup TLS handshake hostname passing

[Fabiano Rosas]

The TLS hostname is doing a tour around the world just to be cached
into s->hostname. We're already abusing MigrationState by doing that,
so incorporate the s->hostname into migration_tls_hostname() and stop
passing the string around.

The old route was roughly:

 -transport code (socket.c, fd.c, etc):
    if (SOCKET_ADDRESS_TYPE_INET)
        hostname = saddr->u.inet.host
    else
        hostname = NULL
    migration_channel_connect(..., hostname)
      s->hostname = hostname;
      migration_tls_client_create(..., hostname)
        if (migrate_tls_hostname())
            qio_channel_tls_new_client(migrate_tls_hostname())
        else
            qio_channel_tls_new_client(hostname)

 -postcopy_preempt_setup:
    postcopy_preempt_send_channel_new
      migration_tls_client_create(..., s->hostname)

New route is:

 -socket.c only:
   if SOCKET_ADDRESS_TYPE_INET
       s->hostname = saddr->u.inet.host
   migration_channel_connect()
     migration_tls_client_create()
       qio_channel_tls_new_client(migrate_tls_hostname())

 -postcopy_preempt_setup:
    postcopy_preempt_send_channel_new
      migration_tls_client_create()
        qio_channel_tls_new_client(migrate_tls_hostname())

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c      |  6 ++----
 migration/channel.h      |  1 -
 migration/exec.c         |  2 +-
 migration/fd.c           |  2 +-
 migration/file.c         |  2 +-
 migration/multifd.c      |  9 +++------
 migration/options.c      |  5 +++++
 migration/postcopy-ram.c |  2 +-
 migration/socket.c       |  9 +++------
 migration/tls.c          | 17 ++++-------------
 migration/tls.h          |  2 --
 migration/trace-events   | 10 +++++-----
 12 files changed, 26 insertions(+), 41 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index b4ab676048..ba14f66d85 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -60,20 +60,18 @@ void migration_channel_process_incoming(QIOChannel *ioc)
  *
  * @s: Current migration state
  * @ioc: Channel to which we are connecting
- * @hostname: Where we want to connect
  * @error: Error indicating failure to connect, free'd here
  */
 void migration_channel_connect(MigrationState *s,
                                QIOChannel *ioc,
-                               const char *hostname,
                                Error *error)
 {
     trace_migration_set_outgoing_channel(
-        ioc, object_get_typename(OBJECT(ioc)), hostname, error);
+        ioc, object_get_typename(OBJECT(ioc)), error);
 
     if (!error) {
         if (migrate_channel_requires_tls_upgrade(ioc)) {
-            migration_tls_channel_connect(s, ioc, hostname, &error);
+            migration_tls_channel_connect(s, ioc, &error);
 
             if (!error) {
                 /* tls_channel_connect will call back to this
diff --git a/migration/channel.h b/migration/channel.h
index 5bdb8208a7..2215091323 100644
--- a/migration/channel.h
+++ b/migration/channel.h
@@ -22,7 +22,6 @@ void migration_channel_process_incoming(QIOChannel *ioc);
 
 void migration_channel_connect(MigrationState *s,
                                QIOChannel *ioc,
-                               const char *hostname,
                                Error *error_in);
 
 int migration_channel_read_peek(QIOChannel *ioc,
diff --git a/migration/exec.c b/migration/exec.c
index 20e6cccf8c..78fe0fff13 100644
--- a/migration/exec.c
+++ b/migration/exec.c
@@ -55,7 +55,7 @@ void exec_start_outgoing_migration(MigrationState *s, strList *command,
     }
 
     qio_channel_set_name(ioc, "migration-exec-outgoing");
-    migration_channel_connect(s, ioc, NULL, NULL);
+    migration_channel_connect(s, ioc, NULL);
     object_unref(OBJECT(ioc));
 }
 
diff --git a/migration/fd.c b/migration/fd.c
index 9bf9be6acb..c956b260a4 100644
--- a/migration/fd.c
+++ b/migration/fd.c
@@ -70,7 +70,7 @@ void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **
     }
 
     qio_channel_set_name(ioc, "migration-fd-outgoing");
-    migration_channel_connect(s, ioc, NULL, NULL);
+    migration_channel_connect(s, ioc, NULL);
     object_unref(OBJECT(ioc));
 }
 
diff --git a/migration/file.c b/migration/file.c
index bb8031e3c7..c490f2b219 100644
--- a/migration/file.c
+++ b/migration/file.c
@@ -122,7 +122,7 @@ void file_start_outgoing_migration(MigrationState *s,
         return;
     }
     qio_channel_set_name(ioc, "migration-file-outgoing");
-    migration_channel_connect(s, ioc, NULL, NULL);
+    migration_channel_connect(s, ioc, NULL);
 }
 
 static gboolean file_accept_incoming_migration(QIOChannel *ioc,
diff --git a/migration/multifd.c b/migration/multifd.c
index bf6da85af8..3fb1a07ba9 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -814,12 +814,10 @@ static bool multifd_tls_channel_connect(MultiFDSendParams *p,
                                         QIOChannel *ioc,
                                         Error **errp)
 {
-    MigrationState *s = migrate_get_current();
-    const char *hostname = s->hostname;
     MultiFDTLSThreadArgs *args;
     QIOChannelTLS *tioc;
 
-    tioc = migration_tls_client_create(ioc, hostname, errp);
+    tioc = migration_tls_client_create(ioc, errp);
     if (!tioc) {
         return false;
     }
@@ -829,7 +827,7 @@ static bool multifd_tls_channel_connect(MultiFDSendParams *p,
      * created TLS channel, which has already taken a reference.
      */
     object_unref(OBJECT(ioc));
-    trace_multifd_tls_outgoing_handshake_start(ioc, tioc, hostname);
+    trace_multifd_tls_outgoing_handshake_start(ioc, tioc);
     qio_channel_set_name(QIO_CHANNEL(tioc), "multifd-tls-outgoing");
 
     args = g_new0(MultiFDTLSThreadArgs, 1);
@@ -876,8 +874,7 @@ static void multifd_new_send_channel_async(QIOTask *task, gpointer opaque)
         goto out;
     }
 
-    trace_multifd_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)),
-                                       migrate_get_current()->hostname);
+    trace_multifd_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)));
 
     if (migrate_channel_requires_tls_upgrade(ioc)) {
         ret = multifd_tls_channel_connect(p, ioc, &local_err);
diff --git a/migration/options.c b/migration/options.c
index 9a5a39c886..881034c289 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -956,6 +956,11 @@ const char *migrate_tls_hostname(void)
         return s->parameters.tls_hostname->u.s;
     }
 
+    /* hostname saved from a previously connected channel */
+    if (s->hostname) {
+        return s->hostname;
+    }
+
     return NULL;
 }
 
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 3623ab9dab..03cb0d8d65 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -1966,7 +1966,7 @@ postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
     }
 
     if (migrate_channel_requires_tls_upgrade(ioc)) {
-        tioc = migration_tls_client_create(ioc, s->hostname, &local_err);
+        tioc = migration_tls_client_create(ioc, &local_err);
         if (!tioc) {
             goto out;
         }
diff --git a/migration/socket.c b/migration/socket.c
index 9e379bf56f..426f363b99 100644
--- a/migration/socket.c
+++ b/migration/socket.c
@@ -44,7 +44,6 @@ void socket_send_channel_create(QIOTaskFunc f, void *data)
 
 struct SocketConnectData {
     MigrationState *s;
-    char *hostname;
 };
 
 static void socket_connect_data_free(void *opaque)
@@ -53,7 +52,6 @@ static void socket_connect_data_free(void *opaque)
     if (!data) {
         return;
     }
-    g_free(data->hostname);
     g_free(data);
 }
 
@@ -69,7 +67,7 @@ static void socket_outgoing_migration(QIOTask *task,
            goto out;
     }
 
-    trace_migration_socket_outgoing_connected(data->hostname);
+    trace_migration_socket_outgoing_connected();
 
     if (migrate_zero_copy_send() &&
         !qio_channel_has_feature(sioc, QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY)) {
@@ -77,7 +75,7 @@ static void socket_outgoing_migration(QIOTask *task,
     }
 
 out:
-    migration_channel_connect(data->s, sioc, data->hostname, err);
+    migration_channel_connect(data->s, sioc, err);
     object_unref(OBJECT(sioc));
 }
 
@@ -96,7 +94,7 @@ void socket_start_outgoing_migration(MigrationState *s,
     outgoing_args.saddr = addr;
 
     if (saddr->type == SOCKET_ADDRESS_TYPE_INET) {
-        data->hostname = g_strdup(saddr->u.inet.host);
+        s->hostname = g_strdup(saddr->u.inet.host);
     }
 
     qio_channel_set_name(QIO_CHANNEL(sioc), "migration-socket-outgoing");
@@ -180,4 +178,3 @@ void socket_start_incoming_migration(SocketAddress *saddr,
         qapi_free_SocketAddress(address);
     }
 }
-
diff --git a/migration/tls.c b/migration/tls.c
index 1df31bdcbb..82f58cbc78 100644
--- a/migration/tls.c
+++ b/migration/tls.c
@@ -112,12 +112,11 @@ static void migration_tls_outgoing_handshake(QIOTask *task,
     } else {
         trace_migration_tls_outgoing_handshake_complete();
     }
-    migration_channel_connect(s, ioc, NULL, err);
+    migration_channel_connect(s, ioc, err);
     object_unref(OBJECT(ioc));
 }
 
 QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
-                                           const char *hostname,
                                            Error **errp)
 {
     QCryptoTLSCreds *creds;
@@ -127,29 +126,21 @@ QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
         return NULL;
     }
 
-    const char *tls_hostname = migrate_tls_hostname();
-    if (tls_hostname) {
-        hostname = tls_hostname;
-    }
-
-    return qio_channel_tls_new_client(ioc, creds, hostname, errp);
+    return qio_channel_tls_new_client(ioc, creds, migrate_tls_hostname(), errp);
 }
 
 void migration_tls_channel_connect(MigrationState *s,
                                    QIOChannel *ioc,
-                                   const char *hostname,
                                    Error **errp)
 {
     QIOChannelTLS *tioc;
 
-    tioc = migration_tls_client_create(ioc, hostname, errp);
+    tioc = migration_tls_client_create(ioc, errp);
     if (!tioc) {
         return;
     }
 
-    /* Save hostname into MigrationState for handshake */
-    s->hostname = g_strdup(hostname);
-    trace_migration_tls_outgoing_handshake_start(hostname);
+    trace_migration_tls_outgoing_handshake_start();
     qio_channel_set_name(QIO_CHANNEL(tioc), "migration-tls-outgoing");
 
     if (migrate_postcopy_ram() || migrate_return_path()) {
diff --git a/migration/tls.h b/migration/tls.h
index 7607cfe803..7cd9c76013 100644
--- a/migration/tls.h
+++ b/migration/tls.h
@@ -27,12 +27,10 @@
 void migration_tls_channel_process_incoming(QIOChannel *ioc, Error **errp);
 
 QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
-                                           const char *hostname,
                                            Error **errp);
 
 void migration_tls_channel_connect(MigrationState *s,
                                    QIOChannel *ioc,
-                                   const char *hostname,
                                    Error **errp);
 void migration_tls_channel_end(QIOChannel *ioc, Error **errp);
 /* Whether the QIO channel requires further TLS handshake? */
diff --git a/migration/trace-events b/migration/trace-events
index bf11b62b17..da8f909cac 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -149,10 +149,10 @@ multifd_send_sync_main_wait(uint8_t id) "channel %u"
 multifd_send_terminate_threads(void) ""
 multifd_send_thread_end(uint8_t id, uint64_t packets) "channel %u packets %" PRIu64
 multifd_send_thread_start(uint8_t id) "%u"
-multifd_tls_outgoing_handshake_start(void *ioc, void *tioc, const char *hostname) "ioc=%p tioc=%p hostname=%s"
+multifd_tls_outgoing_handshake_start(void *ioc, void *tioc) "ioc=%p tioc=%p"
 multifd_tls_outgoing_handshake_error(void *ioc, const char *err) "ioc=%p err=%s"
 multifd_tls_outgoing_handshake_complete(void *ioc) "ioc=%p"
-multifd_set_outgoing_channel(void *ioc, const char *ioctype, const char *hostname)  "ioc=%p ioctype=%s hostname=%s"
+multifd_set_outgoing_channel(void *ioc, const char *ioctype)  "ioc=%p ioctype=%s"
 
 # migration.c
 migrate_set_state(const char *new_state) "new state %s"
@@ -204,7 +204,7 @@ migration_transferred_bytes(uint64_t qemu_file, uint64_t multifd, uint64_t rdma)
 
 # channel.c
 migration_set_incoming_channel(void *ioc, const char *ioctype) "ioc=%p ioctype=%s"
-migration_set_outgoing_channel(void *ioc, const char *ioctype, const char *hostname, void *err)  "ioc=%p ioctype=%s hostname=%s err=%p"
+migration_set_outgoing_channel(void *ioc, const char *ioctype, void *err)  "ioc=%p ioctype=%s err=%p"
 
 # global_state.c
 migrate_state_too_big(void) ""
@@ -328,11 +328,11 @@ migration_file_incoming(const char *filename) "filename=%s"
 
 # socket.c
 migration_socket_incoming_accepted(void) ""
-migration_socket_outgoing_connected(const char *hostname) "hostname=%s"
+migration_socket_outgoing_connected(void) ""
 migration_socket_outgoing_error(const char *err) "error=%s"
 
 # tls.c
-migration_tls_outgoing_handshake_start(const char *hostname) "hostname=%s"
+migration_tls_outgoing_handshake_start(void) ""
 migration_tls_outgoing_handshake_error(const char *err) "err=%s"
 migration_tls_outgoing_handshake_complete(void) ""
 migration_tls_incoming_handshake_start(void) ""
-- 
2.51.0

[RFC PATCH 06/25] migration: Move postcopy_try_recover into migration_incoming_process

[Fabiano Rosas]

The postcopy_try_recover() call doesn't need to be duplicated, move it
into migration_incoming_process().

This removes code from migration_fd_process_incoming() so it can be
removed in the near future.

(the diff is a bit strange because migration_incoming_process() was
moved after postcopy_try_recover())

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/migration.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 974313944c..f2933f7789 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -947,12 +947,6 @@ static void migration_incoming_setup(QEMUFile *f)
     qemu_file_set_blocking(f, false, &error_abort);
 }
 
-void migration_incoming_process(void)
-{
-    Coroutine *co = qemu_coroutine_create(process_incoming_migration_co, NULL);
-    qemu_coroutine_enter(co);
-}
-
 /* Returns true if recovered from a paused migration, otherwise false */
 static bool postcopy_try_recover(void)
 {
@@ -986,12 +980,19 @@ static bool postcopy_try_recover(void)
     return false;
 }
 
+void migration_incoming_process(void)
+{
+    if (postcopy_try_recover()) {
+        return;
+    }
+
+    Coroutine *co = qemu_coroutine_create(process_incoming_migration_co, NULL);
+    qemu_coroutine_enter(co);
+}
+
 void migration_fd_process_incoming(QEMUFile *f)
 {
     migration_incoming_setup(f);
-    if (postcopy_try_recover()) {
-        return;
-    }
     migration_incoming_process();
 }
 
@@ -1087,10 +1088,6 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
     }
 
     if (migration_has_main_and_multifd_channels()) {
-        /* If it's a recovery, we're done */
-        if (postcopy_try_recover()) {
-            return;
-        }
         migration_incoming_process();
     }
 }
-- 
2.51.0

[RFC PATCH 07/25] migration: Use migrate_mode() to query for cpr-transfer

[Fabiano Rosas]

cpr_set_incoming_mode() is only called on the target side, so
migrate_mode() on the source side is the same as s->parameters.mode.

Use the function to reduce explicit access to s->parameters, we have
options.c for that.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/migration.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index f2933f7789..4b1afcab24 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2252,7 +2252,7 @@ void qmp_migrate(const char *uri, bool has_channels,
         return;
     }
 
-    if (s->parameters.mode == MIG_MODE_CPR_TRANSFER && !cpr_channel) {
+    if (migrate_mode() == MIG_MODE_CPR_TRANSFER && !cpr_channel) {
         error_setg(errp, "missing 'cpr' migration channel");
         return;
     }
@@ -2277,7 +2277,7 @@ void qmp_migrate(const char *uri, bool has_channels,
      * in which case the target will not listen for the incoming migration
      * connection, so qmp_migrate_finish will fail to connect, and then recover.
      */
-    if (s->parameters.mode == MIG_MODE_CPR_TRANSFER) {
+    if (migrate_mode() == MIG_MODE_CPR_TRANSFER) {
         migrate_hup_add(s, cpr_state_ioc(), (GSourceFunc)qmp_migrate_finish_cb,
                         QAPI_CLONE(MigrationAddress, addr));
 
-- 
2.51.0

[RFC PATCH 08/25] migration: Free the error earlier in the resume case

[Fabiano Rosas]

Freeing the error at migration_connect() is redundant in the normal
migration case. The freeing already happened at migrate_init():

qmp_migrate()
-> migrate_prepare()
   -> migrate_init()
-> qmp_migrate_finish()
   -> *_start_outgoing_migration()
   -> migration_channel_connect()
      -> migration_connect()

For the resume case, migrate_prepare() returns early and doesn't reach
migrate_init(). Move the extra migrate_error_free() call to
migrate_prepare() along with the resume check.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/migration.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 4b1afcab24..a56f8fb05e 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2088,6 +2088,13 @@ static bool migrate_prepare(MigrationState *s, bool resume, Error **errp)
         migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_PAUSED,
                           MIGRATION_STATUS_POSTCOPY_RECOVER_SETUP);
 
+        /*
+         * If there's a previous error, free it and prepare for
+         * another one. For the non-resume case, this happens at
+         * migrate_init() below.
+         */
+        migrate_error_free(s);
+
         /* This is a resume, skip init status */
         return true;
     }
@@ -4016,13 +4023,6 @@ void migration_connect(MigrationState *s, Error *error_in)
     bool resume = (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER_SETUP);
     int ret;
 
-    /*
-     * If there's a previous error, free it and prepare for another one.
-     * Meanwhile if migration completes successfully, there won't have an error
-     * dumped when calling migration_cleanup().
-     */
-    migrate_error_free(s);
-
     s->expected_downtime = migrate_downtime_limit();
     if (error_in) {
         migration_connect_error_propagate(s, error_in);
-- 
2.51.0

[RFC PATCH 09/25] migration: Move error reporting out of migration_cleanup

[Fabiano Rosas]

In the next patches migration_cleanup() will be used in qmp_migrate(),
which currently does not show an error message. Move the error
reporting out of migration_cleanup() to avoid duplicated messages.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/migration.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index a56f8fb05e..83854d084a 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1528,10 +1528,6 @@ static void migration_cleanup(MigrationState *s)
                           MIGRATION_STATUS_CANCELLED);
     }
 
-    if (s->error) {
-        /* It is used on info migrate.  We can't free it */
-        error_report_err(error_copy(s->error));
-    }
     type = migration_has_failed(s) ? MIG_EVENT_PRECOPY_FAILED :
                                      MIG_EVENT_PRECOPY_DONE;
     migration_call_notifiers(s, type, NULL);
@@ -1540,7 +1536,12 @@ static void migration_cleanup(MigrationState *s)
 
 static void migration_cleanup_bh(void *opaque)
 {
-    migration_cleanup(opaque);
+    MigrationState *s = opaque;
+
+    migration_cleanup(s);
+    if (s->error) {
+        error_report_err(error_copy(s->error));
+    }
 }
 
 /*
@@ -4026,18 +4027,12 @@ void migration_connect(MigrationState *s, Error *error_in)
     s->expected_downtime = migrate_downtime_limit();
     if (error_in) {
         migration_connect_error_propagate(s, error_in);
-        if (resume) {
-            /*
-             * Don't do cleanup for resume if channel is invalid, but only dump
-             * the error.  We wait for another channel connect from the user.
-             * The error_report still gives HMP user a hint on what failed.
-             * It's normally done in migration_cleanup(), but call it here
-             * explicitly.
-             */
-            error_report_err(error_copy(s->error));
-        } else {
+        if (!resume) {
             migration_cleanup(s);
         }
+        if (s->error) {
+            error_report_err(error_copy(s->error));
+        }
         return;
     }
 
@@ -4118,6 +4113,9 @@ fail:
     }
     error_report_err(local_err);
     migration_cleanup(s);
+    if (s->error) {
+        error_report_err(error_copy(s->error));
+    }
 }
 
 static void migration_class_init(ObjectClass *klass, const void *data)
-- 
2.51.0

[RFC PATCH 10/25] migration: Expand migration_connect_error_propagate to cover cancelling

[Fabiano Rosas]

Cover the CANCELLING state in migration_connect_error_propagate() and
use it to funnel errors from migrate_prepare() until the end of
migration_connect().

(add some line breaks for legibility)

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/migration.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 83854d084a..e1c00867ab 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1575,18 +1575,25 @@ static void migrate_error_free(MigrationState *s)
 static void migration_connect_error_propagate(MigrationState *s, Error *error)
 {
     MigrationStatus current = s->state;
-    MigrationStatus next;
-
-    assert(s->to_dst_file == NULL);
+    MigrationStatus next = MIGRATION_STATUS_NONE;
 
     switch (current) {
     case MIGRATION_STATUS_SETUP:
         next = MIGRATION_STATUS_FAILED;
         break;
+
     case MIGRATION_STATUS_POSTCOPY_RECOVER_SETUP:
         /* Never fail a postcopy migration; switch back to PAUSED instead */
         next = MIGRATION_STATUS_POSTCOPY_PAUSED;
         break;
+
+    case MIGRATION_STATUS_CANCELLING:
+        /*
+         * Don't move out of CANCELLING, the only valid transition is to
+         * CANCELLED, at migration_cleanup().
+         */
+        break;
+
     default:
         /*
          * This really shouldn't happen. Just be careful to not crash a VM
@@ -1597,7 +1604,10 @@ static void migration_connect_error_propagate(MigrationState *s, Error *error)
         return;
     }
 
-    migrate_set_state(&s->state, current, next);
+    if (next) {
+        migrate_set_state(&s->state, current, next);
+    }
+
     migrate_error_propagate(s, error);
 }
 
@@ -4107,11 +4117,7 @@ void migration_connect(MigrationState *s, Error *error_in)
     return;
 
 fail:
-    migrate_error_propagate(s, error_copy(local_err));
-    if (s->state != MIGRATION_STATUS_CANCELLING) {
-        migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED);
-    }
-    error_report_err(local_err);
+    migration_connect_error_propagate(s, local_err);
     migration_cleanup(s);
     if (s->error) {
         error_report_err(error_copy(s->error));
-- 
2.51.0

[RFC PATCH 11/25] migration: yank: Move register instance earlier

[Fabiano Rosas]

Move the register_instance call to migrate_prepare() so it can be
paired with the unregister_instance at migration_cleanup(). Otherwise,
the cleanup cannot be run when cpr_state_save() fails because the
instance is registered only after it.

When resuming from a paused postcopy migration, migrate_prepare()
returns early, but migration_cleanup() doesn't run, so the yank will
remain paired.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/migration.c | 26 ++++++++------------------
 1 file changed, 8 insertions(+), 18 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index e1c00867ab..0f1644b276 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2181,11 +2181,12 @@ static bool migrate_prepare(MigrationState *s, bool resume, Error **errp)
         return false;
     }
 
+    yank_register_instance(MIGRATION_YANK_INSTANCE, &error_abort);
+
     return true;
 }
 
-static void qmp_migrate_finish(MigrationAddress *addr, bool resume_requested,
-                               Error **errp);
+static void qmp_migrate_finish(MigrationAddress *addr, Error **errp);
 
 static void migrate_hup_add(MigrationState *s, QIOChannel *ioc, GSourceFunc cb,
                             void *opaque)
@@ -2210,7 +2211,7 @@ static gboolean qmp_migrate_finish_cb(QIOChannel *channel,
 {
     MigrationAddress *addr = opaque;
 
-    qmp_migrate_finish(addr, false, NULL);
+    qmp_migrate_finish(addr, NULL);
 
     cpr_state_close();
     migrate_hup_delete(migrate_get_current());
@@ -2222,7 +2223,6 @@ void qmp_migrate(const char *uri, bool has_channels,
                  MigrationChannelList *channels, bool has_detach, bool detach,
                  bool has_resume, bool resume, Error **errp)
 {
-    bool resume_requested;
     Error *local_err = NULL;
     MigrationState *s = migrate_get_current();
     g_autoptr(MigrationChannel) channel = NULL;
@@ -2275,8 +2275,7 @@ void qmp_migrate(const char *uri, bool has_channels,
         return;
     }
 
-    resume_requested = has_resume && resume;
-    if (!migrate_prepare(s, resume_requested, errp)) {
+    if (!migrate_prepare(s, has_resume && resume, errp)) {
         /* Error detected, put into errp */
         return;
     }
@@ -2300,28 +2299,22 @@ void qmp_migrate(const char *uri, bool has_channels,
                         QAPI_CLONE(MigrationAddress, addr));
 
     } else {
-        qmp_migrate_finish(addr, resume_requested, errp);
+        qmp_migrate_finish(addr, errp);
     }
 
 out:
     if (local_err) {
+        yank_unregister_instance(MIGRATION_YANK_INSTANCE);
         migration_connect_error_propagate(s, error_copy(local_err));
         error_propagate(errp, local_err);
     }
 }
 
-static void qmp_migrate_finish(MigrationAddress *addr, bool resume_requested,
-                               Error **errp)
+static void qmp_migrate_finish(MigrationAddress *addr, Error **errp)
 {
     MigrationState *s = migrate_get_current();
     Error *local_err = NULL;
 
-    if (!resume_requested) {
-        if (!yank_register_instance(MIGRATION_YANK_INSTANCE, errp)) {
-            return;
-        }
-    }
-
     if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
         SocketAddress *saddr = &addr->u.socket;
         if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
@@ -2344,9 +2337,6 @@ static void qmp_migrate_finish(MigrationAddress *addr, bool resume_requested,
     }
 
     if (local_err) {
-        if (!resume_requested) {
-            yank_unregister_instance(MIGRATION_YANK_INSTANCE);
-        }
         migration_connect_error_propagate(s, error_copy(local_err));
         error_propagate(errp, local_err);
         return;
-- 
2.51.0

[RFC PATCH 12/25] migration: Fold migration_cleanup() into migration_connect_error_propagate()

[Fabiano Rosas]

Whenever an error occurs between migrate_init() and the start of
migration_thread, do cleanup immediately after.

This allows the special casing for resume to be removed from
migration_connect(), that check is now done at
migration_connect_error_propagate() which already had a case for
resume.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/migration.c | 42 +++++++++++++++++++++++++++---------------
 1 file changed, 27 insertions(+), 15 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 0f1644b276..a66b2d7aaf 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1576,15 +1576,21 @@ static void migration_connect_error_propagate(MigrationState *s, Error *error)
 {
     MigrationStatus current = s->state;
     MigrationStatus next = MIGRATION_STATUS_NONE;
+    bool resume = false;
 
     switch (current) {
     case MIGRATION_STATUS_SETUP:
         next = MIGRATION_STATUS_FAILED;
         break;
 
+    case MIGRATION_STATUS_POSTCOPY_PAUSED:
+        resume = true;
+        break;
+
     case MIGRATION_STATUS_POSTCOPY_RECOVER_SETUP:
         /* Never fail a postcopy migration; switch back to PAUSED instead */
         next = MIGRATION_STATUS_POSTCOPY_PAUSED;
+        resume = true;
         break;
 
     case MIGRATION_STATUS_CANCELLING:
@@ -1609,6 +1615,10 @@ static void migration_connect_error_propagate(MigrationState *s, Error *error)
     }
 
     migrate_error_propagate(s, error);
+
+    if (!resume) {
+        migration_cleanup(s);
+    }
 }
 
 void migration_cancel(void)
@@ -2209,12 +2219,19 @@ static gboolean qmp_migrate_finish_cb(QIOChannel *channel,
                                       GIOCondition cond,
                                       void *opaque)
 {
+    MigrationState *s = migrate_get_current();
     MigrationAddress *addr = opaque;
+    Error *local_err = NULL;
+
+    qmp_migrate_finish(addr, &local_err);
+
+    if (local_err) {
+        migration_connect_error_propagate(s, local_err);
+    }
 
-    qmp_migrate_finish(addr, NULL);
 
     cpr_state_close();
-    migrate_hup_delete(migrate_get_current());
+    migrate_hup_delete(s);
     qapi_free_MigrationAddress(addr);
     return G_SOURCE_REMOVE;
 }
@@ -2223,7 +2240,6 @@ void qmp_migrate(const char *uri, bool has_channels,
                  MigrationChannelList *channels, bool has_detach, bool detach,
                  bool has_resume, bool resume, Error **errp)
 {
-    Error *local_err = NULL;
     MigrationState *s = migrate_get_current();
     g_autoptr(MigrationChannel) channel = NULL;
     MigrationAddress *addr = NULL;
@@ -2280,6 +2296,13 @@ void qmp_migrate(const char *uri, bool has_channels,
         return;
     }
 
+    /*
+     * The migrate_prepare() above calls migrate_init(). From this
+     * point on, until the end of migration, make sure any failures
+     * eventually result in a call to migration_cleanup().
+     */
+    Error *local_err = NULL;
+
     if (!cpr_state_save(cpr_channel, &local_err)) {
         goto out;
     }
@@ -2299,12 +2322,11 @@ void qmp_migrate(const char *uri, bool has_channels,
                         QAPI_CLONE(MigrationAddress, addr));
 
     } else {
-        qmp_migrate_finish(addr, errp);
+        qmp_migrate_finish(addr, &local_err);
     }
 
 out:
     if (local_err) {
-        yank_unregister_instance(MIGRATION_YANK_INSTANCE);
         migration_connect_error_propagate(s, error_copy(local_err));
         error_propagate(errp, local_err);
     }
@@ -2335,12 +2357,6 @@ static void qmp_migrate_finish(MigrationAddress *addr, Error **errp)
     } else {
         error_setg(&local_err, "uri is not a valid migration protocol");
     }
-
-    if (local_err) {
-        migration_connect_error_propagate(s, error_copy(local_err));
-        error_propagate(errp, local_err);
-        return;
-    }
 }
 
 void qmp_migrate_cancel(Error **errp)
@@ -4027,9 +4043,6 @@ void migration_connect(MigrationState *s, Error *error_in)
     s->expected_downtime = migrate_downtime_limit();
     if (error_in) {
         migration_connect_error_propagate(s, error_in);
-        if (!resume) {
-            migration_cleanup(s);
-        }
         if (s->error) {
             error_report_err(error_copy(s->error));
         }
@@ -4108,7 +4121,6 @@ void migration_connect(MigrationState *s, Error *error_in)
 
 fail:
     migration_connect_error_propagate(s, local_err);
-    migration_cleanup(s);
     if (s->error) {
         error_report_err(error_copy(s->error));
     }
-- 
2.51.0

[RFC PATCH 13/25] migration: Handle error in the early async paths

[Fabiano Rosas]

Simplify migration_channel_connect() and migration_connect() to not
take an error as input. Move the error handling into the paths that
generate the error.

To achive this, call migration_connect_error_propagate() from socket.c
and tls.c, which are the async paths.

For the sync paths, the handling is done as normal by returning all
the way to qmp_migrate_finish(), except that now the sync paths don't
pass the error forward into migration_connect() anymore.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c    | 46 +++++++++++++++++-------------------------
 migration/channel.h    |  4 +---
 migration/exec.c       |  2 +-
 migration/fd.c         |  2 +-
 migration/file.c       |  2 +-
 migration/migration.c  | 11 ++--------
 migration/migration.h  |  3 ++-
 migration/rdma.c       |  2 +-
 migration/socket.c     | 17 ++++++++--------
 migration/tls.c        | 19 ++++++++---------
 migration/tls.h        |  4 +---
 migration/trace-events |  2 +-
 12 files changed, 49 insertions(+), 65 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index ba14f66d85..7243b99108 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -60,38 +60,30 @@ void migration_channel_process_incoming(QIOChannel *ioc)
  *
  * @s: Current migration state
  * @ioc: Channel to which we are connecting
- * @error: Error indicating failure to connect, free'd here
  */
-void migration_channel_connect(MigrationState *s,
-                               QIOChannel *ioc,
-                               Error *error)
+void migration_channel_connect(MigrationState *s, QIOChannel *ioc)
 {
-    trace_migration_set_outgoing_channel(
-        ioc, object_get_typename(OBJECT(ioc)), error);
+    trace_migration_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)));
 
-    if (!error) {
-        if (migrate_channel_requires_tls_upgrade(ioc)) {
-            migration_tls_channel_connect(s, ioc, &error);
+    if (migrate_channel_requires_tls_upgrade(ioc)) {
+        migration_tls_channel_connect(s, ioc);
 
-            if (!error) {
-                /* tls_channel_connect will call back to this
-                 * function after the TLS handshake,
-                 * so we mustn't call migration_connect until then
-                 */
-
-                return;
-            }
-        } else {
-            QEMUFile *f = qemu_file_new_output(ioc);
-
-            migration_ioc_register_yank(ioc);
-
-            qemu_mutex_lock(&s->qemu_file_lock);
-            s->to_dst_file = f;
-            qemu_mutex_unlock(&s->qemu_file_lock);
-        }
+        /*
+         * async: the above will call back to this function after
+         * the TLS handshake is successfully completed.
+         */
+        return;
     }
-    migration_connect(s, error);
+
+    QEMUFile *f = qemu_file_new_output(ioc);
+
+    migration_ioc_register_yank(ioc);
+
+    qemu_mutex_lock(&s->qemu_file_lock);
+    s->to_dst_file = f;
+    qemu_mutex_unlock(&s->qemu_file_lock);
+
+    migration_connect(s);
 }
 
 
diff --git a/migration/channel.h b/migration/channel.h
index 2215091323..ccfeaaef18 100644
--- a/migration/channel.h
+++ b/migration/channel.h
@@ -20,9 +20,7 @@
 
 void migration_channel_process_incoming(QIOChannel *ioc);
 
-void migration_channel_connect(MigrationState *s,
-                               QIOChannel *ioc,
-                               Error *error_in);
+void migration_channel_connect(MigrationState *s, QIOChannel *ioc);
 
 int migration_channel_read_peek(QIOChannel *ioc,
                                 const char *buf,
diff --git a/migration/exec.c b/migration/exec.c
index 78fe0fff13..d83a07435a 100644
--- a/migration/exec.c
+++ b/migration/exec.c
@@ -55,7 +55,7 @@ void exec_start_outgoing_migration(MigrationState *s, strList *command,
     }
 
     qio_channel_set_name(ioc, "migration-exec-outgoing");
-    migration_channel_connect(s, ioc, NULL);
+    migration_channel_connect(s, ioc);
     object_unref(OBJECT(ioc));
 }
 
diff --git a/migration/fd.c b/migration/fd.c
index c956b260a4..0144a70742 100644
--- a/migration/fd.c
+++ b/migration/fd.c
@@ -70,7 +70,7 @@ void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **
     }
 
     qio_channel_set_name(ioc, "migration-fd-outgoing");
-    migration_channel_connect(s, ioc, NULL);
+    migration_channel_connect(s, ioc);
     object_unref(OBJECT(ioc));
 }
 
diff --git a/migration/file.c b/migration/file.c
index c490f2b219..7bb9c1c79f 100644
--- a/migration/file.c
+++ b/migration/file.c
@@ -122,7 +122,7 @@ void file_start_outgoing_migration(MigrationState *s,
         return;
     }
     qio_channel_set_name(ioc, "migration-file-outgoing");
-    migration_channel_connect(s, ioc, NULL);
+    migration_channel_connect(s, ioc);
 }
 
 static gboolean file_accept_incoming_migration(QIOChannel *ioc,
diff --git a/migration/migration.c b/migration/migration.c
index a66b2d7aaf..5c6c76f110 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1572,7 +1572,7 @@ static void migrate_error_free(MigrationState *s)
     }
 }
 
-static void migration_connect_error_propagate(MigrationState *s, Error *error)
+void migration_connect_error_propagate(MigrationState *s, Error *error)
 {
     MigrationStatus current = s->state;
     MigrationStatus next = MIGRATION_STATUS_NONE;
@@ -4033,7 +4033,7 @@ fail_setup:
     return NULL;
 }
 
-void migration_connect(MigrationState *s, Error *error_in)
+void migration_connect(MigrationState *s)
 {
     Error *local_err = NULL;
     uint64_t rate_limit;
@@ -4041,13 +4041,6 @@ void migration_connect(MigrationState *s, Error *error_in)
     int ret;
 
     s->expected_downtime = migrate_downtime_limit();
-    if (error_in) {
-        migration_connect_error_propagate(s, error_in);
-        if (s->error) {
-            error_report_err(error_copy(s->error));
-        }
-        return;
-    }
 
     if (resume) {
         /* This is a resumed migration */
diff --git a/migration/migration.h b/migration/migration.h
index 4d42e8f9a7..f340cd518d 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -532,10 +532,11 @@ void migration_incoming_process(void);
 
 bool  migration_has_all_channels(void);
 
+void migration_connect_error_propagate(MigrationState *s, Error *error);
 void migrate_error_propagate(MigrationState *s, Error *error);
 bool migrate_has_error(MigrationState *s);
 
-void migration_connect(MigrationState *s, Error *error_in);
+void migration_connect(MigrationState *s);
 
 int migration_call_notifiers(MigrationState *s, MigrationEventType type,
                              Error **errp);
diff --git a/migration/rdma.c b/migration/rdma.c
index 337b415889..596a1aba0b 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -3997,7 +3997,7 @@ void rdma_start_outgoing_migration(void *opaque,
 
     s->to_dst_file = rdma_new_output(rdma);
     s->rdma_migration = true;
-    migration_connect(s, NULL);
+    migration_connect(s);
     return;
 return_path_err:
     qemu_rdma_cleanup(rdma);
diff --git a/migration/socket.c b/migration/socket.c
index 426f363b99..298bac30cc 100644
--- a/migration/socket.c
+++ b/migration/socket.c
@@ -59,24 +59,25 @@ static void socket_outgoing_migration(QIOTask *task,
                                       gpointer opaque)
 {
     struct SocketConnectData *data = opaque;
-    QIOChannel *sioc = QIO_CHANNEL(qio_task_get_source(task));
+    g_autoptr(QIOChannel) sioc = QIO_CHANNEL(qio_task_get_source(task));
     Error *err = NULL;
 
     if (qio_task_propagate_error(task, &err)) {
-        trace_migration_socket_outgoing_error(error_get_pretty(err));
-           goto out;
+        goto err;
     }
 
-    trace_migration_socket_outgoing_connected();
-
     if (migrate_zero_copy_send() &&
         !qio_channel_has_feature(sioc, QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY)) {
         error_setg(&err, "Zero copy send feature not detected in host kernel");
+        goto err;
     }
 
-out:
-    migration_channel_connect(data->s, sioc, err);
-    object_unref(OBJECT(sioc));
+    trace_migration_socket_outgoing_connected();
+    migration_channel_connect(data->s, sioc);
+    return;
+err:
+    trace_migration_socket_outgoing_error(error_get_pretty(err));
+    migration_connect_error_propagate(data->s, err);
 }
 
 void socket_start_outgoing_migration(MigrationState *s,
diff --git a/migration/tls.c b/migration/tls.c
index 82f58cbc78..a54e8e6e14 100644
--- a/migration/tls.c
+++ b/migration/tls.c
@@ -104,16 +104,17 @@ static void migration_tls_outgoing_handshake(QIOTask *task,
                                              gpointer opaque)
 {
     MigrationState *s = opaque;
-    QIOChannel *ioc = QIO_CHANNEL(qio_task_get_source(task));
+    g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
     Error *err = NULL;
 
     if (qio_task_propagate_error(task, &err)) {
         trace_migration_tls_outgoing_handshake_error(error_get_pretty(err));
-    } else {
-        trace_migration_tls_outgoing_handshake_complete();
+        migration_connect_error_propagate(s, err);
+        return;
     }
-    migration_channel_connect(s, ioc, err);
-    object_unref(OBJECT(ioc));
+
+    trace_migration_tls_outgoing_handshake_complete();
+    migration_channel_connect(s, ioc);
 }
 
 QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
@@ -129,14 +130,14 @@ QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
     return qio_channel_tls_new_client(ioc, creds, migrate_tls_hostname(), errp);
 }
 
-void migration_tls_channel_connect(MigrationState *s,
-                                   QIOChannel *ioc,
-                                   Error **errp)
+void migration_tls_channel_connect(MigrationState *s, QIOChannel *ioc)
 {
     QIOChannelTLS *tioc;
+    Error *local_err = NULL;
 
-    tioc = migration_tls_client_create(ioc, errp);
+    tioc = migration_tls_client_create(ioc, &local_err);
     if (!tioc) {
+        migration_connect_error_propagate(s, local_err);
         return;
     }
 
diff --git a/migration/tls.h b/migration/tls.h
index 7cd9c76013..7399c42edf 100644
--- a/migration/tls.h
+++ b/migration/tls.h
@@ -29,9 +29,7 @@ void migration_tls_channel_process_incoming(QIOChannel *ioc, Error **errp);
 QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
                                            Error **errp);
 
-void migration_tls_channel_connect(MigrationState *s,
-                                   QIOChannel *ioc,
-                                   Error **errp);
+void migration_tls_channel_connect(MigrationState *s, QIOChannel *ioc);
 void migration_tls_channel_end(QIOChannel *ioc, Error **errp);
 /* Whether the QIO channel requires further TLS handshake? */
 bool migrate_channel_requires_tls_upgrade(QIOChannel *ioc);
diff --git a/migration/trace-events b/migration/trace-events
index da8f909cac..cbf10d0b63 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -204,7 +204,7 @@ migration_transferred_bytes(uint64_t qemu_file, uint64_t multifd, uint64_t rdma)
 
 # channel.c
 migration_set_incoming_channel(void *ioc, const char *ioctype) "ioc=%p ioctype=%s"
-migration_set_outgoing_channel(void *ioc, const char *ioctype, void *err)  "ioc=%p ioctype=%s err=%p"
+migration_set_outgoing_channel(void *ioc, const char *ioctype) "ioc=%p ioctype=%s"
 
 # global_state.c
 migrate_state_too_big(void) ""
-- 
2.51.0

[RFC PATCH 14/25] migration: Remove QEMUFile from channel.c

[Fabiano Rosas]

Make channel.c deal only with QIOChannel objects. Move any handling of
QEMUFile into migration.c. To achieve this in a clean way:

1) Define a migration_outgoing_setup, analogous to
migration_incoming_setup, responsible for creating the QEMUFile from
the QIOChannel.

2) Increase the scope of migration_incoming_setup to create not only
the main channel, but all the others as well. That is currently being
done at migration_ioc_process, so move the code.

3) Adjust RDMA code to pass in the QIOChannel and remove some of the
usage of QEMUFile.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c   | 21 ++++++-----
 migration/migration.c | 88 ++++++++++++++++++++++---------------------
 migration/migration.h |  6 ++-
 migration/multifd.c   |  7 ++--
 migration/multifd.h   |  2 +-
 migration/rdma.c      | 28 ++++----------
 6 files changed, 73 insertions(+), 79 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index 7243b99108..af6c2cc76e 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -14,7 +14,6 @@
 #include "channel.h"
 #include "tls.h"
 #include "migration.h"
-#include "qemu-file.h"
 #include "trace.h"
 #include "qapi/error.h"
 #include "io/channel-tls.h"
@@ -34,6 +33,7 @@ void migration_channel_process_incoming(QIOChannel *ioc)
 {
     MigrationIncomingState *mis = migration_incoming_get_current();
     Error *local_err = NULL;
+    uint8_t ch;
 
     trace_migration_set_incoming_channel(
         ioc, object_get_typename(OBJECT(ioc)));
@@ -42,9 +42,16 @@ void migration_channel_process_incoming(QIOChannel *ioc)
         migration_tls_channel_process_incoming(ioc, &local_err);
     } else {
         migration_ioc_register_yank(ioc);
-        migration_ioc_process_incoming(ioc, &local_err);
-    }
+        ch = migration_ioc_process_incoming(ioc, &local_err);
+        if (!ch) {
+            goto out;
+        }
 
+        if (migration_incoming_setup(ioc, ch, &local_err)) {
+            migration_incoming_process();
+        }
+    }
+out:
     if (local_err) {
         error_report_err(local_err);
         migrate_set_state(&mis->state, mis->state, MIGRATION_STATUS_FAILED);
@@ -75,14 +82,8 @@ void migration_channel_connect(MigrationState *s, QIOChannel *ioc)
         return;
     }
 
-    QEMUFile *f = qemu_file_new_output(ioc);
-
     migration_ioc_register_yank(ioc);
-
-    qemu_mutex_lock(&s->qemu_file_lock);
-    s->to_dst_file = f;
-    qemu_mutex_unlock(&s->qemu_file_lock);
-
+    migration_outgoing_setup(ioc);
     migration_connect(s);
 }
 
diff --git a/migration/migration.c b/migration/migration.c
index 5c6c76f110..677581b5a5 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -92,7 +92,7 @@ enum mig_rp_message_type {
 };
 
 /* Migration channel types */
-enum { CH_MAIN, CH_MULTIFD, CH_POSTCOPY };
+enum { CH_NONE, CH_MAIN, CH_MULTIFD, CH_POSTCOPY };
 
 /* When we add fault tolerance, we could have several
    migrations at once.  For now we don't need to add
@@ -934,17 +934,48 @@ out:
     migrate_incoming_unref_outgoing_state();
 }
 
-/**
- * migration_incoming_setup: Setup incoming migration
- * @f: file for main migration channel
- */
-static void migration_incoming_setup(QEMUFile *f)
+static bool migration_has_main_and_multifd_channels(void);
+
+bool migration_incoming_setup(QIOChannel *ioc, uint8_t channel, Error **errp)
 {
     MigrationIncomingState *mis = migration_incoming_get_current();
+    QEMUFile *f;
 
-    assert(!mis->from_src_file);
-    mis->from_src_file = f;
-    qemu_file_set_blocking(f, false, &error_abort);
+    switch (channel) {
+    case CH_MAIN:
+        f = qemu_file_new_input(ioc);
+        assert(!mis->from_src_file);
+        mis->from_src_file = f;
+        qemu_file_set_blocking(f, false, &error_abort);
+        break;
+
+    case CH_MULTIFD:
+        if (!multifd_recv_new_channel(ioc, errp)) {
+            return false;
+        }
+        break;
+
+    case CH_POSTCOPY:
+        assert(!mis->postcopy_qemufile_dst);
+        f = qemu_file_new_input(ioc);
+        postcopy_preempt_new_channel(mis, f);
+        return false;
+
+    default:
+        g_assert_not_reached();
+    }
+
+    return migration_has_main_and_multifd_channels();
+}
+
+void migration_outgoing_setup(QIOChannel *ioc)
+{
+    MigrationState *s = migrate_get_current();
+    QEMUFile *f = qemu_file_new_output(ioc);
+
+    qemu_mutex_lock(&s->qemu_file_lock);
+    s->to_dst_file = f;
+    qemu_mutex_unlock(&s->qemu_file_lock);
 }
 
 /* Returns true if recovered from a paused migration, otherwise false */
@@ -990,12 +1021,6 @@ void migration_incoming_process(void)
     qemu_coroutine_enter(co);
 }
 
-void migration_fd_process_incoming(QEMUFile *f)
-{
-    migration_incoming_setup(f);
-    migration_incoming_process();
-}
-
 static bool migration_has_main_and_multifd_channels(void)
 {
     MigrationIncomingState *mis = migration_incoming_get_current();
@@ -1012,12 +1037,10 @@ static bool migration_has_main_and_multifd_channels(void)
     return true;
 }
 
-void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
+uint8_t migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
 {
     MigrationIncomingState *mis = migration_incoming_get_current();
-    Error *local_err = NULL;
-    QEMUFile *f;
-    uint8_t channel;
+    uint8_t channel = CH_NONE;
     uint32_t channel_magic = 0;
     int ret = 0;
 
@@ -1036,7 +1059,7 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
             ret = migration_channel_read_peek(ioc, (void *)&channel_magic,
                                               sizeof(channel_magic), errp);
             if (ret != 0) {
-                return;
+                goto out;
             }
 
             channel_magic = be32_to_cpu(channel_magic);
@@ -1051,7 +1074,6 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
                 channel = CH_MAIN;
             } else {
                 error_setg(errp, "unknown channel magic: %u", channel_magic);
-                return;
             }
         } else if (mis->from_src_file && migrate_multifd()) {
             /*
@@ -1063,33 +1085,13 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
             channel = CH_MAIN;
         } else {
             error_setg(errp, "non-peekable channel used without multifd");
-            return;
         }
     } else {
         assert(migrate_postcopy_preempt());
         channel = CH_POSTCOPY;
     }
-
-    if (channel == CH_MAIN) {
-        f = qemu_file_new_input(ioc);
-        migration_incoming_setup(f);
-    } else if (channel == CH_MULTIFD) {
-        /* Multiple connections */
-        multifd_recv_new_channel(ioc, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
-            return;
-        }
-    } else if (channel == CH_POSTCOPY) {
-        assert(!mis->postcopy_qemufile_dst);
-        f = qemu_file_new_input(ioc);
-        postcopy_preempt_new_channel(mis, f);
-        return;
-    }
-
-    if (migration_has_main_and_multifd_channels()) {
-        migration_incoming_process();
-    }
+out:
+    return channel;
 }
 
 /**
diff --git a/migration/migration.h b/migration/migration.h
index f340cd518d..d2b82cf54f 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -526,8 +526,10 @@ struct MigrationState {
 void migrate_set_state(MigrationStatus *state, MigrationStatus old_state,
                        MigrationStatus new_state);
 
-void migration_fd_process_incoming(QEMUFile *f);
-void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp);
+void migration_outgoing_setup(QIOChannel *ioc);
+bool migration_incoming_setup(QIOChannel *ioc, uint8_t channel, Error **errp);
+
+uint8_t migration_ioc_process_incoming(QIOChannel *ioc, Error **errp);
 void migration_incoming_process(void);
 
 bool  migration_has_all_channels(void);
diff --git a/migration/multifd.c b/migration/multifd.c
index 3fb1a07ba9..c6639dbab5 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -1521,7 +1521,7 @@ bool multifd_recv_all_channels_created(void)
  * Try to receive all multifd channels to get ready for the migration.
  * Sets @errp when failing to receive the current channel.
  */
-void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
+bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
 {
     MultiFDRecvParams *p;
     Error *local_err = NULL;
@@ -1536,7 +1536,7 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
                                     "failed to receive packet"
                                     " via multifd channel %d: ",
                                     qatomic_read(&multifd_recv_state->count));
-            return;
+            return false;
         }
         trace_multifd_recv_new_channel(id);
     } else {
@@ -1549,7 +1549,7 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
                    id);
         multifd_recv_terminate_threads(error_copy(local_err));
         error_propagate(errp, local_err);
-        return;
+        return false;
     }
     p->c = ioc;
     object_ref(OBJECT(ioc));
@@ -1558,4 +1558,5 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
     qemu_thread_create(&p->thread, p->name, multifd_recv_thread, p,
                        QEMU_THREAD_JOINABLE);
     qatomic_inc(&multifd_recv_state->count);
+    return true;
 }
diff --git a/migration/multifd.h b/migration/multifd.h
index 9b6d81e7ed..89a395aef2 100644
--- a/migration/multifd.h
+++ b/migration/multifd.h
@@ -42,7 +42,7 @@ int multifd_recv_setup(Error **errp);
 void multifd_recv_cleanup(void);
 void multifd_recv_shutdown(void);
 bool multifd_recv_all_channels_created(void);
-void multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
+bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
 void multifd_recv_sync_main(void);
 int multifd_send_sync_main(MultiFDSyncReq req);
 bool multifd_queue_page(RAMBlock *block, ram_addr_t offset);
diff --git a/migration/rdma.c b/migration/rdma.c
index 596a1aba0b..7bee871e2b 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -384,7 +384,6 @@ struct QIOChannelRDMA {
     QIOChannel parent;
     RDMAContext *rdmain;
     RDMAContext *rdmaout;
-    QEMUFile *file;
     bool blocking; /* XXX we don't actually honour this yet */
 };
 
@@ -3836,32 +3835,20 @@ static void qio_channel_rdma_register_types(void)
 
 type_init(qio_channel_rdma_register_types);
 
-static QEMUFile *rdma_new_input(RDMAContext *rdma)
+static QIOChannel *rdma_new_ioc(RDMAContext *rdma)
 {
     QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(object_new(TYPE_QIO_CHANNEL_RDMA));
 
-    rioc->file = qemu_file_new_input(QIO_CHANNEL(rioc));
-    rioc->rdmain = rdma;
-    rioc->rdmaout = rdma->return_path;
-
-    return rioc->file;
-}
-
-static QEMUFile *rdma_new_output(RDMAContext *rdma)
-{
-    QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(object_new(TYPE_QIO_CHANNEL_RDMA));
-
-    rioc->file = qemu_file_new_output(QIO_CHANNEL(rioc));
     rioc->rdmaout = rdma;
     rioc->rdmain = rdma->return_path;
 
-    return rioc->file;
+    return QIO_CHANNEL(rioc);
 }
 
 static void rdma_accept_incoming_migration(void *opaque)
 {
     RDMAContext *rdma = opaque;
-    QEMUFile *f;
+    QIOChannel *ioc;
 
     trace_qemu_rdma_accept_incoming_migration();
     if (qemu_rdma_accept(rdma) < 0) {
@@ -3875,15 +3862,16 @@ static void rdma_accept_incoming_migration(void *opaque)
         return;
     }
 
-    f = rdma_new_input(rdma);
-    if (f == NULL) {
+    ioc = rdma_new_ioc(rdma);
+    if (!ioc) {
         error_report("RDMA ERROR: could not open RDMA for input");
         qemu_rdma_cleanup(rdma);
         return;
     }
 
     rdma->migration_started_on_destination = 1;
-    migration_fd_process_incoming(f);
+    migration_incoming_setup(ioc, 0, NULL);
+    migration_incoming_process();
 }
 
 void rdma_start_incoming_migration(InetSocketAddress *host_port,
@@ -3995,8 +3983,8 @@ void rdma_start_outgoing_migration(void *opaque,
 
     trace_rdma_start_outgoing_migration_after_rdma_connect();
 
-    s->to_dst_file = rdma_new_output(rdma);
     s->rdma_migration = true;
+    migration_outgoing_setup(rdma_new_ioc(rdma));
     migration_connect(s);
     return;
 return_path_err:
-- 
2.51.0

[RFC PATCH 15/25] migration/channel: Rename migration_channel_connect

[Fabiano Rosas]

Rename migration_channel_connect to indicate this is the source
side. Future patches will do similar changes to the incoming side and
this will avoid inconsistencies in naming.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c | 9 +--------
 migration/channel.h | 2 +-
 migration/exec.c    | 2 +-
 migration/fd.c      | 2 +-
 migration/file.c    | 2 +-
 migration/socket.c  | 2 +-
 migration/tls.c     | 2 +-
 7 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index af6c2cc76e..a8a5f26dfd 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -61,14 +61,7 @@ out:
     }
 }
 
-
-/**
- * @migration_channel_connect - Create new outgoing migration channel
- *
- * @s: Current migration state
- * @ioc: Channel to which we are connecting
- */
-void migration_channel_connect(MigrationState *s, QIOChannel *ioc)
+void migration_channel_connect_outgoing(MigrationState *s, QIOChannel *ioc)
 {
     trace_migration_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)));
 
diff --git a/migration/channel.h b/migration/channel.h
index ccfeaaef18..7d3457271d 100644
--- a/migration/channel.h
+++ b/migration/channel.h
@@ -20,7 +20,7 @@
 
 void migration_channel_process_incoming(QIOChannel *ioc);
 
-void migration_channel_connect(MigrationState *s, QIOChannel *ioc);
+void migration_channel_connect_outgoing(MigrationState *s, QIOChannel *ioc);
 
 int migration_channel_read_peek(QIOChannel *ioc,
                                 const char *buf,
diff --git a/migration/exec.c b/migration/exec.c
index d83a07435a..d1629944dc 100644
--- a/migration/exec.c
+++ b/migration/exec.c
@@ -55,7 +55,7 @@ void exec_start_outgoing_migration(MigrationState *s, strList *command,
     }
 
     qio_channel_set_name(ioc, "migration-exec-outgoing");
-    migration_channel_connect(s, ioc);
+    migration_channel_connect_outgoing(s, ioc);
     object_unref(OBJECT(ioc));
 }
 
diff --git a/migration/fd.c b/migration/fd.c
index 0144a70742..150b236fbf 100644
--- a/migration/fd.c
+++ b/migration/fd.c
@@ -70,7 +70,7 @@ void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **
     }
 
     qio_channel_set_name(ioc, "migration-fd-outgoing");
-    migration_channel_connect(s, ioc);
+    migration_channel_connect_outgoing(s, ioc);
     object_unref(OBJECT(ioc));
 }
 
diff --git a/migration/file.c b/migration/file.c
index 7bb9c1c79f..935402f36b 100644
--- a/migration/file.c
+++ b/migration/file.c
@@ -122,7 +122,7 @@ void file_start_outgoing_migration(MigrationState *s,
         return;
     }
     qio_channel_set_name(ioc, "migration-file-outgoing");
-    migration_channel_connect(s, ioc);
+    migration_channel_connect_outgoing(s, ioc);
 }
 
 static gboolean file_accept_incoming_migration(QIOChannel *ioc,
diff --git a/migration/socket.c b/migration/socket.c
index 298bac30cc..611915f84d 100644
--- a/migration/socket.c
+++ b/migration/socket.c
@@ -73,7 +73,7 @@ static void socket_outgoing_migration(QIOTask *task,
     }
 
     trace_migration_socket_outgoing_connected();
-    migration_channel_connect(data->s, sioc);
+    migration_channel_connect_outgoing(data->s, sioc);
     return;
 err:
     trace_migration_socket_outgoing_error(error_get_pretty(err));
diff --git a/migration/tls.c b/migration/tls.c
index a54e8e6e14..f68e6a533b 100644
--- a/migration/tls.c
+++ b/migration/tls.c
@@ -114,7 +114,7 @@ static void migration_tls_outgoing_handshake(QIOTask *task,
     }
 
     trace_migration_tls_outgoing_handshake_complete();
-    migration_channel_connect(s, ioc);
+    migration_channel_connect_outgoing(s, ioc);
 }
 
 QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
-- 
2.51.0

[RFC PATCH 16/25] migration: Rename instances of start

[Fabiano Rosas]

To make it easier to follow the code, rename the functions that start
the migration thread and migration coroutine to contain the word
"start".

This will give new contributors the chance of seeing the word start
and reaching the actual migration code, instead of twists and turns of
qio_channel_add_watch and qio_task_run_in_thread.

Remove all other instances of "start" and use wording more suitable to
what the current migration stage is. The transport code such as
fd_start_migration_outgoing becomes fd_connect_outgoing, the early
setup code such as qemu_start_incoming_migration becomes
qemu_setup_incoming_migration and so on.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c    |  4 ++--
 migration/exec.c       |  5 ++---
 migration/exec.h       |  5 ++---
 migration/fd.c         |  4 ++--
 migration/fd.h         |  6 +++---
 migration/file.c       |  6 +++---
 migration/file.h       |  6 +++---
 migration/migration.c  | 30 +++++++++++++++---------------
 migration/migration.h  |  5 +----
 migration/rdma.c       | 21 ++++++++++-----------
 migration/rdma.h       |  6 +++---
 migration/socket.c     |  8 +++-----
 migration/socket.h     |  6 +++---
 migration/trace-events | 10 +++++-----
 14 files changed, 57 insertions(+), 65 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index a8a5f26dfd..c5bd89576a 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -48,7 +48,7 @@ void migration_channel_process_incoming(QIOChannel *ioc)
         }
 
         if (migration_incoming_setup(ioc, ch, &local_err)) {
-            migration_incoming_process();
+            migration_start_incoming();
         }
     }
 out:
@@ -77,7 +77,7 @@ void migration_channel_connect_outgoing(MigrationState *s, QIOChannel *ioc)
 
     migration_ioc_register_yank(ioc);
     migration_outgoing_setup(ioc);
-    migration_connect(s);
+    migration_start_outgoing(s);
 }
 
 
diff --git a/migration/exec.c b/migration/exec.c
index d1629944dc..c3085e803e 100644
--- a/migration/exec.c
+++ b/migration/exec.c
@@ -40,8 +40,7 @@ const char *exec_get_cmd_path(void)
 }
 #endif
 
-void exec_start_outgoing_migration(MigrationState *s, strList *command,
-                                   Error **errp)
+void exec_connect_outgoing(MigrationState *s, strList *command, Error **errp)
 {
     QIOChannel *ioc = NULL;
     g_auto(GStrv) argv = strv_from_str_list(command);
@@ -68,7 +67,7 @@ static gboolean exec_accept_incoming_migration(QIOChannel *ioc,
     return G_SOURCE_REMOVE;
 }
 
-void exec_start_incoming_migration(strList *command, Error **errp)
+void exec_connect_incoming(strList *command, Error **errp)
 {
     QIOChannel *ioc;
     g_auto(GStrv) argv = strv_from_str_list(command);
diff --git a/migration/exec.h b/migration/exec.h
index 3107f205e3..e7e8e475ac 100644
--- a/migration/exec.h
+++ b/migration/exec.h
@@ -23,8 +23,7 @@
 #ifdef WIN32
 const char *exec_get_cmd_path(void);
 #endif
-void exec_start_incoming_migration(strList *host_port, Error **errp);
+void exec_connect_incoming(strList *host_port, Error **errp);
 
-void exec_start_outgoing_migration(MigrationState *s, strList *host_port,
-                                   Error **errp);
+void exec_connect_outgoing(MigrationState *s, strList *host_port, Error **errp);
 #endif
diff --git a/migration/fd.c b/migration/fd.c
index 150b236fbf..b689426ad4 100644
--- a/migration/fd.c
+++ b/migration/fd.c
@@ -49,7 +49,7 @@ static bool migration_fd_valid(int fd)
     return false;
 }
 
-void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **errp)
+void fd_connect_outgoing(MigrationState *s, const char *fdname, Error **errp)
 {
     QIOChannel *ioc;
     int fd = monitor_get_fd(monitor_cur(), fdname, errp);
@@ -83,7 +83,7 @@ static gboolean fd_accept_incoming_migration(QIOChannel *ioc,
     return G_SOURCE_REMOVE;
 }
 
-void fd_start_incoming_migration(const char *fdname, Error **errp)
+void fd_connect_incoming(const char *fdname, Error **errp)
 {
     QIOChannel *ioc;
     int fd = monitor_fd_param(monitor_cur(), fdname, errp);
diff --git a/migration/fd.h b/migration/fd.h
index b901bc014e..7211629270 100644
--- a/migration/fd.h
+++ b/migration/fd.h
@@ -16,8 +16,8 @@
 
 #ifndef QEMU_MIGRATION_FD_H
 #define QEMU_MIGRATION_FD_H
-void fd_start_incoming_migration(const char *fdname, Error **errp);
+void fd_connect_incoming(const char *fdname, Error **errp);
 
-void fd_start_outgoing_migration(MigrationState *s, const char *fdname,
-                                 Error **errp);
+void fd_connect_outgoing(MigrationState *s, const char *fdname,
+                         Error **errp);
 #endif
diff --git a/migration/file.c b/migration/file.c
index 935402f36b..b7b0fb5194 100644
--- a/migration/file.c
+++ b/migration/file.c
@@ -93,8 +93,8 @@ out:
     return ret;
 }
 
-void file_start_outgoing_migration(MigrationState *s,
-                                   FileMigrationArgs *file_args, Error **errp)
+void file_connect_outgoing(MigrationState *s,
+                           FileMigrationArgs *file_args, Error **errp)
 {
     g_autoptr(QIOChannelFile) fioc = NULL;
     g_autofree char *filename = g_strdup(file_args->filename);
@@ -173,7 +173,7 @@ static void file_create_incoming_channels(QIOChannel *ioc, char *filename,
     }
 }
 
-void file_start_incoming_migration(FileMigrationArgs *file_args, Error **errp)
+void file_connect_incoming(FileMigrationArgs *file_args, Error **errp)
 {
     g_autofree char *filename = g_strdup(file_args->filename);
     QIOChannelFile *fioc = NULL;
diff --git a/migration/file.h b/migration/file.h
index 1a1115f7f1..9b1e874bb7 100644
--- a/migration/file.h
+++ b/migration/file.h
@@ -13,10 +13,10 @@
 #include "channel.h"
 #include "multifd.h"
 
-void file_start_incoming_migration(FileMigrationArgs *file_args, Error **errp);
+void file_connect_incoming(FileMigrationArgs *file_args, Error **errp);
 
-void file_start_outgoing_migration(MigrationState *s,
-                                   FileMigrationArgs *file_args, Error **errp);
+void file_connect_outgoing(MigrationState *s,
+                           FileMigrationArgs *file_args, Error **errp);
 int file_parse_offset(char *filespec, uint64_t *offsetp, Error **errp);
 void file_cleanup_outgoing_migration(void);
 bool file_send_channel_create(gpointer opaque, Error **errp);
diff --git a/migration/migration.c b/migration/migration.c
index 677581b5a5..42adee5695 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -743,7 +743,7 @@ migration_incoming_state_setup(MigrationIncomingState *mis, Error **errp)
     return true;
 }
 
-static void qemu_start_incoming_migration(const char *uri, bool has_channels,
+static void qemu_setup_incoming_migration(const char *uri, bool has_channels,
                                           MigrationChannelList *channels,
                                           Error **errp)
 {
@@ -795,18 +795,18 @@ static void qemu_start_incoming_migration(const char *uri, bool has_channels,
         if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
             saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
             saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
-            socket_start_incoming_migration(saddr, errp);
+            socket_connect_incoming(saddr, errp);
         } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
-            fd_start_incoming_migration(saddr->u.fd.str, errp);
+            fd_connect_incoming(saddr->u.fd.str, errp);
         }
 #ifdef CONFIG_RDMA
     } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
-        rdma_start_incoming_migration(&addr->u.rdma, errp);
+        rdma_connect_incoming(&addr->u.rdma, errp);
 #endif
     } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
-        exec_start_incoming_migration(addr->u.exec.args, errp);
+        exec_connect_incoming(addr->u.exec.args, errp);
     } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
-        file_start_incoming_migration(&addr->u.file, errp);
+        file_connect_incoming(&addr->u.file, errp);
     } else {
         error_setg(errp, "unknown migration protocol: %s", uri);
     }
@@ -1011,7 +1011,7 @@ static bool postcopy_try_recover(void)
     return false;
 }
 
-void migration_incoming_process(void)
+void migration_start_incoming(void)
 {
     if (postcopy_try_recover()) {
         return;
@@ -1970,7 +1970,7 @@ void qmp_migrate_incoming(const char *uri, bool has_channels,
     mis->exit_on_error =
         has_exit_on_error ? exit_on_error : INMIGRATE_DEFAULT_EXIT_ON_ERROR;
 
-    qemu_start_incoming_migration(uri, has_channels, channels, &local_err);
+    qemu_setup_incoming_migration(uri, has_channels, channels, &local_err);
 
     if (local_err) {
         yank_unregister_instance(MIGRATION_YANK_INSTANCE);
@@ -2017,7 +2017,7 @@ void qmp_migrate_recover(const char *uri, Error **errp)
      * only re-setup the migration stream and poke existing migration
      * to continue using that newly established channel.
      */
-    qemu_start_incoming_migration(uri, false, NULL, errp);
+    qemu_setup_incoming_migration(uri, false, NULL, errp);
 }
 
 void qmp_migrate_pause(Error **errp)
@@ -2344,18 +2344,18 @@ static void qmp_migrate_finish(MigrationAddress *addr, Error **errp)
         if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
             saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
             saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
-            socket_start_outgoing_migration(s, saddr, &local_err);
+            socket_connect_outgoing(s, saddr, &local_err);
         } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
-            fd_start_outgoing_migration(s, saddr->u.fd.str, &local_err);
+            fd_connect_outgoing(s, saddr->u.fd.str, &local_err);
         }
 #ifdef CONFIG_RDMA
     } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
-        rdma_start_outgoing_migration(s, &addr->u.rdma, &local_err);
+        rdma_connect_outgoing(s, &addr->u.rdma, &local_err);
 #endif
     } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
-        exec_start_outgoing_migration(s, addr->u.exec.args, &local_err);
+        exec_connect_outgoing(s, addr->u.exec.args, &local_err);
     } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
-        file_start_outgoing_migration(s, &addr->u.file, &local_err);
+        file_connect_outgoing(s, &addr->u.file, &local_err);
     } else {
         error_setg(&local_err, "uri is not a valid migration protocol");
     }
@@ -4035,7 +4035,7 @@ fail_setup:
     return NULL;
 }
 
-void migration_connect(MigrationState *s)
+void migration_start_outgoing(MigrationState *s)
 {
     Error *local_err = NULL;
     uint64_t rate_limit;
diff --git a/migration/migration.h b/migration/migration.h
index d2b82cf54f..cbe90471c2 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -529,16 +529,13 @@ void migrate_set_state(MigrationStatus *state, MigrationStatus old_state,
 void migration_outgoing_setup(QIOChannel *ioc);
 bool migration_incoming_setup(QIOChannel *ioc, uint8_t channel, Error **errp);
 
-uint8_t migration_ioc_process_incoming(QIOChannel *ioc, Error **errp);
-void migration_incoming_process(void);
-
 bool  migration_has_all_channels(void);
 
 void migration_connect_error_propagate(MigrationState *s, Error *error);
 void migrate_error_propagate(MigrationState *s, Error *error);
 bool migrate_has_error(MigrationState *s);
 
-void migration_connect(MigrationState *s);
+void migration_start_outgoing(MigrationState *s, QEMUFile *file);
 
 int migration_call_notifiers(MigrationState *s, MigrationEventType type,
                              Error **errp);
diff --git a/migration/rdma.c b/migration/rdma.c
index 7bee871e2b..788120a0b1 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -3871,17 +3871,16 @@ static void rdma_accept_incoming_migration(void *opaque)
 
     rdma->migration_started_on_destination = 1;
     migration_incoming_setup(ioc, 0, NULL);
-    migration_incoming_process();
+    migration_start_incoming();
 }
 
-void rdma_start_incoming_migration(InetSocketAddress *host_port,
-                                   Error **errp)
+void rdma_connect_incoming(InetSocketAddress *host_port, Error **errp)
 {
     MigrationState *s = migrate_get_current();
     int ret;
     RDMAContext *rdma;
 
-    trace_rdma_start_incoming_migration();
+    trace_rdma_connect_incoming();
 
     /* Avoid ram_block_discard_disable(), cannot change during migration. */
     if (ram_block_discard_is_required()) {
@@ -3899,7 +3898,7 @@ void rdma_start_incoming_migration(InetSocketAddress *host_port,
         goto err;
     }
 
-    trace_rdma_start_incoming_migration_after_dest_init();
+    trace_rdma_connect_incoming_after_dest_init();
 
     ret = rdma_listen(rdma->listen_id, 5);
 
@@ -3908,7 +3907,7 @@ void rdma_start_incoming_migration(InetSocketAddress *host_port,
         goto cleanup_rdma;
     }
 
-    trace_rdma_start_incoming_migration_after_rdma_listen();
+    trace_rdma_connect_incoming_after_rdma_listen();
     s->rdma_migration = true;
     qemu_set_fd_handler(rdma->channel->fd, rdma_accept_incoming_migration,
                         NULL, (void *)(intptr_t)rdma);
@@ -3923,8 +3922,8 @@ err:
     g_free(rdma);
 }
 
-void rdma_start_outgoing_migration(void *opaque,
-                            InetSocketAddress *host_port, Error **errp)
+void rdma_connect_outgoing(void *opaque,
+                           InetSocketAddress *host_port, Error **errp)
 {
     MigrationState *s = opaque;
     RDMAContext *rdma_return_path = NULL;
@@ -3948,7 +3947,7 @@ void rdma_start_outgoing_migration(void *opaque,
         goto err;
     }
 
-    trace_rdma_start_outgoing_migration_after_rdma_source_init();
+    trace_rdma_connect_outgoing_after_rdma_source_init();
     ret = qemu_rdma_connect(rdma, false, errp);
 
     if (ret < 0) {
@@ -3981,11 +3980,11 @@ void rdma_start_outgoing_migration(void *opaque,
         rdma_return_path->is_return_path = true;
     }
 
-    trace_rdma_start_outgoing_migration_after_rdma_connect();
+    trace_rdma_connect_outgoing_after_rdma_connect();
 
     s->rdma_migration = true;
     migration_outgoing_setup(rdma_new_ioc(rdma));
-    migration_connect(s);
+    migration_start_outgoing(s);
     return;
 return_path_err:
     qemu_rdma_cleanup(rdma);
diff --git a/migration/rdma.h b/migration/rdma.h
index f74f16a459..170c25cf44 100644
--- a/migration/rdma.h
+++ b/migration/rdma.h
@@ -21,10 +21,10 @@
 
 #include "system/memory.h"
 
-void rdma_start_outgoing_migration(void *opaque, InetSocketAddress *host_port,
-                                   Error **errp);
+void rdma_connect_outgoing(void *opaque, InetSocketAddress *host_port,
+                           Error **errp);
 
-void rdma_start_incoming_migration(InetSocketAddress *host_port, Error **errp);
+void rdma_connect_incoming(InetSocketAddress *host_port, Error **errp);
 
 /*
  * Constants used by rdma return codes
diff --git a/migration/socket.c b/migration/socket.c
index 611915f84d..ac3183d5d5 100644
--- a/migration/socket.c
+++ b/migration/socket.c
@@ -80,9 +80,8 @@ err:
     migration_connect_error_propagate(data->s, err);
 }
 
-void socket_start_outgoing_migration(MigrationState *s,
-                                     SocketAddress *saddr,
-                                     Error **errp)
+void socket_connect_outgoing(MigrationState *s, SocketAddress *saddr,
+                             Error **errp)
 {
     QIOChannelSocket *sioc = qio_channel_socket_new();
     struct SocketConnectData *data = g_new0(struct SocketConnectData, 1);
@@ -140,8 +139,7 @@ socket_incoming_migration_end(void *opaque)
     object_unref(OBJECT(listener));
 }
 
-void socket_start_incoming_migration(SocketAddress *saddr,
-                                     Error **errp)
+void socket_connect_incoming(SocketAddress *saddr, Error **errp)
 {
     QIONetListener *listener = qio_net_listener_new();
     MigrationIncomingState *mis = migration_incoming_get_current();
diff --git a/migration/socket.h b/migration/socket.h
index 04ebbe95a1..f0c89b64c7 100644
--- a/migration/socket.h
+++ b/migration/socket.h
@@ -23,10 +23,10 @@
 
 void socket_send_channel_create(QIOTaskFunc f, void *data);
 
-void socket_start_incoming_migration(SocketAddress *saddr, Error **errp);
+void socket_connect_incoming(SocketAddress *saddr, Error **errp);
 
-void socket_start_outgoing_migration(MigrationState *s,
-                                     SocketAddress *saddr, Error **errp);
+void socket_connect_outgoing(MigrationState *s,
+                             SocketAddress *saddr, Error **errp);
 void socket_cleanup_outgoing_migration(void);
 
 #endif
diff --git a/migration/trace-events b/migration/trace-events
index cbf10d0b63..91d7506634 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -271,11 +271,11 @@ rdma_registration_handle_wait(void) ""
 rdma_registration_start(uint64_t flags) "%" PRIu64
 rdma_registration_stop(uint64_t flags) "%" PRIu64
 rdma_registration_stop_ram(void) ""
-rdma_start_incoming_migration(void) ""
-rdma_start_incoming_migration_after_dest_init(void) ""
-rdma_start_incoming_migration_after_rdma_listen(void) ""
-rdma_start_outgoing_migration_after_rdma_connect(void) ""
-rdma_start_outgoing_migration_after_rdma_source_init(void) ""
+rdma_connect_incoming(void) ""
+rdma_connect_incoming_after_dest_init(void) ""
+rdma_connect_incoming_after_rdma_listen(void) ""
+rdma_connect_outgoing_after_rdma_connect(void) ""
+rdma_connect_outgoing_after_rdma_source_init(void) ""
 
 # postcopy-ram.c
 postcopy_discard_send_finish(const char *ramblock, int nwords, int ncmds) "%s mask words sent=%d in %d commands"
-- 
2.51.0

[RFC PATCH 17/25] migration: Move channel code to channel.c

[Fabiano Rosas]

Move the code responsible for the various channels connection into
channel.c. This is all executed before the migration_thread and
process_incoming_migration_co are running, so it helps the reasoning
to have them out of migration.c.

migration_ioc_process_incoming becomes migration_channel_identify
which is more in line with what the function does.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c   | 99 ++++++++++++++++++++++++++++++++++++++++++-
 migration/channel.h   | 12 ++++++
 migration/migration.c | 98 ------------------------------------------
 migration/migration.h |  5 +--
 migration/rdma.c      |  1 +
 5 files changed, 113 insertions(+), 102 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index c5bd89576a..a9ac3711b5 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -14,13 +14,110 @@
 #include "channel.h"
 #include "tls.h"
 #include "migration.h"
+#include "multifd.h"
+#include "savevm.h"
 #include "trace.h"
+#include "options.h"
 #include "qapi/error.h"
 #include "io/channel-tls.h"
 #include "io/channel-socket.h"
 #include "qemu/yank.h"
 #include "yank_functions.h"
 
+bool migration_has_main_and_multifd_channels(void)
+{
+    MigrationIncomingState *mis = migration_incoming_get_current();
+    if (!mis->from_src_file) {
+        /* main channel not established */
+        return false;
+    }
+
+    if (migrate_multifd() && !multifd_recv_all_channels_created()) {
+        return false;
+    }
+
+    /* main and all multifd channels are established */
+    return true;
+}
+
+/**
+ * @migration_has_all_channels: We have received all channels that we need
+ *
+ * Returns true when we have got connections to all the channels that
+ * we need for migration.
+ */
+bool migration_has_all_channels(void)
+{
+    if (!migration_has_main_and_multifd_channels()) {
+        return false;
+    }
+
+    MigrationIncomingState *mis = migration_incoming_get_current();
+    if (migrate_postcopy_preempt() && !mis->postcopy_qemufile_dst) {
+        return false;
+    }
+
+    return true;
+}
+
+static int migration_channel_identify(MigrationIncomingState *mis,
+                                      QIOChannel *ioc, Error **errp)
+{
+    int channel = CH_NONE;
+    uint32_t channel_magic = 0;
+    int ret = 0;
+
+    if (!migration_has_main_and_multifd_channels()) {
+        if (qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_READ_MSG_PEEK)) {
+            /*
+             * With multiple channels, it is possible that we receive channels
+             * out of order on destination side, causing incorrect mapping of
+             * source channels on destination side. Check channel MAGIC to
+             * decide type of channel. Please note this is best effort,
+             * postcopy preempt channel does not send any magic number so
+             * avoid it for postcopy live migration. Also tls live migration
+             * already does tls handshake while initializing main channel so
+             * with tls this issue is not possible.
+             */
+            ret = migration_channel_read_peek(ioc, (void *)&channel_magic,
+                                              sizeof(channel_magic), errp);
+            if (ret != 0) {
+                goto out;
+            }
+
+            channel_magic = be32_to_cpu(channel_magic);
+            if (channel_magic == QEMU_VM_FILE_MAGIC) {
+                channel = CH_MAIN;
+            } else if (channel_magic == MULTIFD_MAGIC) {
+                assert(migrate_multifd());
+                channel = CH_MULTIFD;
+            } else if (!mis->from_src_file &&
+                        mis->state == MIGRATION_STATUS_POSTCOPY_PAUSED) {
+                /* reconnect main channel for postcopy recovery */
+                channel = CH_MAIN;
+            } else {
+                error_setg(errp, "unknown channel magic: %u", channel_magic);
+            }
+        } else if (mis->from_src_file && migrate_multifd()) {
+            /*
+             * Non-peekable channels like tls/file are processed as
+             * multifd channels when multifd is enabled.
+             */
+            channel = CH_MULTIFD;
+        } else if (!mis->from_src_file) {
+            channel = CH_MAIN;
+        } else {
+            error_setg(errp, "non-peekable channel used without multifd");
+        }
+    } else {
+        assert(migrate_postcopy_preempt());
+        channel = CH_POSTCOPY;
+    }
+
+out:
+    return channel;
+}
+
 /**
  * @migration_channel_process_incoming - Create new incoming migration channel
  *
@@ -42,7 +139,7 @@ void migration_channel_process_incoming(QIOChannel *ioc)
         migration_tls_channel_process_incoming(ioc, &local_err);
     } else {
         migration_ioc_register_yank(ioc);
-        ch = migration_ioc_process_incoming(ioc, &local_err);
+        ch = migration_channel_identify(mis, ioc, &local_err);
         if (!ch) {
             goto out;
         }
diff --git a/migration/channel.h b/migration/channel.h
index 7d3457271d..59d169e095 100644
--- a/migration/channel.h
+++ b/migration/channel.h
@@ -18,6 +18,14 @@
 
 #include "io/channel.h"
 
+/* Migration channel types */
+enum {
+    CH_NONE,
+    CH_MAIN,
+    CH_MULTIFD,
+    CH_POSTCOPY
+};
+
 void migration_channel_process_incoming(QIOChannel *ioc);
 
 void migration_channel_connect_outgoing(MigrationState *s, QIOChannel *ioc);
@@ -26,4 +34,8 @@ int migration_channel_read_peek(QIOChannel *ioc,
                                 const char *buf,
                                 const size_t buflen,
                                 Error **errp);
+
+bool migration_has_main_and_multifd_channels(void);
+bool migration_has_all_channels(void);
+
 #endif
diff --git a/migration/migration.c b/migration/migration.c
index 42adee5695..e0aee17317 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -91,9 +91,6 @@ enum mig_rp_message_type {
     MIG_RP_MSG_MAX
 };
 
-/* Migration channel types */
-enum { CH_NONE, CH_MAIN, CH_MULTIFD, CH_POSTCOPY };
-
 /* When we add fault tolerance, we could have several
    migrations at once.  For now we don't need to add
    dynamic creation of migration */
@@ -934,8 +931,6 @@ out:
     migrate_incoming_unref_outgoing_state();
 }
 
-static bool migration_has_main_and_multifd_channels(void);
-
 bool migration_incoming_setup(QIOChannel *ioc, uint8_t channel, Error **errp)
 {
     MigrationIncomingState *mis = migration_incoming_get_current();
@@ -1021,99 +1016,6 @@ void migration_start_incoming(void)
     qemu_coroutine_enter(co);
 }
 
-static bool migration_has_main_and_multifd_channels(void)
-{
-    MigrationIncomingState *mis = migration_incoming_get_current();
-    if (!mis->from_src_file) {
-        /* main channel not established */
-        return false;
-    }
-
-    if (migrate_multifd() && !multifd_recv_all_channels_created()) {
-        return false;
-    }
-
-    /* main and all multifd channels are established */
-    return true;
-}
-
-uint8_t migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
-{
-    MigrationIncomingState *mis = migration_incoming_get_current();
-    uint8_t channel = CH_NONE;
-    uint32_t channel_magic = 0;
-    int ret = 0;
-
-    if (!migration_has_main_and_multifd_channels()) {
-        if (qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_READ_MSG_PEEK)) {
-            /*
-             * With multiple channels, it is possible that we receive channels
-             * out of order on destination side, causing incorrect mapping of
-             * source channels on destination side. Check channel MAGIC to
-             * decide type of channel. Please note this is best effort,
-             * postcopy preempt channel does not send any magic number so
-             * avoid it for postcopy live migration. Also tls live migration
-             * already does tls handshake while initializing main channel so
-             * with tls this issue is not possible.
-             */
-            ret = migration_channel_read_peek(ioc, (void *)&channel_magic,
-                                              sizeof(channel_magic), errp);
-            if (ret != 0) {
-                goto out;
-            }
-
-            channel_magic = be32_to_cpu(channel_magic);
-            if (channel_magic == QEMU_VM_FILE_MAGIC) {
-                channel = CH_MAIN;
-            } else if (channel_magic == MULTIFD_MAGIC) {
-                assert(migrate_multifd());
-                channel = CH_MULTIFD;
-            } else if (!mis->from_src_file &&
-                        mis->state == MIGRATION_STATUS_POSTCOPY_PAUSED) {
-                /* reconnect main channel for postcopy recovery */
-                channel = CH_MAIN;
-            } else {
-                error_setg(errp, "unknown channel magic: %u", channel_magic);
-            }
-        } else if (mis->from_src_file && migrate_multifd()) {
-            /*
-             * Non-peekable channels like tls/file are processed as
-             * multifd channels when multifd is enabled.
-             */
-            channel = CH_MULTIFD;
-        } else if (!mis->from_src_file) {
-            channel = CH_MAIN;
-        } else {
-            error_setg(errp, "non-peekable channel used without multifd");
-        }
-    } else {
-        assert(migrate_postcopy_preempt());
-        channel = CH_POSTCOPY;
-    }
-out:
-    return channel;
-}
-
-/**
- * @migration_has_all_channels: We have received all channels that we need
- *
- * Returns true when we have got connections to all the channels that
- * we need for migration.
- */
-bool migration_has_all_channels(void)
-{
-    if (!migration_has_main_and_multifd_channels()) {
-        return false;
-    }
-
-    MigrationIncomingState *mis = migration_incoming_get_current();
-    if (migrate_postcopy_preempt() && !mis->postcopy_qemufile_dst) {
-        return false;
-    }
-
-    return true;
-}
-
 int migrate_send_rp_switchover_ack(MigrationIncomingState *mis)
 {
     return migrate_send_rp_message(mis, MIG_RP_MSG_SWITCHOVER_ACK, 0, NULL);
diff --git a/migration/migration.h b/migration/migration.h
index cbe90471c2..138831d7d9 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -529,13 +529,12 @@ void migrate_set_state(MigrationStatus *state, MigrationStatus old_state,
 void migration_outgoing_setup(QIOChannel *ioc);
 bool migration_incoming_setup(QIOChannel *ioc, uint8_t channel, Error **errp);
 
-bool  migration_has_all_channels(void);
-
 void migration_connect_error_propagate(MigrationState *s, Error *error);
 void migrate_error_propagate(MigrationState *s, Error *error);
 bool migrate_has_error(MigrationState *s);
 
-void migration_start_outgoing(MigrationState *s, QEMUFile *file);
+void migration_start_outgoing(MigrationState *s);
+void migration_start_incoming(void);
 
 int migration_call_notifiers(MigrationState *s, MigrationEventType type,
                              Error **errp);
diff --git a/migration/rdma.c b/migration/rdma.c
index 788120a0b1..6e9ca5f5f6 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -17,6 +17,7 @@
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "qemu/cutils.h"
+#include "channel.h"
 #include "exec/target_page.h"
 #include "rdma.h"
 #include "migration.h"
-- 
2.51.0

[RFC PATCH 18/25] migration: Move transport connection code into channel.c

[Fabiano Rosas]

Move the <transport>_connect_incoming|outgoing functions to channel.c.
It leaves migration.c to deal with the established connection only.

(I sorted the includes)

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c   | 66 +++++++++++++++++++++++++++++++++++++++----
 migration/channel.h   |  4 +++
 migration/migration.c | 45 ++---------------------------
 3 files changed, 67 insertions(+), 48 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index a9ac3711b5..a06aa8189c 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -12,18 +12,74 @@
 
 #include "qemu/osdep.h"
 #include "channel.h"
-#include "tls.h"
+#include "exec.h"
+#include "fd.h"
+#include "file.h"
+#include "io/channel-socket.h"
+#include "io/channel-tls.h"
 #include "migration.h"
 #include "multifd.h"
-#include "savevm.h"
-#include "trace.h"
 #include "options.h"
+#include "qapi/qapi-types-migration.h"
 #include "qapi/error.h"
-#include "io/channel-tls.h"
-#include "io/channel-socket.h"
+#include "qemu-file.h"
 #include "qemu/yank.h"
+#include "rdma.h"
+#include "savevm.h"
+#include "socket.h"
+#include "tls.h"
+#include "trace.h"
 #include "yank_functions.h"
 
+void migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
+                                Error **errp)
+{
+    if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
+        SocketAddress *saddr = &addr->u.socket;
+        if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
+            saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
+            saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
+            socket_connect_outgoing(s, saddr, errp);
+        } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
+            fd_connect_outgoing(s, saddr->u.fd.str, errp);
+        }
+#ifdef CONFIG_RDMA
+    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
+        rdma_connect_outgoing(s, &addr->u.rdma, errp);
+#endif
+    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
+        exec_connect_outgoing(s, addr->u.exec.args, errp);
+    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
+        file_connect_outgoing(s, &addr->u.file, errp);
+    } else {
+        error_setg(errp, "uri is not a valid migration protocol");
+    }
+}
+
+void migration_connect_incoming(MigrationAddress *addr, Error **errp)
+{
+    if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
+        SocketAddress *saddr = &addr->u.socket;
+        if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
+            saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
+            saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
+            socket_connect_incoming(saddr, errp);
+        } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
+            fd_connect_incoming(saddr->u.fd.str, errp);
+        }
+#ifdef CONFIG_RDMA
+    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
+        rdma_connect_incoming(&addr->u.rdma, errp);
+#endif
+    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
+        exec_connect_incoming(addr->u.exec.args, errp);
+    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
+        file_connect_incoming(&addr->u.file, errp);
+    } else {
+        error_setg(errp, "unknown migration protocol");
+    }
+}
+
 bool migration_has_main_and_multifd_channels(void)
 {
     MigrationIncomingState *mis = migration_incoming_get_current();
diff --git a/migration/channel.h b/migration/channel.h
index 59d169e095..727eabf16c 100644
--- a/migration/channel.h
+++ b/migration/channel.h
@@ -17,6 +17,7 @@
 #define QEMU_MIGRATION_CHANNEL_H
 
 #include "io/channel.h"
+#include "qapi/qapi-types-migration.h"
 
 /* Migration channel types */
 enum {
@@ -38,4 +39,7 @@ int migration_channel_read_peek(QIOChannel *ioc,
 bool migration_has_main_and_multifd_channels(void);
 bool migration_has_all_channels(void);
 
+void migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
+                                Error **errp);
+void migration_connect_incoming(MigrationAddress *addr, Error **errp);
 #endif
diff --git a/migration/migration.c b/migration/migration.c
index e0aee17317..9e69141e86 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -20,13 +20,10 @@
 #include "qemu/main-loop.h"
 #include "migration/blocker.h"
 #include "exec.h"
-#include "fd.h"
 #include "file.h"
-#include "socket.h"
 #include "system/runstate.h"
 #include "system/system.h"
 #include "system/cpu-throttle.h"
-#include "rdma.h"
 #include "ram.h"
 #include "migration/cpr.h"
 #include "migration/global_state.h"
@@ -787,26 +784,7 @@ static void qemu_setup_incoming_migration(const char *uri, bool has_channels,
         return;
     }
 
-    if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
-        SocketAddress *saddr = &addr->u.socket;
-        if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
-            saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
-            saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
-            socket_connect_incoming(saddr, errp);
-        } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
-            fd_connect_incoming(saddr->u.fd.str, errp);
-        }
-#ifdef CONFIG_RDMA
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
-        rdma_connect_incoming(&addr->u.rdma, errp);
-#endif
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
-        exec_connect_incoming(addr->u.exec.args, errp);
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
-        file_connect_incoming(&addr->u.file, errp);
-    } else {
-        error_setg(errp, "unknown migration protocol: %s", uri);
-    }
+    migration_connect_incoming(addr, errp);
 
     /* Close cpr socket to tell source that we are listening */
     cpr_state_close();
@@ -2241,26 +2219,7 @@ static void qmp_migrate_finish(MigrationAddress *addr, Error **errp)
     MigrationState *s = migrate_get_current();
     Error *local_err = NULL;
 
-    if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
-        SocketAddress *saddr = &addr->u.socket;
-        if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
-            saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
-            saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
-            socket_connect_outgoing(s, saddr, &local_err);
-        } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
-            fd_connect_outgoing(s, saddr->u.fd.str, &local_err);
-        }
-#ifdef CONFIG_RDMA
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
-        rdma_connect_outgoing(s, &addr->u.rdma, &local_err);
-#endif
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
-        exec_connect_outgoing(s, addr->u.exec.args, &local_err);
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
-        file_connect_outgoing(s, &addr->u.file, &local_err);
-    } else {
-        error_setg(&local_err, "uri is not a valid migration protocol");
-    }
+    migration_connect_outgoing(s, addr, &local_err);
 }
 
 void qmp_migrate_cancel(Error **errp)
-- 
2.51.0

[RFC PATCH 19/25] migration/channel: Make synchronous calls evident

[Fabiano Rosas]

Make the synchronous calls evident by not hiding the call to
migration_channel_connect_outgoing in the transport code. Have those
functions return and call the migration_connect_outgoing() at the
upper level.

This helps with navigation: the transport code returns the ioc,
there's no need to look into them when browsing the code.

It also allows RDMA in the source side to use the same path as the
rest of the transports.

While here, document the async calls which are the exception.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c   | 30 +++++++++++++++++++++++++-----
 migration/channel.h   |  2 +-
 migration/exec.c      |  8 ++++----
 migration/exec.h      |  5 ++++-
 migration/fd.c        | 13 +++++++------
 migration/fd.h        |  7 +++++--
 migration/file.c      | 18 ++++++++++--------
 migration/file.h      |  5 +++--
 migration/migration.c |  3 +--
 migration/rdma.c      | 11 +++++------
 migration/rdma.h      |  4 ++--
 11 files changed, 67 insertions(+), 39 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index a06aa8189c..205f8a26d1 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -31,29 +31,43 @@
 #include "trace.h"
 #include "yank_functions.h"
 
-void migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
+bool migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
                                 Error **errp)
 {
+    g_autoptr(QIOChannel) ioc = NULL;
+
     if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
         SocketAddress *saddr = &addr->u.socket;
         if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
             saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
             saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
             socket_connect_outgoing(s, saddr, errp);
+            /*
+             * async: after the socket is connected, calls
+             * migration_channel_connect_outgoing() directly.
+             */
+            return true;
         } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
-            fd_connect_outgoing(s, saddr->u.fd.str, errp);
+            ioc = fd_connect_outgoing(s, saddr->u.fd.str, errp);
         }
 #ifdef CONFIG_RDMA
     } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
-        rdma_connect_outgoing(s, &addr->u.rdma, errp);
+        ioc = rdma_connect_outgoing(s, &addr->u.rdma, errp);
 #endif
     } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
-        exec_connect_outgoing(s, addr->u.exec.args, errp);
+        ioc = exec_connect_outgoing(s, addr->u.exec.args, errp);
     } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
-        file_connect_outgoing(s, &addr->u.file, errp);
+        ioc = file_connect_outgoing(s, &addr->u.file, errp);
     } else {
         error_setg(errp, "uri is not a valid migration protocol");
     }
+
+    if (!ioc) {
+        return false;
+    }
+
+    migration_channel_connect_outgoing(s, ioc);
+    return true;
 }
 
 void migration_connect_incoming(MigrationAddress *addr, Error **errp)
@@ -78,6 +92,12 @@ void migration_connect_incoming(MigrationAddress *addr, Error **errp)
     } else {
         error_setg(errp, "unknown migration protocol");
     }
+
+    /*
+     * async: the above routines all wait for the incoming connection
+     * and call back to migration_channel_process_incoming() to start
+     * the migration.
+     */
 }
 
 bool migration_has_main_and_multifd_channels(void)
diff --git a/migration/channel.h b/migration/channel.h
index 727eabf16c..4851179ae6 100644
--- a/migration/channel.h
+++ b/migration/channel.h
@@ -39,7 +39,7 @@ int migration_channel_read_peek(QIOChannel *ioc,
 bool migration_has_main_and_multifd_channels(void);
 bool migration_has_all_channels(void);
 
-void migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
+bool migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
                                 Error **errp);
 void migration_connect_incoming(MigrationAddress *addr, Error **errp);
 #endif
diff --git a/migration/exec.c b/migration/exec.c
index c3085e803e..a1a7ede3b4 100644
--- a/migration/exec.c
+++ b/migration/exec.c
@@ -40,7 +40,8 @@ const char *exec_get_cmd_path(void)
 }
 #endif
 
-void exec_connect_outgoing(MigrationState *s, strList *command, Error **errp)
+QIOChannel *exec_connect_outgoing(MigrationState *s, strList *command,
+                                  Error **errp)
 {
     QIOChannel *ioc = NULL;
     g_auto(GStrv) argv = strv_from_str_list(command);
@@ -50,12 +51,11 @@ void exec_connect_outgoing(MigrationState *s, strList *command, Error **errp)
     trace_migration_exec_outgoing(new_command);
     ioc = QIO_CHANNEL(qio_channel_command_new_spawn(args, O_RDWR, errp));
     if (!ioc) {
-        return;
+        return NULL;
     }
 
     qio_channel_set_name(ioc, "migration-exec-outgoing");
-    migration_channel_connect_outgoing(s, ioc);
-    object_unref(OBJECT(ioc));
+    return ioc;
 }
 
 static gboolean exec_accept_incoming_migration(QIOChannel *ioc,
diff --git a/migration/exec.h b/migration/exec.h
index e7e8e475ac..3e39270dce 100644
--- a/migration/exec.h
+++ b/migration/exec.h
@@ -20,10 +20,13 @@
 #ifndef QEMU_MIGRATION_EXEC_H
 #define QEMU_MIGRATION_EXEC_H
 
+#include "io/channel.h"
+
 #ifdef WIN32
 const char *exec_get_cmd_path(void);
 #endif
 void exec_connect_incoming(strList *host_port, Error **errp);
 
-void exec_connect_outgoing(MigrationState *s, strList *host_port, Error **errp);
+QIOChannel *exec_connect_outgoing(MigrationState *s, strList *host_port,
+                                  Error **errp);
 #endif
diff --git a/migration/fd.c b/migration/fd.c
index b689426ad4..bbf380d1a0 100644
--- a/migration/fd.c
+++ b/migration/fd.c
@@ -49,12 +49,13 @@ static bool migration_fd_valid(int fd)
     return false;
 }
 
-void fd_connect_outgoing(MigrationState *s, const char *fdname, Error **errp)
+QIOChannel *fd_connect_outgoing(MigrationState *s, const char *fdname,
+                                Error **errp)
 {
-    QIOChannel *ioc;
+    QIOChannel *ioc = NULL;
     int fd = monitor_get_fd(monitor_cur(), fdname, errp);
     if (fd == -1) {
-        return;
+        goto out;
     }
 
     if (!migration_fd_valid(fd)) {
@@ -66,12 +67,12 @@ void fd_connect_outgoing(MigrationState *s, const char *fdname, Error **errp)
     ioc = qio_channel_new_fd(fd, errp);
     if (!ioc) {
         close(fd);
-        return;
+        goto out;
     }
 
     qio_channel_set_name(ioc, "migration-fd-outgoing");
-    migration_channel_connect_outgoing(s, ioc);
-    object_unref(OBJECT(ioc));
+out:
+    return ioc;
 }
 
 static gboolean fd_accept_incoming_migration(QIOChannel *ioc,
diff --git a/migration/fd.h b/migration/fd.h
index 7211629270..ce0b751273 100644
--- a/migration/fd.h
+++ b/migration/fd.h
@@ -16,8 +16,11 @@
 
 #ifndef QEMU_MIGRATION_FD_H
 #define QEMU_MIGRATION_FD_H
+
+#include "io/channel.h"
+
 void fd_connect_incoming(const char *fdname, Error **errp);
 
-void fd_connect_outgoing(MigrationState *s, const char *fdname,
-                         Error **errp);
+QIOChannel *fd_connect_outgoing(MigrationState *s, const char *fdname,
+                                Error **errp);
 #endif
diff --git a/migration/file.c b/migration/file.c
index b7b0fb5194..5618aced49 100644
--- a/migration/file.c
+++ b/migration/file.c
@@ -93,36 +93,38 @@ out:
     return ret;
 }
 
-void file_connect_outgoing(MigrationState *s,
-                           FileMigrationArgs *file_args, Error **errp)
+QIOChannel *file_connect_outgoing(MigrationState *s,
+                                  FileMigrationArgs *file_args, Error **errp)
 {
-    g_autoptr(QIOChannelFile) fioc = NULL;
+    QIOChannelFile *fioc = NULL;
     g_autofree char *filename = g_strdup(file_args->filename);
     uint64_t offset = file_args->offset;
-    QIOChannel *ioc;
+    QIOChannel *ioc = NULL;
 
     trace_migration_file_outgoing(filename);
 
     fioc = qio_channel_file_new_path(filename, O_CREAT | O_WRONLY, 0600, errp);
     if (!fioc) {
-        return;
+        goto out;
     }
 
     if (ftruncate(fioc->fd, offset)) {
         error_setg_errno(errp, errno,
                          "failed to truncate migration file to offset %" PRIx64,
                          offset);
-        return;
+        goto out;
     }
 
     outgoing_args.fname = g_strdup(filename);
 
     ioc = QIO_CHANNEL(fioc);
     if (offset && qio_channel_io_seek(ioc, offset, SEEK_SET, errp) < 0) {
-        return;
+        ioc = NULL;
+        goto out;
     }
     qio_channel_set_name(ioc, "migration-file-outgoing");
-    migration_channel_connect_outgoing(s, ioc);
+out:
+    return ioc;
 }
 
 static gboolean file_accept_incoming_migration(QIOChannel *ioc,
diff --git a/migration/file.h b/migration/file.h
index 9b1e874bb7..5936c64fea 100644
--- a/migration/file.h
+++ b/migration/file.h
@@ -9,14 +9,15 @@
 #define QEMU_MIGRATION_FILE_H
 
 #include "qapi/qapi-types-migration.h"
+#include "io/channel.h"
 #include "io/task.h"
 #include "channel.h"
 #include "multifd.h"
 
 void file_connect_incoming(FileMigrationArgs *file_args, Error **errp);
 
-void file_connect_outgoing(MigrationState *s,
-                           FileMigrationArgs *file_args, Error **errp);
+QIOChannel *file_connect_outgoing(MigrationState *s,
+                                  FileMigrationArgs *file_args, Error **errp);
 int file_parse_offset(char *filespec, uint64_t *offsetp, Error **errp);
 void file_cleanup_outgoing_migration(void);
 bool file_send_channel_create(gpointer opaque, Error **errp);
diff --git a/migration/migration.c b/migration/migration.c
index 9e69141e86..c75c2c7e52 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2217,9 +2217,8 @@ out:
 static void qmp_migrate_finish(MigrationAddress *addr, Error **errp)
 {
     MigrationState *s = migrate_get_current();
-    Error *local_err = NULL;
 
-    migration_connect_outgoing(s, addr, &local_err);
+    migration_connect_outgoing(s, addr, errp);
 }
 
 void qmp_migrate_cancel(Error **errp)
diff --git a/migration/rdma.c b/migration/rdma.c
index 6e9ca5f5f6..3db3a89bdb 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -3923,8 +3923,8 @@ err:
     g_free(rdma);
 }
 
-void rdma_connect_outgoing(void *opaque,
-                           InetSocketAddress *host_port, Error **errp)
+QIOChannel *rdma_connect_outgoing(void *opaque,
+                                  InetSocketAddress *host_port, Error **errp)
 {
     MigrationState *s = opaque;
     RDMAContext *rdma_return_path = NULL;
@@ -3934,7 +3934,7 @@ void rdma_connect_outgoing(void *opaque,
     /* Avoid ram_block_discard_disable(), cannot change during migration. */
     if (ram_block_discard_is_required()) {
         error_setg(errp, "RDMA: cannot disable RAM discard");
-        return;
+        return NULL;
     }
 
     rdma = qemu_rdma_data_init(host_port, errp);
@@ -3984,12 +3984,11 @@ void rdma_connect_outgoing(void *opaque,
     trace_rdma_connect_outgoing_after_rdma_connect();
 
     s->rdma_migration = true;
-    migration_outgoing_setup(rdma_new_ioc(rdma));
-    migration_start_outgoing(s);
-    return;
+    return rdma_new_ioc(rdma);
 return_path_err:
     qemu_rdma_cleanup(rdma);
 err:
     g_free(rdma);
     g_free(rdma_return_path);
+    return NULL;
 }
diff --git a/migration/rdma.h b/migration/rdma.h
index 170c25cf44..8a6515f130 100644
--- a/migration/rdma.h
+++ b/migration/rdma.h
@@ -21,8 +21,8 @@
 
 #include "system/memory.h"
 
-void rdma_connect_outgoing(void *opaque, InetSocketAddress *host_port,
-                           Error **errp);
+QIOChannel *rdma_connect_outgoing(void *opaque, InetSocketAddress *host_port,
+                                  Error **errp);
 
 void rdma_connect_incoming(InetSocketAddress *host_port, Error **errp);
 
-- 
2.51.0

[RFC PATCH 20/25] migration/channel: Use switch statements in outgoing code

[Fabiano Rosas]

Make this code easier on the eyes and remove all the visual
clutter. There will be more lines added here in next patches.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index 205f8a26d1..2f33cb2653 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -35,31 +35,49 @@ bool migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
                                 Error **errp)
 {
     g_autoptr(QIOChannel) ioc = NULL;
+    SocketAddress *saddr;
 
-    if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
-        SocketAddress *saddr = &addr->u.socket;
-        if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
-            saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
-            saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
+    switch (addr->transport) {
+    case MIGRATION_ADDRESS_TYPE_SOCKET:
+        saddr = &addr->u.socket;
+
+        switch (saddr->type) {
+        case SOCKET_ADDRESS_TYPE_INET:
+        case SOCKET_ADDRESS_TYPE_UNIX:
+        case SOCKET_ADDRESS_TYPE_VSOCK:
             socket_connect_outgoing(s, saddr, errp);
             /*
              * async: after the socket is connected, calls
              * migration_channel_connect_outgoing() directly.
              */
             return true;
-        } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
+            break;
+        case SOCKET_ADDRESS_TYPE_FD:
             ioc = fd_connect_outgoing(s, saddr->u.fd.str, errp);
+            break;
+        default:
+            g_assert_not_reached();
         }
+
+        break;
+
 #ifdef CONFIG_RDMA
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
+    case MIGRATION_ADDRESS_TYPE_RDMA:
         ioc = rdma_connect_outgoing(s, &addr->u.rdma, errp);
+        break;
 #endif
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
+
+    case MIGRATION_ADDRESS_TYPE_EXEC:
         ioc = exec_connect_outgoing(s, addr->u.exec.args, errp);
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
+        break;
+
+    case MIGRATION_ADDRESS_TYPE_FILE:
         ioc = file_connect_outgoing(s, &addr->u.file, errp);
-    } else {
+        break;
+
+    default:
         error_setg(errp, "uri is not a valid migration protocol");
+        break;
     }
 
     if (!ioc) {
-- 
2.51.0

[RFC PATCH 21/25] migration/channel: Cleanup early passing of MigrationState

[Fabiano Rosas]

MigrationState is being passed around quite a lot, but there are not
many actual users. Reduce the passing around by converting some key
functions to use migrate_get_current(). Although this goes against the
general direction of not using migrate_get_current(), doing this helps
to isolate the places that actually need MigrationState and could
facilitate future cleanups.

In the early connection code, qmp_migrate() needs MigrationState only
to make sure it reaches:

  migrate_prepare()
  migrate_hup_add()
  migration_start_outgoing()
  migration_connect_error_propagate()

The first two are at the top level, so are trivial to change. The last
two actually require passing 's' around between several functions,
making the code way more complex than it needs to be.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c   | 21 +++++++++----------
 migration/channel.h   |  5 ++---
 migration/exec.c      |  3 +--
 migration/exec.h      |  3 +--
 migration/fd.c        |  3 +--
 migration/fd.h        |  3 +--
 migration/file.c      |  3 +--
 migration/file.h      |  3 +--
 migration/migration.c | 49 +++++++++++++++++++++++--------------------
 migration/migration.h |  4 ++--
 migration/rdma.c      |  5 ++---
 migration/rdma.h      |  3 +--
 migration/socket.c    | 32 +++++++---------------------
 migration/socket.h    |  3 +--
 migration/tls.c       | 11 +++++-----
 migration/tls.h       |  2 +-
 16 files changed, 63 insertions(+), 90 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index 2f33cb2653..042e01b224 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -31,8 +31,7 @@
 #include "trace.h"
 #include "yank_functions.h"
 
-bool migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
-                                Error **errp)
+bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
 {
     g_autoptr(QIOChannel) ioc = NULL;
     SocketAddress *saddr;
@@ -45,7 +44,7 @@ bool migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
         case SOCKET_ADDRESS_TYPE_INET:
         case SOCKET_ADDRESS_TYPE_UNIX:
         case SOCKET_ADDRESS_TYPE_VSOCK:
-            socket_connect_outgoing(s, saddr, errp);
+            socket_connect_outgoing(saddr, errp);
             /*
              * async: after the socket is connected, calls
              * migration_channel_connect_outgoing() directly.
@@ -53,7 +52,7 @@ bool migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
             return true;
             break;
         case SOCKET_ADDRESS_TYPE_FD:
-            ioc = fd_connect_outgoing(s, saddr->u.fd.str, errp);
+            ioc = fd_connect_outgoing(saddr->u.fd.str, errp);
             break;
         default:
             g_assert_not_reached();
@@ -63,16 +62,16 @@ bool migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
 
 #ifdef CONFIG_RDMA
     case MIGRATION_ADDRESS_TYPE_RDMA:
-        ioc = rdma_connect_outgoing(s, &addr->u.rdma, errp);
+        ioc = rdma_connect_outgoing(&addr->u.rdma, errp);
         break;
 #endif
 
     case MIGRATION_ADDRESS_TYPE_EXEC:
-        ioc = exec_connect_outgoing(s, addr->u.exec.args, errp);
+        ioc = exec_connect_outgoing(addr->u.exec.args, errp);
         break;
 
     case MIGRATION_ADDRESS_TYPE_FILE:
-        ioc = file_connect_outgoing(s, &addr->u.file, errp);
+        ioc = file_connect_outgoing(&addr->u.file, errp);
         break;
 
     default:
@@ -84,7 +83,7 @@ bool migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
         return false;
     }
 
-    migration_channel_connect_outgoing(s, ioc);
+    migration_channel_connect_outgoing(ioc);
     return true;
 }
 
@@ -252,12 +251,12 @@ out:
     }
 }
 
-void migration_channel_connect_outgoing(MigrationState *s, QIOChannel *ioc)
+void migration_channel_connect_outgoing(QIOChannel *ioc)
 {
     trace_migration_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)));
 
     if (migrate_channel_requires_tls_upgrade(ioc)) {
-        migration_tls_channel_connect(s, ioc);
+        migration_tls_channel_connect(ioc);
 
         /*
          * async: the above will call back to this function after
@@ -268,7 +267,7 @@ void migration_channel_connect_outgoing(MigrationState *s, QIOChannel *ioc)
 
     migration_ioc_register_yank(ioc);
     migration_outgoing_setup(ioc);
-    migration_start_outgoing(s);
+    migration_start_outgoing();
 }
 
 
diff --git a/migration/channel.h b/migration/channel.h
index 4851179ae6..8cf16bfda9 100644
--- a/migration/channel.h
+++ b/migration/channel.h
@@ -29,7 +29,7 @@ enum {
 
 void migration_channel_process_incoming(QIOChannel *ioc);
 
-void migration_channel_connect_outgoing(MigrationState *s, QIOChannel *ioc);
+void migration_channel_connect_outgoing(QIOChannel *ioc);
 
 int migration_channel_read_peek(QIOChannel *ioc,
                                 const char *buf,
@@ -39,7 +39,6 @@ int migration_channel_read_peek(QIOChannel *ioc,
 bool migration_has_main_and_multifd_channels(void);
 bool migration_has_all_channels(void);
 
-bool migration_connect_outgoing(MigrationState *s, MigrationAddress *addr,
-                                Error **errp);
+bool migration_connect_outgoing(MigrationAddress *addr, Error **errp);
 void migration_connect_incoming(MigrationAddress *addr, Error **errp);
 #endif
diff --git a/migration/exec.c b/migration/exec.c
index a1a7ede3b4..a62fc0d00b 100644
--- a/migration/exec.c
+++ b/migration/exec.c
@@ -40,8 +40,7 @@ const char *exec_get_cmd_path(void)
 }
 #endif
 
-QIOChannel *exec_connect_outgoing(MigrationState *s, strList *command,
-                                  Error **errp)
+QIOChannel *exec_connect_outgoing(strList *command, Error **errp)
 {
     QIOChannel *ioc = NULL;
     g_auto(GStrv) argv = strv_from_str_list(command);
diff --git a/migration/exec.h b/migration/exec.h
index 3e39270dce..03c494b73c 100644
--- a/migration/exec.h
+++ b/migration/exec.h
@@ -27,6 +27,5 @@ const char *exec_get_cmd_path(void);
 #endif
 void exec_connect_incoming(strList *host_port, Error **errp);
 
-QIOChannel *exec_connect_outgoing(MigrationState *s, strList *host_port,
-                                  Error **errp);
+QIOChannel *exec_connect_outgoing(strList *host_port, Error **errp);
 #endif
diff --git a/migration/fd.c b/migration/fd.c
index bbf380d1a0..2480f48f2b 100644
--- a/migration/fd.c
+++ b/migration/fd.c
@@ -49,8 +49,7 @@ static bool migration_fd_valid(int fd)
     return false;
 }
 
-QIOChannel *fd_connect_outgoing(MigrationState *s, const char *fdname,
-                                Error **errp)
+QIOChannel *fd_connect_outgoing(const char *fdname, Error **errp)
 {
     QIOChannel *ioc = NULL;
     int fd = monitor_get_fd(monitor_cur(), fdname, errp);
diff --git a/migration/fd.h b/migration/fd.h
index ce0b751273..dfadbf4cc5 100644
--- a/migration/fd.h
+++ b/migration/fd.h
@@ -21,6 +21,5 @@
 
 void fd_connect_incoming(const char *fdname, Error **errp);
 
-QIOChannel *fd_connect_outgoing(MigrationState *s, const char *fdname,
-                                Error **errp);
+QIOChannel *fd_connect_outgoing(const char *fdname, Error **errp);
 #endif
diff --git a/migration/file.c b/migration/file.c
index 5618aced49..9cdb55d94e 100644
--- a/migration/file.c
+++ b/migration/file.c
@@ -93,8 +93,7 @@ out:
     return ret;
 }
 
-QIOChannel *file_connect_outgoing(MigrationState *s,
-                                  FileMigrationArgs *file_args, Error **errp)
+QIOChannel *file_connect_outgoing(FileMigrationArgs *file_args, Error **errp)
 {
     QIOChannelFile *fioc = NULL;
     g_autofree char *filename = g_strdup(file_args->filename);
diff --git a/migration/file.h b/migration/file.h
index 5936c64fea..74efd48abf 100644
--- a/migration/file.h
+++ b/migration/file.h
@@ -16,8 +16,7 @@
 
 void file_connect_incoming(FileMigrationArgs *file_args, Error **errp);
 
-QIOChannel *file_connect_outgoing(MigrationState *s,
-                                  FileMigrationArgs *file_args, Error **errp);
+QIOChannel *file_connect_outgoing(FileMigrationArgs *file_args, Error **errp);
 int file_parse_offset(char *filespec, uint64_t *offsetp, Error **errp);
 void file_cleanup_outgoing_migration(void);
 bool file_send_channel_create(gpointer opaque, Error **errp);
diff --git a/migration/migration.c b/migration/migration.c
index c75c2c7e52..c11cd4ebf6 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -101,7 +101,7 @@ static bool migration_object_check(MigrationState *ms, Error **errp);
 static bool migration_switchover_start(MigrationState *s, Error **errp);
 static bool close_return_path_on_source(MigrationState *s);
 static void migration_completion_end(MigrationState *s);
-static void migrate_hup_delete(MigrationState *s);
+static void migrate_hup_delete(void);
 
 static void migration_downtime_start(MigrationState *s)
 {
@@ -1372,7 +1372,7 @@ static void migration_cleanup(MigrationState *s)
 
     qemu_savevm_state_cleanup();
     cpr_state_close();
-    migrate_hup_delete(s);
+    migrate_hup_delete();
 
     close_return_path_on_source(s);
 
@@ -1454,8 +1454,9 @@ static void migrate_error_free(MigrationState *s)
     }
 }
 
-void migration_connect_error_propagate(MigrationState *s, Error *error)
+void migration_connect_error_propagate(Error *error)
 {
+    MigrationState *s = migrate_get_current();
     MigrationStatus current = s->state;
     MigrationStatus next = MIGRATION_STATUS_NONE;
     bool resume = false;
@@ -1555,7 +1556,7 @@ void migration_cancel(void)
         migrate_set_state(&s->state, MIGRATION_STATUS_CANCELLING,
                           MIGRATION_STATUS_CANCELLED);
         cpr_state_close();
-        migrate_hup_delete(s);
+        migrate_hup_delete();
     }
 }
 
@@ -1961,8 +1962,10 @@ bool migration_is_blocked(Error **errp)
 }
 
 /* Returns true if continue to migrate, or false if error detected */
-static bool migrate_prepare(MigrationState *s, bool resume, Error **errp)
+static bool migrate_prepare(bool resume, Error **errp)
 {
+    MigrationState *s = migrate_get_current();
+
     if (resume) {
         if (s->state != MIGRATION_STATUS_POSTCOPY_PAUSED) {
             error_setg(errp, "Cannot resume if there is no "
@@ -2080,16 +2083,19 @@ static bool migrate_prepare(MigrationState *s, bool resume, Error **errp)
 
 static void qmp_migrate_finish(MigrationAddress *addr, Error **errp);
 
-static void migrate_hup_add(MigrationState *s, QIOChannel *ioc, GSourceFunc cb,
-                            void *opaque)
+static void migrate_hup_add(QIOChannel *ioc, GSourceFunc cb, void *opaque)
 {
-        s->hup_source = qio_channel_create_watch(ioc, G_IO_HUP);
-        g_source_set_callback(s->hup_source, cb, opaque, NULL);
-        g_source_attach(s->hup_source, NULL);
+    MigrationState *s = migrate_get_current();
+
+    s->hup_source = qio_channel_create_watch(ioc, G_IO_HUP);
+    g_source_set_callback(s->hup_source, cb, opaque, NULL);
+    g_source_attach(s->hup_source, NULL);
 }
 
-static void migrate_hup_delete(MigrationState *s)
+static void migrate_hup_delete(void)
 {
+    MigrationState *s = migrate_get_current();
+
     if (s->hup_source) {
         g_source_destroy(s->hup_source);
         g_source_unref(s->hup_source);
@@ -2101,19 +2107,18 @@ static gboolean qmp_migrate_finish_cb(QIOChannel *channel,
                                       GIOCondition cond,
                                       void *opaque)
 {
-    MigrationState *s = migrate_get_current();
     MigrationAddress *addr = opaque;
     Error *local_err = NULL;
 
     qmp_migrate_finish(addr, &local_err);
 
     if (local_err) {
-        migration_connect_error_propagate(s, local_err);
+        migration_connect_error_propagate(local_err);
     }
 
 
     cpr_state_close();
-    migrate_hup_delete(s);
+    migrate_hup_delete();
     qapi_free_MigrationAddress(addr);
     return G_SOURCE_REMOVE;
 }
@@ -2122,7 +2127,6 @@ void qmp_migrate(const char *uri, bool has_channels,
                  MigrationChannelList *channels, bool has_detach, bool detach,
                  bool has_resume, bool resume, Error **errp)
 {
-    MigrationState *s = migrate_get_current();
     g_autoptr(MigrationChannel) channel = NULL;
     MigrationAddress *addr = NULL;
     MigrationChannel *channelv[MIGRATION_CHANNEL_TYPE__MAX] = { NULL };
@@ -2173,7 +2177,7 @@ void qmp_migrate(const char *uri, bool has_channels,
         return;
     }
 
-    if (!migrate_prepare(s, has_resume && resume, errp)) {
+    if (!migrate_prepare(has_resume && resume, errp)) {
         /* Error detected, put into errp */
         return;
     }
@@ -2200,7 +2204,7 @@ void qmp_migrate(const char *uri, bool has_channels,
      * connection, so qmp_migrate_finish will fail to connect, and then recover.
      */
     if (migrate_mode() == MIG_MODE_CPR_TRANSFER) {
-        migrate_hup_add(s, cpr_state_ioc(), (GSourceFunc)qmp_migrate_finish_cb,
+        migrate_hup_add(cpr_state_ioc(), (GSourceFunc)qmp_migrate_finish_cb,
                         QAPI_CLONE(MigrationAddress, addr));
 
     } else {
@@ -2209,16 +2213,14 @@ void qmp_migrate(const char *uri, bool has_channels,
 
 out:
     if (local_err) {
-        migration_connect_error_propagate(s, error_copy(local_err));
+        migration_connect_error_propagate(error_copy(local_err));
         error_propagate(errp, local_err);
     }
 }
 
 static void qmp_migrate_finish(MigrationAddress *addr, Error **errp)
 {
-    MigrationState *s = migrate_get_current();
-
-    migration_connect_outgoing(s, addr, errp);
+    migration_connect_outgoing(addr, errp);
 }
 
 void qmp_migrate_cancel(Error **errp)
@@ -3895,8 +3897,9 @@ fail_setup:
     return NULL;
 }
 
-void migration_start_outgoing(MigrationState *s)
+void migration_start_outgoing(void)
 {
+    MigrationState *s = migrate_get_current();
     Error *local_err = NULL;
     uint64_t rate_limit;
     bool resume = (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER_SETUP);
@@ -3975,7 +3978,7 @@ void migration_start_outgoing(MigrationState *s)
     return;
 
 fail:
-    migration_connect_error_propagate(s, local_err);
+    migration_connect_error_propagate(local_err);
     if (s->error) {
         error_report_err(error_copy(s->error));
     }
diff --git a/migration/migration.h b/migration/migration.h
index 138831d7d9..1292c1ee3a 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -529,11 +529,11 @@ void migrate_set_state(MigrationStatus *state, MigrationStatus old_state,
 void migration_outgoing_setup(QIOChannel *ioc);
 bool migration_incoming_setup(QIOChannel *ioc, uint8_t channel, Error **errp);
 
-void migration_connect_error_propagate(MigrationState *s, Error *error);
+void migration_connect_error_propagate(Error *error);
 void migrate_error_propagate(MigrationState *s, Error *error);
 bool migrate_has_error(MigrationState *s);
 
-void migration_start_outgoing(MigrationState *s);
+void migration_start_outgoing(void);
 void migration_start_incoming(void);
 
 int migration_call_notifiers(MigrationState *s, MigrationEventType type,
diff --git a/migration/rdma.c b/migration/rdma.c
index 3db3a89bdb..56e0ee8aa9 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -3923,10 +3923,9 @@ err:
     g_free(rdma);
 }
 
-QIOChannel *rdma_connect_outgoing(void *opaque,
-                                  InetSocketAddress *host_port, Error **errp)
+QIOChannel *rdma_connect_outgoing(InetSocketAddress *host_port, Error **errp)
 {
-    MigrationState *s = opaque;
+    MigrationState *s = migrate_get_current();
     RDMAContext *rdma_return_path = NULL;
     RDMAContext *rdma;
     int ret;
diff --git a/migration/rdma.h b/migration/rdma.h
index 8a6515f130..205184f244 100644
--- a/migration/rdma.h
+++ b/migration/rdma.h
@@ -21,8 +21,7 @@
 
 #include "system/memory.h"
 
-QIOChannel *rdma_connect_outgoing(void *opaque, InetSocketAddress *host_port,
-                                  Error **errp);
+QIOChannel *rdma_connect_outgoing(InetSocketAddress *host_port, Error **errp);
 
 void rdma_connect_incoming(InetSocketAddress *host_port, Error **errp);
 
diff --git a/migration/socket.c b/migration/socket.c
index ac3183d5d5..34ce7abbd3 100644
--- a/migration/socket.c
+++ b/migration/socket.c
@@ -42,23 +42,8 @@ void socket_send_channel_create(QIOTaskFunc f, void *data)
                                      f, data, NULL, NULL);
 }
 
-struct SocketConnectData {
-    MigrationState *s;
-};
-
-static void socket_connect_data_free(void *opaque)
+static void socket_outgoing_migration(QIOTask *task, gpointer opaque)
 {
-    struct SocketConnectData *data = opaque;
-    if (!data) {
-        return;
-    }
-    g_free(data);
-}
-
-static void socket_outgoing_migration(QIOTask *task,
-                                      gpointer opaque)
-{
-    struct SocketConnectData *data = opaque;
     g_autoptr(QIOChannel) sioc = QIO_CHANNEL(qio_task_get_source(task));
     Error *err = NULL;
 
@@ -73,22 +58,19 @@ static void socket_outgoing_migration(QIOTask *task,
     }
 
     trace_migration_socket_outgoing_connected();
-    migration_channel_connect_outgoing(data->s, sioc);
+    migration_channel_connect_outgoing(sioc);
     return;
 err:
     trace_migration_socket_outgoing_error(error_get_pretty(err));
-    migration_connect_error_propagate(data->s, err);
+    migration_connect_error_propagate(err);
 }
 
-void socket_connect_outgoing(MigrationState *s, SocketAddress *saddr,
-                             Error **errp)
+void socket_connect_outgoing(SocketAddress *saddr, Error **errp)
 {
+    MigrationState *s = migrate_get_current();
     QIOChannelSocket *sioc = qio_channel_socket_new();
-    struct SocketConnectData *data = g_new0(struct SocketConnectData, 1);
     SocketAddress *addr = QAPI_CLONE(SocketAddress, saddr);
 
-    data->s = s;
-
     /* in case previous migration leaked it */
     qapi_free_SocketAddress(outgoing_args.saddr);
     outgoing_args.saddr = addr;
@@ -101,8 +83,8 @@ void socket_connect_outgoing(MigrationState *s, SocketAddress *saddr,
     qio_channel_socket_connect_async(sioc,
                                      saddr,
                                      socket_outgoing_migration,
-                                     data,
-                                     socket_connect_data_free,
+                                     NULL,
+                                     NULL,
                                      NULL);
 }
 
diff --git a/migration/socket.h b/migration/socket.h
index f0c89b64c7..0ddff7e9df 100644
--- a/migration/socket.h
+++ b/migration/socket.h
@@ -25,8 +25,7 @@ void socket_send_channel_create(QIOTaskFunc f, void *data);
 
 void socket_connect_incoming(SocketAddress *saddr, Error **errp);
 
-void socket_connect_outgoing(MigrationState *s,
-                             SocketAddress *saddr, Error **errp);
+void socket_connect_outgoing(SocketAddress *saddr, Error **errp);
 void socket_cleanup_outgoing_migration(void);
 
 #endif
diff --git a/migration/tls.c b/migration/tls.c
index f68e6a533b..d71d3f9ea6 100644
--- a/migration/tls.c
+++ b/migration/tls.c
@@ -103,18 +103,17 @@ void migration_tls_channel_process_incoming(QIOChannel *ioc, Error **errp)
 static void migration_tls_outgoing_handshake(QIOTask *task,
                                              gpointer opaque)
 {
-    MigrationState *s = opaque;
     g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
     Error *err = NULL;
 
     if (qio_task_propagate_error(task, &err)) {
         trace_migration_tls_outgoing_handshake_error(error_get_pretty(err));
-        migration_connect_error_propagate(s, err);
+        migration_connect_error_propagate(err);
         return;
     }
 
     trace_migration_tls_outgoing_handshake_complete();
-    migration_channel_connect_outgoing(s, ioc);
+    migration_channel_connect_outgoing(ioc);
 }
 
 QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
@@ -130,14 +129,14 @@ QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
     return qio_channel_tls_new_client(ioc, creds, migrate_tls_hostname(), errp);
 }
 
-void migration_tls_channel_connect(MigrationState *s, QIOChannel *ioc)
+void migration_tls_channel_connect(QIOChannel *ioc)
 {
     QIOChannelTLS *tioc;
     Error *local_err = NULL;
 
     tioc = migration_tls_client_create(ioc, &local_err);
     if (!tioc) {
-        migration_connect_error_propagate(s, local_err);
+        migration_connect_error_propagate(local_err);
         return;
     }
 
@@ -150,7 +149,7 @@ void migration_tls_channel_connect(MigrationState *s, QIOChannel *ioc)
     }
     qio_channel_tls_handshake(tioc,
                               migration_tls_outgoing_handshake,
-                              s,
+                              NULL,
                               NULL,
                               NULL);
 }
diff --git a/migration/tls.h b/migration/tls.h
index 7399c42edf..7ccd495f81 100644
--- a/migration/tls.h
+++ b/migration/tls.h
@@ -29,7 +29,7 @@ void migration_tls_channel_process_incoming(QIOChannel *ioc, Error **errp);
 QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
                                            Error **errp);
 
-void migration_tls_channel_connect(MigrationState *s, QIOChannel *ioc);
+void migration_tls_channel_connect(QIOChannel *ioc);
 void migration_tls_channel_end(QIOChannel *ioc, Error **errp);
 /* Whether the QIO channel requires further TLS handshake? */
 bool migrate_channel_requires_tls_upgrade(QIOChannel *ioc);
-- 
2.51.0

[RFC PATCH 22/25] migration/channel: Merge both sides of the connection initiation code

[Fabiano Rosas]

Now that everything is in channel.c, it's easier to browse this code
if it's all in the same place. It's also easier to grasp what the
connection flow is if both sides of the connection are close together.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c | 86 +++++++++++++++++++++++----------------------
 migration/channel.h | 14 ++++++--
 2 files changed, 56 insertions(+), 44 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index 042e01b224..ba9aa1c58b 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -31,10 +31,11 @@
 #include "trace.h"
 #include "yank_functions.h"
 
-bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
+bool migration_connect(MigrationAddress *addr, bool out, Error **errp)
 {
     g_autoptr(QIOChannel) ioc = NULL;
     SocketAddress *saddr;
+    ERRP_GUARD();
 
     switch (addr->transport) {
     case MIGRATION_ADDRESS_TYPE_SOCKET:
@@ -44,15 +45,24 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
         case SOCKET_ADDRESS_TYPE_INET:
         case SOCKET_ADDRESS_TYPE_UNIX:
         case SOCKET_ADDRESS_TYPE_VSOCK:
-            socket_connect_outgoing(saddr, errp);
-            /*
-             * async: after the socket is connected, calls
-             * migration_channel_connect_outgoing() directly.
-             */
-            return true;
+            if (out) {
+                socket_connect_outgoing(saddr, errp);
+                /*
+                 * async: after the socket is connected, calls
+                 * migration_channel_connect_outgoing() directly.
+                 */
+                return true;
+            } else {
+                socket_connect_incoming(saddr, errp);
+            }
+
             break;
         case SOCKET_ADDRESS_TYPE_FD:
-            ioc = fd_connect_outgoing(saddr->u.fd.str, errp);
+            if (out) {
+                ioc = fd_connect_outgoing(saddr->u.fd.str, errp);
+            } else {
+                fd_connect_incoming(saddr->u.fd.str, errp);
+            }
             break;
         default:
             g_assert_not_reached();
@@ -62,16 +72,28 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
 
 #ifdef CONFIG_RDMA
     case MIGRATION_ADDRESS_TYPE_RDMA:
-        ioc = rdma_connect_outgoing(&addr->u.rdma, errp);
+        if (out) {
+            ioc = rdma_connect_outgoing(&addr->u.rdma, errp);
+        } else {
+            rdma_connect_incoming(&addr->u.rdma, errp);
+        }
         break;
 #endif
 
     case MIGRATION_ADDRESS_TYPE_EXEC:
-        ioc = exec_connect_outgoing(addr->u.exec.args, errp);
+        if (out) {
+            ioc = exec_connect_outgoing(addr->u.exec.args, errp);
+        } else {
+            exec_connect_incoming(addr->u.exec.args, errp);
+        }
         break;
 
     case MIGRATION_ADDRESS_TYPE_FILE:
-        ioc = file_connect_outgoing(&addr->u.file, errp);
+        if (out) {
+            ioc = file_connect_outgoing(&addr->u.file, errp);
+        } else {
+            file_connect_incoming(&addr->u.file, errp);
+        }
         break;
 
     default:
@@ -79,42 +101,22 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
         break;
     }
 
-    if (!ioc) {
-        return false;
-    }
-
-    migration_channel_connect_outgoing(ioc);
-    return true;
-}
-
-void migration_connect_incoming(MigrationAddress *addr, Error **errp)
-{
-    if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
-        SocketAddress *saddr = &addr->u.socket;
-        if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
-            saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
-            saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
-            socket_connect_incoming(saddr, errp);
-        } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
-            fd_connect_incoming(saddr->u.fd.str, errp);
+    if (out) {
+        if (!ioc) {
+            return false;
         }
-#ifdef CONFIG_RDMA
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
-        rdma_connect_incoming(&addr->u.rdma, errp);
-#endif
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
-        exec_connect_incoming(addr->u.exec.args, errp);
-    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
-        file_connect_incoming(&addr->u.file, errp);
-    } else {
-        error_setg(errp, "unknown migration protocol");
+
+        migration_channel_connect_outgoing(ioc);
+        return true;
     }
 
     /*
-     * async: the above routines all wait for the incoming connection
-     * and call back to migration_channel_process_incoming() to start
-     * the migration.
+     * async: on the incoming side all of the transport routines above
+     * wait for the incoming connection and call back to
+     * migration_channel_process_incoming() to start the migration.
      */
+
+    return !*errp;
 }
 
 bool migration_has_main_and_multifd_channels(void)
diff --git a/migration/channel.h b/migration/channel.h
index 8cf16bfda9..86934fee38 100644
--- a/migration/channel.h
+++ b/migration/channel.h
@@ -39,6 +39,16 @@ int migration_channel_read_peek(QIOChannel *ioc,
 bool migration_has_main_and_multifd_channels(void);
 bool migration_has_all_channels(void);
 
-bool migration_connect_outgoing(MigrationAddress *addr, Error **errp);
-void migration_connect_incoming(MigrationAddress *addr, Error **errp);
+bool migration_connect(MigrationAddress *addr, bool out, Error **errp);
+static inline bool migration_connect_outgoing(MigrationAddress *addr,
+                                              Error **errp)
+{
+    return migration_connect(addr, true, errp);
+}
+
+static inline bool migration_connect_incoming(MigrationAddress *addr,
+                                              Error **errp)
+{
+    return migration_connect(addr, false, errp);
+}
 #endif
-- 
2.51.0

[RFC PATCH 23/25] migration: Move channel parsing to channel.c

[Fabiano Rosas]

Encapsulate the MigrationChannelList parsing in a new
migrate_channels_parse() located at channel.c.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c   | 54 +++++++++++++++++++++++++++++++++++++++++++
 migration/channel.h   |  5 ++++
 migration/migration.c | 50 +++++++++++----------------------------
 3 files changed, 73 insertions(+), 36 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index ba9aa1c58b..8b43c3d983 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -11,6 +11,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/cutils.h"
 #include "channel.h"
 #include "exec.h"
 #include "fd.h"
@@ -20,7 +21,9 @@
 #include "migration.h"
 #include "multifd.h"
 #include "options.h"
+#include "qapi/clone-visitor.h"
 #include "qapi/qapi-types-migration.h"
+#include "qapi/qapi-visit-migration.h"
 #include "qapi/error.h"
 #include "qemu-file.h"
 #include "qemu/yank.h"
@@ -314,3 +317,54 @@ int migration_channel_read_peek(QIOChannel *ioc,
 
     return 0;
 }
+
+bool migrate_channels_parse(MigrationChannelList *channels,
+                            MigrationChannel **main_channelp,
+                            MigrationChannel **cpr_channelp,
+                            Error **errp)
+{
+    MigrationChannel *channelv[MIGRATION_CHANNEL_TYPE__MAX] = { NULL };
+    bool single_channel;
+
+    if (cpr_channelp) {
+        single_channel = false;
+    } else {
+        single_channel = true;
+    }
+
+    for ( ; channels; channels = channels->next) {
+        MigrationChannelType type;
+
+        type = channels->value->channel_type;
+        if (channelv[type]) {
+            error_setg(errp, "Channel list has more than one %s entry",
+                       MigrationChannelType_str(type));
+            return false;
+        }
+        channelv[type] = channels->value;
+
+        if (single_channel) {
+            if (channels->next) {
+                error_setg(errp, "Channel list must have only one entry, "
+                           "for type 'main'");
+                return false;
+            }
+            break;
+        }
+    }
+
+    if (cpr_channelp) {
+        *cpr_channelp = QAPI_CLONE(MigrationChannel,
+                                   channelv[MIGRATION_CHANNEL_TYPE_CPR]);
+    }
+
+    *main_channelp = QAPI_CLONE(MigrationChannel,
+                                channelv[MIGRATION_CHANNEL_TYPE_MAIN]);
+
+    if (!(*main_channelp)->addr) {
+        error_setg(errp, "Channel list has no main entry");
+        return false;
+    }
+
+    return true;
+}
diff --git a/migration/channel.h b/migration/channel.h
index 86934fee38..b3276550b7 100644
--- a/migration/channel.h
+++ b/migration/channel.h
@@ -51,4 +51,9 @@ static inline bool migration_connect_incoming(MigrationAddress *addr,
 {
     return migration_connect(addr, false, errp);
 }
+
+bool migrate_channels_parse(MigrationChannelList *channels,
+                            MigrationChannel **main_channelp,
+                            MigrationChannel **cpr_channelp,
+                            Error **errp);
 #endif
diff --git a/migration/migration.c b/migration/migration.c
index c11cd4ebf6..6064f1e5ea 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -741,8 +741,7 @@ static void qemu_setup_incoming_migration(const char *uri, bool has_channels,
                                           MigrationChannelList *channels,
                                           Error **errp)
 {
-    g_autoptr(MigrationChannel) channel = NULL;
-    MigrationAddress *addr = NULL;
+    g_autoptr(MigrationChannel) main_ch = NULL;
     MigrationIncomingState *mis = migration_incoming_get_current();
 
     /*
@@ -754,25 +753,20 @@ static void qemu_setup_incoming_migration(const char *uri, bool has_channels,
     }
 
     if (channels) {
-        /* To verify that Migrate channel list has only item */
-        if (channels->next) {
-            error_setg(errp, "Channel list must have only one entry, "
-                             "for type 'main'");
+        if (!migrate_channels_parse(channels, &main_ch, NULL, errp)) {
             return;
         }
-        addr = channels->value->addr;
     }
 
     if (uri) {
         /* caller uses the old URI syntax */
-        if (!migrate_uri_parse(uri, &channel, errp)) {
+        if (!migrate_uri_parse(uri, &main_ch, errp)) {
             return;
         }
-        addr = channel->addr;
     }
 
     /* transport mechanism not suitable for migration? */
-    if (!migration_transport_compatible(addr, errp)) {
+    if (!migration_transport_compatible(main_ch->addr, errp)) {
         return;
     }
 
@@ -784,7 +778,7 @@ static void qemu_setup_incoming_migration(const char *uri, bool has_channels,
         return;
     }
 
-    migration_connect_incoming(addr, errp);
+    migration_connect_incoming(main_ch->addr, errp);
 
     /* Close cpr socket to tell source that we are listening */
     cpr_state_close();
@@ -2127,10 +2121,8 @@ void qmp_migrate(const char *uri, bool has_channels,
                  MigrationChannelList *channels, bool has_detach, bool detach,
                  bool has_resume, bool resume, Error **errp)
 {
-    g_autoptr(MigrationChannel) channel = NULL;
-    MigrationAddress *addr = NULL;
-    MigrationChannel *channelv[MIGRATION_CHANNEL_TYPE__MAX] = { NULL };
-    MigrationChannel *cpr_channel = NULL;
+    g_autoptr(MigrationChannel) main_ch = NULL;
+    g_autoptr(MigrationChannel) cpr_ch = NULL;
 
     /*
      * Having preliminary checks for uri and channel
@@ -2141,38 +2133,24 @@ void qmp_migrate(const char *uri, bool has_channels,
     }
 
     if (channels) {
-        for ( ; channels; channels = channels->next) {
-            MigrationChannelType type = channels->value->channel_type;
-
-            if (channelv[type]) {
-                error_setg(errp, "Channel list has more than one %s entry",
-                           MigrationChannelType_str(type));
-                return;
-            }
-            channelv[type] = channels->value;
-        }
-        cpr_channel = channelv[MIGRATION_CHANNEL_TYPE_CPR];
-        addr = channelv[MIGRATION_CHANNEL_TYPE_MAIN]->addr;
-        if (!addr) {
-            error_setg(errp, "Channel list has no main entry");
+        if (!migrate_channels_parse(channels, &main_ch, &cpr_ch, errp)) {
             return;
         }
     }
 
     if (uri) {
         /* caller uses the old URI syntax */
-        if (!migrate_uri_parse(uri, &channel, errp)) {
+        if (!migrate_uri_parse(uri, &main_ch, errp)) {
             return;
         }
-        addr = channel->addr;
     }
 
     /* transport mechanism not suitable for migration? */
-    if (!migration_transport_compatible(addr, errp)) {
+    if (!migration_transport_compatible(main_ch->addr, errp)) {
         return;
     }
 
-    if (migrate_mode() == MIG_MODE_CPR_TRANSFER && !cpr_channel) {
+    if (migrate_mode() == MIG_MODE_CPR_TRANSFER && !cpr_ch) {
         error_setg(errp, "missing 'cpr' migration channel");
         return;
     }
@@ -2189,7 +2167,7 @@ void qmp_migrate(const char *uri, bool has_channels,
      */
     Error *local_err = NULL;
 
-    if (!cpr_state_save(cpr_channel, &local_err)) {
+    if (!cpr_state_save(cpr_ch, &local_err)) {
         goto out;
     }
 
@@ -2205,10 +2183,10 @@ void qmp_migrate(const char *uri, bool has_channels,
      */
     if (migrate_mode() == MIG_MODE_CPR_TRANSFER) {
         migrate_hup_add(cpr_state_ioc(), (GSourceFunc)qmp_migrate_finish_cb,
-                        QAPI_CLONE(MigrationAddress, addr));
+                        QAPI_CLONE(MigrationAddress, main_ch->addr));
 
     } else {
-        qmp_migrate_finish(addr, &local_err);
+        qmp_migrate_finish(main_ch->addr, &local_err);
     }
 
 out:
-- 
2.51.0

[RFC PATCH 24/25] migration: Move URI parsing to channel.c

[Fabiano Rosas]

The migrate_uri_parse function is responsible for converting the URI
string into a MigrationChannel for consumption by the rest of the
code. Move it to channel.c and add a wrapper that calls both URI and
channels parsing.

While here, add some words about the memory management of the
MigrationChannel object, which is slightly different from
migrate_uri_parse() and migrate_channels_parse(). The former takes a
string and has to allocate a MigrationChannel, the latter takes a QAPI
object that is managed by the QAPI code.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/channel.c   | 97 +++++++++++++++++++++++++++++++++++++++++--
 migration/channel.h   |  9 ++--
 migration/migration.c | 95 ++----------------------------------------
 3 files changed, 101 insertions(+), 100 deletions(-)

diff --git a/migration/channel.c b/migration/channel.c
index 8b43c3d983..d30e29c9b3 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -40,6 +40,12 @@ bool migration_connect(MigrationAddress *addr, bool out, Error **errp)
     SocketAddress *saddr;
     ERRP_GUARD();
 
+    /*
+     * This is reached from a QMP command, the transport code below
+     * must copy the relevant parts of 'addr' before this function
+     * returns because the QAPI code will free it.
+     */
+
     switch (addr->transport) {
     case MIGRATION_ADDRESS_TYPE_SOCKET:
         saddr = &addr->u.socket;
@@ -318,10 +324,10 @@ int migration_channel_read_peek(QIOChannel *ioc,
     return 0;
 }
 
-bool migrate_channels_parse(MigrationChannelList *channels,
-                            MigrationChannel **main_channelp,
-                            MigrationChannel **cpr_channelp,
-                            Error **errp)
+static bool migrate_channels_parse(MigrationChannelList *channels,
+                                   MigrationChannel **main_channelp,
+                                   MigrationChannel **cpr_channelp,
+                                   Error **errp)
 {
     MigrationChannel *channelv[MIGRATION_CHANNEL_TYPE__MAX] = { NULL };
     bool single_channel;
@@ -353,6 +359,15 @@ bool migrate_channels_parse(MigrationChannelList *channels,
         }
     }
 
+    /*
+     * These don't technically need to be cloned because they come
+     * from a QAPI object ('channels'). The top-level caller
+     * (qmp_migrate) needs to copy the necessary information before
+     * returning from the QMP command. Cloning here is just to keep
+     * the interface consistent with migrate_uri_parse() that _does
+     * not_ take a QAPI object and instead allocates and transfers
+     * ownership of a MigrationChannel to qmp_migrate.
+     */
     if (cpr_channelp) {
         *cpr_channelp = QAPI_CLONE(MigrationChannel,
                                    channelv[MIGRATION_CHANNEL_TYPE_CPR]);
@@ -368,3 +383,77 @@ bool migrate_channels_parse(MigrationChannelList *channels,
 
     return true;
 }
+
+bool migrate_uri_parse(const char *uri, MigrationChannel **channel,
+                       Error **errp)
+{
+    g_autoptr(MigrationChannel) val = g_new0(MigrationChannel, 1);
+    g_autoptr(MigrationAddress) addr = g_new0(MigrationAddress, 1);
+    InetSocketAddress *isock = &addr->u.rdma;
+    strList **tail = &addr->u.exec.args;
+
+    if (strstart(uri, "exec:", NULL)) {
+        addr->transport = MIGRATION_ADDRESS_TYPE_EXEC;
+#ifdef WIN32
+        QAPI_LIST_APPEND(tail, g_strdup(exec_get_cmd_path()));
+        QAPI_LIST_APPEND(tail, g_strdup("/c"));
+#else
+        QAPI_LIST_APPEND(tail, g_strdup("/bin/sh"));
+        QAPI_LIST_APPEND(tail, g_strdup("-c"));
+#endif
+        QAPI_LIST_APPEND(tail, g_strdup(uri + strlen("exec:")));
+    } else if (strstart(uri, "rdma:", NULL)) {
+        if (inet_parse(isock, uri + strlen("rdma:"), errp)) {
+            qapi_free_InetSocketAddress(isock);
+            return false;
+        }
+        addr->transport = MIGRATION_ADDRESS_TYPE_RDMA;
+    } else if (strstart(uri, "tcp:", NULL) ||
+                strstart(uri, "unix:", NULL) ||
+                strstart(uri, "vsock:", NULL) ||
+                strstart(uri, "fd:", NULL)) {
+        addr->transport = MIGRATION_ADDRESS_TYPE_SOCKET;
+        SocketAddress *saddr = socket_parse(uri, errp);
+        if (!saddr) {
+            return false;
+        }
+        addr->u.socket.type = saddr->type;
+        addr->u.socket.u = saddr->u;
+        /* Don't free the objects inside; their ownership moved to "addr" */
+        g_free(saddr);
+    } else if (strstart(uri, "file:", NULL)) {
+        addr->transport = MIGRATION_ADDRESS_TYPE_FILE;
+        addr->u.file.filename = g_strdup(uri + strlen("file:"));
+        if (file_parse_offset(addr->u.file.filename, &addr->u.file.offset,
+                              errp)) {
+            return false;
+        }
+    } else {
+        error_setg(errp, "unknown migration protocol: %s", uri);
+        return false;
+    }
+
+    val->channel_type = MIGRATION_CHANNEL_TYPE_MAIN;
+    val->addr = g_steal_pointer(&addr);
+    *channel = g_steal_pointer(&val);
+    return true;
+}
+
+bool migration_channel_parse_input(const char *uri,
+                                   MigrationChannelList *channels,
+                                   MigrationChannel **main_channelp,
+                                   MigrationChannel **cpr_channelp,
+                                   Error **errp)
+{
+    if (!uri == !channels) {
+        error_setg(errp, "need either 'uri' or 'channels' argument");
+        return false;
+    }
+
+    if (channels) {
+        return migrate_channels_parse(channels, main_channelp, cpr_channelp,
+                                      errp);
+    } else {
+        return migrate_uri_parse(uri, main_channelp, errp);
+    }
+}
diff --git a/migration/channel.h b/migration/channel.h
index b3276550b7..3724b0493a 100644
--- a/migration/channel.h
+++ b/migration/channel.h
@@ -52,8 +52,9 @@ static inline bool migration_connect_incoming(MigrationAddress *addr,
     return migration_connect(addr, false, errp);
 }
 
-bool migrate_channels_parse(MigrationChannelList *channels,
-                            MigrationChannel **main_channelp,
-                            MigrationChannel **cpr_channelp,
-                            Error **errp);
+bool migration_channel_parse_input(const char *uri,
+                                   MigrationChannelList *channels,
+                                   MigrationChannel **main_channelp,
+                                   MigrationChannel **cpr_channelp,
+                                   Error **errp);
 #endif
diff --git a/migration/migration.c b/migration/migration.c
index 6064f1e5ea..15d8459a81 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -15,7 +15,6 @@
 
 #include "qemu/osdep.h"
 #include "qemu/ctype.h"
-#include "qemu/cutils.h"
 #include "qemu/error-report.h"
 #include "qemu/main-loop.h"
 #include "migration/blocker.h"
@@ -659,61 +658,6 @@ bool migrate_is_uri(const char *uri)
     return *uri == ':';
 }
 
-bool migrate_uri_parse(const char *uri, MigrationChannel **channel,
-                       Error **errp)
-{
-    g_autoptr(MigrationChannel) val = g_new0(MigrationChannel, 1);
-    g_autoptr(MigrationAddress) addr = g_new0(MigrationAddress, 1);
-    InetSocketAddress *isock = &addr->u.rdma;
-    strList **tail = &addr->u.exec.args;
-
-    if (strstart(uri, "exec:", NULL)) {
-        addr->transport = MIGRATION_ADDRESS_TYPE_EXEC;
-#ifdef WIN32
-        QAPI_LIST_APPEND(tail, g_strdup(exec_get_cmd_path()));
-        QAPI_LIST_APPEND(tail, g_strdup("/c"));
-#else
-        QAPI_LIST_APPEND(tail, g_strdup("/bin/sh"));
-        QAPI_LIST_APPEND(tail, g_strdup("-c"));
-#endif
-        QAPI_LIST_APPEND(tail, g_strdup(uri + strlen("exec:")));
-    } else if (strstart(uri, "rdma:", NULL)) {
-        if (inet_parse(isock, uri + strlen("rdma:"), errp)) {
-            qapi_free_InetSocketAddress(isock);
-            return false;
-        }
-        addr->transport = MIGRATION_ADDRESS_TYPE_RDMA;
-    } else if (strstart(uri, "tcp:", NULL) ||
-                strstart(uri, "unix:", NULL) ||
-                strstart(uri, "vsock:", NULL) ||
-                strstart(uri, "fd:", NULL)) {
-        addr->transport = MIGRATION_ADDRESS_TYPE_SOCKET;
-        SocketAddress *saddr = socket_parse(uri, errp);
-        if (!saddr) {
-            return false;
-        }
-        addr->u.socket.type = saddr->type;
-        addr->u.socket.u = saddr->u;
-        /* Don't free the objects inside; their ownership moved to "addr" */
-        g_free(saddr);
-    } else if (strstart(uri, "file:", NULL)) {
-        addr->transport = MIGRATION_ADDRESS_TYPE_FILE;
-        addr->u.file.filename = g_strdup(uri + strlen("file:"));
-        if (file_parse_offset(addr->u.file.filename, &addr->u.file.offset,
-                              errp)) {
-            return false;
-        }
-    } else {
-        error_setg(errp, "unknown migration protocol: %s", uri);
-        return false;
-    }
-
-    val->channel_type = MIGRATION_CHANNEL_TYPE_MAIN;
-    val->addr = g_steal_pointer(&addr);
-    *channel = g_steal_pointer(&val);
-    return true;
-}
-
 static bool
 migration_incoming_state_setup(MigrationIncomingState *mis, Error **errp)
 {
@@ -744,27 +688,10 @@ static void qemu_setup_incoming_migration(const char *uri, bool has_channels,
     g_autoptr(MigrationChannel) main_ch = NULL;
     MigrationIncomingState *mis = migration_incoming_get_current();
 
-    /*
-     * Having preliminary checks for uri and channel
-     */
-    if (!uri == !channels) {
-        error_setg(errp, "need either 'uri' or 'channels' argument");
+    if (!migration_channel_parse_input(uri, channels, &main_ch, NULL, errp)) {
         return;
     }
 
-    if (channels) {
-        if (!migrate_channels_parse(channels, &main_ch, NULL, errp)) {
-            return;
-        }
-    }
-
-    if (uri) {
-        /* caller uses the old URI syntax */
-        if (!migrate_uri_parse(uri, &main_ch, errp)) {
-            return;
-        }
-    }
-
     /* transport mechanism not suitable for migration? */
     if (!migration_transport_compatible(main_ch->addr, errp)) {
         return;
@@ -2124,27 +2051,11 @@ void qmp_migrate(const char *uri, bool has_channels,
     g_autoptr(MigrationChannel) main_ch = NULL;
     g_autoptr(MigrationChannel) cpr_ch = NULL;
 
-    /*
-     * Having preliminary checks for uri and channel
-     */
-    if (!uri == !channels) {
-        error_setg(errp, "need either 'uri' or 'channels' argument");
+    if (!migration_channel_parse_input(uri, channels, &main_ch, &cpr_ch,
+                                       errp)) {
         return;
     }
 
-    if (channels) {
-        if (!migrate_channels_parse(channels, &main_ch, &cpr_ch, errp)) {
-            return;
-        }
-    }
-
-    if (uri) {
-        /* caller uses the old URI syntax */
-        if (!migrate_uri_parse(uri, &main_ch, errp)) {
-            return;
-        }
-    }
-
     /* transport mechanism not suitable for migration? */
     if (!migration_transport_compatible(main_ch->addr, errp)) {
         return;
-- 
2.51.0

[RFC PATCH 25/25] migration: Remove qmp_migrate_finish

[Fabiano Rosas]

With recent cleanups, the qmp_migrate_finish() function has now become
just a call to migration_connect_outgoing(), which makes sense because
that's what the "second part of qmp_migrate" does. The
qmp_migrate_finish is (in retrospect) too confusing because it never
had a matching qmp_migrate_start. I think it's best to just remove
this function and call migration_connect_outgoing() directly.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/migration.c | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 15d8459a81..228e322de1 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1470,8 +1470,8 @@ void migration_cancel(void)
     }
 
     /*
-     * If qmp_migrate_finish has not been called, then there is no path that
-     * will complete the cancellation.  Do it now.
+     * If migration_connect_outgoing has not been called, then there
+     * is no path that will complete the cancellation.  Do it now.
      */
     if (setup && !s->to_dst_file) {
         migrate_set_state(&s->state, MIGRATION_STATUS_CANCELLING,
@@ -2002,8 +2002,6 @@ static bool migrate_prepare(bool resume, Error **errp)
     return true;
 }
 
-static void qmp_migrate_finish(MigrationAddress *addr, Error **errp);
-
 static void migrate_hup_add(QIOChannel *ioc, GSourceFunc cb, void *opaque)
 {
     MigrationState *s = migrate_get_current();
@@ -2031,7 +2029,7 @@ static gboolean qmp_migrate_finish_cb(QIOChannel *channel,
     MigrationAddress *addr = opaque;
     Error *local_err = NULL;
 
-    qmp_migrate_finish(addr, &local_err);
+    migration_connect_outgoing(addr, &local_err);
 
     if (local_err) {
         migration_connect_error_propagate(local_err);
@@ -2086,18 +2084,19 @@ void qmp_migrate(const char *uri, bool has_channels,
      * For cpr-transfer, the target may not be listening yet on the migration
      * channel, because first it must finish cpr_load_state.  The target tells
      * us it is listening by closing the cpr-state socket.  Wait for that HUP
-     * event before connecting in qmp_migrate_finish.
+     * event before connecting in migration_connect_outgoing.
      *
      * The HUP could occur because the target fails while reading CPR state,
      * in which case the target will not listen for the incoming migration
-     * connection, so qmp_migrate_finish will fail to connect, and then recover.
+     * connection, so migration_connect_outgoing fail to connect, and
+     * then recover.
      */
     if (migrate_mode() == MIG_MODE_CPR_TRANSFER) {
         migrate_hup_add(cpr_state_ioc(), (GSourceFunc)qmp_migrate_finish_cb,
                         QAPI_CLONE(MigrationAddress, main_ch->addr));
 
     } else {
-        qmp_migrate_finish(main_ch->addr, &local_err);
+        migration_connect_outgoing(main_ch->addr, &local_err);
     }
 
 out:
@@ -2107,11 +2106,6 @@ out:
     }
 }
 
-static void qmp_migrate_finish(MigrationAddress *addr, Error **errp)
-{
-    migration_connect_outgoing(addr, errp);
-}
-
 void qmp_migrate_cancel(Error **errp)
 {
     /*
-- 
2.51.0

Re: [RFC PATCH 01/25] migration: Remove redundant state change

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:03PM -0300, Fabiano Rosas wrote:
> If local_err is set, migration_connect_error_propagate() will be
> called and that function already has a state transtion from SETUP to
> FAILED.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu

Re: [RFC PATCH 02/25] migration: Fix state change at migration_channel_process_incoming

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:04PM -0300, Fabiano Rosas wrote:
> When the incoming migration fails during the channel connection phase,
> the state transition to FAILED is currently being done in the
> MigrationState->state, but the MigrationIncomingState->state is the
> one that should be used.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu

Re: [RFC PATCH 03/25] migration/tls: Remove unused parameter

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:05PM -0300, Fabiano Rosas wrote:
> MigrationState is not used at migration_tls_channel_process_incoming().
> 
> The last usage was removed by commit 3f461a0c0b ("migration: Drop
> unused parameter for migration_tls_get_creds()")
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu

Re: [RFC PATCH 04/25] migration: Move multifd_recv_setup call

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:06PM -0300, Fabiano Rosas wrote:
> The multifd_recv_setup() call is currently in a place where it will be
> called for every channel that appears. That doesn't make much
> sense.
> 
> It seems it was moved when the channel discovery mechanism was added
> back at commit 6720c2b327 (migration: check magic value for deciding
> the mapping of channels, 2022-12-20). The original place was
> migration_incoming_setup() which would run for just the main channel,
> but it was discovered that the main channel might arrive after a
> multifd channel.
> 
> Move the call back to a place where it will be called only once.
> 
> With respect to cleanup, this new location at
> qemu_start_incoming_migration() has the same issue as the previous
> callsite at migration_ioc_process_incoming(): no cleanup ever happens.
> 
> The error message goes from being emitted via error_report_err(), to
> being returned to the qmp_migrate_incoming() incoming command, which
> is arguably better, since this is setup code.

This is not the only and real reason that you moved it, right?

Neither should it be the reason that you want it to be called only exactly
once; after all the function will be no-op in the 2nd+ calls.

I'll keep reading.. I'm guessing I'll find it later, but IMHO it'll always
be good to mention the real motivation in the commit log.

> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
>  migration/migration.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 71efe945f6..974313944c 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -786,6 +786,10 @@ static void qemu_start_incoming_migration(const char *uri, bool has_channels,
>          return;
>      }
>  
> +    if (multifd_recv_setup(errp) != 0) {
> +        return;
> +    }
> +
>      if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
>          SocketAddress *saddr = &addr->u.socket;
>          if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
> @@ -1065,10 +1069,6 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>          channel = CH_POSTCOPY;
>      }
>  
> -    if (multifd_recv_setup(errp) != 0) {
> -        return;
> -    }
> -
>      if (channel == CH_MAIN) {
>          f = qemu_file_new_input(ioc);
>          migration_incoming_setup(f);
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 05/25] migration: Cleanup TLS handshake hostname passing

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:07PM -0300, Fabiano Rosas wrote:
> The TLS hostname is doing a tour around the world just to be cached
> into s->hostname. We're already abusing MigrationState by doing that,
> so incorporate the s->hostname into migration_tls_hostname() and stop
> passing the string around.
> 
> The old route was roughly:
> 
>  -transport code (socket.c, fd.c, etc):
>     if (SOCKET_ADDRESS_TYPE_INET)
>         hostname = saddr->u.inet.host
>     else
>         hostname = NULL
>     migration_channel_connect(..., hostname)
>       s->hostname = hostname;
>       migration_tls_client_create(..., hostname)
>         if (migrate_tls_hostname())
>             qio_channel_tls_new_client(migrate_tls_hostname())
>         else
>             qio_channel_tls_new_client(hostname)
> 
>  -postcopy_preempt_setup:
>     postcopy_preempt_send_channel_new
>       migration_tls_client_create(..., s->hostname)
> 
> New route is:
> 
>  -socket.c only:
>    if SOCKET_ADDRESS_TYPE_INET
>        s->hostname = saddr->u.inet.host
>    migration_channel_connect()
>      migration_tls_client_create()
>        qio_channel_tls_new_client(migrate_tls_hostname())
> 
>  -postcopy_preempt_setup:
>     postcopy_preempt_send_channel_new
>       migration_tls_client_create()
>         qio_channel_tls_new_client(migrate_tls_hostname())
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

I suggest let's still copy Dan on all tls changes, though. I've done it
here.

Looks alright to me:

Reviewed-by: Peter Xu <peterx@redhat.com>

Two trivial comments on top..

- Maybe, we can get rid of SocketConnectData altogether now

- Maybe, we want to keep at least one tracepoint that would dump the
  hostname used

> ---
>  migration/channel.c      |  6 ++----
>  migration/channel.h      |  1 -
>  migration/exec.c         |  2 +-
>  migration/fd.c           |  2 +-
>  migration/file.c         |  2 +-
>  migration/multifd.c      |  9 +++------
>  migration/options.c      |  5 +++++
>  migration/postcopy-ram.c |  2 +-
>  migration/socket.c       |  9 +++------
>  migration/tls.c          | 17 ++++-------------
>  migration/tls.h          |  2 --
>  migration/trace-events   | 10 +++++-----
>  12 files changed, 26 insertions(+), 41 deletions(-)
> 
> diff --git a/migration/channel.c b/migration/channel.c
> index b4ab676048..ba14f66d85 100644
> --- a/migration/channel.c
> +++ b/migration/channel.c
> @@ -60,20 +60,18 @@ void migration_channel_process_incoming(QIOChannel *ioc)
>   *
>   * @s: Current migration state
>   * @ioc: Channel to which we are connecting
> - * @hostname: Where we want to connect
>   * @error: Error indicating failure to connect, free'd here
>   */
>  void migration_channel_connect(MigrationState *s,
>                                 QIOChannel *ioc,
> -                               const char *hostname,
>                                 Error *error)
>  {
>      trace_migration_set_outgoing_channel(
> -        ioc, object_get_typename(OBJECT(ioc)), hostname, error);
> +        ioc, object_get_typename(OBJECT(ioc)), error);
>  
>      if (!error) {
>          if (migrate_channel_requires_tls_upgrade(ioc)) {
> -            migration_tls_channel_connect(s, ioc, hostname, &error);
> +            migration_tls_channel_connect(s, ioc, &error);
>  
>              if (!error) {
>                  /* tls_channel_connect will call back to this
> diff --git a/migration/channel.h b/migration/channel.h
> index 5bdb8208a7..2215091323 100644
> --- a/migration/channel.h
> +++ b/migration/channel.h
> @@ -22,7 +22,6 @@ void migration_channel_process_incoming(QIOChannel *ioc);
>  
>  void migration_channel_connect(MigrationState *s,
>                                 QIOChannel *ioc,
> -                               const char *hostname,
>                                 Error *error_in);
>  
>  int migration_channel_read_peek(QIOChannel *ioc,
> diff --git a/migration/exec.c b/migration/exec.c
> index 20e6cccf8c..78fe0fff13 100644
> --- a/migration/exec.c
> +++ b/migration/exec.c
> @@ -55,7 +55,7 @@ void exec_start_outgoing_migration(MigrationState *s, strList *command,
>      }
>  
>      qio_channel_set_name(ioc, "migration-exec-outgoing");
> -    migration_channel_connect(s, ioc, NULL, NULL);
> +    migration_channel_connect(s, ioc, NULL);
>      object_unref(OBJECT(ioc));
>  }
>  
> diff --git a/migration/fd.c b/migration/fd.c
> index 9bf9be6acb..c956b260a4 100644
> --- a/migration/fd.c
> +++ b/migration/fd.c
> @@ -70,7 +70,7 @@ void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **
>      }
>  
>      qio_channel_set_name(ioc, "migration-fd-outgoing");
> -    migration_channel_connect(s, ioc, NULL, NULL);
> +    migration_channel_connect(s, ioc, NULL);
>      object_unref(OBJECT(ioc));
>  }
>  
> diff --git a/migration/file.c b/migration/file.c
> index bb8031e3c7..c490f2b219 100644
> --- a/migration/file.c
> +++ b/migration/file.c
> @@ -122,7 +122,7 @@ void file_start_outgoing_migration(MigrationState *s,
>          return;
>      }
>      qio_channel_set_name(ioc, "migration-file-outgoing");
> -    migration_channel_connect(s, ioc, NULL, NULL);
> +    migration_channel_connect(s, ioc, NULL);
>  }
>  
>  static gboolean file_accept_incoming_migration(QIOChannel *ioc,
> diff --git a/migration/multifd.c b/migration/multifd.c
> index bf6da85af8..3fb1a07ba9 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -814,12 +814,10 @@ static bool multifd_tls_channel_connect(MultiFDSendParams *p,
>                                          QIOChannel *ioc,
>                                          Error **errp)
>  {
> -    MigrationState *s = migrate_get_current();
> -    const char *hostname = s->hostname;
>      MultiFDTLSThreadArgs *args;
>      QIOChannelTLS *tioc;
>  
> -    tioc = migration_tls_client_create(ioc, hostname, errp);
> +    tioc = migration_tls_client_create(ioc, errp);
>      if (!tioc) {
>          return false;
>      }
> @@ -829,7 +827,7 @@ static bool multifd_tls_channel_connect(MultiFDSendParams *p,
>       * created TLS channel, which has already taken a reference.
>       */
>      object_unref(OBJECT(ioc));
> -    trace_multifd_tls_outgoing_handshake_start(ioc, tioc, hostname);
> +    trace_multifd_tls_outgoing_handshake_start(ioc, tioc);
>      qio_channel_set_name(QIO_CHANNEL(tioc), "multifd-tls-outgoing");
>  
>      args = g_new0(MultiFDTLSThreadArgs, 1);
> @@ -876,8 +874,7 @@ static void multifd_new_send_channel_async(QIOTask *task, gpointer opaque)
>          goto out;
>      }
>  
> -    trace_multifd_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)),
> -                                       migrate_get_current()->hostname);
> +    trace_multifd_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)));
>  
>      if (migrate_channel_requires_tls_upgrade(ioc)) {
>          ret = multifd_tls_channel_connect(p, ioc, &local_err);
> diff --git a/migration/options.c b/migration/options.c
> index 9a5a39c886..881034c289 100644
> --- a/migration/options.c
> +++ b/migration/options.c
> @@ -956,6 +956,11 @@ const char *migrate_tls_hostname(void)
>          return s->parameters.tls_hostname->u.s;
>      }
>  
> +    /* hostname saved from a previously connected channel */
> +    if (s->hostname) {
> +        return s->hostname;
> +    }
> +
>      return NULL;
>  }
>  
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index 3623ab9dab..03cb0d8d65 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -1966,7 +1966,7 @@ postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
>      }
>  
>      if (migrate_channel_requires_tls_upgrade(ioc)) {
> -        tioc = migration_tls_client_create(ioc, s->hostname, &local_err);
> +        tioc = migration_tls_client_create(ioc, &local_err);
>          if (!tioc) {
>              goto out;
>          }
> diff --git a/migration/socket.c b/migration/socket.c
> index 9e379bf56f..426f363b99 100644
> --- a/migration/socket.c
> +++ b/migration/socket.c
> @@ -44,7 +44,6 @@ void socket_send_channel_create(QIOTaskFunc f, void *data)
>  
>  struct SocketConnectData {
>      MigrationState *s;
> -    char *hostname;
>  };
>  
>  static void socket_connect_data_free(void *opaque)
> @@ -53,7 +52,6 @@ static void socket_connect_data_free(void *opaque)
>      if (!data) {
>          return;
>      }
> -    g_free(data->hostname);
>      g_free(data);
>  }
>  
> @@ -69,7 +67,7 @@ static void socket_outgoing_migration(QIOTask *task,
>             goto out;
>      }
>  
> -    trace_migration_socket_outgoing_connected(data->hostname);
> +    trace_migration_socket_outgoing_connected();
>  
>      if (migrate_zero_copy_send() &&
>          !qio_channel_has_feature(sioc, QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY)) {
> @@ -77,7 +75,7 @@ static void socket_outgoing_migration(QIOTask *task,
>      }
>  
>  out:
> -    migration_channel_connect(data->s, sioc, data->hostname, err);
> +    migration_channel_connect(data->s, sioc, err);
>      object_unref(OBJECT(sioc));
>  }
>  
> @@ -96,7 +94,7 @@ void socket_start_outgoing_migration(MigrationState *s,
>      outgoing_args.saddr = addr;
>  
>      if (saddr->type == SOCKET_ADDRESS_TYPE_INET) {
> -        data->hostname = g_strdup(saddr->u.inet.host);
> +        s->hostname = g_strdup(saddr->u.inet.host);
>      }
>  
>      qio_channel_set_name(QIO_CHANNEL(sioc), "migration-socket-outgoing");
> @@ -180,4 +178,3 @@ void socket_start_incoming_migration(SocketAddress *saddr,
>          qapi_free_SocketAddress(address);
>      }
>  }
> -
> diff --git a/migration/tls.c b/migration/tls.c
> index 1df31bdcbb..82f58cbc78 100644
> --- a/migration/tls.c
> +++ b/migration/tls.c
> @@ -112,12 +112,11 @@ static void migration_tls_outgoing_handshake(QIOTask *task,
>      } else {
>          trace_migration_tls_outgoing_handshake_complete();
>      }
> -    migration_channel_connect(s, ioc, NULL, err);
> +    migration_channel_connect(s, ioc, err);
>      object_unref(OBJECT(ioc));
>  }
>  
>  QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
> -                                           const char *hostname,
>                                             Error **errp)
>  {
>      QCryptoTLSCreds *creds;
> @@ -127,29 +126,21 @@ QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
>          return NULL;
>      }
>  
> -    const char *tls_hostname = migrate_tls_hostname();
> -    if (tls_hostname) {
> -        hostname = tls_hostname;
> -    }
> -
> -    return qio_channel_tls_new_client(ioc, creds, hostname, errp);
> +    return qio_channel_tls_new_client(ioc, creds, migrate_tls_hostname(), errp);
>  }
>  
>  void migration_tls_channel_connect(MigrationState *s,
>                                     QIOChannel *ioc,
> -                                   const char *hostname,
>                                     Error **errp)
>  {
>      QIOChannelTLS *tioc;
>  
> -    tioc = migration_tls_client_create(ioc, hostname, errp);
> +    tioc = migration_tls_client_create(ioc, errp);
>      if (!tioc) {
>          return;
>      }
>  
> -    /* Save hostname into MigrationState for handshake */
> -    s->hostname = g_strdup(hostname);
> -    trace_migration_tls_outgoing_handshake_start(hostname);
> +    trace_migration_tls_outgoing_handshake_start();
>      qio_channel_set_name(QIO_CHANNEL(tioc), "migration-tls-outgoing");
>  
>      if (migrate_postcopy_ram() || migrate_return_path()) {
> diff --git a/migration/tls.h b/migration/tls.h
> index 7607cfe803..7cd9c76013 100644
> --- a/migration/tls.h
> +++ b/migration/tls.h
> @@ -27,12 +27,10 @@
>  void migration_tls_channel_process_incoming(QIOChannel *ioc, Error **errp);
>  
>  QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
> -                                           const char *hostname,
>                                             Error **errp);
>  
>  void migration_tls_channel_connect(MigrationState *s,
>                                     QIOChannel *ioc,
> -                                   const char *hostname,
>                                     Error **errp);
>  void migration_tls_channel_end(QIOChannel *ioc, Error **errp);
>  /* Whether the QIO channel requires further TLS handshake? */
> diff --git a/migration/trace-events b/migration/trace-events
> index bf11b62b17..da8f909cac 100644
> --- a/migration/trace-events
> +++ b/migration/trace-events
> @@ -149,10 +149,10 @@ multifd_send_sync_main_wait(uint8_t id) "channel %u"
>  multifd_send_terminate_threads(void) ""
>  multifd_send_thread_end(uint8_t id, uint64_t packets) "channel %u packets %" PRIu64
>  multifd_send_thread_start(uint8_t id) "%u"
> -multifd_tls_outgoing_handshake_start(void *ioc, void *tioc, const char *hostname) "ioc=%p tioc=%p hostname=%s"
> +multifd_tls_outgoing_handshake_start(void *ioc, void *tioc) "ioc=%p tioc=%p"
>  multifd_tls_outgoing_handshake_error(void *ioc, const char *err) "ioc=%p err=%s"
>  multifd_tls_outgoing_handshake_complete(void *ioc) "ioc=%p"
> -multifd_set_outgoing_channel(void *ioc, const char *ioctype, const char *hostname)  "ioc=%p ioctype=%s hostname=%s"
> +multifd_set_outgoing_channel(void *ioc, const char *ioctype)  "ioc=%p ioctype=%s"
>  
>  # migration.c
>  migrate_set_state(const char *new_state) "new state %s"
> @@ -204,7 +204,7 @@ migration_transferred_bytes(uint64_t qemu_file, uint64_t multifd, uint64_t rdma)
>  
>  # channel.c
>  migration_set_incoming_channel(void *ioc, const char *ioctype) "ioc=%p ioctype=%s"
> -migration_set_outgoing_channel(void *ioc, const char *ioctype, const char *hostname, void *err)  "ioc=%p ioctype=%s hostname=%s err=%p"
> +migration_set_outgoing_channel(void *ioc, const char *ioctype, void *err)  "ioc=%p ioctype=%s err=%p"
>  
>  # global_state.c
>  migrate_state_too_big(void) ""
> @@ -328,11 +328,11 @@ migration_file_incoming(const char *filename) "filename=%s"
>  
>  # socket.c
>  migration_socket_incoming_accepted(void) ""
> -migration_socket_outgoing_connected(const char *hostname) "hostname=%s"
> +migration_socket_outgoing_connected(void) ""
>  migration_socket_outgoing_error(const char *err) "error=%s"
>  
>  # tls.c
> -migration_tls_outgoing_handshake_start(const char *hostname) "hostname=%s"
> +migration_tls_outgoing_handshake_start(void) ""
>  migration_tls_outgoing_handshake_error(const char *err) "err=%s"
>  migration_tls_outgoing_handshake_complete(void) ""
>  migration_tls_incoming_handshake_start(void) ""
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 06/25] migration: Move postcopy_try_recover into migration_incoming_process

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:08PM -0300, Fabiano Rosas wrote:
> The postcopy_try_recover() call doesn't need to be duplicated, move it
> into migration_incoming_process().
> 
> This removes code from migration_fd_process_incoming() so it can be
> removed in the near future.
> 
> (the diff is a bit strange because migration_incoming_process() was
> moved after postcopy_try_recover())
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu

Re: [RFC PATCH 07/25] migration: Use migrate_mode() to query for cpr-transfer

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:09PM -0300, Fabiano Rosas wrote:
> cpr_set_incoming_mode() is only called on the target side, so
> migrate_mode() on the source side is the same as s->parameters.mode.
> 
> Use the function to reduce explicit access to s->parameters, we have
> options.c for that.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Reviewed-by: Peter Xu <peterx@redhat.com>

Said that, we have three more users outside options.c.  Wanna do it
together?  They are:

  migration_call_notifiers, migrate_mode_is_cpr, migrate_prepare.

> ---
>  migration/migration.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index f2933f7789..4b1afcab24 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2252,7 +2252,7 @@ void qmp_migrate(const char *uri, bool has_channels,
>          return;
>      }
>  
> -    if (s->parameters.mode == MIG_MODE_CPR_TRANSFER && !cpr_channel) {
> +    if (migrate_mode() == MIG_MODE_CPR_TRANSFER && !cpr_channel) {
>          error_setg(errp, "missing 'cpr' migration channel");
>          return;
>      }
> @@ -2277,7 +2277,7 @@ void qmp_migrate(const char *uri, bool has_channels,
>       * in which case the target will not listen for the incoming migration
>       * connection, so qmp_migrate_finish will fail to connect, and then recover.
>       */
> -    if (s->parameters.mode == MIG_MODE_CPR_TRANSFER) {
> +    if (migrate_mode() == MIG_MODE_CPR_TRANSFER) {
>          migrate_hup_add(s, cpr_state_ioc(), (GSourceFunc)qmp_migrate_finish_cb,
>                          QAPI_CLONE(MigrationAddress, addr));
>  
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 08/25] migration: Free the error earlier in the resume case'

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:10PM -0300, Fabiano Rosas wrote:
> Freeing the error at migration_connect() is redundant in the normal
> migration case. The freeing already happened at migrate_init():
> 
> qmp_migrate()
> -> migrate_prepare()
>    -> migrate_init()
> -> qmp_migrate_finish()
>    -> *_start_outgoing_migration()
>    -> migration_channel_connect()
>       -> migration_connect()
> 
> For the resume case, migrate_prepare() returns early and doesn't reach
> migrate_init(). Move the extra migrate_error_free() call to
> migrate_prepare() along with the resume check.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Reviewed-by: Peter Xu <peterx@redhat.com>

We could also use migrate_error_free() in migrate_init(), to be clear on
when the error can be erased.

> ---
>  migration/migration.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 4b1afcab24..a56f8fb05e 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2088,6 +2088,13 @@ static bool migrate_prepare(MigrationState *s, bool resume, Error **errp)
>          migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_PAUSED,
>                            MIGRATION_STATUS_POSTCOPY_RECOVER_SETUP);
>  
> +        /*
> +         * If there's a previous error, free it and prepare for
> +         * another one. For the non-resume case, this happens at
> +         * migrate_init() below.
> +         */
> +        migrate_error_free(s);
> +
>          /* This is a resume, skip init status */
>          return true;
>      }
> @@ -4016,13 +4023,6 @@ void migration_connect(MigrationState *s, Error *error_in)
>      bool resume = (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER_SETUP);
>      int ret;
>  
> -    /*
> -     * If there's a previous error, free it and prepare for another one.
> -     * Meanwhile if migration completes successfully, there won't have an error
> -     * dumped when calling migration_cleanup().
> -     */
> -    migrate_error_free(s);
> -
>      s->expected_downtime = migrate_downtime_limit();
>      if (error_in) {
>          migration_connect_error_propagate(s, error_in);
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 09/25] migration: Move error reporting out of migration_cleanup

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:11PM -0300, Fabiano Rosas wrote:
> In the next patches migration_cleanup() will be used in qmp_migrate(),
> which currently does not show an error message. Move the error
> reporting out of migration_cleanup() to avoid duplicated messages.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Reviewed-by: Peter Xu <peterx@redhat.com>

With one comment on top below:

> ---
>  migration/migration.c | 28 +++++++++++++---------------
>  1 file changed, 13 insertions(+), 15 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index a56f8fb05e..83854d084a 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1528,10 +1528,6 @@ static void migration_cleanup(MigrationState *s)
>                            MIGRATION_STATUS_CANCELLED);
>      }
>  
> -    if (s->error) {
> -        /* It is used on info migrate.  We can't free it */
> -        error_report_err(error_copy(s->error));
> -    }
>      type = migration_has_failed(s) ? MIG_EVENT_PRECOPY_FAILED :
>                                       MIG_EVENT_PRECOPY_DONE;
>      migration_call_notifiers(s, type, NULL);
> @@ -1540,7 +1536,12 @@ static void migration_cleanup(MigrationState *s)
>  
>  static void migration_cleanup_bh(void *opaque)
>  {
> -    migration_cleanup(opaque);
> +    MigrationState *s = opaque;
> +
> +    migration_cleanup(s);
> +    if (s->error) {
> +        error_report_err(error_copy(s->error));
> +    }
>  }
>  
>  /*
> @@ -4026,18 +4027,12 @@ void migration_connect(MigrationState *s, Error *error_in)
>      s->expected_downtime = migrate_downtime_limit();
>      if (error_in) {
>          migration_connect_error_propagate(s, error_in);
> -        if (resume) {
> -            /*
> -             * Don't do cleanup for resume if channel is invalid, but only dump
> -             * the error.  We wait for another channel connect from the user.
> -             * The error_report still gives HMP user a hint on what failed.
> -             * It's normally done in migration_cleanup(), but call it here
> -             * explicitly.
> -             */
> -            error_report_err(error_copy(s->error));
> -        } else {
> +        if (!resume) {
>              migration_cleanup(s);
>          }
> +        if (s->error) {
> +            error_report_err(error_copy(s->error));
> +        }
>          return;
>      }
>  
> @@ -4118,6 +4113,9 @@ fail:
>      }
>      error_report_err(local_err);

[1]

>      migration_cleanup(s);
> +    if (s->error) {
> +        error_report_err(error_copy(s->error));
> +    }

This should keep no functional difference, which looks correct from that
regard.

Said that, I wonder if we can drop [1] above, because when reaching here
error_in must not be set, so I don't yet see how s->error can be different
from local_err.

>  }
>  
>  static void migration_class_init(ObjectClass *klass, const void *data)
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 10/25] migration: Expand migration_connect_error_propagate to cover cancelling

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:12PM -0300, Fabiano Rosas wrote:
> Cover the CANCELLING state in migration_connect_error_propagate() and
> use it to funnel errors from migrate_prepare() until the end of
> migration_connect().
> 
> (add some line breaks for legibility)
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
>  migration/migration.c | 24 +++++++++++++++---------
>  1 file changed, 15 insertions(+), 9 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 83854d084a..e1c00867ab 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1575,18 +1575,25 @@ static void migrate_error_free(MigrationState *s)
>  static void migration_connect_error_propagate(MigrationState *s, Error *error)
>  {
>      MigrationStatus current = s->state;
> -    MigrationStatus next;
> -
> -    assert(s->to_dst_file == NULL);
> +    MigrationStatus next = MIGRATION_STATUS_NONE;
>  
>      switch (current) {
>      case MIGRATION_STATUS_SETUP:
>          next = MIGRATION_STATUS_FAILED;
>          break;
> +
>      case MIGRATION_STATUS_POSTCOPY_RECOVER_SETUP:
>          /* Never fail a postcopy migration; switch back to PAUSED instead */
>          next = MIGRATION_STATUS_POSTCOPY_PAUSED;
>          break;
> +
> +    case MIGRATION_STATUS_CANCELLING:
> +        /*
> +         * Don't move out of CANCELLING, the only valid transition is to
> +         * CANCELLED, at migration_cleanup().
> +         */
> +        break;
> +
>      default:
>          /*
>           * This really shouldn't happen. Just be careful to not crash a VM
> @@ -1597,7 +1604,10 @@ static void migration_connect_error_propagate(MigrationState *s, Error *error)
>          return;
>      }
>  
> -    migrate_set_state(&s->state, current, next);
> +    if (next) {
> +        migrate_set_state(&s->state, current, next);
> +    }
> +
>      migrate_error_propagate(s, error);
>  }
>  
> @@ -4107,11 +4117,7 @@ void migration_connect(MigrationState *s, Error *error_in)
>      return;
>  
>  fail:
> -    migrate_error_propagate(s, error_copy(local_err));
> -    if (s->state != MIGRATION_STATUS_CANCELLING) {
> -        migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED);
> -    }
> -    error_report_err(local_err);

OK you removed this line here..  maybe it should belong to the previous
patch?

If you agree, feel free to take:

Reviewed-by: Peter Xu <peterx@redhat.com>

> +    migration_connect_error_propagate(s, local_err);
>      migration_cleanup(s);
>      if (s->error) {
>          error_report_err(error_copy(s->error));
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 11/25] migration: yank: Move register instance earlier

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:13PM -0300, Fabiano Rosas wrote:
> Move the register_instance call to migrate_prepare() so it can be
> paired with the unregister_instance at migration_cleanup(). Otherwise,
> the cleanup cannot be run when cpr_state_save() fails because the
> instance is registered only after it.
> 
> When resuming from a paused postcopy migration, migrate_prepare()
> returns early, but migration_cleanup() doesn't run, so the yank will
> remain paired.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu

Re: [RFC PATCH 12/25] migration: Fold migration_cleanup() into migration_connect_error_propagate()

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:14PM -0300, Fabiano Rosas wrote:
> Whenever an error occurs between migrate_init() and the start of
> migration_thread, do cleanup immediately after.
> 
> This allows the special casing for resume to be removed from
> migration_connect(), that check is now done at
> migration_connect_error_propagate() which already had a case for
> resume.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Didn't spot anything wrong,

Reviewed-by: Peter Xu <peterx@redhat.com>

One nitpick below,

> ---
>  migration/migration.c | 42 +++++++++++++++++++++++++++---------------
>  1 file changed, 27 insertions(+), 15 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 0f1644b276..a66b2d7aaf 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1576,15 +1576,21 @@ static void migration_connect_error_propagate(MigrationState *s, Error *error)
>  {
>      MigrationStatus current = s->state;
>      MigrationStatus next = MIGRATION_STATUS_NONE;
> +    bool resume = false;
>  
>      switch (current) {
>      case MIGRATION_STATUS_SETUP:
>          next = MIGRATION_STATUS_FAILED;
>          break;
>  
> +    case MIGRATION_STATUS_POSTCOPY_PAUSED:
> +        resume = true;
> +        break;
> +
>      case MIGRATION_STATUS_POSTCOPY_RECOVER_SETUP:
>          /* Never fail a postcopy migration; switch back to PAUSED instead */
>          next = MIGRATION_STATUS_POSTCOPY_PAUSED;
> +        resume = true;
>          break;
>  
>      case MIGRATION_STATUS_CANCELLING:
> @@ -1609,6 +1615,10 @@ static void migration_connect_error_propagate(MigrationState *s, Error *error)
>      }
>  
>      migrate_error_propagate(s, error);
> +
> +    if (!resume) {
> +        migration_cleanup(s);
> +    }
>  }
>  
>  void migration_cancel(void)
> @@ -2209,12 +2219,19 @@ static gboolean qmp_migrate_finish_cb(QIOChannel *channel,
>                                        GIOCondition cond,
>                                        void *opaque)
>  {
> +    MigrationState *s = migrate_get_current();
>      MigrationAddress *addr = opaque;
> +    Error *local_err = NULL;
> +
> +    qmp_migrate_finish(addr, &local_err);
> +
> +    if (local_err) {
> +        migration_connect_error_propagate(s, local_err);
> +    }
>  
> -    qmp_migrate_finish(addr, NULL);
>  
>      cpr_state_close();
> -    migrate_hup_delete(migrate_get_current());
> +    migrate_hup_delete(s);

IMHO we should drop these two lines.  For error cases, now they'll be done
in migration_cleanup() above.  Actually for success, it's the same, but in
the cleanup BH.

Maybe there're other cases where we can clean the code a bit on cpr;
there're codes that always does "if (xxx)" and calling them all over the
places, so it's easy to write such code when drafting a feature, but hard
to maintain, because it'll be obscure when it'll really trigger, like this
one.  We can leave the rest for later if there're applicable similar
cleanups.

>      qapi_free_MigrationAddress(addr);
>      return G_SOURCE_REMOVE;
>  }
> @@ -2223,7 +2240,6 @@ void qmp_migrate(const char *uri, bool has_channels,
>                   MigrationChannelList *channels, bool has_detach, bool detach,
>                   bool has_resume, bool resume, Error **errp)
>  {
> -    Error *local_err = NULL;
>      MigrationState *s = migrate_get_current();
>      g_autoptr(MigrationChannel) channel = NULL;
>      MigrationAddress *addr = NULL;
> @@ -2280,6 +2296,13 @@ void qmp_migrate(const char *uri, bool has_channels,
>          return;
>      }
>  
> +    /*
> +     * The migrate_prepare() above calls migrate_init(). From this
> +     * point on, until the end of migration, make sure any failures
> +     * eventually result in a call to migration_cleanup().
> +     */
> +    Error *local_err = NULL;
> +
>      if (!cpr_state_save(cpr_channel, &local_err)) {
>          goto out;
>      }
> @@ -2299,12 +2322,11 @@ void qmp_migrate(const char *uri, bool has_channels,
>                          QAPI_CLONE(MigrationAddress, addr));
>  
>      } else {
> -        qmp_migrate_finish(addr, errp);
> +        qmp_migrate_finish(addr, &local_err);
>      }
>  
>  out:
>      if (local_err) {
> -        yank_unregister_instance(MIGRATION_YANK_INSTANCE);
>          migration_connect_error_propagate(s, error_copy(local_err));
>          error_propagate(errp, local_err);
>      }
> @@ -2335,12 +2357,6 @@ static void qmp_migrate_finish(MigrationAddress *addr, Error **errp)
>      } else {
>          error_setg(&local_err, "uri is not a valid migration protocol");
>      }
> -
> -    if (local_err) {
> -        migration_connect_error_propagate(s, error_copy(local_err));
> -        error_propagate(errp, local_err);
> -        return;
> -    }
>  }
>  
>  void qmp_migrate_cancel(Error **errp)
> @@ -4027,9 +4043,6 @@ void migration_connect(MigrationState *s, Error *error_in)
>      s->expected_downtime = migrate_downtime_limit();
>      if (error_in) {
>          migration_connect_error_propagate(s, error_in);
> -        if (!resume) {
> -            migration_cleanup(s);
> -        }
>          if (s->error) {
>              error_report_err(error_copy(s->error));
>          }
> @@ -4108,7 +4121,6 @@ void migration_connect(MigrationState *s, Error *error_in)
>  
>  fail:
>      migration_connect_error_propagate(s, local_err);
> -    migration_cleanup(s);
>      if (s->error) {
>          error_report_err(error_copy(s->error));
>      }
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 13/25] migration: Handle error in the early async paths

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:15PM -0300, Fabiano Rosas wrote:
> Simplify migration_channel_connect() and migration_connect() to not
> take an error as input. Move the error handling into the paths that
> generate the error.
> 
> To achive this, call migration_connect_error_propagate() from socket.c
> and tls.c, which are the async paths.
> 
> For the sync paths, the handling is done as normal by returning all
> the way to qmp_migrate_finish(), except that now the sync paths don't
> pass the error forward into migration_connect() anymore.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Yeah this looks better in general, feel free to take:

Reviewed-by: Peter Xu <peterx@redhat.com>

One thing to mention:

Strictly speaking, migration_tls_channel_connect() doesn't fall into the
"async op" category - it was invoked from migration core, so logically it
can still keep its errp, then the migration core should also be able to
process the error in migration_channel_connect().  It's not like the other
two "async ops" where migration context was lost.

IOW, I can kind of see why we used to pass an Error into the current
migration_channel_connect(), and it still makes some sense.  OTOH, it
doesn't really make sense to me to keep passing it to migration_connect()..

But since that's the only user of migration_tls_channel_connect(), I assume
it's not a huge deal, anyway.

> ---
>  migration/channel.c    | 46 +++++++++++++++++-------------------------
>  migration/channel.h    |  4 +---
>  migration/exec.c       |  2 +-
>  migration/fd.c         |  2 +-
>  migration/file.c       |  2 +-
>  migration/migration.c  | 11 ++--------
>  migration/migration.h  |  3 ++-
>  migration/rdma.c       |  2 +-
>  migration/socket.c     | 17 ++++++++--------
>  migration/tls.c        | 19 ++++++++---------
>  migration/tls.h        |  4 +---
>  migration/trace-events |  2 +-
>  12 files changed, 49 insertions(+), 65 deletions(-)
> 
> diff --git a/migration/channel.c b/migration/channel.c
> index ba14f66d85..7243b99108 100644
> --- a/migration/channel.c
> +++ b/migration/channel.c
> @@ -60,38 +60,30 @@ void migration_channel_process_incoming(QIOChannel *ioc)
>   *
>   * @s: Current migration state
>   * @ioc: Channel to which we are connecting
> - * @error: Error indicating failure to connect, free'd here
>   */
> -void migration_channel_connect(MigrationState *s,
> -                               QIOChannel *ioc,
> -                               Error *error)
> +void migration_channel_connect(MigrationState *s, QIOChannel *ioc)
>  {
> -    trace_migration_set_outgoing_channel(
> -        ioc, object_get_typename(OBJECT(ioc)), error);
> +    trace_migration_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)));
>  
> -    if (!error) {
> -        if (migrate_channel_requires_tls_upgrade(ioc)) {
> -            migration_tls_channel_connect(s, ioc, &error);
> +    if (migrate_channel_requires_tls_upgrade(ioc)) {
> +        migration_tls_channel_connect(s, ioc);
>  
> -            if (!error) {
> -                /* tls_channel_connect will call back to this
> -                 * function after the TLS handshake,
> -                 * so we mustn't call migration_connect until then
> -                 */
> -
> -                return;
> -            }
> -        } else {
> -            QEMUFile *f = qemu_file_new_output(ioc);
> -
> -            migration_ioc_register_yank(ioc);
> -
> -            qemu_mutex_lock(&s->qemu_file_lock);
> -            s->to_dst_file = f;
> -            qemu_mutex_unlock(&s->qemu_file_lock);
> -        }
> +        /*
> +         * async: the above will call back to this function after
> +         * the TLS handshake is successfully completed.
> +         */
> +        return;
>      }
> -    migration_connect(s, error);
> +
> +    QEMUFile *f = qemu_file_new_output(ioc);
> +
> +    migration_ioc_register_yank(ioc);
> +
> +    qemu_mutex_lock(&s->qemu_file_lock);
> +    s->to_dst_file = f;
> +    qemu_mutex_unlock(&s->qemu_file_lock);
> +
> +    migration_connect(s);
>  }
>  
>  
> diff --git a/migration/channel.h b/migration/channel.h
> index 2215091323..ccfeaaef18 100644
> --- a/migration/channel.h
> +++ b/migration/channel.h
> @@ -20,9 +20,7 @@
>  
>  void migration_channel_process_incoming(QIOChannel *ioc);
>  
> -void migration_channel_connect(MigrationState *s,
> -                               QIOChannel *ioc,
> -                               Error *error_in);
> +void migration_channel_connect(MigrationState *s, QIOChannel *ioc);
>  
>  int migration_channel_read_peek(QIOChannel *ioc,
>                                  const char *buf,
> diff --git a/migration/exec.c b/migration/exec.c
> index 78fe0fff13..d83a07435a 100644
> --- a/migration/exec.c
> +++ b/migration/exec.c
> @@ -55,7 +55,7 @@ void exec_start_outgoing_migration(MigrationState *s, strList *command,
>      }
>  
>      qio_channel_set_name(ioc, "migration-exec-outgoing");
> -    migration_channel_connect(s, ioc, NULL);
> +    migration_channel_connect(s, ioc);
>      object_unref(OBJECT(ioc));
>  }
>  
> diff --git a/migration/fd.c b/migration/fd.c
> index c956b260a4..0144a70742 100644
> --- a/migration/fd.c
> +++ b/migration/fd.c
> @@ -70,7 +70,7 @@ void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **
>      }
>  
>      qio_channel_set_name(ioc, "migration-fd-outgoing");
> -    migration_channel_connect(s, ioc, NULL);
> +    migration_channel_connect(s, ioc);
>      object_unref(OBJECT(ioc));
>  }
>  
> diff --git a/migration/file.c b/migration/file.c
> index c490f2b219..7bb9c1c79f 100644
> --- a/migration/file.c
> +++ b/migration/file.c
> @@ -122,7 +122,7 @@ void file_start_outgoing_migration(MigrationState *s,
>          return;
>      }
>      qio_channel_set_name(ioc, "migration-file-outgoing");
> -    migration_channel_connect(s, ioc, NULL);
> +    migration_channel_connect(s, ioc);
>  }
>  
>  static gboolean file_accept_incoming_migration(QIOChannel *ioc,
> diff --git a/migration/migration.c b/migration/migration.c
> index a66b2d7aaf..5c6c76f110 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1572,7 +1572,7 @@ static void migrate_error_free(MigrationState *s)
>      }
>  }
>  
> -static void migration_connect_error_propagate(MigrationState *s, Error *error)
> +void migration_connect_error_propagate(MigrationState *s, Error *error)
>  {
>      MigrationStatus current = s->state;
>      MigrationStatus next = MIGRATION_STATUS_NONE;
> @@ -4033,7 +4033,7 @@ fail_setup:
>      return NULL;
>  }
>  
> -void migration_connect(MigrationState *s, Error *error_in)
> +void migration_connect(MigrationState *s)
>  {
>      Error *local_err = NULL;
>      uint64_t rate_limit;
> @@ -4041,13 +4041,6 @@ void migration_connect(MigrationState *s, Error *error_in)
>      int ret;
>  
>      s->expected_downtime = migrate_downtime_limit();
> -    if (error_in) {
> -        migration_connect_error_propagate(s, error_in);
> -        if (s->error) {
> -            error_report_err(error_copy(s->error));
> -        }
> -        return;
> -    }
>  
>      if (resume) {
>          /* This is a resumed migration */
> diff --git a/migration/migration.h b/migration/migration.h
> index 4d42e8f9a7..f340cd518d 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -532,10 +532,11 @@ void migration_incoming_process(void);
>  
>  bool  migration_has_all_channels(void);
>  
> +void migration_connect_error_propagate(MigrationState *s, Error *error);
>  void migrate_error_propagate(MigrationState *s, Error *error);
>  bool migrate_has_error(MigrationState *s);
>  
> -void migration_connect(MigrationState *s, Error *error_in);
> +void migration_connect(MigrationState *s);
>  
>  int migration_call_notifiers(MigrationState *s, MigrationEventType type,
>                               Error **errp);
> diff --git a/migration/rdma.c b/migration/rdma.c
> index 337b415889..596a1aba0b 100644
> --- a/migration/rdma.c
> +++ b/migration/rdma.c
> @@ -3997,7 +3997,7 @@ void rdma_start_outgoing_migration(void *opaque,
>  
>      s->to_dst_file = rdma_new_output(rdma);
>      s->rdma_migration = true;
> -    migration_connect(s, NULL);
> +    migration_connect(s);
>      return;
>  return_path_err:
>      qemu_rdma_cleanup(rdma);
> diff --git a/migration/socket.c b/migration/socket.c
> index 426f363b99..298bac30cc 100644
> --- a/migration/socket.c
> +++ b/migration/socket.c
> @@ -59,24 +59,25 @@ static void socket_outgoing_migration(QIOTask *task,
>                                        gpointer opaque)
>  {
>      struct SocketConnectData *data = opaque;
> -    QIOChannel *sioc = QIO_CHANNEL(qio_task_get_source(task));
> +    g_autoptr(QIOChannel) sioc = QIO_CHANNEL(qio_task_get_source(task));
>      Error *err = NULL;
>  
>      if (qio_task_propagate_error(task, &err)) {
> -        trace_migration_socket_outgoing_error(error_get_pretty(err));
> -           goto out;
> +        goto err;
>      }
>  
> -    trace_migration_socket_outgoing_connected();
> -
>      if (migrate_zero_copy_send() &&
>          !qio_channel_has_feature(sioc, QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY)) {
>          error_setg(&err, "Zero copy send feature not detected in host kernel");
> +        goto err;
>      }
>  
> -out:
> -    migration_channel_connect(data->s, sioc, err);
> -    object_unref(OBJECT(sioc));
> +    trace_migration_socket_outgoing_connected();
> +    migration_channel_connect(data->s, sioc);
> +    return;
> +err:
> +    trace_migration_socket_outgoing_error(error_get_pretty(err));
> +    migration_connect_error_propagate(data->s, err);
>  }
>  
>  void socket_start_outgoing_migration(MigrationState *s,
> diff --git a/migration/tls.c b/migration/tls.c
> index 82f58cbc78..a54e8e6e14 100644
> --- a/migration/tls.c
> +++ b/migration/tls.c
> @@ -104,16 +104,17 @@ static void migration_tls_outgoing_handshake(QIOTask *task,
>                                               gpointer opaque)
>  {
>      MigrationState *s = opaque;
> -    QIOChannel *ioc = QIO_CHANNEL(qio_task_get_source(task));
> +    g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
>      Error *err = NULL;
>  
>      if (qio_task_propagate_error(task, &err)) {
>          trace_migration_tls_outgoing_handshake_error(error_get_pretty(err));
> -    } else {
> -        trace_migration_tls_outgoing_handshake_complete();
> +        migration_connect_error_propagate(s, err);
> +        return;
>      }
> -    migration_channel_connect(s, ioc, err);
> -    object_unref(OBJECT(ioc));
> +
> +    trace_migration_tls_outgoing_handshake_complete();
> +    migration_channel_connect(s, ioc);
>  }
>  
>  QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
> @@ -129,14 +130,14 @@ QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
>      return qio_channel_tls_new_client(ioc, creds, migrate_tls_hostname(), errp);
>  }
>  
> -void migration_tls_channel_connect(MigrationState *s,
> -                                   QIOChannel *ioc,
> -                                   Error **errp)
> +void migration_tls_channel_connect(MigrationState *s, QIOChannel *ioc)
>  {
>      QIOChannelTLS *tioc;
> +    Error *local_err = NULL;
>  
> -    tioc = migration_tls_client_create(ioc, errp);
> +    tioc = migration_tls_client_create(ioc, &local_err);
>      if (!tioc) {
> +        migration_connect_error_propagate(s, local_err);
>          return;
>      }
>  
> diff --git a/migration/tls.h b/migration/tls.h
> index 7cd9c76013..7399c42edf 100644
> --- a/migration/tls.h
> +++ b/migration/tls.h
> @@ -29,9 +29,7 @@ void migration_tls_channel_process_incoming(QIOChannel *ioc, Error **errp);
>  QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
>                                             Error **errp);
>  
> -void migration_tls_channel_connect(MigrationState *s,
> -                                   QIOChannel *ioc,
> -                                   Error **errp);
> +void migration_tls_channel_connect(MigrationState *s, QIOChannel *ioc);
>  void migration_tls_channel_end(QIOChannel *ioc, Error **errp);
>  /* Whether the QIO channel requires further TLS handshake? */
>  bool migrate_channel_requires_tls_upgrade(QIOChannel *ioc);
> diff --git a/migration/trace-events b/migration/trace-events
> index da8f909cac..cbf10d0b63 100644
> --- a/migration/trace-events
> +++ b/migration/trace-events
> @@ -204,7 +204,7 @@ migration_transferred_bytes(uint64_t qemu_file, uint64_t multifd, uint64_t rdma)
>  
>  # channel.c
>  migration_set_incoming_channel(void *ioc, const char *ioctype) "ioc=%p ioctype=%s"
> -migration_set_outgoing_channel(void *ioc, const char *ioctype, void *err)  "ioc=%p ioctype=%s err=%p"
> +migration_set_outgoing_channel(void *ioc, const char *ioctype) "ioc=%p ioctype=%s"
>  
>  # global_state.c
>  migrate_state_too_big(void) ""
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 04/25] migration: Move multifd_recv_setup call

[Fabiano Rosas]

Peter Xu <peterx@redhat.com> writes:

> On Fri, Dec 26, 2025 at 06:19:06PM -0300, Fabiano Rosas wrote:
>> The multifd_recv_setup() call is currently in a place where it will be
>> called for every channel that appears. That doesn't make much
>> sense.
>> 
>> It seems it was moved when the channel discovery mechanism was added
>> back at commit 6720c2b327 (migration: check magic value for deciding
>> the mapping of channels, 2022-12-20). The original place was
>> migration_incoming_setup() which would run for just the main channel,
>> but it was discovered that the main channel might arrive after a
>> multifd channel.
>> 
>> Move the call back to a place where it will be called only once.
>> 
>> With respect to cleanup, this new location at
>> qemu_start_incoming_migration() has the same issue as the previous
>> callsite at migration_ioc_process_incoming(): no cleanup ever happens.
>> 
>> The error message goes from being emitted via error_report_err(), to
>> being returned to the qmp_migrate_incoming() incoming command, which
>> is arguably better, since this is setup code.
>
> This is not the only and real reason that you moved it, right?
>

It was odd where it was and I just moved it. It could probably remain
there even after the rest of the series, I didn't check.

I think it would then need to move to channel.c which would make that
file access multifd code, so maybe it's a layering argument.

> Neither should it be the reason that you want it to be called only exactly
> once; after all the function will be no-op in the 2nd+ calls.
>

It's not a no-op. But yes, it returns early on subsequent calls.

> I'll keep reading.. I'm guessing I'll find it later, but IMHO it'll always
> be good to mention the real motivation in the commit log.
>
>> 
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>> ---
>>  migration/migration.c | 8 ++++----
>>  1 file changed, 4 insertions(+), 4 deletions(-)
>> 
>> diff --git a/migration/migration.c b/migration/migration.c
>> index 71efe945f6..974313944c 100644
>> --- a/migration/migration.c
>> +++ b/migration/migration.c
>> @@ -786,6 +786,10 @@ static void qemu_start_incoming_migration(const char *uri, bool has_channels,
>>          return;
>>      }
>>  
>> +    if (multifd_recv_setup(errp) != 0) {
>> +        return;
>> +    }
>> +
>>      if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
>>          SocketAddress *saddr = &addr->u.socket;
>>          if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
>> @@ -1065,10 +1069,6 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>>          channel = CH_POSTCOPY;
>>      }
>>  
>> -    if (multifd_recv_setup(errp) != 0) {
>> -        return;
>> -    }
>> -
>>      if (channel == CH_MAIN) {
>>          f = qemu_file_new_input(ioc);
>>          migration_incoming_setup(f);
>> -- 
>> 2.51.0
>> 

Re: [RFC PATCH 07/25] migration: Use migrate_mode() to query for cpr-transfer

[Fabiano Rosas]

Peter Xu <peterx@redhat.com> writes:

> On Fri, Dec 26, 2025 at 06:19:09PM -0300, Fabiano Rosas wrote:
>> cpr_set_incoming_mode() is only called on the target side, so
>> migrate_mode() on the source side is the same as s->parameters.mode.
>> 
>> Use the function to reduce explicit access to s->parameters, we have
>> options.c for that.
>> 
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>
> Reviewed-by: Peter Xu <peterx@redhat.com>
>
> Said that, we have three more users outside options.c.  Wanna do it
> together?  They are:
>
>   migration_call_notifiers, migrate_mode_is_cpr, migrate_prepare.
>

Yep

Re: [RFC PATCH 12/25] migration: Fold migration_cleanup() into migration_connect_error_propagate()

[Fabiano Rosas]

Peter Xu <peterx@redhat.com> writes:

> On Fri, Dec 26, 2025 at 06:19:14PM -0300, Fabiano Rosas wrote:
>> Whenever an error occurs between migrate_init() and the start of
>> migration_thread, do cleanup immediately after.
>> 
>> This allows the special casing for resume to be removed from
>> migration_connect(), that check is now done at
>> migration_connect_error_propagate() which already had a case for
>> resume.
>> 
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>
> Didn't spot anything wrong,
>
> Reviewed-by: Peter Xu <peterx@redhat.com>
>
> One nitpick below,
>
>> ---
>>  migration/migration.c | 42 +++++++++++++++++++++++++++---------------
>>  1 file changed, 27 insertions(+), 15 deletions(-)
>> 
>> diff --git a/migration/migration.c b/migration/migration.c
>> index 0f1644b276..a66b2d7aaf 100644
>> --- a/migration/migration.c
>> +++ b/migration/migration.c
>> @@ -1576,15 +1576,21 @@ static void migration_connect_error_propagate(MigrationState *s, Error *error)
>>  {
>>      MigrationStatus current = s->state;
>>      MigrationStatus next = MIGRATION_STATUS_NONE;
>> +    bool resume = false;
>>  
>>      switch (current) {
>>      case MIGRATION_STATUS_SETUP:
>>          next = MIGRATION_STATUS_FAILED;
>>          break;
>>  
>> +    case MIGRATION_STATUS_POSTCOPY_PAUSED:
>> +        resume = true;
>> +        break;
>> +
>>      case MIGRATION_STATUS_POSTCOPY_RECOVER_SETUP:
>>          /* Never fail a postcopy migration; switch back to PAUSED instead */
>>          next = MIGRATION_STATUS_POSTCOPY_PAUSED;
>> +        resume = true;
>>          break;
>>  
>>      case MIGRATION_STATUS_CANCELLING:
>> @@ -1609,6 +1615,10 @@ static void migration_connect_error_propagate(MigrationState *s, Error *error)
>>      }
>>  
>>      migrate_error_propagate(s, error);
>> +
>> +    if (!resume) {
>> +        migration_cleanup(s);
>> +    }
>>  }
>>  
>>  void migration_cancel(void)
>> @@ -2209,12 +2219,19 @@ static gboolean qmp_migrate_finish_cb(QIOChannel *channel,
>>                                        GIOCondition cond,
>>                                        void *opaque)
>>  {
>> +    MigrationState *s = migrate_get_current();
>>      MigrationAddress *addr = opaque;
>> +    Error *local_err = NULL;
>> +
>> +    qmp_migrate_finish(addr, &local_err);
>> +
>> +    if (local_err) {
>> +        migration_connect_error_propagate(s, local_err);
>> +    }
>>  
>> -    qmp_migrate_finish(addr, NULL);
>>  
>>      cpr_state_close();
>> -    migrate_hup_delete(migrate_get_current());
>> +    migrate_hup_delete(s);
>
> IMHO we should drop these two lines.  For error cases, now they'll be done
> in migration_cleanup() above.  Actually for success, it's the same, but in
> the cleanup BH.
>

Hmm that would be good, I'll look into it.

> Maybe there're other cases where we can clean the code a bit on cpr;
> there're codes that always does "if (xxx)" and calling them all over the
> places, so it's easy to write such code when drafting a feature, but hard
> to maintain, because it'll be obscure when it'll really trigger, like this
> one.  We can leave the rest for later if there're applicable similar
> cleanups.
>
>>      qapi_free_MigrationAddress(addr);
>>      return G_SOURCE_REMOVE;
>>  }
>> @@ -2223,7 +2240,6 @@ void qmp_migrate(const char *uri, bool has_channels,
>>                   MigrationChannelList *channels, bool has_detach, bool detach,
>>                   bool has_resume, bool resume, Error **errp)
>>  {
>> -    Error *local_err = NULL;
>>      MigrationState *s = migrate_get_current();
>>      g_autoptr(MigrationChannel) channel = NULL;
>>      MigrationAddress *addr = NULL;
>> @@ -2280,6 +2296,13 @@ void qmp_migrate(const char *uri, bool has_channels,
>>          return;
>>      }
>>  
>> +    /*
>> +     * The migrate_prepare() above calls migrate_init(). From this
>> +     * point on, until the end of migration, make sure any failures
>> +     * eventually result in a call to migration_cleanup().
>> +     */
>> +    Error *local_err = NULL;
>> +
>>      if (!cpr_state_save(cpr_channel, &local_err)) {
>>          goto out;
>>      }
>> @@ -2299,12 +2322,11 @@ void qmp_migrate(const char *uri, bool has_channels,
>>                          QAPI_CLONE(MigrationAddress, addr));
>>  
>>      } else {
>> -        qmp_migrate_finish(addr, errp);
>> +        qmp_migrate_finish(addr, &local_err);
>>      }
>>  
>>  out:
>>      if (local_err) {
>> -        yank_unregister_instance(MIGRATION_YANK_INSTANCE);
>>          migration_connect_error_propagate(s, error_copy(local_err));
>>          error_propagate(errp, local_err);
>>      }
>> @@ -2335,12 +2357,6 @@ static void qmp_migrate_finish(MigrationAddress *addr, Error **errp)
>>      } else {
>>          error_setg(&local_err, "uri is not a valid migration protocol");
>>      }
>> -
>> -    if (local_err) {
>> -        migration_connect_error_propagate(s, error_copy(local_err));
>> -        error_propagate(errp, local_err);
>> -        return;
>> -    }
>>  }
>>  
>>  void qmp_migrate_cancel(Error **errp)
>> @@ -4027,9 +4043,6 @@ void migration_connect(MigrationState *s, Error *error_in)
>>      s->expected_downtime = migrate_downtime_limit();
>>      if (error_in) {
>>          migration_connect_error_propagate(s, error_in);
>> -        if (!resume) {
>> -            migration_cleanup(s);
>> -        }
>>          if (s->error) {
>>              error_report_err(error_copy(s->error));
>>          }
>> @@ -4108,7 +4121,6 @@ void migration_connect(MigrationState *s, Error *error_in)
>>  
>>  fail:
>>      migration_connect_error_propagate(s, local_err);
>> -    migration_cleanup(s);
>>      if (s->error) {
>>          error_report_err(error_copy(s->error));
>>      }
>> -- 
>> 2.51.0
>> 

Re: [RFC PATCH 13/25] migration: Handle error in the early async paths

[Fabiano Rosas]

Peter Xu <peterx@redhat.com> writes:

> On Fri, Dec 26, 2025 at 06:19:15PM -0300, Fabiano Rosas wrote:
>> Simplify migration_channel_connect() and migration_connect() to not
>> take an error as input. Move the error handling into the paths that
>> generate the error.
>> 
>> To achive this, call migration_connect_error_propagate() from socket.c
>> and tls.c, which are the async paths.
>> 
>> For the sync paths, the handling is done as normal by returning all
>> the way to qmp_migrate_finish(), except that now the sync paths don't
>> pass the error forward into migration_connect() anymore.
>> 
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>
> Yeah this looks better in general, feel free to take:
>
> Reviewed-by: Peter Xu <peterx@redhat.com>
>
> One thing to mention:
>
> Strictly speaking, migration_tls_channel_connect() doesn't fall into the
> "async op" category - it was invoked from migration core, so logically it
> can still keep its errp, then the migration core should also be able to
> process the error in migration_channel_connect().  It's not like the other
> two "async ops" where migration context was lost.
>

I actually had it return the error in a previous version. Let me check
if it still makes sense to do that.

> IOW, I can kind of see why we used to pass an Error into the current
> migration_channel_connect(), and it still makes some sense.

Yes, it was definitely not incorrect. I just think it's become a
surprising thing to do given how the code has evolved.

> OTOH, it doesn't really make sense to me to keep passing it to
> migration_connect()..
>
> But since that's the only user of migration_tls_channel_connect(), I assume
> it's not a huge deal, anyway.
>
>> ---
>>  migration/channel.c    | 46 +++++++++++++++++-------------------------
>>  migration/channel.h    |  4 +---
>>  migration/exec.c       |  2 +-
>>  migration/fd.c         |  2 +-
>>  migration/file.c       |  2 +-
>>  migration/migration.c  | 11 ++--------
>>  migration/migration.h  |  3 ++-
>>  migration/rdma.c       |  2 +-
>>  migration/socket.c     | 17 ++++++++--------
>>  migration/tls.c        | 19 ++++++++---------
>>  migration/tls.h        |  4 +---
>>  migration/trace-events |  2 +-
>>  12 files changed, 49 insertions(+), 65 deletions(-)
>> 
>> diff --git a/migration/channel.c b/migration/channel.c
>> index ba14f66d85..7243b99108 100644
>> --- a/migration/channel.c
>> +++ b/migration/channel.c
>> @@ -60,38 +60,30 @@ void migration_channel_process_incoming(QIOChannel *ioc)
>>   *
>>   * @s: Current migration state
>>   * @ioc: Channel to which we are connecting
>> - * @error: Error indicating failure to connect, free'd here
>>   */
>> -void migration_channel_connect(MigrationState *s,
>> -                               QIOChannel *ioc,
>> -                               Error *error)
>> +void migration_channel_connect(MigrationState *s, QIOChannel *ioc)
>>  {
>> -    trace_migration_set_outgoing_channel(
>> -        ioc, object_get_typename(OBJECT(ioc)), error);
>> +    trace_migration_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)));
>>  
>> -    if (!error) {
>> -        if (migrate_channel_requires_tls_upgrade(ioc)) {
>> -            migration_tls_channel_connect(s, ioc, &error);
>> +    if (migrate_channel_requires_tls_upgrade(ioc)) {
>> +        migration_tls_channel_connect(s, ioc);
>>  
>> -            if (!error) {
>> -                /* tls_channel_connect will call back to this
>> -                 * function after the TLS handshake,
>> -                 * so we mustn't call migration_connect until then
>> -                 */
>> -
>> -                return;
>> -            }
>> -        } else {
>> -            QEMUFile *f = qemu_file_new_output(ioc);
>> -
>> -            migration_ioc_register_yank(ioc);
>> -
>> -            qemu_mutex_lock(&s->qemu_file_lock);
>> -            s->to_dst_file = f;
>> -            qemu_mutex_unlock(&s->qemu_file_lock);
>> -        }
>> +        /*
>> +         * async: the above will call back to this function after
>> +         * the TLS handshake is successfully completed.
>> +         */
>> +        return;
>>      }
>> -    migration_connect(s, error);
>> +
>> +    QEMUFile *f = qemu_file_new_output(ioc);
>> +
>> +    migration_ioc_register_yank(ioc);
>> +
>> +    qemu_mutex_lock(&s->qemu_file_lock);
>> +    s->to_dst_file = f;
>> +    qemu_mutex_unlock(&s->qemu_file_lock);
>> +
>> +    migration_connect(s);
>>  }
>>  
>>  
>> diff --git a/migration/channel.h b/migration/channel.h
>> index 2215091323..ccfeaaef18 100644
>> --- a/migration/channel.h
>> +++ b/migration/channel.h
>> @@ -20,9 +20,7 @@
>>  
>>  void migration_channel_process_incoming(QIOChannel *ioc);
>>  
>> -void migration_channel_connect(MigrationState *s,
>> -                               QIOChannel *ioc,
>> -                               Error *error_in);
>> +void migration_channel_connect(MigrationState *s, QIOChannel *ioc);
>>  
>>  int migration_channel_read_peek(QIOChannel *ioc,
>>                                  const char *buf,
>> diff --git a/migration/exec.c b/migration/exec.c
>> index 78fe0fff13..d83a07435a 100644
>> --- a/migration/exec.c
>> +++ b/migration/exec.c
>> @@ -55,7 +55,7 @@ void exec_start_outgoing_migration(MigrationState *s, strList *command,
>>      }
>>  
>>      qio_channel_set_name(ioc, "migration-exec-outgoing");
>> -    migration_channel_connect(s, ioc, NULL);
>> +    migration_channel_connect(s, ioc);
>>      object_unref(OBJECT(ioc));
>>  }
>>  
>> diff --git a/migration/fd.c b/migration/fd.c
>> index c956b260a4..0144a70742 100644
>> --- a/migration/fd.c
>> +++ b/migration/fd.c
>> @@ -70,7 +70,7 @@ void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **
>>      }
>>  
>>      qio_channel_set_name(ioc, "migration-fd-outgoing");
>> -    migration_channel_connect(s, ioc, NULL);
>> +    migration_channel_connect(s, ioc);
>>      object_unref(OBJECT(ioc));
>>  }
>>  
>> diff --git a/migration/file.c b/migration/file.c
>> index c490f2b219..7bb9c1c79f 100644
>> --- a/migration/file.c
>> +++ b/migration/file.c
>> @@ -122,7 +122,7 @@ void file_start_outgoing_migration(MigrationState *s,
>>          return;
>>      }
>>      qio_channel_set_name(ioc, "migration-file-outgoing");
>> -    migration_channel_connect(s, ioc, NULL);
>> +    migration_channel_connect(s, ioc);
>>  }
>>  
>>  static gboolean file_accept_incoming_migration(QIOChannel *ioc,
>> diff --git a/migration/migration.c b/migration/migration.c
>> index a66b2d7aaf..5c6c76f110 100644
>> --- a/migration/migration.c
>> +++ b/migration/migration.c
>> @@ -1572,7 +1572,7 @@ static void migrate_error_free(MigrationState *s)
>>      }
>>  }
>>  
>> -static void migration_connect_error_propagate(MigrationState *s, Error *error)
>> +void migration_connect_error_propagate(MigrationState *s, Error *error)
>>  {
>>      MigrationStatus current = s->state;
>>      MigrationStatus next = MIGRATION_STATUS_NONE;
>> @@ -4033,7 +4033,7 @@ fail_setup:
>>      return NULL;
>>  }
>>  
>> -void migration_connect(MigrationState *s, Error *error_in)
>> +void migration_connect(MigrationState *s)
>>  {
>>      Error *local_err = NULL;
>>      uint64_t rate_limit;
>> @@ -4041,13 +4041,6 @@ void migration_connect(MigrationState *s, Error *error_in)
>>      int ret;
>>  
>>      s->expected_downtime = migrate_downtime_limit();
>> -    if (error_in) {
>> -        migration_connect_error_propagate(s, error_in);
>> -        if (s->error) {
>> -            error_report_err(error_copy(s->error));
>> -        }
>> -        return;
>> -    }
>>  
>>      if (resume) {
>>          /* This is a resumed migration */
>> diff --git a/migration/migration.h b/migration/migration.h
>> index 4d42e8f9a7..f340cd518d 100644
>> --- a/migration/migration.h
>> +++ b/migration/migration.h
>> @@ -532,10 +532,11 @@ void migration_incoming_process(void);
>>  
>>  bool  migration_has_all_channels(void);
>>  
>> +void migration_connect_error_propagate(MigrationState *s, Error *error);
>>  void migrate_error_propagate(MigrationState *s, Error *error);
>>  bool migrate_has_error(MigrationState *s);
>>  
>> -void migration_connect(MigrationState *s, Error *error_in);
>> +void migration_connect(MigrationState *s);
>>  
>>  int migration_call_notifiers(MigrationState *s, MigrationEventType type,
>>                               Error **errp);
>> diff --git a/migration/rdma.c b/migration/rdma.c
>> index 337b415889..596a1aba0b 100644
>> --- a/migration/rdma.c
>> +++ b/migration/rdma.c
>> @@ -3997,7 +3997,7 @@ void rdma_start_outgoing_migration(void *opaque,
>>  
>>      s->to_dst_file = rdma_new_output(rdma);
>>      s->rdma_migration = true;
>> -    migration_connect(s, NULL);
>> +    migration_connect(s);
>>      return;
>>  return_path_err:
>>      qemu_rdma_cleanup(rdma);
>> diff --git a/migration/socket.c b/migration/socket.c
>> index 426f363b99..298bac30cc 100644
>> --- a/migration/socket.c
>> +++ b/migration/socket.c
>> @@ -59,24 +59,25 @@ static void socket_outgoing_migration(QIOTask *task,
>>                                        gpointer opaque)
>>  {
>>      struct SocketConnectData *data = opaque;
>> -    QIOChannel *sioc = QIO_CHANNEL(qio_task_get_source(task));
>> +    g_autoptr(QIOChannel) sioc = QIO_CHANNEL(qio_task_get_source(task));
>>      Error *err = NULL;
>>  
>>      if (qio_task_propagate_error(task, &err)) {
>> -        trace_migration_socket_outgoing_error(error_get_pretty(err));
>> -           goto out;
>> +        goto err;
>>      }
>>  
>> -    trace_migration_socket_outgoing_connected();
>> -
>>      if (migrate_zero_copy_send() &&
>>          !qio_channel_has_feature(sioc, QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY)) {
>>          error_setg(&err, "Zero copy send feature not detected in host kernel");
>> +        goto err;
>>      }
>>  
>> -out:
>> -    migration_channel_connect(data->s, sioc, err);
>> -    object_unref(OBJECT(sioc));
>> +    trace_migration_socket_outgoing_connected();
>> +    migration_channel_connect(data->s, sioc);
>> +    return;
>> +err:
>> +    trace_migration_socket_outgoing_error(error_get_pretty(err));
>> +    migration_connect_error_propagate(data->s, err);
>>  }
>>  
>>  void socket_start_outgoing_migration(MigrationState *s,
>> diff --git a/migration/tls.c b/migration/tls.c
>> index 82f58cbc78..a54e8e6e14 100644
>> --- a/migration/tls.c
>> +++ b/migration/tls.c
>> @@ -104,16 +104,17 @@ static void migration_tls_outgoing_handshake(QIOTask *task,
>>                                               gpointer opaque)
>>  {
>>      MigrationState *s = opaque;
>> -    QIOChannel *ioc = QIO_CHANNEL(qio_task_get_source(task));
>> +    g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
>>      Error *err = NULL;
>>  
>>      if (qio_task_propagate_error(task, &err)) {
>>          trace_migration_tls_outgoing_handshake_error(error_get_pretty(err));
>> -    } else {
>> -        trace_migration_tls_outgoing_handshake_complete();
>> +        migration_connect_error_propagate(s, err);
>> +        return;
>>      }
>> -    migration_channel_connect(s, ioc, err);
>> -    object_unref(OBJECT(ioc));
>> +
>> +    trace_migration_tls_outgoing_handshake_complete();
>> +    migration_channel_connect(s, ioc);
>>  }
>>  
>>  QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
>> @@ -129,14 +130,14 @@ QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
>>      return qio_channel_tls_new_client(ioc, creds, migrate_tls_hostname(), errp);
>>  }
>>  
>> -void migration_tls_channel_connect(MigrationState *s,
>> -                                   QIOChannel *ioc,
>> -                                   Error **errp)
>> +void migration_tls_channel_connect(MigrationState *s, QIOChannel *ioc)
>>  {
>>      QIOChannelTLS *tioc;
>> +    Error *local_err = NULL;
>>  
>> -    tioc = migration_tls_client_create(ioc, errp);
>> +    tioc = migration_tls_client_create(ioc, &local_err);
>>      if (!tioc) {
>> +        migration_connect_error_propagate(s, local_err);
>>          return;
>>      }
>>  
>> diff --git a/migration/tls.h b/migration/tls.h
>> index 7cd9c76013..7399c42edf 100644
>> --- a/migration/tls.h
>> +++ b/migration/tls.h
>> @@ -29,9 +29,7 @@ void migration_tls_channel_process_incoming(QIOChannel *ioc, Error **errp);
>>  QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
>>                                             Error **errp);
>>  
>> -void migration_tls_channel_connect(MigrationState *s,
>> -                                   QIOChannel *ioc,
>> -                                   Error **errp);
>> +void migration_tls_channel_connect(MigrationState *s, QIOChannel *ioc);
>>  void migration_tls_channel_end(QIOChannel *ioc, Error **errp);
>>  /* Whether the QIO channel requires further TLS handshake? */
>>  bool migrate_channel_requires_tls_upgrade(QIOChannel *ioc);
>> diff --git a/migration/trace-events b/migration/trace-events
>> index da8f909cac..cbf10d0b63 100644
>> --- a/migration/trace-events
>> +++ b/migration/trace-events
>> @@ -204,7 +204,7 @@ migration_transferred_bytes(uint64_t qemu_file, uint64_t multifd, uint64_t rdma)
>>  
>>  # channel.c
>>  migration_set_incoming_channel(void *ioc, const char *ioctype) "ioc=%p ioctype=%s"
>> -migration_set_outgoing_channel(void *ioc, const char *ioctype, void *err)  "ioc=%p ioctype=%s err=%p"
>> +migration_set_outgoing_channel(void *ioc, const char *ioctype) "ioc=%p ioctype=%s"
>>  
>>  # global_state.c
>>  migrate_state_too_big(void) ""
>> -- 
>> 2.51.0
>> 

Re: [RFC PATCH 14/25] migration: Remove QEMUFile from channel.c

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:16PM -0300, Fabiano Rosas wrote:
> Make channel.c deal only with QIOChannel objects. Move any handling of
> QEMUFile into migration.c. To achieve this in a clean way:
> 
> 1) Define a migration_outgoing_setup, analogous to
> migration_incoming_setup, responsible for creating the QEMUFile from
> the QIOChannel.
> 
> 2) Increase the scope of migration_incoming_setup to create not only
> the main channel, but all the others as well. That is currently being
> done at migration_ioc_process, so move the code.
> 
> 3) Adjust RDMA code to pass in the QIOChannel and remove some of the
> usage of QEMUFile.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
>  migration/channel.c   | 21 ++++++-----
>  migration/migration.c | 88 ++++++++++++++++++++++---------------------
>  migration/migration.h |  6 ++-
>  migration/multifd.c   |  7 ++--
>  migration/multifd.h   |  2 +-
>  migration/rdma.c      | 28 ++++----------
>  6 files changed, 73 insertions(+), 79 deletions(-)
> 
> diff --git a/migration/channel.c b/migration/channel.c
> index 7243b99108..af6c2cc76e 100644
> --- a/migration/channel.c
> +++ b/migration/channel.c
> @@ -14,7 +14,6 @@
>  #include "channel.h"
>  #include "tls.h"
>  #include "migration.h"
> -#include "qemu-file.h"
>  #include "trace.h"
>  #include "qapi/error.h"
>  #include "io/channel-tls.h"
> @@ -34,6 +33,7 @@ void migration_channel_process_incoming(QIOChannel *ioc)
>  {
>      MigrationIncomingState *mis = migration_incoming_get_current();
>      Error *local_err = NULL;
> +    uint8_t ch;
>  
>      trace_migration_set_incoming_channel(
>          ioc, object_get_typename(OBJECT(ioc)));
> @@ -42,9 +42,16 @@ void migration_channel_process_incoming(QIOChannel *ioc)
>          migration_tls_channel_process_incoming(ioc, &local_err);
>      } else {
>          migration_ioc_register_yank(ioc);
> -        migration_ioc_process_incoming(ioc, &local_err);
> -    }
> +        ch = migration_ioc_process_incoming(ioc, &local_err);
> +        if (!ch) {
> +            goto out;
> +        }
>  
> +        if (migration_incoming_setup(ioc, ch, &local_err)) {
> +            migration_incoming_process();
> +        }
> +    }
> +out:
>      if (local_err) {
>          error_report_err(local_err);
>          migrate_set_state(&mis->state, mis->state, MIGRATION_STATUS_FAILED);
> @@ -75,14 +82,8 @@ void migration_channel_connect(MigrationState *s, QIOChannel *ioc)
>          return;
>      }
>  
> -    QEMUFile *f = qemu_file_new_output(ioc);
> -
>      migration_ioc_register_yank(ioc);
> -
> -    qemu_mutex_lock(&s->qemu_file_lock);
> -    s->to_dst_file = f;
> -    qemu_mutex_unlock(&s->qemu_file_lock);
> -
> +    migration_outgoing_setup(ioc);
>      migration_connect(s);
>  }
>  
> diff --git a/migration/migration.c b/migration/migration.c
> index 5c6c76f110..677581b5a5 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -92,7 +92,7 @@ enum mig_rp_message_type {
>  };
>  
>  /* Migration channel types */
> -enum { CH_MAIN, CH_MULTIFD, CH_POSTCOPY };
> +enum { CH_NONE, CH_MAIN, CH_MULTIFD, CH_POSTCOPY };
>  
>  /* When we add fault tolerance, we could have several
>     migrations at once.  For now we don't need to add
> @@ -934,17 +934,48 @@ out:
>      migrate_incoming_unref_outgoing_state();
>  }
>  
> -/**
> - * migration_incoming_setup: Setup incoming migration
> - * @f: file for main migration channel
> - */
> -static void migration_incoming_setup(QEMUFile *f)
> +static bool migration_has_main_and_multifd_channels(void);
> +
> +bool migration_incoming_setup(QIOChannel *ioc, uint8_t channel, Error **errp)
>  {
>      MigrationIncomingState *mis = migration_incoming_get_current();
> +    QEMUFile *f;
>  
> -    assert(!mis->from_src_file);
> -    mis->from_src_file = f;
> -    qemu_file_set_blocking(f, false, &error_abort);
> +    switch (channel) {
> +    case CH_MAIN:
> +        f = qemu_file_new_input(ioc);
> +        assert(!mis->from_src_file);
> +        mis->from_src_file = f;
> +        qemu_file_set_blocking(f, false, &error_abort);
> +        break;
> +
> +    case CH_MULTIFD:
> +        if (!multifd_recv_new_channel(ioc, errp)) {
> +            return false;
> +        }
> +        break;
> +
> +    case CH_POSTCOPY:
> +        assert(!mis->postcopy_qemufile_dst);
> +        f = qemu_file_new_input(ioc);
> +        postcopy_preempt_new_channel(mis, f);
> +        return false;
> +
> +    default:
> +        g_assert_not_reached();
> +    }
> +
> +    return migration_has_main_and_multifd_channels();
> +}
> +
> +void migration_outgoing_setup(QIOChannel *ioc)
> +{
> +    MigrationState *s = migrate_get_current();
> +    QEMUFile *f = qemu_file_new_output(ioc);
> +
> +    qemu_mutex_lock(&s->qemu_file_lock);
> +    s->to_dst_file = f;
> +    qemu_mutex_unlock(&s->qemu_file_lock);
>  }
>  
>  /* Returns true if recovered from a paused migration, otherwise false */
> @@ -990,12 +1021,6 @@ void migration_incoming_process(void)
>      qemu_coroutine_enter(co);
>  }
>  
> -void migration_fd_process_incoming(QEMUFile *f)
> -{
> -    migration_incoming_setup(f);
> -    migration_incoming_process();
> -}
> -
>  static bool migration_has_main_and_multifd_channels(void)
>  {
>      MigrationIncomingState *mis = migration_incoming_get_current();
> @@ -1012,12 +1037,10 @@ static bool migration_has_main_and_multifd_channels(void)
>      return true;
>  }
>  
> -void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> +uint8_t migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>  {
>      MigrationIncomingState *mis = migration_incoming_get_current();
> -    Error *local_err = NULL;
> -    QEMUFile *f;
> -    uint8_t channel;
> +    uint8_t channel = CH_NONE;
>      uint32_t channel_magic = 0;
>      int ret = 0;
>  
> @@ -1036,7 +1059,7 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>              ret = migration_channel_read_peek(ioc, (void *)&channel_magic,
>                                                sizeof(channel_magic), errp);
>              if (ret != 0) {
> -                return;
> +                goto out;
>              }
>  
>              channel_magic = be32_to_cpu(channel_magic);
> @@ -1051,7 +1074,6 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>                  channel = CH_MAIN;
>              } else {
>                  error_setg(errp, "unknown channel magic: %u", channel_magic);
> -                return;
>              }
>          } else if (mis->from_src_file && migrate_multifd()) {
>              /*
> @@ -1063,33 +1085,13 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>              channel = CH_MAIN;
>          } else {
>              error_setg(errp, "non-peekable channel used without multifd");
> -            return;
>          }
>      } else {
>          assert(migrate_postcopy_preempt());
>          channel = CH_POSTCOPY;
>      }
> -
> -    if (channel == CH_MAIN) {
> -        f = qemu_file_new_input(ioc);
> -        migration_incoming_setup(f);
> -    } else if (channel == CH_MULTIFD) {
> -        /* Multiple connections */
> -        multifd_recv_new_channel(ioc, &local_err);
> -        if (local_err) {
> -            error_propagate(errp, local_err);
> -            return;
> -        }
> -    } else if (channel == CH_POSTCOPY) {
> -        assert(!mis->postcopy_qemufile_dst);
> -        f = qemu_file_new_input(ioc);
> -        postcopy_preempt_new_channel(mis, f);
> -        return;
> -    }
> -
> -    if (migration_has_main_and_multifd_channels()) {
> -        migration_incoming_process();
> -    }
> +out:
> +    return channel;
>  }
>  
>  /**
> diff --git a/migration/migration.h b/migration/migration.h
> index f340cd518d..d2b82cf54f 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -526,8 +526,10 @@ struct MigrationState {
>  void migrate_set_state(MigrationStatus *state, MigrationStatus old_state,
>                         MigrationStatus new_state);
>  
> -void migration_fd_process_incoming(QEMUFile *f);
> -void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp);
> +void migration_outgoing_setup(QIOChannel *ioc);
> +bool migration_incoming_setup(QIOChannel *ioc, uint8_t channel, Error **errp);
> +
> +uint8_t migration_ioc_process_incoming(QIOChannel *ioc, Error **errp);
>  void migration_incoming_process(void);
>  
>  bool  migration_has_all_channels(void);
> diff --git a/migration/multifd.c b/migration/multifd.c
> index 3fb1a07ba9..c6639dbab5 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -1521,7 +1521,7 @@ bool multifd_recv_all_channels_created(void)
>   * Try to receive all multifd channels to get ready for the migration.
>   * Sets @errp when failing to receive the current channel.
>   */
> -void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
> +bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
>  {
>      MultiFDRecvParams *p;
>      Error *local_err = NULL;
> @@ -1536,7 +1536,7 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
>                                      "failed to receive packet"
>                                      " via multifd channel %d: ",
>                                      qatomic_read(&multifd_recv_state->count));
> -            return;
> +            return false;
>          }
>          trace_multifd_recv_new_channel(id);
>      } else {
> @@ -1549,7 +1549,7 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
>                     id);
>          multifd_recv_terminate_threads(error_copy(local_err));
>          error_propagate(errp, local_err);
> -        return;
> +        return false;
>      }
>      p->c = ioc;
>      object_ref(OBJECT(ioc));
> @@ -1558,4 +1558,5 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
>      qemu_thread_create(&p->thread, p->name, multifd_recv_thread, p,
>                         QEMU_THREAD_JOINABLE);
>      qatomic_inc(&multifd_recv_state->count);
> +    return true;
>  }
> diff --git a/migration/multifd.h b/migration/multifd.h
> index 9b6d81e7ed..89a395aef2 100644
> --- a/migration/multifd.h
> +++ b/migration/multifd.h
> @@ -42,7 +42,7 @@ int multifd_recv_setup(Error **errp);
>  void multifd_recv_cleanup(void);
>  void multifd_recv_shutdown(void);
>  bool multifd_recv_all_channels_created(void);
> -void multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
> +bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
>  void multifd_recv_sync_main(void);
>  int multifd_send_sync_main(MultiFDSyncReq req);
>  bool multifd_queue_page(RAMBlock *block, ram_addr_t offset);
> diff --git a/migration/rdma.c b/migration/rdma.c
> index 596a1aba0b..7bee871e2b 100644
> --- a/migration/rdma.c
> +++ b/migration/rdma.c
> @@ -384,7 +384,6 @@ struct QIOChannelRDMA {
>      QIOChannel parent;
>      RDMAContext *rdmain;
>      RDMAContext *rdmaout;
> -    QEMUFile *file;
>      bool blocking; /* XXX we don't actually honour this yet */
>  };
>  
> @@ -3836,32 +3835,20 @@ static void qio_channel_rdma_register_types(void)
>  
>  type_init(qio_channel_rdma_register_types);
>  
> -static QEMUFile *rdma_new_input(RDMAContext *rdma)
> +static QIOChannel *rdma_new_ioc(RDMAContext *rdma)
>  {
>      QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(object_new(TYPE_QIO_CHANNEL_RDMA));
>  
> -    rioc->file = qemu_file_new_input(QIO_CHANNEL(rioc));
> -    rioc->rdmain = rdma;
> -    rioc->rdmaout = rdma->return_path;
> -
> -    return rioc->file;
> -}
> -
> -static QEMUFile *rdma_new_output(RDMAContext *rdma)
> -{
> -    QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(object_new(TYPE_QIO_CHANNEL_RDMA));
> -
> -    rioc->file = qemu_file_new_output(QIO_CHANNEL(rioc));
>      rioc->rdmaout = rdma;
>      rioc->rdmain = rdma->return_path;

Likely it was overlooked rdmaout/rdmain was set in reverse order in these
two functions.  I gave it a quick run on rdma and it was indeed broken
starting from this patch.

The goal of the change looks reasonable in general otherwise, said that,
maybe there's way to split the patch somehow?

>  
> -    return rioc->file;
> +    return QIO_CHANNEL(rioc);
>  }
>  
>  static void rdma_accept_incoming_migration(void *opaque)
>  {
>      RDMAContext *rdma = opaque;
> -    QEMUFile *f;
> +    QIOChannel *ioc;
>  
>      trace_qemu_rdma_accept_incoming_migration();
>      if (qemu_rdma_accept(rdma) < 0) {
> @@ -3875,15 +3862,16 @@ static void rdma_accept_incoming_migration(void *opaque)
>          return;
>      }
>  
> -    f = rdma_new_input(rdma);
> -    if (f == NULL) {
> +    ioc = rdma_new_ioc(rdma);
> +    if (!ioc) {
>          error_report("RDMA ERROR: could not open RDMA for input");
>          qemu_rdma_cleanup(rdma);
>          return;
>      }
>  
>      rdma->migration_started_on_destination = 1;
> -    migration_fd_process_incoming(f);
> +    migration_incoming_setup(ioc, 0, NULL);
> +    migration_incoming_process();
>  }
>  
>  void rdma_start_incoming_migration(InetSocketAddress *host_port,
> @@ -3995,8 +3983,8 @@ void rdma_start_outgoing_migration(void *opaque,
>  
>      trace_rdma_start_outgoing_migration_after_rdma_connect();
>  
> -    s->to_dst_file = rdma_new_output(rdma);
>      s->rdma_migration = true;
> +    migration_outgoing_setup(rdma_new_ioc(rdma));
>      migration_connect(s);
>      return;
>  return_path_err:
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 05/25] migration: Cleanup TLS handshake hostname passing

[Fabiano Rosas]

Peter Xu <peterx@redhat.com> writes:

> On Fri, Dec 26, 2025 at 06:19:07PM -0300, Fabiano Rosas wrote:
>> The TLS hostname is doing a tour around the world just to be cached
>> into s->hostname. We're already abusing MigrationState by doing that,
>> so incorporate the s->hostname into migration_tls_hostname() and stop
>> passing the string around.
>> 
>> The old route was roughly:
>> 
>>  -transport code (socket.c, fd.c, etc):
>>     if (SOCKET_ADDRESS_TYPE_INET)
>>         hostname = saddr->u.inet.host
>>     else
>>         hostname = NULL
>>     migration_channel_connect(..., hostname)
>>       s->hostname = hostname;
>>       migration_tls_client_create(..., hostname)
>>         if (migrate_tls_hostname())
>>             qio_channel_tls_new_client(migrate_tls_hostname())
>>         else
>>             qio_channel_tls_new_client(hostname)
>> 
>>  -postcopy_preempt_setup:
>>     postcopy_preempt_send_channel_new
>>       migration_tls_client_create(..., s->hostname)
>> 
>> New route is:
>> 
>>  -socket.c only:
>>    if SOCKET_ADDRESS_TYPE_INET
>>        s->hostname = saddr->u.inet.host
>>    migration_channel_connect()
>>      migration_tls_client_create()
>>        qio_channel_tls_new_client(migrate_tls_hostname())
>> 
>>  -postcopy_preempt_setup:
>>     postcopy_preempt_send_channel_new
>>       migration_tls_client_create()
>>         qio_channel_tls_new_client(migrate_tls_hostname())
>> 
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>
> I suggest let's still copy Dan on all tls changes, though. I've done it
> here.
>

Thanks

> Looks alright to me:
>
> Reviewed-by: Peter Xu <peterx@redhat.com>
>
> Two trivial comments on top..
>
> - Maybe, we can get rid of SocketConnectData altogether now
>

It goes away voluntarily on patch 21.

> - Maybe, we want to keep at least one tracepoint that would dump the
>   hostname used
>

I can add one just in case.

>> ---
>>  migration/channel.c      |  6 ++----
>>  migration/channel.h      |  1 -
>>  migration/exec.c         |  2 +-
>>  migration/fd.c           |  2 +-
>>  migration/file.c         |  2 +-
>>  migration/multifd.c      |  9 +++------
>>  migration/options.c      |  5 +++++
>>  migration/postcopy-ram.c |  2 +-
>>  migration/socket.c       |  9 +++------
>>  migration/tls.c          | 17 ++++-------------
>>  migration/tls.h          |  2 --
>>  migration/trace-events   | 10 +++++-----
>>  12 files changed, 26 insertions(+), 41 deletions(-)
>> 
>> diff --git a/migration/channel.c b/migration/channel.c
>> index b4ab676048..ba14f66d85 100644
>> --- a/migration/channel.c
>> +++ b/migration/channel.c
>> @@ -60,20 +60,18 @@ void migration_channel_process_incoming(QIOChannel *ioc)
>>   *
>>   * @s: Current migration state
>>   * @ioc: Channel to which we are connecting
>> - * @hostname: Where we want to connect
>>   * @error: Error indicating failure to connect, free'd here
>>   */
>>  void migration_channel_connect(MigrationState *s,
>>                                 QIOChannel *ioc,
>> -                               const char *hostname,
>>                                 Error *error)
>>  {
>>      trace_migration_set_outgoing_channel(
>> -        ioc, object_get_typename(OBJECT(ioc)), hostname, error);
>> +        ioc, object_get_typename(OBJECT(ioc)), error);
>>  
>>      if (!error) {
>>          if (migrate_channel_requires_tls_upgrade(ioc)) {
>> -            migration_tls_channel_connect(s, ioc, hostname, &error);
>> +            migration_tls_channel_connect(s, ioc, &error);
>>  
>>              if (!error) {
>>                  /* tls_channel_connect will call back to this
>> diff --git a/migration/channel.h b/migration/channel.h
>> index 5bdb8208a7..2215091323 100644
>> --- a/migration/channel.h
>> +++ b/migration/channel.h
>> @@ -22,7 +22,6 @@ void migration_channel_process_incoming(QIOChannel *ioc);
>>  
>>  void migration_channel_connect(MigrationState *s,
>>                                 QIOChannel *ioc,
>> -                               const char *hostname,
>>                                 Error *error_in);
>>  
>>  int migration_channel_read_peek(QIOChannel *ioc,
>> diff --git a/migration/exec.c b/migration/exec.c
>> index 20e6cccf8c..78fe0fff13 100644
>> --- a/migration/exec.c
>> +++ b/migration/exec.c
>> @@ -55,7 +55,7 @@ void exec_start_outgoing_migration(MigrationState *s, strList *command,
>>      }
>>  
>>      qio_channel_set_name(ioc, "migration-exec-outgoing");
>> -    migration_channel_connect(s, ioc, NULL, NULL);
>> +    migration_channel_connect(s, ioc, NULL);
>>      object_unref(OBJECT(ioc));
>>  }
>>  
>> diff --git a/migration/fd.c b/migration/fd.c
>> index 9bf9be6acb..c956b260a4 100644
>> --- a/migration/fd.c
>> +++ b/migration/fd.c
>> @@ -70,7 +70,7 @@ void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **
>>      }
>>  
>>      qio_channel_set_name(ioc, "migration-fd-outgoing");
>> -    migration_channel_connect(s, ioc, NULL, NULL);
>> +    migration_channel_connect(s, ioc, NULL);
>>      object_unref(OBJECT(ioc));
>>  }
>>  
>> diff --git a/migration/file.c b/migration/file.c
>> index bb8031e3c7..c490f2b219 100644
>> --- a/migration/file.c
>> +++ b/migration/file.c
>> @@ -122,7 +122,7 @@ void file_start_outgoing_migration(MigrationState *s,
>>          return;
>>      }
>>      qio_channel_set_name(ioc, "migration-file-outgoing");
>> -    migration_channel_connect(s, ioc, NULL, NULL);
>> +    migration_channel_connect(s, ioc, NULL);
>>  }
>>  
>>  static gboolean file_accept_incoming_migration(QIOChannel *ioc,
>> diff --git a/migration/multifd.c b/migration/multifd.c
>> index bf6da85af8..3fb1a07ba9 100644
>> --- a/migration/multifd.c
>> +++ b/migration/multifd.c
>> @@ -814,12 +814,10 @@ static bool multifd_tls_channel_connect(MultiFDSendParams *p,
>>                                          QIOChannel *ioc,
>>                                          Error **errp)
>>  {
>> -    MigrationState *s = migrate_get_current();
>> -    const char *hostname = s->hostname;
>>      MultiFDTLSThreadArgs *args;
>>      QIOChannelTLS *tioc;
>>  
>> -    tioc = migration_tls_client_create(ioc, hostname, errp);
>> +    tioc = migration_tls_client_create(ioc, errp);
>>      if (!tioc) {
>>          return false;
>>      }
>> @@ -829,7 +827,7 @@ static bool multifd_tls_channel_connect(MultiFDSendParams *p,
>>       * created TLS channel, which has already taken a reference.
>>       */
>>      object_unref(OBJECT(ioc));
>> -    trace_multifd_tls_outgoing_handshake_start(ioc, tioc, hostname);
>> +    trace_multifd_tls_outgoing_handshake_start(ioc, tioc);
>>      qio_channel_set_name(QIO_CHANNEL(tioc), "multifd-tls-outgoing");
>>  
>>      args = g_new0(MultiFDTLSThreadArgs, 1);
>> @@ -876,8 +874,7 @@ static void multifd_new_send_channel_async(QIOTask *task, gpointer opaque)
>>          goto out;
>>      }
>>  
>> -    trace_multifd_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)),
>> -                                       migrate_get_current()->hostname);
>> +    trace_multifd_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)));
>>  
>>      if (migrate_channel_requires_tls_upgrade(ioc)) {
>>          ret = multifd_tls_channel_connect(p, ioc, &local_err);
>> diff --git a/migration/options.c b/migration/options.c
>> index 9a5a39c886..881034c289 100644
>> --- a/migration/options.c
>> +++ b/migration/options.c
>> @@ -956,6 +956,11 @@ const char *migrate_tls_hostname(void)
>>          return s->parameters.tls_hostname->u.s;
>>      }
>>  
>> +    /* hostname saved from a previously connected channel */
>> +    if (s->hostname) {
>> +        return s->hostname;
>> +    }
>> +
>>      return NULL;
>>  }
>>  
>> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
>> index 3623ab9dab..03cb0d8d65 100644
>> --- a/migration/postcopy-ram.c
>> +++ b/migration/postcopy-ram.c
>> @@ -1966,7 +1966,7 @@ postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
>>      }
>>  
>>      if (migrate_channel_requires_tls_upgrade(ioc)) {
>> -        tioc = migration_tls_client_create(ioc, s->hostname, &local_err);
>> +        tioc = migration_tls_client_create(ioc, &local_err);
>>          if (!tioc) {
>>              goto out;
>>          }
>> diff --git a/migration/socket.c b/migration/socket.c
>> index 9e379bf56f..426f363b99 100644
>> --- a/migration/socket.c
>> +++ b/migration/socket.c
>> @@ -44,7 +44,6 @@ void socket_send_channel_create(QIOTaskFunc f, void *data)
>>  
>>  struct SocketConnectData {
>>      MigrationState *s;
>> -    char *hostname;
>>  };
>>  
>>  static void socket_connect_data_free(void *opaque)
>> @@ -53,7 +52,6 @@ static void socket_connect_data_free(void *opaque)
>>      if (!data) {
>>          return;
>>      }
>> -    g_free(data->hostname);
>>      g_free(data);
>>  }
>>  
>> @@ -69,7 +67,7 @@ static void socket_outgoing_migration(QIOTask *task,
>>             goto out;
>>      }
>>  
>> -    trace_migration_socket_outgoing_connected(data->hostname);
>> +    trace_migration_socket_outgoing_connected();
>>  
>>      if (migrate_zero_copy_send() &&
>>          !qio_channel_has_feature(sioc, QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY)) {
>> @@ -77,7 +75,7 @@ static void socket_outgoing_migration(QIOTask *task,
>>      }
>>  
>>  out:
>> -    migration_channel_connect(data->s, sioc, data->hostname, err);
>> +    migration_channel_connect(data->s, sioc, err);
>>      object_unref(OBJECT(sioc));
>>  }
>>  
>> @@ -96,7 +94,7 @@ void socket_start_outgoing_migration(MigrationState *s,
>>      outgoing_args.saddr = addr;
>>  
>>      if (saddr->type == SOCKET_ADDRESS_TYPE_INET) {
>> -        data->hostname = g_strdup(saddr->u.inet.host);
>> +        s->hostname = g_strdup(saddr->u.inet.host);
>>      }
>>  
>>      qio_channel_set_name(QIO_CHANNEL(sioc), "migration-socket-outgoing");
>> @@ -180,4 +178,3 @@ void socket_start_incoming_migration(SocketAddress *saddr,
>>          qapi_free_SocketAddress(address);
>>      }
>>  }
>> -
>> diff --git a/migration/tls.c b/migration/tls.c
>> index 1df31bdcbb..82f58cbc78 100644
>> --- a/migration/tls.c
>> +++ b/migration/tls.c
>> @@ -112,12 +112,11 @@ static void migration_tls_outgoing_handshake(QIOTask *task,
>>      } else {
>>          trace_migration_tls_outgoing_handshake_complete();
>>      }
>> -    migration_channel_connect(s, ioc, NULL, err);
>> +    migration_channel_connect(s, ioc, err);
>>      object_unref(OBJECT(ioc));
>>  }
>>  
>>  QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
>> -                                           const char *hostname,
>>                                             Error **errp)
>>  {
>>      QCryptoTLSCreds *creds;
>> @@ -127,29 +126,21 @@ QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
>>          return NULL;
>>      }
>>  
>> -    const char *tls_hostname = migrate_tls_hostname();
>> -    if (tls_hostname) {
>> -        hostname = tls_hostname;
>> -    }
>> -
>> -    return qio_channel_tls_new_client(ioc, creds, hostname, errp);
>> +    return qio_channel_tls_new_client(ioc, creds, migrate_tls_hostname(), errp);
>>  }
>>  
>>  void migration_tls_channel_connect(MigrationState *s,
>>                                     QIOChannel *ioc,
>> -                                   const char *hostname,
>>                                     Error **errp)
>>  {
>>      QIOChannelTLS *tioc;
>>  
>> -    tioc = migration_tls_client_create(ioc, hostname, errp);
>> +    tioc = migration_tls_client_create(ioc, errp);
>>      if (!tioc) {
>>          return;
>>      }
>>  
>> -    /* Save hostname into MigrationState for handshake */
>> -    s->hostname = g_strdup(hostname);
>> -    trace_migration_tls_outgoing_handshake_start(hostname);
>> +    trace_migration_tls_outgoing_handshake_start();
>>      qio_channel_set_name(QIO_CHANNEL(tioc), "migration-tls-outgoing");
>>  
>>      if (migrate_postcopy_ram() || migrate_return_path()) {
>> diff --git a/migration/tls.h b/migration/tls.h
>> index 7607cfe803..7cd9c76013 100644
>> --- a/migration/tls.h
>> +++ b/migration/tls.h
>> @@ -27,12 +27,10 @@
>>  void migration_tls_channel_process_incoming(QIOChannel *ioc, Error **errp);
>>  
>>  QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
>> -                                           const char *hostname,
>>                                             Error **errp);
>>  
>>  void migration_tls_channel_connect(MigrationState *s,
>>                                     QIOChannel *ioc,
>> -                                   const char *hostname,
>>                                     Error **errp);
>>  void migration_tls_channel_end(QIOChannel *ioc, Error **errp);
>>  /* Whether the QIO channel requires further TLS handshake? */
>> diff --git a/migration/trace-events b/migration/trace-events
>> index bf11b62b17..da8f909cac 100644
>> --- a/migration/trace-events
>> +++ b/migration/trace-events
>> @@ -149,10 +149,10 @@ multifd_send_sync_main_wait(uint8_t id) "channel %u"
>>  multifd_send_terminate_threads(void) ""
>>  multifd_send_thread_end(uint8_t id, uint64_t packets) "channel %u packets %" PRIu64
>>  multifd_send_thread_start(uint8_t id) "%u"
>> -multifd_tls_outgoing_handshake_start(void *ioc, void *tioc, const char *hostname) "ioc=%p tioc=%p hostname=%s"
>> +multifd_tls_outgoing_handshake_start(void *ioc, void *tioc) "ioc=%p tioc=%p"
>>  multifd_tls_outgoing_handshake_error(void *ioc, const char *err) "ioc=%p err=%s"
>>  multifd_tls_outgoing_handshake_complete(void *ioc) "ioc=%p"
>> -multifd_set_outgoing_channel(void *ioc, const char *ioctype, const char *hostname)  "ioc=%p ioctype=%s hostname=%s"
>> +multifd_set_outgoing_channel(void *ioc, const char *ioctype)  "ioc=%p ioctype=%s"
>>  
>>  # migration.c
>>  migrate_set_state(const char *new_state) "new state %s"
>> @@ -204,7 +204,7 @@ migration_transferred_bytes(uint64_t qemu_file, uint64_t multifd, uint64_t rdma)
>>  
>>  # channel.c
>>  migration_set_incoming_channel(void *ioc, const char *ioctype) "ioc=%p ioctype=%s"
>> -migration_set_outgoing_channel(void *ioc, const char *ioctype, const char *hostname, void *err)  "ioc=%p ioctype=%s hostname=%s err=%p"
>> +migration_set_outgoing_channel(void *ioc, const char *ioctype, void *err)  "ioc=%p ioctype=%s err=%p"
>>  
>>  # global_state.c
>>  migrate_state_too_big(void) ""
>> @@ -328,11 +328,11 @@ migration_file_incoming(const char *filename) "filename=%s"
>>  
>>  # socket.c
>>  migration_socket_incoming_accepted(void) ""
>> -migration_socket_outgoing_connected(const char *hostname) "hostname=%s"
>> +migration_socket_outgoing_connected(void) ""
>>  migration_socket_outgoing_error(const char *err) "error=%s"
>>  
>>  # tls.c
>> -migration_tls_outgoing_handshake_start(const char *hostname) "hostname=%s"
>> +migration_tls_outgoing_handshake_start(void) ""
>>  migration_tls_outgoing_handshake_error(const char *err) "err=%s"
>>  migration_tls_outgoing_handshake_complete(void) ""
>>  migration_tls_incoming_handshake_start(void) ""
>> -- 
>> 2.51.0
>> 

Re: [RFC PATCH 15/25] migration/channel: Rename migration_channel_connect

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:17PM -0300, Fabiano Rosas wrote:
> Rename migration_channel_connect to indicate this is the source
> side. Future patches will do similar changes to the incoming side and
> this will avoid inconsistencies in naming.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

We have a lot of other helpers are using this pattern as names:

  migration_incoming*

So I wonder if we want to unify it with

  migration_outgoing*

?

Said that, I don't think it's always the case, so it's not a rule either.
Adding "outgoing" anywhere should indeed be an improvement already.

Whichever you prefer:

Reviewed-by: Peter Xu <peterx@redhat.com>

> ---
>  migration/channel.c | 9 +--------
>  migration/channel.h | 2 +-
>  migration/exec.c    | 2 +-
>  migration/fd.c      | 2 +-
>  migration/file.c    | 2 +-
>  migration/socket.c  | 2 +-
>  migration/tls.c     | 2 +-
>  7 files changed, 7 insertions(+), 14 deletions(-)
> 
> diff --git a/migration/channel.c b/migration/channel.c
> index af6c2cc76e..a8a5f26dfd 100644
> --- a/migration/channel.c
> +++ b/migration/channel.c
> @@ -61,14 +61,7 @@ out:
>      }
>  }
>  
> -
> -/**
> - * @migration_channel_connect - Create new outgoing migration channel
> - *
> - * @s: Current migration state
> - * @ioc: Channel to which we are connecting
> - */
> -void migration_channel_connect(MigrationState *s, QIOChannel *ioc)
> +void migration_channel_connect_outgoing(MigrationState *s, QIOChannel *ioc)
>  {
>      trace_migration_set_outgoing_channel(ioc, object_get_typename(OBJECT(ioc)));
>  
> diff --git a/migration/channel.h b/migration/channel.h
> index ccfeaaef18..7d3457271d 100644
> --- a/migration/channel.h
> +++ b/migration/channel.h
> @@ -20,7 +20,7 @@
>  
>  void migration_channel_process_incoming(QIOChannel *ioc);
>  
> -void migration_channel_connect(MigrationState *s, QIOChannel *ioc);
> +void migration_channel_connect_outgoing(MigrationState *s, QIOChannel *ioc);
>  
>  int migration_channel_read_peek(QIOChannel *ioc,
>                                  const char *buf,
> diff --git a/migration/exec.c b/migration/exec.c
> index d83a07435a..d1629944dc 100644
> --- a/migration/exec.c
> +++ b/migration/exec.c
> @@ -55,7 +55,7 @@ void exec_start_outgoing_migration(MigrationState *s, strList *command,
>      }
>  
>      qio_channel_set_name(ioc, "migration-exec-outgoing");
> -    migration_channel_connect(s, ioc);
> +    migration_channel_connect_outgoing(s, ioc);
>      object_unref(OBJECT(ioc));
>  }
>  
> diff --git a/migration/fd.c b/migration/fd.c
> index 0144a70742..150b236fbf 100644
> --- a/migration/fd.c
> +++ b/migration/fd.c
> @@ -70,7 +70,7 @@ void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **
>      }
>  
>      qio_channel_set_name(ioc, "migration-fd-outgoing");
> -    migration_channel_connect(s, ioc);
> +    migration_channel_connect_outgoing(s, ioc);
>      object_unref(OBJECT(ioc));
>  }
>  
> diff --git a/migration/file.c b/migration/file.c
> index 7bb9c1c79f..935402f36b 100644
> --- a/migration/file.c
> +++ b/migration/file.c
> @@ -122,7 +122,7 @@ void file_start_outgoing_migration(MigrationState *s,
>          return;
>      }
>      qio_channel_set_name(ioc, "migration-file-outgoing");
> -    migration_channel_connect(s, ioc);
> +    migration_channel_connect_outgoing(s, ioc);
>  }
>  
>  static gboolean file_accept_incoming_migration(QIOChannel *ioc,
> diff --git a/migration/socket.c b/migration/socket.c
> index 298bac30cc..611915f84d 100644
> --- a/migration/socket.c
> +++ b/migration/socket.c
> @@ -73,7 +73,7 @@ static void socket_outgoing_migration(QIOTask *task,
>      }
>  
>      trace_migration_socket_outgoing_connected();
> -    migration_channel_connect(data->s, sioc);
> +    migration_channel_connect_outgoing(data->s, sioc);
>      return;
>  err:
>      trace_migration_socket_outgoing_error(error_get_pretty(err));
> diff --git a/migration/tls.c b/migration/tls.c
> index a54e8e6e14..f68e6a533b 100644
> --- a/migration/tls.c
> +++ b/migration/tls.c
> @@ -114,7 +114,7 @@ static void migration_tls_outgoing_handshake(QIOTask *task,
>      }
>  
>      trace_migration_tls_outgoing_handshake_complete();
> -    migration_channel_connect(s, ioc);
> +    migration_channel_connect_outgoing(s, ioc);
>  }
>  
>  QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 14/25] migration: Remove QEMUFile from channel.c

[Fabiano Rosas]

Peter Xu <peterx@redhat.com> writes:

> On Fri, Dec 26, 2025 at 06:19:16PM -0300, Fabiano Rosas wrote:
>> Make channel.c deal only with QIOChannel objects. Move any handling of
>> QEMUFile into migration.c. To achieve this in a clean way:
>> 
>> 1) Define a migration_outgoing_setup, analogous to
>> migration_incoming_setup, responsible for creating the QEMUFile from
>> the QIOChannel.
>> 
>> 2) Increase the scope of migration_incoming_setup to create not only
>> the main channel, but all the others as well. That is currently being
>> done at migration_ioc_process, so move the code.
>> 
>> 3) Adjust RDMA code to pass in the QIOChannel and remove some of the
>> usage of QEMUFile.
>> 
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>> ---
>>  migration/channel.c   | 21 ++++++-----
>>  migration/migration.c | 88 ++++++++++++++++++++++---------------------
>>  migration/migration.h |  6 ++-
>>  migration/multifd.c   |  7 ++--
>>  migration/multifd.h   |  2 +-
>>  migration/rdma.c      | 28 ++++----------
>>  6 files changed, 73 insertions(+), 79 deletions(-)
>> 
>> diff --git a/migration/channel.c b/migration/channel.c
>> index 7243b99108..af6c2cc76e 100644
>> --- a/migration/channel.c
>> +++ b/migration/channel.c
>> @@ -14,7 +14,6 @@
>>  #include "channel.h"
>>  #include "tls.h"
>>  #include "migration.h"
>> -#include "qemu-file.h"
>>  #include "trace.h"
>>  #include "qapi/error.h"
>>  #include "io/channel-tls.h"
>> @@ -34,6 +33,7 @@ void migration_channel_process_incoming(QIOChannel *ioc)
>>  {
>>      MigrationIncomingState *mis = migration_incoming_get_current();
>>      Error *local_err = NULL;
>> +    uint8_t ch;
>>  
>>      trace_migration_set_incoming_channel(
>>          ioc, object_get_typename(OBJECT(ioc)));
>> @@ -42,9 +42,16 @@ void migration_channel_process_incoming(QIOChannel *ioc)
>>          migration_tls_channel_process_incoming(ioc, &local_err);
>>      } else {
>>          migration_ioc_register_yank(ioc);
>> -        migration_ioc_process_incoming(ioc, &local_err);
>> -    }
>> +        ch = migration_ioc_process_incoming(ioc, &local_err);
>> +        if (!ch) {
>> +            goto out;
>> +        }
>>  
>> +        if (migration_incoming_setup(ioc, ch, &local_err)) {
>> +            migration_incoming_process();
>> +        }
>> +    }
>> +out:
>>      if (local_err) {
>>          error_report_err(local_err);
>>          migrate_set_state(&mis->state, mis->state, MIGRATION_STATUS_FAILED);
>> @@ -75,14 +82,8 @@ void migration_channel_connect(MigrationState *s, QIOChannel *ioc)
>>          return;
>>      }
>>  
>> -    QEMUFile *f = qemu_file_new_output(ioc);
>> -
>>      migration_ioc_register_yank(ioc);
>> -
>> -    qemu_mutex_lock(&s->qemu_file_lock);
>> -    s->to_dst_file = f;
>> -    qemu_mutex_unlock(&s->qemu_file_lock);
>> -
>> +    migration_outgoing_setup(ioc);
>>      migration_connect(s);
>>  }
>>  
>> diff --git a/migration/migration.c b/migration/migration.c
>> index 5c6c76f110..677581b5a5 100644
>> --- a/migration/migration.c
>> +++ b/migration/migration.c
>> @@ -92,7 +92,7 @@ enum mig_rp_message_type {
>>  };
>>  
>>  /* Migration channel types */
>> -enum { CH_MAIN, CH_MULTIFD, CH_POSTCOPY };
>> +enum { CH_NONE, CH_MAIN, CH_MULTIFD, CH_POSTCOPY };
>>  
>>  /* When we add fault tolerance, we could have several
>>     migrations at once.  For now we don't need to add
>> @@ -934,17 +934,48 @@ out:
>>      migrate_incoming_unref_outgoing_state();
>>  }
>>  
>> -/**
>> - * migration_incoming_setup: Setup incoming migration
>> - * @f: file for main migration channel
>> - */
>> -static void migration_incoming_setup(QEMUFile *f)
>> +static bool migration_has_main_and_multifd_channels(void);
>> +
>> +bool migration_incoming_setup(QIOChannel *ioc, uint8_t channel, Error **errp)
>>  {
>>      MigrationIncomingState *mis = migration_incoming_get_current();
>> +    QEMUFile *f;
>>  
>> -    assert(!mis->from_src_file);
>> -    mis->from_src_file = f;
>> -    qemu_file_set_blocking(f, false, &error_abort);
>> +    switch (channel) {
>> +    case CH_MAIN:
>> +        f = qemu_file_new_input(ioc);
>> +        assert(!mis->from_src_file);
>> +        mis->from_src_file = f;
>> +        qemu_file_set_blocking(f, false, &error_abort);
>> +        break;
>> +
>> +    case CH_MULTIFD:
>> +        if (!multifd_recv_new_channel(ioc, errp)) {
>> +            return false;
>> +        }
>> +        break;
>> +
>> +    case CH_POSTCOPY:
>> +        assert(!mis->postcopy_qemufile_dst);
>> +        f = qemu_file_new_input(ioc);
>> +        postcopy_preempt_new_channel(mis, f);
>> +        return false;
>> +
>> +    default:
>> +        g_assert_not_reached();
>> +    }
>> +
>> +    return migration_has_main_and_multifd_channels();
>> +}
>> +
>> +void migration_outgoing_setup(QIOChannel *ioc)
>> +{
>> +    MigrationState *s = migrate_get_current();
>> +    QEMUFile *f = qemu_file_new_output(ioc);
>> +
>> +    qemu_mutex_lock(&s->qemu_file_lock);
>> +    s->to_dst_file = f;
>> +    qemu_mutex_unlock(&s->qemu_file_lock);
>>  }
>>  
>>  /* Returns true if recovered from a paused migration, otherwise false */
>> @@ -990,12 +1021,6 @@ void migration_incoming_process(void)
>>      qemu_coroutine_enter(co);
>>  }
>>  
>> -void migration_fd_process_incoming(QEMUFile *f)
>> -{
>> -    migration_incoming_setup(f);
>> -    migration_incoming_process();
>> -}
>> -
>>  static bool migration_has_main_and_multifd_channels(void)
>>  {
>>      MigrationIncomingState *mis = migration_incoming_get_current();
>> @@ -1012,12 +1037,10 @@ static bool migration_has_main_and_multifd_channels(void)
>>      return true;
>>  }
>>  
>> -void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>> +uint8_t migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>>  {
>>      MigrationIncomingState *mis = migration_incoming_get_current();
>> -    Error *local_err = NULL;
>> -    QEMUFile *f;
>> -    uint8_t channel;
>> +    uint8_t channel = CH_NONE;
>>      uint32_t channel_magic = 0;
>>      int ret = 0;
>>  
>> @@ -1036,7 +1059,7 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>>              ret = migration_channel_read_peek(ioc, (void *)&channel_magic,
>>                                                sizeof(channel_magic), errp);
>>              if (ret != 0) {
>> -                return;
>> +                goto out;
>>              }
>>  
>>              channel_magic = be32_to_cpu(channel_magic);
>> @@ -1051,7 +1074,6 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>>                  channel = CH_MAIN;
>>              } else {
>>                  error_setg(errp, "unknown channel magic: %u", channel_magic);
>> -                return;
>>              }
>>          } else if (mis->from_src_file && migrate_multifd()) {
>>              /*
>> @@ -1063,33 +1085,13 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>>              channel = CH_MAIN;
>>          } else {
>>              error_setg(errp, "non-peekable channel used without multifd");
>> -            return;
>>          }
>>      } else {
>>          assert(migrate_postcopy_preempt());
>>          channel = CH_POSTCOPY;
>>      }
>> -
>> -    if (channel == CH_MAIN) {
>> -        f = qemu_file_new_input(ioc);
>> -        migration_incoming_setup(f);
>> -    } else if (channel == CH_MULTIFD) {
>> -        /* Multiple connections */
>> -        multifd_recv_new_channel(ioc, &local_err);
>> -        if (local_err) {
>> -            error_propagate(errp, local_err);
>> -            return;
>> -        }
>> -    } else if (channel == CH_POSTCOPY) {
>> -        assert(!mis->postcopy_qemufile_dst);
>> -        f = qemu_file_new_input(ioc);
>> -        postcopy_preempt_new_channel(mis, f);
>> -        return;
>> -    }
>> -
>> -    if (migration_has_main_and_multifd_channels()) {
>> -        migration_incoming_process();
>> -    }
>> +out:
>> +    return channel;
>>  }
>>  
>>  /**
>> diff --git a/migration/migration.h b/migration/migration.h
>> index f340cd518d..d2b82cf54f 100644
>> --- a/migration/migration.h
>> +++ b/migration/migration.h
>> @@ -526,8 +526,10 @@ struct MigrationState {
>>  void migrate_set_state(MigrationStatus *state, MigrationStatus old_state,
>>                         MigrationStatus new_state);
>>  
>> -void migration_fd_process_incoming(QEMUFile *f);
>> -void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp);
>> +void migration_outgoing_setup(QIOChannel *ioc);
>> +bool migration_incoming_setup(QIOChannel *ioc, uint8_t channel, Error **errp);
>> +
>> +uint8_t migration_ioc_process_incoming(QIOChannel *ioc, Error **errp);
>>  void migration_incoming_process(void);
>>  
>>  bool  migration_has_all_channels(void);
>> diff --git a/migration/multifd.c b/migration/multifd.c
>> index 3fb1a07ba9..c6639dbab5 100644
>> --- a/migration/multifd.c
>> +++ b/migration/multifd.c
>> @@ -1521,7 +1521,7 @@ bool multifd_recv_all_channels_created(void)
>>   * Try to receive all multifd channels to get ready for the migration.
>>   * Sets @errp when failing to receive the current channel.
>>   */
>> -void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
>> +bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
>>  {
>>      MultiFDRecvParams *p;
>>      Error *local_err = NULL;
>> @@ -1536,7 +1536,7 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
>>                                      "failed to receive packet"
>>                                      " via multifd channel %d: ",
>>                                      qatomic_read(&multifd_recv_state->count));
>> -            return;
>> +            return false;
>>          }
>>          trace_multifd_recv_new_channel(id);
>>      } else {
>> @@ -1549,7 +1549,7 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
>>                     id);
>>          multifd_recv_terminate_threads(error_copy(local_err));
>>          error_propagate(errp, local_err);
>> -        return;
>> +        return false;
>>      }
>>      p->c = ioc;
>>      object_ref(OBJECT(ioc));
>> @@ -1558,4 +1558,5 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
>>      qemu_thread_create(&p->thread, p->name, multifd_recv_thread, p,
>>                         QEMU_THREAD_JOINABLE);
>>      qatomic_inc(&multifd_recv_state->count);
>> +    return true;
>>  }
>> diff --git a/migration/multifd.h b/migration/multifd.h
>> index 9b6d81e7ed..89a395aef2 100644
>> --- a/migration/multifd.h
>> +++ b/migration/multifd.h
>> @@ -42,7 +42,7 @@ int multifd_recv_setup(Error **errp);
>>  void multifd_recv_cleanup(void);
>>  void multifd_recv_shutdown(void);
>>  bool multifd_recv_all_channels_created(void);
>> -void multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
>> +bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
>>  void multifd_recv_sync_main(void);
>>  int multifd_send_sync_main(MultiFDSyncReq req);
>>  bool multifd_queue_page(RAMBlock *block, ram_addr_t offset);
>> diff --git a/migration/rdma.c b/migration/rdma.c
>> index 596a1aba0b..7bee871e2b 100644
>> --- a/migration/rdma.c
>> +++ b/migration/rdma.c
>> @@ -384,7 +384,6 @@ struct QIOChannelRDMA {
>>      QIOChannel parent;
>>      RDMAContext *rdmain;
>>      RDMAContext *rdmaout;
>> -    QEMUFile *file;
>>      bool blocking; /* XXX we don't actually honour this yet */
>>  };
>>  
>> @@ -3836,32 +3835,20 @@ static void qio_channel_rdma_register_types(void)
>>  
>>  type_init(qio_channel_rdma_register_types);
>>  
>> -static QEMUFile *rdma_new_input(RDMAContext *rdma)
>> +static QIOChannel *rdma_new_ioc(RDMAContext *rdma)
>>  {
>>      QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(object_new(TYPE_QIO_CHANNEL_RDMA));
>>  
>> -    rioc->file = qemu_file_new_input(QIO_CHANNEL(rioc));
>> -    rioc->rdmain = rdma;
>> -    rioc->rdmaout = rdma->return_path;
>> -
>> -    return rioc->file;
>> -}
>> -
>> -static QEMUFile *rdma_new_output(RDMAContext *rdma)
>> -{
>> -    QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(object_new(TYPE_QIO_CHANNEL_RDMA));
>> -
>> -    rioc->file = qemu_file_new_output(QIO_CHANNEL(rioc));
>>      rioc->rdmaout = rdma;
>>      rioc->rdmain = rdma->return_path;
>
> Likely it was overlooked rdmaout/rdmain was set in reverse order in these
> two functions.  I gave it a quick run on rdma and it was indeed broken
> starting from this patch.
>

I'll remember to test rdma next time, thanks for catching this.

> The goal of the change looks reasonable in general otherwise, said that,
> maybe there's way to split the patch somehow?
>

Yes, no problem.

Re: [RFC PATCH 22/25] migration/channel: Merge both sides of the connection initiation code

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:24PM -0300, Fabiano Rosas wrote:
> Now that everything is in channel.c, it's easier to browse this code
> if it's all in the same place. It's also easier to grasp what the
> connection flow is if both sides of the connection are close together.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
>  migration/channel.c | 86 +++++++++++++++++++++++----------------------
>  migration/channel.h | 14 ++++++--
>  2 files changed, 56 insertions(+), 44 deletions(-)
> 
> diff --git a/migration/channel.c b/migration/channel.c
> index 042e01b224..ba9aa1c58b 100644
> --- a/migration/channel.c
> +++ b/migration/channel.c
> @@ -31,10 +31,11 @@
>  #include "trace.h"
>  #include "yank_functions.h"
>  
> -bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
> +bool migration_connect(MigrationAddress *addr, bool out, Error **errp)
>  {
>      g_autoptr(QIOChannel) ioc = NULL;
>      SocketAddress *saddr;
> +    ERRP_GUARD();
>  
>      switch (addr->transport) {
>      case MIGRATION_ADDRESS_TYPE_SOCKET:
> @@ -44,15 +45,24 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
>          case SOCKET_ADDRESS_TYPE_INET:
>          case SOCKET_ADDRESS_TYPE_UNIX:
>          case SOCKET_ADDRESS_TYPE_VSOCK:
> -            socket_connect_outgoing(saddr, errp);
> -            /*
> -             * async: after the socket is connected, calls
> -             * migration_channel_connect_outgoing() directly.
> -             */
> -            return true;
> +            if (out) {

Personally I wouldn't suggest we merge the outgoing / incoming with
migration_connect() then split paths once more in this exact function.

I got this conclusion when I started to count how many "if (out)" are
there..  When there're too much, it may imply we need to think more..

This also answers part of my confusion when reading the previous patch - if
that was only paving way for this one, IMHO it may not be as worthwhile,
and I would tend to avoid both.

Thoughts?

> +                socket_connect_outgoing(saddr, errp);
> +                /*
> +                 * async: after the socket is connected, calls
> +                 * migration_channel_connect_outgoing() directly.
> +                 */
> +                return true;
> +            } else {
> +                socket_connect_incoming(saddr, errp);
> +            }
> +
>              break;
>          case SOCKET_ADDRESS_TYPE_FD:
> -            ioc = fd_connect_outgoing(saddr->u.fd.str, errp);
> +            if (out) {
> +                ioc = fd_connect_outgoing(saddr->u.fd.str, errp);
> +            } else {
> +                fd_connect_incoming(saddr->u.fd.str, errp);
> +            }
>              break;
>          default:
>              g_assert_not_reached();
> @@ -62,16 +72,28 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
>  
>  #ifdef CONFIG_RDMA
>      case MIGRATION_ADDRESS_TYPE_RDMA:
> -        ioc = rdma_connect_outgoing(&addr->u.rdma, errp);
> +        if (out) {
> +            ioc = rdma_connect_outgoing(&addr->u.rdma, errp);
> +        } else {
> +            rdma_connect_incoming(&addr->u.rdma, errp);
> +        }
>          break;
>  #endif
>  
>      case MIGRATION_ADDRESS_TYPE_EXEC:
> -        ioc = exec_connect_outgoing(addr->u.exec.args, errp);
> +        if (out) {
> +            ioc = exec_connect_outgoing(addr->u.exec.args, errp);
> +        } else {
> +            exec_connect_incoming(addr->u.exec.args, errp);
> +        }
>          break;
>  
>      case MIGRATION_ADDRESS_TYPE_FILE:
> -        ioc = file_connect_outgoing(&addr->u.file, errp);
> +        if (out) {
> +            ioc = file_connect_outgoing(&addr->u.file, errp);
> +        } else {
> +            file_connect_incoming(&addr->u.file, errp);
> +        }
>          break;
>  
>      default:
> @@ -79,42 +101,22 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
>          break;
>      }
>  
> -    if (!ioc) {
> -        return false;
> -    }
> -
> -    migration_channel_connect_outgoing(ioc);
> -    return true;
> -}
> -
> -void migration_connect_incoming(MigrationAddress *addr, Error **errp)
> -{
> -    if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
> -        SocketAddress *saddr = &addr->u.socket;
> -        if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
> -            saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
> -            saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
> -            socket_connect_incoming(saddr, errp);
> -        } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
> -            fd_connect_incoming(saddr->u.fd.str, errp);
> +    if (out) {
> +        if (!ioc) {
> +            return false;
>          }
> -#ifdef CONFIG_RDMA
> -    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
> -        rdma_connect_incoming(&addr->u.rdma, errp);
> -#endif
> -    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
> -        exec_connect_incoming(addr->u.exec.args, errp);
> -    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
> -        file_connect_incoming(&addr->u.file, errp);
> -    } else {
> -        error_setg(errp, "unknown migration protocol");
> +
> +        migration_channel_connect_outgoing(ioc);
> +        return true;
>      }
>  
>      /*
> -     * async: the above routines all wait for the incoming connection
> -     * and call back to migration_channel_process_incoming() to start
> -     * the migration.
> +     * async: on the incoming side all of the transport routines above
> +     * wait for the incoming connection and call back to
> +     * migration_channel_process_incoming() to start the migration.
>       */
> +
> +    return !*errp;
>  }
>  
>  bool migration_has_main_and_multifd_channels(void)
> diff --git a/migration/channel.h b/migration/channel.h
> index 8cf16bfda9..86934fee38 100644
> --- a/migration/channel.h
> +++ b/migration/channel.h
> @@ -39,6 +39,16 @@ int migration_channel_read_peek(QIOChannel *ioc,
>  bool migration_has_main_and_multifd_channels(void);
>  bool migration_has_all_channels(void);
>  
> -bool migration_connect_outgoing(MigrationAddress *addr, Error **errp);
> -void migration_connect_incoming(MigrationAddress *addr, Error **errp);
> +bool migration_connect(MigrationAddress *addr, bool out, Error **errp);
> +static inline bool migration_connect_outgoing(MigrationAddress *addr,
> +                                              Error **errp)
> +{
> +    return migration_connect(addr, true, errp);
> +}
> +
> +static inline bool migration_connect_incoming(MigrationAddress *addr,
> +                                              Error **errp)
> +{
> +    return migration_connect(addr, false, errp);
> +}
>  #endif
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 23/25] migration: Move channel parsing to channel.c

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:25PM -0300, Fabiano Rosas wrote:
> Encapsulate the MigrationChannelList parsing in a new
> migrate_channels_parse() located at channel.c.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu

Re: [RFC PATCH 24/25] migration: Move URI parsing to channel.c

[Peter Xu]

On Fri, Dec 26, 2025 at 06:19:26PM -0300, Fabiano Rosas wrote:
> The migrate_uri_parse function is responsible for converting the URI
> string into a MigrationChannel for consumption by the rest of the
> code. Move it to channel.c and add a wrapper that calls both URI and
> channels parsing.
> 
> While here, add some words about the memory management of the
> MigrationChannel object, which is slightly different from
> migrate_uri_parse() and migrate_channels_parse(). The former takes a
> string and has to allocate a MigrationChannel, the latter takes a QAPI
> object that is managed by the QAPI code.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

There're some comments added into migration_connect(), that I still don't
think I fully agree upon.. but the rest looks all good to me.

That's probably to be discussed separately anyway, I think you can take
mine here:

Reviewed-by: Peter Xu <peterx@redhat.com>

> ---
>  migration/channel.c   | 97 +++++++++++++++++++++++++++++++++++++++++--
>  migration/channel.h   |  9 ++--
>  migration/migration.c | 95 ++----------------------------------------
>  3 files changed, 101 insertions(+), 100 deletions(-)
> 
> diff --git a/migration/channel.c b/migration/channel.c
> index 8b43c3d983..d30e29c9b3 100644
> --- a/migration/channel.c
> +++ b/migration/channel.c
> @@ -40,6 +40,12 @@ bool migration_connect(MigrationAddress *addr, bool out, Error **errp)
>      SocketAddress *saddr;
>      ERRP_GUARD();
>  
> +    /*
> +     * This is reached from a QMP command, the transport code below
> +     * must copy the relevant parts of 'addr' before this function
> +     * returns because the QAPI code will free it.
> +     */
> +
>      switch (addr->transport) {
>      case MIGRATION_ADDRESS_TYPE_SOCKET:
>          saddr = &addr->u.socket;
> @@ -318,10 +324,10 @@ int migration_channel_read_peek(QIOChannel *ioc,
>      return 0;
>  }
>  
> -bool migrate_channels_parse(MigrationChannelList *channels,
> -                            MigrationChannel **main_channelp,
> -                            MigrationChannel **cpr_channelp,
> -                            Error **errp)
> +static bool migrate_channels_parse(MigrationChannelList *channels,
> +                                   MigrationChannel **main_channelp,
> +                                   MigrationChannel **cpr_channelp,
> +                                   Error **errp)
>  {
>      MigrationChannel *channelv[MIGRATION_CHANNEL_TYPE__MAX] = { NULL };
>      bool single_channel;
> @@ -353,6 +359,15 @@ bool migrate_channels_parse(MigrationChannelList *channels,
>          }
>      }
>  
> +    /*
> +     * These don't technically need to be cloned because they come
> +     * from a QAPI object ('channels'). The top-level caller
> +     * (qmp_migrate) needs to copy the necessary information before
> +     * returning from the QMP command. Cloning here is just to keep
> +     * the interface consistent with migrate_uri_parse() that _does
> +     * not_ take a QAPI object and instead allocates and transfers
> +     * ownership of a MigrationChannel to qmp_migrate.
> +     */
>      if (cpr_channelp) {
>          *cpr_channelp = QAPI_CLONE(MigrationChannel,
>                                     channelv[MIGRATION_CHANNEL_TYPE_CPR]);
> @@ -368,3 +383,77 @@ bool migrate_channels_parse(MigrationChannelList *channels,
>  
>      return true;
>  }
> +
> +bool migrate_uri_parse(const char *uri, MigrationChannel **channel,
> +                       Error **errp)
> +{
> +    g_autoptr(MigrationChannel) val = g_new0(MigrationChannel, 1);
> +    g_autoptr(MigrationAddress) addr = g_new0(MigrationAddress, 1);
> +    InetSocketAddress *isock = &addr->u.rdma;
> +    strList **tail = &addr->u.exec.args;
> +
> +    if (strstart(uri, "exec:", NULL)) {
> +        addr->transport = MIGRATION_ADDRESS_TYPE_EXEC;
> +#ifdef WIN32
> +        QAPI_LIST_APPEND(tail, g_strdup(exec_get_cmd_path()));
> +        QAPI_LIST_APPEND(tail, g_strdup("/c"));
> +#else
> +        QAPI_LIST_APPEND(tail, g_strdup("/bin/sh"));
> +        QAPI_LIST_APPEND(tail, g_strdup("-c"));
> +#endif
> +        QAPI_LIST_APPEND(tail, g_strdup(uri + strlen("exec:")));
> +    } else if (strstart(uri, "rdma:", NULL)) {
> +        if (inet_parse(isock, uri + strlen("rdma:"), errp)) {
> +            qapi_free_InetSocketAddress(isock);
> +            return false;
> +        }
> +        addr->transport = MIGRATION_ADDRESS_TYPE_RDMA;
> +    } else if (strstart(uri, "tcp:", NULL) ||
> +                strstart(uri, "unix:", NULL) ||
> +                strstart(uri, "vsock:", NULL) ||
> +                strstart(uri, "fd:", NULL)) {
> +        addr->transport = MIGRATION_ADDRESS_TYPE_SOCKET;
> +        SocketAddress *saddr = socket_parse(uri, errp);
> +        if (!saddr) {
> +            return false;
> +        }
> +        addr->u.socket.type = saddr->type;
> +        addr->u.socket.u = saddr->u;
> +        /* Don't free the objects inside; their ownership moved to "addr" */
> +        g_free(saddr);
> +    } else if (strstart(uri, "file:", NULL)) {
> +        addr->transport = MIGRATION_ADDRESS_TYPE_FILE;
> +        addr->u.file.filename = g_strdup(uri + strlen("file:"));
> +        if (file_parse_offset(addr->u.file.filename, &addr->u.file.offset,
> +                              errp)) {
> +            return false;
> +        }
> +    } else {
> +        error_setg(errp, "unknown migration protocol: %s", uri);
> +        return false;
> +    }
> +
> +    val->channel_type = MIGRATION_CHANNEL_TYPE_MAIN;
> +    val->addr = g_steal_pointer(&addr);
> +    *channel = g_steal_pointer(&val);
> +    return true;
> +}
> +
> +bool migration_channel_parse_input(const char *uri,
> +                                   MigrationChannelList *channels,
> +                                   MigrationChannel **main_channelp,
> +                                   MigrationChannel **cpr_channelp,
> +                                   Error **errp)
> +{
> +    if (!uri == !channels) {
> +        error_setg(errp, "need either 'uri' or 'channels' argument");
> +        return false;
> +    }
> +
> +    if (channels) {
> +        return migrate_channels_parse(channels, main_channelp, cpr_channelp,
> +                                      errp);
> +    } else {
> +        return migrate_uri_parse(uri, main_channelp, errp);
> +    }
> +}
> diff --git a/migration/channel.h b/migration/channel.h
> index b3276550b7..3724b0493a 100644
> --- a/migration/channel.h
> +++ b/migration/channel.h
> @@ -52,8 +52,9 @@ static inline bool migration_connect_incoming(MigrationAddress *addr,
>      return migration_connect(addr, false, errp);
>  }
>  
> -bool migrate_channels_parse(MigrationChannelList *channels,
> -                            MigrationChannel **main_channelp,
> -                            MigrationChannel **cpr_channelp,
> -                            Error **errp);
> +bool migration_channel_parse_input(const char *uri,
> +                                   MigrationChannelList *channels,
> +                                   MigrationChannel **main_channelp,
> +                                   MigrationChannel **cpr_channelp,
> +                                   Error **errp);
>  #endif
> diff --git a/migration/migration.c b/migration/migration.c
> index 6064f1e5ea..15d8459a81 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -15,7 +15,6 @@
>  
>  #include "qemu/osdep.h"
>  #include "qemu/ctype.h"
> -#include "qemu/cutils.h"
>  #include "qemu/error-report.h"
>  #include "qemu/main-loop.h"
>  #include "migration/blocker.h"
> @@ -659,61 +658,6 @@ bool migrate_is_uri(const char *uri)
>      return *uri == ':';
>  }
>  
> -bool migrate_uri_parse(const char *uri, MigrationChannel **channel,
> -                       Error **errp)
> -{
> -    g_autoptr(MigrationChannel) val = g_new0(MigrationChannel, 1);
> -    g_autoptr(MigrationAddress) addr = g_new0(MigrationAddress, 1);
> -    InetSocketAddress *isock = &addr->u.rdma;
> -    strList **tail = &addr->u.exec.args;
> -
> -    if (strstart(uri, "exec:", NULL)) {
> -        addr->transport = MIGRATION_ADDRESS_TYPE_EXEC;
> -#ifdef WIN32
> -        QAPI_LIST_APPEND(tail, g_strdup(exec_get_cmd_path()));
> -        QAPI_LIST_APPEND(tail, g_strdup("/c"));
> -#else
> -        QAPI_LIST_APPEND(tail, g_strdup("/bin/sh"));
> -        QAPI_LIST_APPEND(tail, g_strdup("-c"));
> -#endif
> -        QAPI_LIST_APPEND(tail, g_strdup(uri + strlen("exec:")));
> -    } else if (strstart(uri, "rdma:", NULL)) {
> -        if (inet_parse(isock, uri + strlen("rdma:"), errp)) {
> -            qapi_free_InetSocketAddress(isock);
> -            return false;
> -        }
> -        addr->transport = MIGRATION_ADDRESS_TYPE_RDMA;
> -    } else if (strstart(uri, "tcp:", NULL) ||
> -                strstart(uri, "unix:", NULL) ||
> -                strstart(uri, "vsock:", NULL) ||
> -                strstart(uri, "fd:", NULL)) {
> -        addr->transport = MIGRATION_ADDRESS_TYPE_SOCKET;
> -        SocketAddress *saddr = socket_parse(uri, errp);
> -        if (!saddr) {
> -            return false;
> -        }
> -        addr->u.socket.type = saddr->type;
> -        addr->u.socket.u = saddr->u;
> -        /* Don't free the objects inside; their ownership moved to "addr" */
> -        g_free(saddr);
> -    } else if (strstart(uri, "file:", NULL)) {
> -        addr->transport = MIGRATION_ADDRESS_TYPE_FILE;
> -        addr->u.file.filename = g_strdup(uri + strlen("file:"));
> -        if (file_parse_offset(addr->u.file.filename, &addr->u.file.offset,
> -                              errp)) {
> -            return false;
> -        }
> -    } else {
> -        error_setg(errp, "unknown migration protocol: %s", uri);
> -        return false;
> -    }
> -
> -    val->channel_type = MIGRATION_CHANNEL_TYPE_MAIN;
> -    val->addr = g_steal_pointer(&addr);
> -    *channel = g_steal_pointer(&val);
> -    return true;
> -}
> -
>  static bool
>  migration_incoming_state_setup(MigrationIncomingState *mis, Error **errp)
>  {
> @@ -744,27 +688,10 @@ static void qemu_setup_incoming_migration(const char *uri, bool has_channels,
>      g_autoptr(MigrationChannel) main_ch = NULL;
>      MigrationIncomingState *mis = migration_incoming_get_current();
>  
> -    /*
> -     * Having preliminary checks for uri and channel
> -     */
> -    if (!uri == !channels) {
> -        error_setg(errp, "need either 'uri' or 'channels' argument");
> +    if (!migration_channel_parse_input(uri, channels, &main_ch, NULL, errp)) {
>          return;
>      }
>  
> -    if (channels) {
> -        if (!migrate_channels_parse(channels, &main_ch, NULL, errp)) {
> -            return;
> -        }
> -    }
> -
> -    if (uri) {
> -        /* caller uses the old URI syntax */
> -        if (!migrate_uri_parse(uri, &main_ch, errp)) {
> -            return;
> -        }
> -    }
> -
>      /* transport mechanism not suitable for migration? */
>      if (!migration_transport_compatible(main_ch->addr, errp)) {
>          return;
> @@ -2124,27 +2051,11 @@ void qmp_migrate(const char *uri, bool has_channels,
>      g_autoptr(MigrationChannel) main_ch = NULL;
>      g_autoptr(MigrationChannel) cpr_ch = NULL;
>  
> -    /*
> -     * Having preliminary checks for uri and channel
> -     */
> -    if (!uri == !channels) {
> -        error_setg(errp, "need either 'uri' or 'channels' argument");
> +    if (!migration_channel_parse_input(uri, channels, &main_ch, &cpr_ch,
> +                                       errp)) {
>          return;
>      }
>  
> -    if (channels) {
> -        if (!migrate_channels_parse(channels, &main_ch, &cpr_ch, errp)) {
> -            return;
> -        }
> -    }
> -
> -    if (uri) {
> -        /* caller uses the old URI syntax */
> -        if (!migrate_uri_parse(uri, &main_ch, errp)) {
> -            return;
> -        }
> -    }
> -
>      /* transport mechanism not suitable for migration? */
>      if (!migration_transport_compatible(main_ch->addr, errp)) {
>          return;
> -- 
> 2.51.0
> 

-- 
Peter Xu

Re: [RFC PATCH 22/25] migration/channel: Merge both sides of the connection initiation code

[Fabiano Rosas]

Peter Xu <peterx@redhat.com> writes:

> On Fri, Dec 26, 2025 at 06:19:24PM -0300, Fabiano Rosas wrote:
>> Now that everything is in channel.c, it's easier to browse this code
>> if it's all in the same place. It's also easier to grasp what the
>> connection flow is if both sides of the connection are close together.
>> 
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>> ---
>>  migration/channel.c | 86 +++++++++++++++++++++++----------------------
>>  migration/channel.h | 14 ++++++--
>>  2 files changed, 56 insertions(+), 44 deletions(-)
>> 
>> diff --git a/migration/channel.c b/migration/channel.c
>> index 042e01b224..ba9aa1c58b 100644
>> --- a/migration/channel.c
>> +++ b/migration/channel.c
>> @@ -31,10 +31,11 @@
>>  #include "trace.h"
>>  #include "yank_functions.h"
>>  
>> -bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
>> +bool migration_connect(MigrationAddress *addr, bool out, Error **errp)
>>  {
>>      g_autoptr(QIOChannel) ioc = NULL;
>>      SocketAddress *saddr;
>> +    ERRP_GUARD();
>>  
>>      switch (addr->transport) {
>>      case MIGRATION_ADDRESS_TYPE_SOCKET:
>> @@ -44,15 +45,24 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
>>          case SOCKET_ADDRESS_TYPE_INET:
>>          case SOCKET_ADDRESS_TYPE_UNIX:
>>          case SOCKET_ADDRESS_TYPE_VSOCK:
>> -            socket_connect_outgoing(saddr, errp);
>> -            /*
>> -             * async: after the socket is connected, calls
>> -             * migration_channel_connect_outgoing() directly.
>> -             */
>> -            return true;
>> +            if (out) {
>
> Personally I wouldn't suggest we merge the outgoing / incoming with
> migration_connect() then split paths once more in this exact function.
>
> I got this conclusion when I started to count how many "if (out)" are
> there..  When there're too much, it may imply we need to think more..
>

Well, compared to before, there 50% less "if (addr->transport == ...)",
this is top level programming! =D

This part of the series is highly subjective, if there's a patch you
don't like it we can drop it, let's not dwell on it.. Just read my words
below on the previous patch, which I think you may be mistaken about.

> This also answers part of my confusion when reading the previous patch - if
> that was only paving way for this one, IMHO it may not be as worthwhile,
> and I would tend to avoid both.
>

Patch 21 is just a cleanup after patch 19 moves the call to
migration_channel_connect_outgoing from being inside the transport
routines to this top level here at migration_connect(), which moves the
places where MigrationState is used as well. So it removes unused
passing of MigrationState along with the SocketConnectionData.

> Thoughts?
>
>> +                socket_connect_outgoing(saddr, errp);
>> +                /*
>> +                 * async: after the socket is connected, calls
>> +                 * migration_channel_connect_outgoing() directly.
>> +                 */
>> +                return true;
>> +            } else {
>> +                socket_connect_incoming(saddr, errp);
>> +            }
>> +
>>              break;
>>          case SOCKET_ADDRESS_TYPE_FD:
>> -            ioc = fd_connect_outgoing(saddr->u.fd.str, errp);
>> +            if (out) {
>> +                ioc = fd_connect_outgoing(saddr->u.fd.str, errp);
>> +            } else {
>> +                fd_connect_incoming(saddr->u.fd.str, errp);
>> +            }
>>              break;
>>          default:
>>              g_assert_not_reached();
>> @@ -62,16 +72,28 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
>>  
>>  #ifdef CONFIG_RDMA
>>      case MIGRATION_ADDRESS_TYPE_RDMA:
>> -        ioc = rdma_connect_outgoing(&addr->u.rdma, errp);
>> +        if (out) {
>> +            ioc = rdma_connect_outgoing(&addr->u.rdma, errp);
>> +        } else {
>> +            rdma_connect_incoming(&addr->u.rdma, errp);
>> +        }
>>          break;
>>  #endif
>>  
>>      case MIGRATION_ADDRESS_TYPE_EXEC:
>> -        ioc = exec_connect_outgoing(addr->u.exec.args, errp);
>> +        if (out) {
>> +            ioc = exec_connect_outgoing(addr->u.exec.args, errp);
>> +        } else {
>> +            exec_connect_incoming(addr->u.exec.args, errp);
>> +        }
>>          break;
>>  
>>      case MIGRATION_ADDRESS_TYPE_FILE:
>> -        ioc = file_connect_outgoing(&addr->u.file, errp);
>> +        if (out) {
>> +            ioc = file_connect_outgoing(&addr->u.file, errp);
>> +        } else {
>> +            file_connect_incoming(&addr->u.file, errp);
>> +        }
>>          break;
>>  
>>      default:
>> @@ -79,42 +101,22 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
>>          break;
>>      }
>>  
>> -    if (!ioc) {
>> -        return false;
>> -    }
>> -
>> -    migration_channel_connect_outgoing(ioc);
>> -    return true;
>> -}
>> -
>> -void migration_connect_incoming(MigrationAddress *addr, Error **errp)
>> -{
>> -    if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
>> -        SocketAddress *saddr = &addr->u.socket;
>> -        if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
>> -            saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
>> -            saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
>> -            socket_connect_incoming(saddr, errp);
>> -        } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
>> -            fd_connect_incoming(saddr->u.fd.str, errp);
>> +    if (out) {
>> +        if (!ioc) {
>> +            return false;
>>          }
>> -#ifdef CONFIG_RDMA
>> -    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
>> -        rdma_connect_incoming(&addr->u.rdma, errp);
>> -#endif
>> -    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
>> -        exec_connect_incoming(addr->u.exec.args, errp);
>> -    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
>> -        file_connect_incoming(&addr->u.file, errp);
>> -    } else {
>> -        error_setg(errp, "unknown migration protocol");
>> +
>> +        migration_channel_connect_outgoing(ioc);
>> +        return true;
>>      }
>>  
>>      /*
>> -     * async: the above routines all wait for the incoming connection
>> -     * and call back to migration_channel_process_incoming() to start
>> -     * the migration.
>> +     * async: on the incoming side all of the transport routines above
>> +     * wait for the incoming connection and call back to
>> +     * migration_channel_process_incoming() to start the migration.
>>       */
>> +
>> +    return !*errp;
>>  }
>>  
>>  bool migration_has_main_and_multifd_channels(void)
>> diff --git a/migration/channel.h b/migration/channel.h
>> index 8cf16bfda9..86934fee38 100644
>> --- a/migration/channel.h
>> +++ b/migration/channel.h
>> @@ -39,6 +39,16 @@ int migration_channel_read_peek(QIOChannel *ioc,
>>  bool migration_has_main_and_multifd_channels(void);
>>  bool migration_has_all_channels(void);
>>  
>> -bool migration_connect_outgoing(MigrationAddress *addr, Error **errp);
>> -void migration_connect_incoming(MigrationAddress *addr, Error **errp);
>> +bool migration_connect(MigrationAddress *addr, bool out, Error **errp);
>> +static inline bool migration_connect_outgoing(MigrationAddress *addr,
>> +                                              Error **errp)
>> +{
>> +    return migration_connect(addr, true, errp);
>> +}
>> +
>> +static inline bool migration_connect_incoming(MigrationAddress *addr,
>> +                                              Error **errp)
>> +{
>> +    return migration_connect(addr, false, errp);
>> +}
>>  #endif
>> -- 
>> 2.51.0
>> 

Re: [RFC PATCH 24/25] migration: Move URI parsing to channel.c

[Fabiano Rosas]

Peter Xu <peterx@redhat.com> writes:

> On Fri, Dec 26, 2025 at 06:19:26PM -0300, Fabiano Rosas wrote:
>> The migrate_uri_parse function is responsible for converting the URI
>> string into a MigrationChannel for consumption by the rest of the
>> code. Move it to channel.c and add a wrapper that calls both URI and
>> channels parsing.
>> 
>> While here, add some words about the memory management of the
>> MigrationChannel object, which is slightly different from
>> migrate_uri_parse() and migrate_channels_parse(). The former takes a
>> string and has to allocate a MigrationChannel, the latter takes a QAPI
>> object that is managed by the QAPI code.
>> 
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>
> There're some comments added into migration_connect(), that I still don't
> think I fully agree upon.. but the rest looks all good to me.
>

You're talking about the comments not being at the right place? I can
duplicate them in migration_connect_outgoing|incoming.

> That's probably to be discussed separately anyway, I think you can take
> mine here:
>
> Reviewed-by: Peter Xu <peterx@redhat.com>
>
>> ---
>>  migration/channel.c   | 97 +++++++++++++++++++++++++++++++++++++++++--
>>  migration/channel.h   |  9 ++--
>>  migration/migration.c | 95 ++----------------------------------------
>>  3 files changed, 101 insertions(+), 100 deletions(-)
>> 
>> diff --git a/migration/channel.c b/migration/channel.c
>> index 8b43c3d983..d30e29c9b3 100644
>> --- a/migration/channel.c
>> +++ b/migration/channel.c
>> @@ -40,6 +40,12 @@ bool migration_connect(MigrationAddress *addr, bool out, Error **errp)
>>      SocketAddress *saddr;
>>      ERRP_GUARD();
>>  
>> +    /*
>> +     * This is reached from a QMP command, the transport code below
>> +     * must copy the relevant parts of 'addr' before this function
>> +     * returns because the QAPI code will free it.
>> +     */
>> +
>>      switch (addr->transport) {
>>      case MIGRATION_ADDRESS_TYPE_SOCKET:
>>          saddr = &addr->u.socket;
>> @@ -318,10 +324,10 @@ int migration_channel_read_peek(QIOChannel *ioc,
>>      return 0;
>>  }
>>  
>> -bool migrate_channels_parse(MigrationChannelList *channels,
>> -                            MigrationChannel **main_channelp,
>> -                            MigrationChannel **cpr_channelp,
>> -                            Error **errp)
>> +static bool migrate_channels_parse(MigrationChannelList *channels,
>> +                                   MigrationChannel **main_channelp,
>> +                                   MigrationChannel **cpr_channelp,
>> +                                   Error **errp)
>>  {
>>      MigrationChannel *channelv[MIGRATION_CHANNEL_TYPE__MAX] = { NULL };
>>      bool single_channel;
>> @@ -353,6 +359,15 @@ bool migrate_channels_parse(MigrationChannelList *channels,
>>          }
>>      }
>>  
>> +    /*
>> +     * These don't technically need to be cloned because they come
>> +     * from a QAPI object ('channels'). The top-level caller
>> +     * (qmp_migrate) needs to copy the necessary information before
>> +     * returning from the QMP command. Cloning here is just to keep
>> +     * the interface consistent with migrate_uri_parse() that _does
>> +     * not_ take a QAPI object and instead allocates and transfers
>> +     * ownership of a MigrationChannel to qmp_migrate.
>> +     */
>>      if (cpr_channelp) {
>>          *cpr_channelp = QAPI_CLONE(MigrationChannel,
>>                                     channelv[MIGRATION_CHANNEL_TYPE_CPR]);
>> @@ -368,3 +383,77 @@ bool migrate_channels_parse(MigrationChannelList *channels,
>>  
>>      return true;
>>  }
>> +
>> +bool migrate_uri_parse(const char *uri, MigrationChannel **channel,
>> +                       Error **errp)
>> +{
>> +    g_autoptr(MigrationChannel) val = g_new0(MigrationChannel, 1);
>> +    g_autoptr(MigrationAddress) addr = g_new0(MigrationAddress, 1);
>> +    InetSocketAddress *isock = &addr->u.rdma;
>> +    strList **tail = &addr->u.exec.args;
>> +
>> +    if (strstart(uri, "exec:", NULL)) {
>> +        addr->transport = MIGRATION_ADDRESS_TYPE_EXEC;
>> +#ifdef WIN32
>> +        QAPI_LIST_APPEND(tail, g_strdup(exec_get_cmd_path()));
>> +        QAPI_LIST_APPEND(tail, g_strdup("/c"));
>> +#else
>> +        QAPI_LIST_APPEND(tail, g_strdup("/bin/sh"));
>> +        QAPI_LIST_APPEND(tail, g_strdup("-c"));
>> +#endif
>> +        QAPI_LIST_APPEND(tail, g_strdup(uri + strlen("exec:")));
>> +    } else if (strstart(uri, "rdma:", NULL)) {
>> +        if (inet_parse(isock, uri + strlen("rdma:"), errp)) {
>> +            qapi_free_InetSocketAddress(isock);
>> +            return false;
>> +        }
>> +        addr->transport = MIGRATION_ADDRESS_TYPE_RDMA;
>> +    } else if (strstart(uri, "tcp:", NULL) ||
>> +                strstart(uri, "unix:", NULL) ||
>> +                strstart(uri, "vsock:", NULL) ||
>> +                strstart(uri, "fd:", NULL)) {
>> +        addr->transport = MIGRATION_ADDRESS_TYPE_SOCKET;
>> +        SocketAddress *saddr = socket_parse(uri, errp);
>> +        if (!saddr) {
>> +            return false;
>> +        }
>> +        addr->u.socket.type = saddr->type;
>> +        addr->u.socket.u = saddr->u;
>> +        /* Don't free the objects inside; their ownership moved to "addr" */
>> +        g_free(saddr);
>> +    } else if (strstart(uri, "file:", NULL)) {
>> +        addr->transport = MIGRATION_ADDRESS_TYPE_FILE;
>> +        addr->u.file.filename = g_strdup(uri + strlen("file:"));
>> +        if (file_parse_offset(addr->u.file.filename, &addr->u.file.offset,
>> +                              errp)) {
>> +            return false;
>> +        }
>> +    } else {
>> +        error_setg(errp, "unknown migration protocol: %s", uri);
>> +        return false;
>> +    }
>> +
>> +    val->channel_type = MIGRATION_CHANNEL_TYPE_MAIN;
>> +    val->addr = g_steal_pointer(&addr);
>> +    *channel = g_steal_pointer(&val);
>> +    return true;
>> +}
>> +
>> +bool migration_channel_parse_input(const char *uri,
>> +                                   MigrationChannelList *channels,
>> +                                   MigrationChannel **main_channelp,
>> +                                   MigrationChannel **cpr_channelp,
>> +                                   Error **errp)
>> +{
>> +    if (!uri == !channels) {
>> +        error_setg(errp, "need either 'uri' or 'channels' argument");
>> +        return false;
>> +    }
>> +
>> +    if (channels) {
>> +        return migrate_channels_parse(channels, main_channelp, cpr_channelp,
>> +                                      errp);
>> +    } else {
>> +        return migrate_uri_parse(uri, main_channelp, errp);
>> +    }
>> +}
>> diff --git a/migration/channel.h b/migration/channel.h
>> index b3276550b7..3724b0493a 100644
>> --- a/migration/channel.h
>> +++ b/migration/channel.h
>> @@ -52,8 +52,9 @@ static inline bool migration_connect_incoming(MigrationAddress *addr,
>>      return migration_connect(addr, false, errp);
>>  }
>>  
>> -bool migrate_channels_parse(MigrationChannelList *channels,
>> -                            MigrationChannel **main_channelp,
>> -                            MigrationChannel **cpr_channelp,
>> -                            Error **errp);
>> +bool migration_channel_parse_input(const char *uri,
>> +                                   MigrationChannelList *channels,
>> +                                   MigrationChannel **main_channelp,
>> +                                   MigrationChannel **cpr_channelp,
>> +                                   Error **errp);
>>  #endif
>> diff --git a/migration/migration.c b/migration/migration.c
>> index 6064f1e5ea..15d8459a81 100644
>> --- a/migration/migration.c
>> +++ b/migration/migration.c
>> @@ -15,7 +15,6 @@
>>  
>>  #include "qemu/osdep.h"
>>  #include "qemu/ctype.h"
>> -#include "qemu/cutils.h"
>>  #include "qemu/error-report.h"
>>  #include "qemu/main-loop.h"
>>  #include "migration/blocker.h"
>> @@ -659,61 +658,6 @@ bool migrate_is_uri(const char *uri)
>>      return *uri == ':';
>>  }
>>  
>> -bool migrate_uri_parse(const char *uri, MigrationChannel **channel,
>> -                       Error **errp)
>> -{
>> -    g_autoptr(MigrationChannel) val = g_new0(MigrationChannel, 1);
>> -    g_autoptr(MigrationAddress) addr = g_new0(MigrationAddress, 1);
>> -    InetSocketAddress *isock = &addr->u.rdma;
>> -    strList **tail = &addr->u.exec.args;
>> -
>> -    if (strstart(uri, "exec:", NULL)) {
>> -        addr->transport = MIGRATION_ADDRESS_TYPE_EXEC;
>> -#ifdef WIN32
>> -        QAPI_LIST_APPEND(tail, g_strdup(exec_get_cmd_path()));
>> -        QAPI_LIST_APPEND(tail, g_strdup("/c"));
>> -#else
>> -        QAPI_LIST_APPEND(tail, g_strdup("/bin/sh"));
>> -        QAPI_LIST_APPEND(tail, g_strdup("-c"));
>> -#endif
>> -        QAPI_LIST_APPEND(tail, g_strdup(uri + strlen("exec:")));
>> -    } else if (strstart(uri, "rdma:", NULL)) {
>> -        if (inet_parse(isock, uri + strlen("rdma:"), errp)) {
>> -            qapi_free_InetSocketAddress(isock);
>> -            return false;
>> -        }
>> -        addr->transport = MIGRATION_ADDRESS_TYPE_RDMA;
>> -    } else if (strstart(uri, "tcp:", NULL) ||
>> -                strstart(uri, "unix:", NULL) ||
>> -                strstart(uri, "vsock:", NULL) ||
>> -                strstart(uri, "fd:", NULL)) {
>> -        addr->transport = MIGRATION_ADDRESS_TYPE_SOCKET;
>> -        SocketAddress *saddr = socket_parse(uri, errp);
>> -        if (!saddr) {
>> -            return false;
>> -        }
>> -        addr->u.socket.type = saddr->type;
>> -        addr->u.socket.u = saddr->u;
>> -        /* Don't free the objects inside; their ownership moved to "addr" */
>> -        g_free(saddr);
>> -    } else if (strstart(uri, "file:", NULL)) {
>> -        addr->transport = MIGRATION_ADDRESS_TYPE_FILE;
>> -        addr->u.file.filename = g_strdup(uri + strlen("file:"));
>> -        if (file_parse_offset(addr->u.file.filename, &addr->u.file.offset,
>> -                              errp)) {
>> -            return false;
>> -        }
>> -    } else {
>> -        error_setg(errp, "unknown migration protocol: %s", uri);
>> -        return false;
>> -    }
>> -
>> -    val->channel_type = MIGRATION_CHANNEL_TYPE_MAIN;
>> -    val->addr = g_steal_pointer(&addr);
>> -    *channel = g_steal_pointer(&val);
>> -    return true;
>> -}
>> -
>>  static bool
>>  migration_incoming_state_setup(MigrationIncomingState *mis, Error **errp)
>>  {
>> @@ -744,27 +688,10 @@ static void qemu_setup_incoming_migration(const char *uri, bool has_channels,
>>      g_autoptr(MigrationChannel) main_ch = NULL;
>>      MigrationIncomingState *mis = migration_incoming_get_current();
>>  
>> -    /*
>> -     * Having preliminary checks for uri and channel
>> -     */
>> -    if (!uri == !channels) {
>> -        error_setg(errp, "need either 'uri' or 'channels' argument");
>> +    if (!migration_channel_parse_input(uri, channels, &main_ch, NULL, errp)) {
>>          return;
>>      }
>>  
>> -    if (channels) {
>> -        if (!migrate_channels_parse(channels, &main_ch, NULL, errp)) {
>> -            return;
>> -        }
>> -    }
>> -
>> -    if (uri) {
>> -        /* caller uses the old URI syntax */
>> -        if (!migrate_uri_parse(uri, &main_ch, errp)) {
>> -            return;
>> -        }
>> -    }
>> -
>>      /* transport mechanism not suitable for migration? */
>>      if (!migration_transport_compatible(main_ch->addr, errp)) {
>>          return;
>> @@ -2124,27 +2051,11 @@ void qmp_migrate(const char *uri, bool has_channels,
>>      g_autoptr(MigrationChannel) main_ch = NULL;
>>      g_autoptr(MigrationChannel) cpr_ch = NULL;
>>  
>> -    /*
>> -     * Having preliminary checks for uri and channel
>> -     */
>> -    if (!uri == !channels) {
>> -        error_setg(errp, "need either 'uri' or 'channels' argument");
>> +    if (!migration_channel_parse_input(uri, channels, &main_ch, &cpr_ch,
>> +                                       errp)) {
>>          return;
>>      }
>>  
>> -    if (channels) {
>> -        if (!migrate_channels_parse(channels, &main_ch, &cpr_ch, errp)) {
>> -            return;
>> -        }
>> -    }
>> -
>> -    if (uri) {
>> -        /* caller uses the old URI syntax */
>> -        if (!migrate_uri_parse(uri, &main_ch, errp)) {
>> -            return;
>> -        }
>> -    }
>> -
>>      /* transport mechanism not suitable for migration? */
>>      if (!migration_transport_compatible(main_ch->addr, errp)) {
>>          return;
>> -- 
>> 2.51.0
>> 

Re: [RFC PATCH 22/25] migration/channel: Merge both sides of the connection initiation code

[Peter Xu]

On Mon, Dec 29, 2025 at 06:14:52PM -0300, Fabiano Rosas wrote:
> Peter Xu <peterx@redhat.com> writes:
> 
> > On Fri, Dec 26, 2025 at 06:19:24PM -0300, Fabiano Rosas wrote:
> >> Now that everything is in channel.c, it's easier to browse this code
> >> if it's all in the same place. It's also easier to grasp what the
> >> connection flow is if both sides of the connection are close together.
> >> 
> >> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> >> ---
> >>  migration/channel.c | 86 +++++++++++++++++++++++----------------------
> >>  migration/channel.h | 14 ++++++--
> >>  2 files changed, 56 insertions(+), 44 deletions(-)
> >> 
> >> diff --git a/migration/channel.c b/migration/channel.c
> >> index 042e01b224..ba9aa1c58b 100644
> >> --- a/migration/channel.c
> >> +++ b/migration/channel.c
> >> @@ -31,10 +31,11 @@
> >>  #include "trace.h"
> >>  #include "yank_functions.h"
> >>  
> >> -bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
> >> +bool migration_connect(MigrationAddress *addr, bool out, Error **errp)
> >>  {
> >>      g_autoptr(QIOChannel) ioc = NULL;
> >>      SocketAddress *saddr;
> >> +    ERRP_GUARD();
> >>  
> >>      switch (addr->transport) {
> >>      case MIGRATION_ADDRESS_TYPE_SOCKET:
> >> @@ -44,15 +45,24 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
> >>          case SOCKET_ADDRESS_TYPE_INET:
> >>          case SOCKET_ADDRESS_TYPE_UNIX:
> >>          case SOCKET_ADDRESS_TYPE_VSOCK:
> >> -            socket_connect_outgoing(saddr, errp);
> >> -            /*
> >> -             * async: after the socket is connected, calls
> >> -             * migration_channel_connect_outgoing() directly.
> >> -             */
> >> -            return true;
> >> +            if (out) {
> >
> > Personally I wouldn't suggest we merge the outgoing / incoming with
> > migration_connect() then split paths once more in this exact function.
> >
> > I got this conclusion when I started to count how many "if (out)" are
> > there..  When there're too much, it may imply we need to think more..
> >
> 
> Well, compared to before, there 50% less "if (addr->transport == ...)",
> this is top level programming! =D

Yep, though that'll be the only part got deduplicated.

Reading migration_connect() will definitely break my flow of thoughts when
hitting so many "if (out)", and I'll be a bit puzzled on how the code runs.

I'm not sure if I'm the only one, though.

If we really want, we can introduce a MigrationAddressOps, providing one
ops for each type of MigrationAddress, differently on both sides:

/* Return true if success; when false errp will be set */
bool (*MigrationAddressOp)(MigrationAddress *addr, QIOChannel **channel, Error **errp)

Then define:

MigrationAddressOps[MIGRATION_ADDRESS_TYPE__MAX] addr_ops_outgoing = { ... };
MigrationAddressOps[MIGRATION_ADDRESS_TYPE__MAX] addr_ops_incoming = { ... };

And use them..  but it may also be an overkill when we only have incoming /
outgoing anyway..  So IMHO the existing code (after you refactored many of
the rest!) looks still pretty decent to me.

> 
> This part of the series is highly subjective, if there's a patch you
> don't like it we can drop it, let's not dwell on it.. Just read my words
> below on the previous patch, which I think you may be mistaken about.

Thanks, yes I was indeed mistaken and overlooked something. :)

> 
> > This also answers part of my confusion when reading the previous patch - if
> > that was only paving way for this one, IMHO it may not be as worthwhile,
> > and I would tend to avoid both.
> >
> 
> Patch 21 is just a cleanup after patch 19 moves the call to
> migration_channel_connect_outgoing from being inside the transport
> routines to this top level here at migration_connect(), which moves the
> places where MigrationState is used as well. So it removes unused
> passing of MigrationState along with the SocketConnectionData.

Now after I read it again, I agree with those removal of *s where they're
not used, like for:

  fd_connect_outgoing()
  exec_connect_outgoing()
  file_connect_outgoing()

I think socket_connect_outgoing() should also be fine, but maybe better to
have a pre-requisite patch removing SocketConnectData?

For most of the rest, IMHO we don't get much benefit from removing *s from
the parameters, especially inside qmp_migrate()..

So IMHO you were right in the commit log there, that we should justify
every use of migrate_get_current() to deserve fetching from a global, and
we should avoid using it in new code whenever possible.  IMHO we should
stick with that.

Imagine the old days we debug when *s can become null, and the more we
reference the global, the harder we fight those things (taking one refcount
from the very top caller would work for all the sub-callers OTOH, when we
justify one place thread-safe and justify all the rest).  More referencing
globals normally will just make things harder for us.  This rule applies to
all the globals.. not only *s.

> 
> > Thoughts?
> >
> >> +                socket_connect_outgoing(saddr, errp);
> >> +                /*
> >> +                 * async: after the socket is connected, calls
> >> +                 * migration_channel_connect_outgoing() directly.
> >> +                 */
> >> +                return true;
> >> +            } else {
> >> +                socket_connect_incoming(saddr, errp);
> >> +            }
> >> +
> >>              break;
> >>          case SOCKET_ADDRESS_TYPE_FD:
> >> -            ioc = fd_connect_outgoing(saddr->u.fd.str, errp);
> >> +            if (out) {
> >> +                ioc = fd_connect_outgoing(saddr->u.fd.str, errp);
> >> +            } else {
> >> +                fd_connect_incoming(saddr->u.fd.str, errp);
> >> +            }
> >>              break;
> >>          default:
> >>              g_assert_not_reached();
> >> @@ -62,16 +72,28 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
> >>  
> >>  #ifdef CONFIG_RDMA
> >>      case MIGRATION_ADDRESS_TYPE_RDMA:
> >> -        ioc = rdma_connect_outgoing(&addr->u.rdma, errp);
> >> +        if (out) {
> >> +            ioc = rdma_connect_outgoing(&addr->u.rdma, errp);
> >> +        } else {
> >> +            rdma_connect_incoming(&addr->u.rdma, errp);
> >> +        }
> >>          break;
> >>  #endif
> >>  
> >>      case MIGRATION_ADDRESS_TYPE_EXEC:
> >> -        ioc = exec_connect_outgoing(addr->u.exec.args, errp);
> >> +        if (out) {
> >> +            ioc = exec_connect_outgoing(addr->u.exec.args, errp);
> >> +        } else {
> >> +            exec_connect_incoming(addr->u.exec.args, errp);
> >> +        }
> >>          break;
> >>  
> >>      case MIGRATION_ADDRESS_TYPE_FILE:
> >> -        ioc = file_connect_outgoing(&addr->u.file, errp);
> >> +        if (out) {
> >> +            ioc = file_connect_outgoing(&addr->u.file, errp);
> >> +        } else {
> >> +            file_connect_incoming(&addr->u.file, errp);
> >> +        }
> >>          break;
> >>  
> >>      default:
> >> @@ -79,42 +101,22 @@ bool migration_connect_outgoing(MigrationAddress *addr, Error **errp)
> >>          break;
> >>      }
> >>  
> >> -    if (!ioc) {
> >> -        return false;
> >> -    }
> >> -
> >> -    migration_channel_connect_outgoing(ioc);
> >> -    return true;
> >> -}
> >> -
> >> -void migration_connect_incoming(MigrationAddress *addr, Error **errp)
> >> -{
> >> -    if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
> >> -        SocketAddress *saddr = &addr->u.socket;
> >> -        if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
> >> -            saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
> >> -            saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
> >> -            socket_connect_incoming(saddr, errp);
> >> -        } else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
> >> -            fd_connect_incoming(saddr->u.fd.str, errp);
> >> +    if (out) {
> >> +        if (!ioc) {
> >> +            return false;
> >>          }
> >> -#ifdef CONFIG_RDMA
> >> -    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
> >> -        rdma_connect_incoming(&addr->u.rdma, errp);
> >> -#endif
> >> -    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
> >> -        exec_connect_incoming(addr->u.exec.args, errp);
> >> -    } else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
> >> -        file_connect_incoming(&addr->u.file, errp);
> >> -    } else {
> >> -        error_setg(errp, "unknown migration protocol");
> >> +
> >> +        migration_channel_connect_outgoing(ioc);
> >> +        return true;
> >>      }
> >>  
> >>      /*
> >> -     * async: the above routines all wait for the incoming connection
> >> -     * and call back to migration_channel_process_incoming() to start
> >> -     * the migration.
> >> +     * async: on the incoming side all of the transport routines above
> >> +     * wait for the incoming connection and call back to
> >> +     * migration_channel_process_incoming() to start the migration.
> >>       */
> >> +
> >> +    return !*errp;
> >>  }
> >>  
> >>  bool migration_has_main_and_multifd_channels(void)
> >> diff --git a/migration/channel.h b/migration/channel.h
> >> index 8cf16bfda9..86934fee38 100644
> >> --- a/migration/channel.h
> >> +++ b/migration/channel.h
> >> @@ -39,6 +39,16 @@ int migration_channel_read_peek(QIOChannel *ioc,
> >>  bool migration_has_main_and_multifd_channels(void);
> >>  bool migration_has_all_channels(void);
> >>  
> >> -bool migration_connect_outgoing(MigrationAddress *addr, Error **errp);
> >> -void migration_connect_incoming(MigrationAddress *addr, Error **errp);
> >> +bool migration_connect(MigrationAddress *addr, bool out, Error **errp);
> >> +static inline bool migration_connect_outgoing(MigrationAddress *addr,
> >> +                                              Error **errp)
> >> +{
> >> +    return migration_connect(addr, true, errp);
> >> +}
> >> +
> >> +static inline bool migration_connect_incoming(MigrationAddress *addr,
> >> +                                              Error **errp)
> >> +{
> >> +    return migration_connect(addr, false, errp);
> >> +}
> >>  #endif
> >> -- 
> >> 2.51.0
> >> 
> 

-- 
Peter Xu

Re: [RFC PATCH 24/25] migration: Move URI parsing to channel.c

[Peter Xu]

On Mon, Dec 29, 2025 at 06:22:04PM -0300, Fabiano Rosas wrote:
> You're talking about the comments not being at the right place? I can
> duplicate them in migration_connect_outgoing|incoming.

Yep, dup it is fine, or just drop them?

Normally we should assume all parameters to be freed anytime by default for
a function.  AFAIU that's the common case.

OTOH, IMHO we may better need comments where the function can transit
ownership of the memory of the parameters... while this is not the case.

-- 
Peter Xu