[PATCH v10 1/8] Introduce yank feature

[PATCH v10 1/8] Introduce yank feature

[Lukas Straub]

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The yank feature allows to recover from hanging qemu by "yanking"
at various parts. Other qemu systems can register themselves and
multiple yank functions. Then all yank functions for selected
instances can be called by the 'yank' out-of-band qmp command.
Available instances can be queried by a 'query-yank' oob command.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 include/qemu/yank.h   |  95 +++++++++++++++++++
 qapi/meson.build      |   1 +
 qapi/qapi-schema.json |   1 +
 qapi/yank.json        | 115 ++++++++++++++++++++++
 util/meson.build      |   1 +
 util/yank.c           | 216 ++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 429 insertions(+)
 create mode 100644 include/qemu/yank.h
 create mode 100644 qapi/yank.json
 create mode 100644 util/yank.c

diff --git a/include/qemu/yank.h b/include/qemu/yank.h
new file mode 100644
index 0000000000..96f5b2626f
--- /dev/null
+++ b/include/qemu/yank.h
@@ -0,0 +1,95 @@
+/*
+ * QEMU yank feature
+ *
+ * Copyright (c) Lukas Straub <lukasstraub2@web.de>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef YANK_H
+#define YANK_H
+
+#include "qapi/qapi-types-yank.h"
+
+typedef void (YankFn)(void *opaque);
+
+/**
+ * yank_register_instance: Register a new instance.
+ *
+ * This registers a new instance for yanking. Must be called before any yank
+ * function is registered for this instance.
+ *
+ * This function is thread-safe.
+ *
+ * @instance: The instance.
+ * @errp: Error object.
+ */
+void yank_register_instance(const YankInstance *instance, Error **errp);
+
+/**
+ * yank_unregister_instance: Unregister a instance.
+ *
+ * This unregisters a instance. Must be called only after every yank function
+ * of the instance has been unregistered.
+ *
+ * This function is thread-safe.
+ *
+ * @instance: The instance.
+ */
+void yank_unregister_instance(const YankInstance *instance);
+
+/**
+ * yank_register_function: Register a yank function
+ *
+ * This registers a yank function. All limitations of qmp oob commands apply
+ * to the yank function as well. See docs/devel/qapi-code-gen.txt under
+ * "An OOB-capable command handler must satisfy the following conditions".
+ *
+ * This function is thread-safe.
+ *
+ * @instance: The instance.
+ * @func: The yank function.
+ * @opaque: Will be passed to the yank function.
+ */
+void yank_register_function(const YankInstance *instance,
+                            YankFn *func,
+                            void *opaque);
+
+/**
+ * yank_unregister_function: Unregister a yank function
+ *
+ * This unregisters a yank function.
+ *
+ * This function is thread-safe.
+ *
+ * @instance: The instance.
+ * @func: func that was passed to yank_register_function.
+ * @opaque: opaque that was passed to yank_register_function.
+ */
+void yank_unregister_function(const YankInstance *instance,
+                              YankFn *func,
+                              void *opaque);
+
+/**
+ * yank_generic_iochannel: Generic yank function for iochannel
+ *
+ * This is a generic yank function which will call qio_channel_shutdown on the
+ * provided QIOChannel.
+ *
+ * @opaque: QIOChannel to shutdown
+ */
+void yank_generic_iochannel(void *opaque);
+
+#define BLOCKDEV_YANK_INSTANCE(the_node_name) (&(YankInstance) { \
+        .type = YANK_INSTANCE_TYPE_BLOCK_NODE, \
+        .u.block_node.node_name = (the_node_name) })
+
+#define CHARDEV_YANK_INSTANCE(the_id) (&(YankInstance) { \
+        .type = YANK_INSTANCE_TYPE_CHARDEV, \
+        .u.chardev.id = (the_id) })
+
+#define MIGRATION_YANK_INSTANCE (&(YankInstance) { \
+        .type = YANK_INSTANCE_TYPE_MIGRATION })
+
+#endif
diff --git a/qapi/meson.build b/qapi/meson.build
index 0e98146f1f..ab68e7900e 100644
--- a/qapi/meson.build
+++ b/qapi/meson.build
@@ -47,6 +47,7 @@ qapi_all_modules = [
   'trace',
   'transaction',
   'ui',
+  'yank',
 ]

 qapi_storage_daemon_modules = [
diff --git a/qapi/qapi-schema.json b/qapi/qapi-schema.json
index 0b444b76d2..79c1705ed7 100644
--- a/qapi/qapi-schema.json
+++ b/qapi/qapi-schema.json
@@ -91,3 +91,4 @@
 { 'include': 'audio.json' }
 { 'include': 'acpi.json' }
 { 'include': 'pci.json' }
+{ 'include': 'yank.json' }
diff --git a/qapi/yank.json b/qapi/yank.json
new file mode 100644
index 0000000000..1964a2202e
--- /dev/null
+++ b/qapi/yank.json
@@ -0,0 +1,115 @@
+# -*- Mode: Python -*-
+# vim: filetype=python
+#
+
+##
+# @YankInstanceType:
+#
+# An enumeration of yank instance types. See @YankInstance for more
+# information.
+#
+# Since: 5.2
+##
+{ 'enum': 'YankInstanceType',
+  'data': [ 'block-node', 'chardev', 'migration' ] }
+
+##
+# @YankInstanceBlockNode:
+#
+# Specifies which block graph node to yank. See @YankInstance for more
+# information.
+#
+# @node-name: the name of the block graph node
+#
+# Since: 5.2
+##
+{ 'struct': 'YankInstanceBlockNode',
+  'data': { 'node-name': 'str' } }
+
+##
+# @YankInstanceChardev:
+#
+# Specifies which character device to yank. See @YankInstance for more
+# information.
+#
+# @id: the chardev's ID
+#
+# Since: 5.2
+##
+{ 'struct': 'YankInstanceChardev',
+  'data': { 'id': 'str' } }
+
+##
+# @YankInstance:
+#
+# A yank instance can be yanked with the @yank qmp command to recover from a
+# hanging QEMU.
+#
+# Currently implemented yank instances:
+#  - nbd block device:
+#    Yanking it will shut down the connection to the nbd server without
+#    attempting to reconnect.
+#  - socket chardev:
+#    Yanking it will shut down the connected socket.
+#  - migration:
+#    Yanking it will shut down all migration connections. Unlike
+#    @migrate_cancel, it will not notify the migration process, so migration
+#    will go into @failed state, instead of @cancelled state. @yank should be
+#    used to recover from hangs.
+#
+# Since: 5.2
+##
+{ 'union': 'YankInstance',
+  'base': { 'type': 'YankInstanceType' },
+  'discriminator': 'type',
+  'data': {
+      'block-node': 'YankInstanceBlockNode',
+      'chardev': 'YankInstanceChardev' } }
+
+##
+# @yank:
+#
+# Try to recover from hanging QEMU by yanking the specified instances. See
+# @YankInstance for more information.
+#
+# Takes a list of @YankInstance as argument.
+#
+# Returns: - Nothing on success
+#          - @DeviceNotFound error, if any of the YankInstances doesn't exist
+#
+# Example:
+#
+# -> { "execute": "yank",
+#      "arguments": {
+#          "instances": [
+#               { "type": "block-node",
+#                 "node-name": "nbd0" }
+#          ] } }
+# <- { "return": {} }
+#
+# Since: 5.2
+##
+{ 'command': 'yank',
+  'data': { 'instances': ['YankInstance'] },
+  'allow-oob': true }
+
+##
+# @query-yank:
+#
+# Query yank instances. See @YankInstance for more information.
+#
+# Returns: list of @YankInstance
+#
+# Example:
+#
+# -> { "execute": "query-yank" }
+# <- { "return": [
+#          { "type": "block-node",
+#            "node-name": "nbd0" }
+#      ] }
+#
+# Since: 5.2
+##
+{ 'command': 'query-yank',
+  'returns': ['YankInstance'],
+  'allow-oob': true }
diff --git a/util/meson.build b/util/meson.build
index c5159ad79d..dbda9d9123 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -50,6 +50,7 @@ endif

 if have_system
   util_ss.add(when: 'CONFIG_GIO', if_true: [files('dbus.c'), gio])
+  util_ss.add(files('yank.c'))
 endif

 if have_block
diff --git a/util/yank.c b/util/yank.c
new file mode 100644
index 0000000000..4a0f538359
--- /dev/null
+++ b/util/yank.c
@@ -0,0 +1,216 @@
+/*
+ * QEMU yank feature
+ *
+ * Copyright (c) Lukas Straub <lukasstraub2@web.de>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/thread.h"
+#include "qemu/queue.h"
+#include "qapi/qapi-commands-yank.h"
+#include "qapi/qapi-visit-yank.h"
+#include "qapi/clone-visitor.h"
+#include "io/channel.h"
+#include "qemu/yank.h"
+
+struct YankFuncAndParam {
+    YankFn *func;
+    void *opaque;
+    QLIST_ENTRY(YankFuncAndParam) next;
+};
+
+struct YankInstanceEntry {
+    YankInstance *instance;
+    QLIST_HEAD(, YankFuncAndParam) yankfns;
+    QLIST_ENTRY(YankInstanceEntry) next;
+};
+
+typedef struct YankFuncAndParam YankFuncAndParam;
+typedef struct YankInstanceEntry YankInstanceEntry;
+
+/*
+ * This lock protects the yank_instance_list below. Because it's taken by
+ * OOB-capable commands, it must be "fast", i.e. it may only be held for a
+ * bounded, short time. See docs/devel/qapi-code-gen.txt for additional
+ * information.
+ */
+static QemuMutex yank_lock;
+
+static QLIST_HEAD(, YankInstanceEntry) yank_instance_list
+    = QLIST_HEAD_INITIALIZER(yank_instance_list);
+
+static bool yank_compare_instances(const YankInstance *a, const YankInstance *b)
+{
+    if (a->type != b->type) {
+        return false;
+    }
+
+    switch (a->type) {
+    case YANK_INSTANCE_TYPE_BLOCK_NODE:
+        return !strcmp(a->u.block_node.node_name, b->u.block_node.node_name);
+    break;
+
+    case YANK_INSTANCE_TYPE_CHARDEV:
+        return !strcmp(a->u.chardev.id, b->u.chardev.id);
+    break;
+
+    case YANK_INSTANCE_TYPE_MIGRATION:
+        return true;
+    break;
+
+    default:
+        abort();
+    }
+}
+
+static YankInstanceEntry *yank_find_entry(const YankInstance *instance)
+{
+    YankInstanceEntry *entry;
+
+    QLIST_FOREACH(entry, &yank_instance_list, next) {
+        if (yank_compare_instances(entry->instance, instance)) {
+            return entry;
+        }
+    }
+    return NULL;
+}
+
+void yank_register_instance(const YankInstance *instance, Error **errp)
+{
+    YankInstanceEntry *entry;
+
+    qemu_mutex_lock(&yank_lock);
+
+    if (yank_find_entry(instance)) {
+        error_setg(errp, "duplicate yank instance");
+        qemu_mutex_unlock(&yank_lock);
+        return;
+    }
+
+    entry = g_slice_new(YankInstanceEntry);
+    entry->instance = QAPI_CLONE(YankInstance, instance);
+    QLIST_INIT(&entry->yankfns);
+    QLIST_INSERT_HEAD(&yank_instance_list, entry, next);
+
+    qemu_mutex_unlock(&yank_lock);
+}
+
+void yank_unregister_instance(const YankInstance *instance)
+{
+    YankInstanceEntry *entry;
+
+    qemu_mutex_lock(&yank_lock);
+    entry = yank_find_entry(instance);
+    assert(entry);
+
+    assert(QLIST_EMPTY(&entry->yankfns));
+    QLIST_REMOVE(entry, next);
+    qapi_free_YankInstance(entry->instance);
+    g_slice_free(YankInstanceEntry, entry);
+
+    qemu_mutex_unlock(&yank_lock);
+}
+
+void yank_register_function(const YankInstance *instance,
+                            YankFn *func,
+                            void *opaque)
+{
+    YankInstanceEntry *entry;
+    YankFuncAndParam *func_entry;
+
+    qemu_mutex_lock(&yank_lock);
+    entry = yank_find_entry(instance);
+    assert(entry);
+
+    func_entry = g_slice_new(YankFuncAndParam);
+    func_entry->func = func;
+    func_entry->opaque = opaque;
+
+    QLIST_INSERT_HEAD(&entry->yankfns, func_entry, next);
+    qemu_mutex_unlock(&yank_lock);
+}
+
+void yank_unregister_function(const YankInstance *instance,
+                              YankFn *func,
+                              void *opaque)
+{
+    YankInstanceEntry *entry;
+    YankFuncAndParam *func_entry;
+
+    qemu_mutex_lock(&yank_lock);
+    entry = yank_find_entry(instance);
+    assert(entry);
+
+    QLIST_FOREACH(func_entry, &entry->yankfns, next) {
+        if (func_entry->func == func && func_entry->opaque == opaque) {
+            QLIST_REMOVE(func_entry, next);
+            g_slice_free(YankFuncAndParam, func_entry);
+            qemu_mutex_unlock(&yank_lock);
+            return;
+        }
+    }
+
+    abort();
+}
+
+void yank_generic_iochannel(void *opaque)
+{
+    QIOChannel *ioc = QIO_CHANNEL(opaque);
+
+    qio_channel_shutdown(ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
+}
+
+void qmp_yank(YankInstanceList *instances,
+              Error **errp)
+{
+    YankInstanceList *tail;
+    YankInstanceEntry *entry;
+    YankFuncAndParam *func_entry;
+
+    qemu_mutex_lock(&yank_lock);
+    for (tail = instances; tail; tail = tail->next) {
+        entry = yank_find_entry(tail->value);
+        if (!entry) {
+            error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND, "Instance not found");
+            qemu_mutex_unlock(&yank_lock);
+            return;
+        }
+    }
+    for (tail = instances; tail; tail = tail->next) {
+        entry = yank_find_entry(tail->value);
+        assert(entry);
+        QLIST_FOREACH(func_entry, &entry->yankfns, next) {
+            func_entry->func(func_entry->opaque);
+        }
+    }
+    qemu_mutex_unlock(&yank_lock);
+}
+
+YankInstanceList *qmp_query_yank(Error **errp)
+{
+    YankInstanceEntry *entry;
+    YankInstanceList *ret;
+
+    ret = NULL;
+
+    qemu_mutex_lock(&yank_lock);
+    QLIST_FOREACH(entry, &yank_instance_list, next) {
+        YankInstanceList *new_entry;
+        new_entry = g_new0(YankInstanceList, 1);
+        new_entry->value = QAPI_CLONE(YankInstance, entry->instance);
+        new_entry->next = ret;
+        ret = new_entry;
+    }
+    qemu_mutex_unlock(&yank_lock);
+
+    return ret;
+}
+
+static void __attribute__((__constructor__)) yank_init(void)
+{
+    qemu_mutex_init(&yank_lock);
+}
--
2.20.1


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Re: [PATCH v10 1/8] Introduce yank feature

[Markus Armbruster]

Lukas Straub <lukasstraub2@web.de> writes:

> The yank feature allows to recover from hanging qemu by "yanking"
> at various parts. Other qemu systems can register themselves and
> multiple yank functions. Then all yank functions for selected
> instances can be called by the 'yank' out-of-band qmp command.
> Available instances can be queried by a 'query-yank' oob command.
>
> Signed-off-by: Lukas Straub <lukasstraub2@web.de>
> Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
[...]
>  qapi_storage_daemon_modules = [
> diff --git a/qapi/qapi-schema.json b/qapi/qapi-schema.json
> index 0b444b76d2..79c1705ed7 100644
> --- a/qapi/qapi-schema.json
> +++ b/qapi/qapi-schema.json
> @@ -91,3 +91,4 @@
>  { 'include': 'audio.json' }
>  { 'include': 'acpi.json' }
>  { 'include': 'pci.json' }
> +{ 'include': 'yank.json' }

This adds the documentation at the very end of the reference manual.  Is
this where you want it to go?  Check generated
docs/interop/qemu-qmp-ref.html.

> diff --git a/qapi/yank.json b/qapi/yank.json
> new file mode 100644
> index 0000000000..1964a2202e
> --- /dev/null
> +++ b/qapi/yank.json
> @@ -0,0 +1,115 @@
> +# -*- Mode: Python -*-
> +# vim: filetype=python
> +#
> +

Please add a suitable heading here.  Headings look like this:

   ##
   # Text of heading goes here
   ##

Without it, the yank stuff gets squashed into the previous section
(happens to be PCI).

If you want to add an introduction or overview, it goes right below the
heading.  I'm not asking you to do that, I'm only telling you what's
possible.

[...]

Solid work, pleasant to review, thanks!

Reviewed-by: Markus Armbruster <armbru@redhat.com>

Re: [PATCH v10 1/8] Introduce yank feature

[Lukas Straub]

[-- Attachment #1: Type: text/plain, Size: 2001 bytes --]

On Mon, 02 Nov 2020 07:32:55 +0100
Markus Armbruster <armbru@redhat.com> wrote:

> Lukas Straub <lukasstraub2@web.de> writes:
> 
> > The yank feature allows to recover from hanging qemu by "yanking"
> > at various parts. Other qemu systems can register themselves and
> > multiple yank functions. Then all yank functions for selected
> > instances can be called by the 'yank' out-of-band qmp command.
> > Available instances can be queried by a 'query-yank' oob command.
> >
> > Signed-off-by: Lukas Straub <lukasstraub2@web.de>
> > Acked-by: Stefan Hajnoczi <stefanha@redhat.com>  
> [...]
> >  qapi_storage_daemon_modules = [
> > diff --git a/qapi/qapi-schema.json b/qapi/qapi-schema.json
> > index 0b444b76d2..79c1705ed7 100644
> > --- a/qapi/qapi-schema.json
> > +++ b/qapi/qapi-schema.json
> > @@ -91,3 +91,4 @@
> >  { 'include': 'audio.json' }
> >  { 'include': 'acpi.json' }
> >  { 'include': 'pci.json' }
> > +{ 'include': 'yank.json' }  
> 
> This adds the documentation at the very end of the reference manual.  Is
> this where you want it to go?  Check generated
> docs/interop/qemu-qmp-ref.html.

I've moved it above misc for the next version.

> > diff --git a/qapi/yank.json b/qapi/yank.json
> > new file mode 100644
> > index 0000000000..1964a2202e
> > --- /dev/null
> > +++ b/qapi/yank.json
> > @@ -0,0 +1,115 @@
> > +# -*- Mode: Python -*-
> > +# vim: filetype=python
> > +#
> > +  
> 
> Please add a suitable heading here.  Headings look like this:
> 
>    ##
>    # Text of heading goes here
>    ##

Changed for the next version.

> Without it, the yank stuff gets squashed into the previous section
> (happens to be PCI).
> 
> If you want to add an introduction or overview, it goes right below the
> heading.  I'm not asking you to do that, I'm only telling you what's
> possible.
> 
> [...]
> 
> Solid work, pleasant to review, thanks!
> 
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> 

Thanks!

-- 


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[PATCH v10 2/8] block/nbd.c: Add yank feature

[Lukas Straub]

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Register a yank function which shuts down the socket and sets
s->state = NBD_CLIENT_QUIT. This is the same behaviour as if an
error occured.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/nbd.c | 154 +++++++++++++++++++++++++++++++---------------------
 1 file changed, 93 insertions(+), 61 deletions(-)

diff --git a/block/nbd.c b/block/nbd.c
index 4548046cd7..d66c84ee40 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -35,6 +35,7 @@
 #include "qemu/option.h"
 #include "qemu/cutils.h"
 #include "qemu/main-loop.h"
+#include "qemu/atomic.h"

 #include "qapi/qapi-visit-sockets.h"
 #include "qapi/qmp/qstring.h"
@@ -44,6 +45,8 @@
 #include "block/nbd.h"
 #include "block/block_int.h"

+#include "qemu/yank.h"
+
 #define EN_OPTSTR ":exportname="
 #define MAX_NBD_REQUESTS    16

@@ -140,14 +143,13 @@ typedef struct BDRVNBDState {
     NBDConnectThread *connect_thread;
 } BDRVNBDState;

-static QIOChannelSocket *nbd_establish_connection(SocketAddress *saddr,
-                                                  Error **errp);
-static QIOChannelSocket *nbd_co_establish_connection(BlockDriverState *bs,
-                                                     Error **errp);
+static int nbd_establish_connection(BlockDriverState *bs, SocketAddress *saddr,
+                                    Error **errp);
+static int nbd_co_establish_connection(BlockDriverState *bs, Error **errp);
 static void nbd_co_establish_connection_cancel(BlockDriverState *bs,
                                                bool detach);
-static int nbd_client_handshake(BlockDriverState *bs, QIOChannelSocket *sioc,
-                                Error **errp);
+static int nbd_client_handshake(BlockDriverState *bs, Error **errp);
+static void nbd_yank(void *opaque);

 static void nbd_clear_bdrvstate(BDRVNBDState *s)
 {
@@ -165,12 +167,12 @@ static void nbd_clear_bdrvstate(BDRVNBDState *s)
 static void nbd_channel_error(BDRVNBDState *s, int ret)
 {
     if (ret == -EIO) {
-        if (s->state == NBD_CLIENT_CONNECTED) {
+        if (qatomic_load_acquire(&s->state) == NBD_CLIENT_CONNECTED) {
             s->state = s->reconnect_delay ? NBD_CLIENT_CONNECTING_WAIT :
                                             NBD_CLIENT_CONNECTING_NOWAIT;
         }
     } else {
-        if (s->state == NBD_CLIENT_CONNECTED) {
+        if (qatomic_load_acquire(&s->state) == NBD_CLIENT_CONNECTED) {
             qio_channel_shutdown(s->ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
         }
         s->state = NBD_CLIENT_QUIT;
@@ -203,7 +205,7 @@ static void reconnect_delay_timer_cb(void *opaque)
 {
     BDRVNBDState *s = opaque;

-    if (s->state == NBD_CLIENT_CONNECTING_WAIT) {
+    if (qatomic_load_acquire(&s->state) == NBD_CLIENT_CONNECTING_WAIT) {
         s->state = NBD_CLIENT_CONNECTING_NOWAIT;
         while (qemu_co_enter_next(&s->free_sema, NULL)) {
             /* Resume all queued requests */
@@ -215,7 +217,7 @@ static void reconnect_delay_timer_cb(void *opaque)

 static void reconnect_delay_timer_init(BDRVNBDState *s, uint64_t expire_time_ns)
 {
-    if (s->state != NBD_CLIENT_CONNECTING_WAIT) {
+    if (qatomic_load_acquire(&s->state) != NBD_CLIENT_CONNECTING_WAIT) {
         return;
     }

@@ -260,7 +262,7 @@ static void nbd_client_attach_aio_context(BlockDriverState *bs,
      * s->connection_co is either yielded from nbd_receive_reply or from
      * nbd_co_reconnect_loop()
      */
-    if (s->state == NBD_CLIENT_CONNECTED) {
+    if (qatomic_load_acquire(&s->state) == NBD_CLIENT_CONNECTED) {
         qio_channel_attach_aio_context(QIO_CHANNEL(s->ioc), new_context);
     }

@@ -286,7 +288,7 @@ static void coroutine_fn nbd_client_co_drain_begin(BlockDriverState *bs)

     reconnect_delay_timer_del(s);

-    if (s->state == NBD_CLIENT_CONNECTING_WAIT) {
+    if (qatomic_load_acquire(&s->state) == NBD_CLIENT_CONNECTING_WAIT) {
         s->state = NBD_CLIENT_CONNECTING_NOWAIT;
         qemu_co_queue_restart_all(&s->free_sema);
     }
@@ -337,13 +339,14 @@ static void nbd_teardown_connection(BlockDriverState *bs)

 static bool nbd_client_connecting(BDRVNBDState *s)
 {
-    return s->state == NBD_CLIENT_CONNECTING_WAIT ||
-        s->state == NBD_CLIENT_CONNECTING_NOWAIT;
+    NBDClientState state = qatomic_load_acquire(&s->state);
+    return state == NBD_CLIENT_CONNECTING_WAIT ||
+        state == NBD_CLIENT_CONNECTING_NOWAIT;
 }

 static bool nbd_client_connecting_wait(BDRVNBDState *s)
 {
-    return s->state == NBD_CLIENT_CONNECTING_WAIT;
+    return qatomic_load_acquire(&s->state) == NBD_CLIENT_CONNECTING_WAIT;
 }

 static void connect_bh(void *opaque)
@@ -423,12 +426,12 @@ static void *connect_thread_func(void *opaque)
     return NULL;
 }

-static QIOChannelSocket *coroutine_fn
+static int coroutine_fn
 nbd_co_establish_connection(BlockDriverState *bs, Error **errp)
 {
+    int ret;
     QemuThread thread;
     BDRVNBDState *s = bs->opaque;
-    QIOChannelSocket *res;
     NBDConnectThread *thr = s->connect_thread;

     qemu_mutex_lock(&thr->mutex);
@@ -445,10 +448,12 @@ nbd_co_establish_connection(BlockDriverState *bs, Error **errp)
     case CONNECT_THREAD_SUCCESS:
         /* Previous attempt finally succeeded in background */
         thr->state = CONNECT_THREAD_NONE;
-        res = thr->sioc;
+        s->sioc = thr->sioc;
         thr->sioc = NULL;
+        yank_register_function(BLOCKDEV_YANK_INSTANCE(bs->node_name),
+                               nbd_yank, bs);
         qemu_mutex_unlock(&thr->mutex);
-        return res;
+        return 0;
     case CONNECT_THREAD_RUNNING:
         /* Already running, will wait */
         break;
@@ -480,8 +485,13 @@ nbd_co_establish_connection(BlockDriverState *bs, Error **errp)
         thr->state = CONNECT_THREAD_NONE;
         error_propagate(errp, thr->err);
         thr->err = NULL;
-        res = thr->sioc;
+        s->sioc = thr->sioc;
         thr->sioc = NULL;
+        if (s->sioc) {
+            yank_register_function(BLOCKDEV_YANK_INSTANCE(bs->node_name),
+                                   nbd_yank, bs);
+        }
+        ret = (s->sioc ? 0 : -1);
         break;
     case CONNECT_THREAD_RUNNING:
     case CONNECT_THREAD_RUNNING_DETACHED:
@@ -490,7 +500,7 @@ nbd_co_establish_connection(BlockDriverState *bs, Error **errp)
          * failed. Still connect thread is executing in background, and its
          * result may be used for next connection attempt.
          */
-        res = NULL;
+        ret = -1;
         error_setg(errp, "Connection attempt cancelled by other operation");
         break;

@@ -507,7 +517,7 @@ nbd_co_establish_connection(BlockDriverState *bs, Error **errp)

     qemu_mutex_unlock(&thr->mutex);

-    return res;
+    return ret;
 }

 /*
@@ -560,7 +570,6 @@ static coroutine_fn void nbd_reconnect_attempt(BDRVNBDState *s)
 {
     int ret;
     Error *local_err = NULL;
-    QIOChannelSocket *sioc;

     if (!nbd_client_connecting(s)) {
         return;
@@ -593,21 +602,22 @@ static coroutine_fn void nbd_reconnect_attempt(BDRVNBDState *s)
     /* Finalize previous connection if any */
     if (s->ioc) {
         qio_channel_detach_aio_context(QIO_CHANNEL(s->ioc));
+        yank_unregister_function(BLOCKDEV_YANK_INSTANCE(s->bs->node_name),
+                                 nbd_yank, s->bs);
         object_unref(OBJECT(s->sioc));
         s->sioc = NULL;
         object_unref(OBJECT(s->ioc));
         s->ioc = NULL;
     }

-    sioc = nbd_co_establish_connection(s->bs, &local_err);
-    if (!sioc) {
+    if (nbd_co_establish_connection(s->bs, &local_err) < 0) {
         ret = -ECONNREFUSED;
         goto out;
     }

     bdrv_dec_in_flight(s->bs);

-    ret = nbd_client_handshake(s->bs, sioc, &local_err);
+    ret = nbd_client_handshake(s->bs, &local_err);

     if (s->drained) {
         s->wait_drained_end = true;
@@ -639,7 +649,7 @@ static coroutine_fn void nbd_co_reconnect_loop(BDRVNBDState *s)
     uint64_t timeout = 1 * NANOSECONDS_PER_SECOND;
     uint64_t max_timeout = 16 * NANOSECONDS_PER_SECOND;

-    if (s->state == NBD_CLIENT_CONNECTING_WAIT) {
+    if (qatomic_load_acquire(&s->state) == NBD_CLIENT_CONNECTING_WAIT) {
         reconnect_delay_timer_init(s, qemu_clock_get_ns(QEMU_CLOCK_REALTIME) +
                                    s->reconnect_delay * NANOSECONDS_PER_SECOND);
     }
@@ -682,7 +692,7 @@ static coroutine_fn void nbd_connection_entry(void *opaque)
     int ret = 0;
     Error *local_err = NULL;

-    while (s->state != NBD_CLIENT_QUIT) {
+    while (qatomic_load_acquire(&s->state) != NBD_CLIENT_QUIT) {
         /*
          * The NBD client can only really be considered idle when it has
          * yielded from qio_channel_readv_all_eof(), waiting for data. This is
@@ -697,7 +707,7 @@ static coroutine_fn void nbd_connection_entry(void *opaque)
             nbd_co_reconnect_loop(s);
         }

-        if (s->state != NBD_CLIENT_CONNECTED) {
+        if (qatomic_load_acquire(&s->state) != NBD_CLIENT_CONNECTED) {
             continue;
         }

@@ -752,6 +762,8 @@ static coroutine_fn void nbd_connection_entry(void *opaque)
     s->connection_co = NULL;
     if (s->ioc) {
         qio_channel_detach_aio_context(QIO_CHANNEL(s->ioc));
+        yank_unregister_function(BLOCKDEV_YANK_INSTANCE(s->bs->node_name),
+                                 nbd_yank, s->bs);
         object_unref(OBJECT(s->sioc));
         s->sioc = NULL;
         object_unref(OBJECT(s->ioc));
@@ -776,7 +788,7 @@ static int nbd_co_send_request(BlockDriverState *bs,
         qemu_co_queue_wait(&s->free_sema, &s->send_mutex);
     }

-    if (s->state != NBD_CLIENT_CONNECTED) {
+    if (qatomic_load_acquire(&s->state) != NBD_CLIENT_CONNECTED) {
         rc = -EIO;
         goto err;
     }
@@ -803,7 +815,8 @@ static int nbd_co_send_request(BlockDriverState *bs,
     if (qiov) {
         qio_channel_set_cork(s->ioc, true);
         rc = nbd_send_request(s->ioc, request);
-        if (rc >= 0 && s->state == NBD_CLIENT_CONNECTED) {
+        if (qatomic_load_acquire(&s->state) == NBD_CLIENT_CONNECTED &&
+            rc >= 0) {
             if (qio_channel_writev_all(s->ioc, qiov->iov, qiov->niov,
                                        NULL) < 0) {
                 rc = -EIO;
@@ -1118,7 +1131,7 @@ static coroutine_fn int nbd_co_do_receive_one_chunk(
     s->requests[i].receiving = true;
     qemu_coroutine_yield();
     s->requests[i].receiving = false;
-    if (s->state != NBD_CLIENT_CONNECTED) {
+    if (qatomic_load_acquire(&s->state) != NBD_CLIENT_CONNECTED) {
         error_setg(errp, "Connection closed");
         return -EIO;
     }
@@ -1277,7 +1290,7 @@ static bool nbd_reply_chunk_iter_receive(BDRVNBDState *s,
     NBDReply local_reply;
     NBDStructuredReplyChunk *chunk;
     Error *local_err = NULL;
-    if (s->state != NBD_CLIENT_CONNECTED) {
+    if (qatomic_load_acquire(&s->state) != NBD_CLIENT_CONNECTED) {
         error_setg(&local_err, "Connection closed");
         nbd_iter_channel_error(iter, -EIO, &local_err);
         goto break_loop;
@@ -1302,7 +1315,8 @@ static bool nbd_reply_chunk_iter_receive(BDRVNBDState *s,
     }

     /* Do not execute the body of NBD_FOREACH_REPLY_CHUNK for simple reply. */
-    if (nbd_reply_is_simple(reply) || s->state != NBD_CLIENT_CONNECTED) {
+    if (nbd_reply_is_simple(reply) ||
+        qatomic_load_acquire(&s->state) != NBD_CLIENT_CONNECTED) {
         goto break_loop;
     }

@@ -1734,6 +1748,15 @@ static int nbd_client_reopen_prepare(BDRVReopenState *state,
     return 0;
 }

+static void nbd_yank(void *opaque)
+{
+    BlockDriverState *bs = opaque;
+    BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
+
+    qatomic_store_release(&s->state, NBD_CLIENT_QUIT);
+    qio_channel_shutdown(QIO_CHANNEL(s->sioc), QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
+}
+
 static void nbd_client_close(BlockDriverState *bs)
 {
     BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
@@ -1746,52 +1769,53 @@ static void nbd_client_close(BlockDriverState *bs)
     nbd_teardown_connection(bs);
 }

-static QIOChannelSocket *nbd_establish_connection(SocketAddress *saddr,
-                                                  Error **errp)
+static int nbd_establish_connection(BlockDriverState *bs,
+                                    SocketAddress *saddr,
+                                    Error **errp)
 {
     ERRP_GUARD();
-    QIOChannelSocket *sioc;
+    BDRVNBDState *s = (BDRVNBDState *)bs->opaque;

-    sioc = qio_channel_socket_new();
-    qio_channel_set_name(QIO_CHANNEL(sioc), "nbd-client");
+    s->sioc = qio_channel_socket_new();
+    qio_channel_set_name(QIO_CHANNEL(s->sioc), "nbd-client");

-    qio_channel_socket_connect_sync(sioc, saddr, errp);
+    qio_channel_socket_connect_sync(s->sioc, saddr, errp);
     if (*errp) {
-        object_unref(OBJECT(sioc));
-        return NULL;
+        object_unref(OBJECT(s->sioc));
+        s->sioc = NULL;
+        return -1;
     }

-    qio_channel_set_delay(QIO_CHANNEL(sioc), false);
+    yank_register_function(BLOCKDEV_YANK_INSTANCE(bs->node_name), nbd_yank, bs);
+    qio_channel_set_delay(QIO_CHANNEL(s->sioc), false);

-    return sioc;
+    return 0;
 }

-/* nbd_client_handshake takes ownership on sioc. On failure it is unref'ed. */
-static int nbd_client_handshake(BlockDriverState *bs, QIOChannelSocket *sioc,
-                                Error **errp)
+/* nbd_client_handshake takes ownership on s->sioc. On failure it's unref'ed. */
+static int nbd_client_handshake(BlockDriverState *bs, Error **errp)
 {
     BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
     AioContext *aio_context = bdrv_get_aio_context(bs);
     int ret;

     trace_nbd_client_handshake(s->export);
-
-    s->sioc = sioc;
-
-    qio_channel_set_blocking(QIO_CHANNEL(sioc), false, NULL);
-    qio_channel_attach_aio_context(QIO_CHANNEL(sioc), aio_context);
+    qio_channel_set_blocking(QIO_CHANNEL(s->sioc), false, NULL);
+    qio_channel_attach_aio_context(QIO_CHANNEL(s->sioc), aio_context);

     s->info.request_sizes = true;
     s->info.structured_reply = true;
     s->info.base_allocation = true;
     s->info.x_dirty_bitmap = g_strdup(s->x_dirty_bitmap);
     s->info.name = g_strdup(s->export ?: "");
-    ret = nbd_receive_negotiate(aio_context, QIO_CHANNEL(sioc), s->tlscreds,
+    ret = nbd_receive_negotiate(aio_context, QIO_CHANNEL(s->sioc), s->tlscreds,
                                 s->hostname, &s->ioc, &s->info, errp);
     g_free(s->info.x_dirty_bitmap);
     g_free(s->info.name);
     if (ret < 0) {
-        object_unref(OBJECT(sioc));
+        yank_unregister_function(BLOCKDEV_YANK_INSTANCE(bs->node_name),
+                                 nbd_yank, bs);
+        object_unref(OBJECT(s->sioc));
         s->sioc = NULL;
         return ret;
     }
@@ -1819,7 +1843,7 @@ static int nbd_client_handshake(BlockDriverState *bs, QIOChannelSocket *sioc,
     }

     if (!s->ioc) {
-        s->ioc = QIO_CHANNEL(sioc);
+        s->ioc = QIO_CHANNEL(s->sioc);
         object_ref(OBJECT(s->ioc));
     }

@@ -1835,9 +1859,11 @@ static int nbd_client_handshake(BlockDriverState *bs, QIOChannelSocket *sioc,
     {
         NBDRequest request = { .type = NBD_CMD_DISC };

-        nbd_send_request(s->ioc ?: QIO_CHANNEL(sioc), &request);
+        nbd_send_request(s->ioc ?: QIO_CHANNEL(s->sioc), &request);

-        object_unref(OBJECT(sioc));
+        yank_unregister_function(BLOCKDEV_YANK_INSTANCE(bs->node_name),
+                                 nbd_yank, bs);
+        object_unref(OBJECT(s->sioc));
         s->sioc = NULL;

         return ret;
@@ -2229,7 +2255,6 @@ static int nbd_open(BlockDriverState *bs, QDict *options, int flags,
 {
     int ret;
     BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
-    QIOChannelSocket *sioc;

     ret = nbd_process_options(bs, options, errp);
     if (ret < 0) {
@@ -2240,17 +2265,23 @@ static int nbd_open(BlockDriverState *bs, QDict *options, int flags,
     qemu_co_mutex_init(&s->send_mutex);
     qemu_co_queue_init(&s->free_sema);

+    yank_register_instance(BLOCKDEV_YANK_INSTANCE(bs->node_name), errp);
+    if (*errp) {
+        return -EEXIST;
+    }
+
     /*
      * establish TCP connection, return error if it fails
      * TODO: Configurable retry-until-timeout behaviour.
      */
-    sioc = nbd_establish_connection(s->saddr, errp);
-    if (!sioc) {
+    if (nbd_establish_connection(bs, s->saddr, errp) < 0) {
+        yank_unregister_instance(BLOCKDEV_YANK_INSTANCE(bs->node_name));
         return -ECONNREFUSED;
     }

-    ret = nbd_client_handshake(bs, sioc, errp);
+    ret = nbd_client_handshake(bs, errp);
     if (ret < 0) {
+        yank_unregister_instance(BLOCKDEV_YANK_INSTANCE(bs->node_name));
         nbd_clear_bdrvstate(s);
         return ret;
     }
@@ -2310,6 +2341,7 @@ static void nbd_close(BlockDriverState *bs)
     BDRVNBDState *s = bs->opaque;

     nbd_client_close(bs);
+    yank_unregister_instance(BLOCKDEV_YANK_INSTANCE(bs->node_name));
     nbd_clear_bdrvstate(s);
 }

--
2.20.1


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[PATCH v10 3/8] chardev/char-socket.c: Add yank feature

[Lukas Straub]

[-- Attachment #1: Type: text/plain, Size: 4819 bytes --]

Register a yank function to shutdown the socket on yank.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 chardev/char-socket.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index 95e45812d5..5947cbe8bb 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -34,6 +34,7 @@
 #include "qapi/error.h"
 #include "qapi/clone-visitor.h"
 #include "qapi/qapi-visit-sockets.h"
+#include "qemu/yank.h"

 #include "chardev/char-io.h"
 #include "qom/object.h"
@@ -70,6 +71,7 @@ struct SocketChardev {
     size_t read_msgfds_num;
     int *write_msgfds;
     size_t write_msgfds_num;
+    bool registered_yank;

     SocketAddress *addr;
     bool is_listen;
@@ -415,6 +417,12 @@ static void tcp_chr_free_connection(Chardev *chr)

     tcp_set_msgfds(chr, NULL, 0);
     remove_fd_in_watch(chr);
+    if (s->state == TCP_CHARDEV_STATE_CONNECTING
+        || s->state == TCP_CHARDEV_STATE_CONNECTED) {
+        yank_unregister_function(CHARDEV_YANK_INSTANCE(chr->label),
+                                 yank_generic_iochannel,
+                                 QIO_CHANNEL(s->sioc));
+    }
     object_unref(OBJECT(s->sioc));
     s->sioc = NULL;
     object_unref(OBJECT(s->ioc));
@@ -918,6 +926,9 @@ static int tcp_chr_add_client(Chardev *chr, int fd)
     }
     tcp_chr_change_state(s, TCP_CHARDEV_STATE_CONNECTING);
     tcp_chr_set_client_ioc_name(chr, sioc);
+    yank_register_function(CHARDEV_YANK_INSTANCE(chr->label),
+                           yank_generic_iochannel,
+                           QIO_CHANNEL(sioc));
     ret = tcp_chr_new_client(chr, sioc);
     object_unref(OBJECT(sioc));
     return ret;
@@ -932,6 +943,9 @@ static void tcp_chr_accept(QIONetListener *listener,

     tcp_chr_change_state(s, TCP_CHARDEV_STATE_CONNECTING);
     tcp_chr_set_client_ioc_name(chr, cioc);
+    yank_register_function(CHARDEV_YANK_INSTANCE(chr->label),
+                           yank_generic_iochannel,
+                           QIO_CHANNEL(cioc));
     tcp_chr_new_client(chr, cioc);
 }

@@ -947,6 +961,9 @@ static int tcp_chr_connect_client_sync(Chardev *chr, Error **errp)
         object_unref(OBJECT(sioc));
         return -1;
     }
+    yank_register_function(CHARDEV_YANK_INSTANCE(chr->label),
+                           yank_generic_iochannel,
+                           QIO_CHANNEL(sioc));
     tcp_chr_new_client(chr, sioc);
     object_unref(OBJECT(sioc));
     return 0;
@@ -962,6 +979,9 @@ static void tcp_chr_accept_server_sync(Chardev *chr)
     tcp_chr_change_state(s, TCP_CHARDEV_STATE_CONNECTING);
     sioc = qio_net_listener_wait_client(s->listener);
     tcp_chr_set_client_ioc_name(chr, sioc);
+    yank_register_function(CHARDEV_YANK_INSTANCE(chr->label),
+                           yank_generic_iochannel,
+                           QIO_CHANNEL(sioc));
     tcp_chr_new_client(chr, sioc);
     object_unref(OBJECT(sioc));
 }
@@ -1072,6 +1092,9 @@ static void char_socket_finalize(Object *obj)
         object_unref(OBJECT(s->tls_creds));
     }
     g_free(s->tls_authz);
+    if (s->registered_yank) {
+        yank_unregister_instance(CHARDEV_YANK_INSTANCE(chr->label));
+    }

     qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
 }
@@ -1087,6 +1110,9 @@ static void qemu_chr_socket_connected(QIOTask *task, void *opaque)

     if (qio_task_propagate_error(task, &err)) {
         tcp_chr_change_state(s, TCP_CHARDEV_STATE_DISCONNECTED);
+        yank_unregister_function(CHARDEV_YANK_INSTANCE(chr->label),
+                                 yank_generic_iochannel,
+                                 QIO_CHANNEL(sioc));
         check_report_connect_error(chr, err);
         goto cleanup;
     }
@@ -1120,6 +1146,9 @@ static void tcp_chr_connect_client_async(Chardev *chr)
     tcp_chr_change_state(s, TCP_CHARDEV_STATE_CONNECTING);
     sioc = qio_channel_socket_new();
     tcp_chr_set_client_ioc_name(chr, sioc);
+    yank_register_function(CHARDEV_YANK_INSTANCE(chr->label),
+                           yank_generic_iochannel,
+                           QIO_CHANNEL(sioc));
     /*
      * Normally code would use the qio_channel_socket_connect_async
      * method which uses a QIOTask + qio_task_set_error internally
@@ -1362,6 +1391,12 @@ static void qmp_chardev_open_socket(Chardev *chr,
         qemu_chr_set_feature(chr, QEMU_CHAR_FEATURE_FD_PASS);
     }

+    yank_register_instance(CHARDEV_YANK_INSTANCE(chr->label), errp);
+    if (*errp) {
+        return;
+    }
+    s->registered_yank = true;
+
     /* be isn't opened until we get a connection */
     *be_opened = false;

--
2.20.1


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[PATCH v10 4/8] migration: Add yank feature

[Lukas Straub]

[-- Attachment #1: Type: text/plain, Size: 7924 bytes --]

Register yank functions on sockets to shut them down.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/channel.c           | 13 +++++++++++++
 migration/migration.c         | 25 +++++++++++++++++++++++++
 migration/multifd.c           | 10 ++++++++++
 migration/qemu-file-channel.c |  7 +++++++
 migration/savevm.c            |  6 ++++++
 5 files changed, 61 insertions(+)

diff --git a/migration/channel.c b/migration/channel.c
index 8a783baa0b..35fe234e9c 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -18,6 +18,8 @@
 #include "trace.h"
 #include "qapi/error.h"
 #include "io/channel-tls.h"
+#include "io/channel-socket.h"
+#include "qemu/yank.h"

 /**
  * @migration_channel_process_incoming - Create new incoming migration channel
@@ -35,6 +37,11 @@ void migration_channel_process_incoming(QIOChannel *ioc)
     trace_migration_set_incoming_channel(
         ioc, object_get_typename(OBJECT(ioc)));

+    if (object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_SOCKET)) {
+        yank_register_function(MIGRATION_YANK_INSTANCE, yank_generic_iochannel,
+                               QIO_CHANNEL(ioc));
+    }
+
     if (s->parameters.tls_creds &&
         *s->parameters.tls_creds &&
         !object_dynamic_cast(OBJECT(ioc),
@@ -67,6 +74,12 @@ void migration_channel_connect(MigrationState *s,
         ioc, object_get_typename(OBJECT(ioc)), hostname, error);

     if (!error) {
+        if (object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_SOCKET)) {
+            yank_register_function(MIGRATION_YANK_INSTANCE,
+                                   yank_generic_iochannel,
+                                   QIO_CHANNEL(ioc));
+        }
+
         if (s->parameters.tls_creds &&
             *s->parameters.tls_creds &&
             !object_dynamic_cast(OBJECT(ioc),
diff --git a/migration/migration.c b/migration/migration.c
index 9bb4fee5ac..0b0442df37 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -56,6 +56,7 @@
 #include "net/announce.h"
 #include "qemu/queue.h"
 #include "multifd.h"
+#include "qemu/yank.h"

 #define MAX_THROTTLE  (128 << 20)      /* Migration transfer speed throttling */

@@ -248,6 +249,8 @@ void migration_incoming_state_destroy(void)
         qapi_free_SocketAddressList(mis->socket_address_list);
         mis->socket_address_list = NULL;
     }
+
+    yank_unregister_instance(MIGRATION_YANK_INSTANCE);
 }

 static void migrate_generate_event(int new_state)
@@ -425,8 +428,14 @@ void qemu_start_incoming_migration(const char *uri, Error **errp)
 {
     const char *p = NULL;

+    yank_register_instance(MIGRATION_YANK_INSTANCE, errp);
+    if (*errp) {
+        return;
+    }
+
     qapi_event_send_migration(MIGRATION_STATUS_SETUP);
     if (!strcmp(uri, "defer")) {
+        yank_unregister_instance(MIGRATION_YANK_INSTANCE);
         deferred_incoming_migration(errp);
     } else if (strstart(uri, "tcp:", &p) ||
                strstart(uri, "unix:", NULL) ||
@@ -441,6 +450,7 @@ void qemu_start_incoming_migration(const char *uri, Error **errp)
     } else if (strstart(uri, "fd:", &p)) {
         fd_start_incoming_migration(p, errp);
     } else {
+        yank_unregister_instance(MIGRATION_YANK_INSTANCE);
         error_setg(errp, "unknown migration protocol: %s", uri);
     }
 }
@@ -1733,6 +1743,7 @@ static void migrate_fd_cleanup(MigrationState *s)
     }
     notifier_list_notify(&migration_state_notifiers, s);
     block_cleanup_parameters(s);
+    yank_unregister_instance(MIGRATION_YANK_INSTANCE);
 }

 static void migrate_fd_cleanup_schedule(MigrationState *s)
@@ -2007,6 +2018,7 @@ 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.
      */
+    yank_unregister_instance(MIGRATION_YANK_INSTANCE);
     qemu_start_incoming_migration(uri, errp);
 }

@@ -2144,6 +2156,13 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
         return;
     }

+    if (!(has_resume && resume)) {
+        yank_register_instance(MIGRATION_YANK_INSTANCE, errp);
+        if (*errp) {
+            return;
+        }
+    }
+
     if (strstart(uri, "tcp:", &p) ||
         strstart(uri, "unix:", NULL) ||
         strstart(uri, "vsock:", NULL)) {
@@ -2157,6 +2176,9 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
     } else if (strstart(uri, "fd:", &p)) {
         fd_start_outgoing_migration(s, p, &local_err);
     } else {
+        if (!(has_resume && resume)) {
+            yank_unregister_instance(MIGRATION_YANK_INSTANCE);
+        }
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "uri",
                    "a valid migration protocol");
         migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
@@ -2166,6 +2188,9 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
     }

     if (local_err) {
+        if (!(has_resume && resume)) {
+            yank_unregister_instance(MIGRATION_YANK_INSTANCE);
+        }
         migrate_fd_error(s, local_err);
         error_propagate(errp, local_err);
         return;
diff --git a/migration/multifd.c b/migration/multifd.c
index 68b171fb61..620b55f5d9 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -25,6 +25,9 @@
 #include "trace.h"
 #include "multifd.h"

+#include "qemu/yank.h"
+#include "io/channel-socket.h"
+
 /* Multiple fd's */

 #define MULTIFD_MAGIC 0x11223344U
@@ -962,6 +965,13 @@ int multifd_load_cleanup(Error **errp)
     for (i = 0; i < migrate_multifd_channels(); i++) {
         MultiFDRecvParams *p = &multifd_recv_state->params[i];

+        if (object_dynamic_cast(OBJECT(p->c), TYPE_QIO_CHANNEL_SOCKET)
+            && OBJECT(p->c)->ref == 1) {
+            yank_unregister_function(MIGRATION_YANK_INSTANCE,
+                                     yank_generic_iochannel,
+                                     QIO_CHANNEL(p->c));
+        }
+
         object_unref(OBJECT(p->c));
         p->c = NULL;
         qemu_mutex_destroy(&p->mutex);
diff --git a/migration/qemu-file-channel.c b/migration/qemu-file-channel.c
index d2ce32f4b9..afc3a7f642 100644
--- a/migration/qemu-file-channel.c
+++ b/migration/qemu-file-channel.c
@@ -27,6 +27,7 @@
 #include "qemu-file.h"
 #include "io/channel-socket.h"
 #include "qemu/iov.h"
+#include "qemu/yank.h"


 static ssize_t channel_writev_buffer(void *opaque,
@@ -104,6 +105,12 @@ static int channel_close(void *opaque, Error **errp)
     int ret;
     QIOChannel *ioc = QIO_CHANNEL(opaque);
     ret = qio_channel_close(ioc, errp);
+    if (object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_SOCKET)
+        && OBJECT(ioc)->ref == 1) {
+        yank_unregister_function(MIGRATION_YANK_INSTANCE,
+                                 yank_generic_iochannel,
+                                 QIO_CHANNEL(ioc));
+    }
     object_unref(OBJECT(ioc));
     return ret;
 }
diff --git a/migration/savevm.c b/migration/savevm.c
index 21ccba9fb3..c7648a9388 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -62,6 +62,7 @@
 #include "migration/colo.h"
 #include "qemu/bitmap.h"
 #include "net/announce.h"
+#include "qemu/yank.h"

 const unsigned int postcopy_ram_discard_version;

@@ -2997,6 +2998,11 @@ int load_snapshot(const char *name, Error **errp)
     qemu_system_reset(SHUTDOWN_CAUSE_NONE);
     mis->from_src_file = f;

+    yank_register_instance(MIGRATION_YANK_INSTANCE, errp);
+    if (*errp) {
+        ret = -EINVAL;
+        goto err_drain;
+    }
     aio_context_acquire(aio_context);
     ret = qemu_loadvm_state(f);
     migration_incoming_state_destroy();
--
2.20.1


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[PATCH v10 5/8] io/channel-tls.c: make qio_channel_tls_shutdown thread-safe

[Lukas Straub]

[-- Attachment #1: Type: text/plain, Size: 1381 bytes --]

Make qio_channel_tls_shutdown thread-safe by using atomics when
accessing tioc->shutdown.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
---
 io/channel-tls.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/io/channel-tls.c b/io/channel-tls.c
index 7ec8ceff2f..10d0bf59aa 100644
--- a/io/channel-tls.c
+++ b/io/channel-tls.c
@@ -23,6 +23,7 @@
 #include "qemu/module.h"
 #include "io/channel-tls.h"
 #include "trace.h"
+#include "qemu/atomic.h"


 static ssize_t qio_channel_tls_write_handler(const char *buf,
@@ -277,7 +278,8 @@ static ssize_t qio_channel_tls_readv(QIOChannel *ioc,
                     return QIO_CHANNEL_ERR_BLOCK;
                 }
             } else if (errno == ECONNABORTED &&
-                       (tioc->shutdown & QIO_CHANNEL_SHUTDOWN_READ)) {
+                       (qatomic_load_acquire(&tioc->shutdown) &
+                        QIO_CHANNEL_SHUTDOWN_READ)) {
                 return 0;
             }

@@ -361,7 +363,7 @@ static int qio_channel_tls_shutdown(QIOChannel *ioc,
 {
     QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);

-    tioc->shutdown |= how;
+    qatomic_or(&tioc->shutdown, how);

     return qio_channel_shutdown(tioc->master, how, errp);
 }
--
2.20.1


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[PATCH v10 6/8] io: Document qmp oob suitability of qio_channel_shutdown and io_shutdown

[Lukas Straub]

[-- Attachment #1: Type: text/plain, Size: 1250 bytes --]

Migration and yank code assume that qio_channel_shutdown is thread
-safe and can be called from qmp oob handler. Document this after
checking the code.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
---
 include/io/channel.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/io/channel.h b/include/io/channel.h
index 3c04f0edda..e0b9fc615d 100644
--- a/include/io/channel.h
+++ b/include/io/channel.h
@@ -92,7 +92,8 @@ struct QIOChannel {
  * provide additional optional features.
  *
  * Consult the corresponding public API docs for a description
- * of the semantics of each callback
+ * of the semantics of each callback. io_shutdown in particular
+ * must be thread-safe, terminate quickly and must not block.
  */
 struct QIOChannelClass {
     ObjectClass parent;
@@ -510,6 +511,8 @@ int qio_channel_close(QIOChannel *ioc,
  * QIO_CHANNEL_FEATURE_SHUTDOWN prior to calling
  * this method.
  *
+ * This function is thread-safe, terminates quickly and does not block.
+ *
  * Returns: 0 on success, -1 on error
  */
 int qio_channel_shutdown(QIOChannel *ioc,
--
2.20.1


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[PATCH v10 7/8] MAINTAINERS: Add myself as maintainer for yank feature

[Lukas Straub]

[-- Attachment #1: Type: text/plain, Size: 697 bytes --]

I'll maintain this for now as the colo usecase is the first user
of this functionality.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 MAINTAINERS | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 8c744a9bdf..81288fd219 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2676,6 +2676,13 @@ F: util/uuid.c
 F: include/qemu/uuid.h
 F: tests/test-uuid.c

+Yank feature
+M: Lukas Straub <lukasstraub2@web.de>
+S: Odd fixes
+F: util/yank.c
+F: include/qemu/yank.h
+F: qapi/yank.json
+
 COLO Framework
 M: zhanghailiang <zhang.zhanghailiang@huawei.com>
 S: Maintained
--
2.20.1


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Re: [PATCH v10 7/8] MAINTAINERS: Add myself as maintainer for yank feature

[Markus Armbruster]

Lukas Straub <lukasstraub2@web.de> writes:

> I'll maintain this for now as the colo usecase is the first user
> of this functionality.
>
> Signed-off-by: Lukas Straub <lukasstraub2@web.de>
> Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  MAINTAINERS | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 8c744a9bdf..81288fd219 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2676,6 +2676,13 @@ F: util/uuid.c
>  F: include/qemu/uuid.h
>  F: tests/test-uuid.c
>
> +Yank feature
> +M: Lukas Straub <lukasstraub2@web.de>
> +S: Odd fixes
> +F: util/yank.c
> +F: include/qemu/yank.h
> +F: qapi/yank.json
> +
>  COLO Framework
>  M: zhanghailiang <zhang.zhanghailiang@huawei.com>
>  S: Maintained

I'd squash this into PATCH 1 to mollify checkpatch.pl.

Regardless,
Reviewed-by: Markus Armbruster <armbru@redhat.com>

Re: [PATCH v10 7/8] MAINTAINERS: Add myself as maintainer for yank feature

[Lukas Straub]

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On Mon, 02 Nov 2020 07:33:54 +0100
Markus Armbruster <armbru@redhat.com> wrote:

> Lukas Straub <lukasstraub2@web.de> writes:
> 
> > I'll maintain this for now as the colo usecase is the first user
> > of this functionality.
> >
> > Signed-off-by: Lukas Straub <lukasstraub2@web.de>
> > Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
> > ---
> >  MAINTAINERS | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 8c744a9bdf..81288fd219 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -2676,6 +2676,13 @@ F: util/uuid.c
> >  F: include/qemu/uuid.h
> >  F: tests/test-uuid.c
> >
> > +Yank feature
> > +M: Lukas Straub <lukasstraub2@web.de>
> > +S: Odd fixes
> > +F: util/yank.c
> > +F: include/qemu/yank.h
> > +F: qapi/yank.json
> > +
> >  COLO Framework
> >  M: zhanghailiang <zhang.zhanghailiang@huawei.com>
> >  S: Maintained  
> 
> I'd squash this into PATCH 1 to mollify checkpatch.pl.
> 
> Regardless,
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> 

Changed for the next version.

-- 


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[PATCH v10 8/8] tests/test-char.c: Wait for the chardev to connect in char_socket_client_dupid_test

[Lukas Straub]

[-- Attachment #1: Type: text/plain, Size: 1055 bytes --]

A connecting chardev object has an additional reference by the connecting
thread, so if the chardev is still connecting by the end of the test,
then the chardev object won't be freed. This in turn means that the yank
instance won't be unregistered and when running the next test-case
yank_register_instance will abort, because the yank instance is
already/still registered.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
---
 tests/test-char.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/test-char.c b/tests/test-char.c
index 9196e566e9..aedb5c9eda 100644
--- a/tests/test-char.c
+++ b/tests/test-char.c
@@ -937,6 +937,7 @@ static void char_socket_client_dupid_test(gconstpointer opaque)
     g_assert_nonnull(opts);
     chr1 = qemu_chr_new_from_opts(opts, NULL, &error_abort);
     g_assert_nonnull(chr1);
+    qemu_chr_wait_connected(chr1, &error_abort);

     chr2 = qemu_chr_new_from_opts(opts, NULL, &local_err);
     g_assert_null(chr2);
--
2.20.1

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