[Qemu-devel] [PATCH 4/6] cancel mechanism for an already running dump bitmap process

[Sanidhya Kashyap <sanidhya.iiith@gmail.com>]

This patch introduces both hmp and qmp (log-dirty-bitmap-cancel) interface
to cancel an already executing dump process.

Signed-off-by: Sanidhya Kashyap <sanidhya.iiith@gmail.com>
---
 hmp-commands.hx  | 14 ++++++++++++++
 hmp.c            |  5 +++++
 hmp.h            |  1 +
 qapi-schema.json |  5 +++++
 qmp-commands.hx  | 20 ++++++++++++++++++++
 savevm.c         | 19 +++++++++++++++++++
 6 files changed, 64 insertions(+)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index 032a320..a8e13b3 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1791,6 +1791,20 @@ STEXI
 umps the writable working set of the VM's memoryto a file
 ETEXI
 
+	{
+	.name       = "ldbc|log-dirty-bitmap-cancel",
+	.args_type  = "",
+	.params     = "",
+	.help       = "cancel the current VM logging",
+	.mhandler.cmd = hmp_log_dirty_bitmap_cancel,
+},
+
+STEXI
+@item ldbc or log-dirty-bitmap-cancel
+@findex log-dirty-bitmap-cancel
+Cancel the current VM migration.
+ETEXI
+
 STEXI
 @end table
 ETEXI
diff --git a/hmp.c b/hmp.c
index cc54988..7bbbaad 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1328,6 +1328,11 @@ void hmp_log_dirty_bitmap(Monitor *mon, const QDict *qdict)
     }
 }
 
+void hmp_log_dirty_bitmap_cancel(Monitor *mon, const QDict *qdict)
+{
+    qmp_log_dirty_bitmap_cancel(NULL);
+}
+
 void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict)
 {
     Error *err = NULL;
diff --git a/hmp.h b/hmp.h
index bf6cc2a..d98b2ae 100644
--- a/hmp.h
+++ b/hmp.h
@@ -94,6 +94,7 @@ void hmp_cpu_add(Monitor *mon, const QDict *qdict);
 void hmp_object_add(Monitor *mon, const QDict *qdict);
 void hmp_object_del(Monitor *mon, const QDict *qdict);
 void hmp_log_dirty_bitmap(Monitor *mon, const QDict *qdict);
+void hmp_log_dirty_bitmap_cancel(Monitor *mon, const QDict *qdict);
 void object_add_completion(ReadLineState *rs, int nb_args, const char *str);
 void object_del_completion(ReadLineState *rs, int nb_args, const char *str);
 void device_add_completion(ReadLineState *rs, int nb_args, const char *str);
diff --git a/qapi-schema.json b/qapi-schema.json
index c1dba64..e897adb 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -4710,3 +4710,8 @@
                 '*epochs'       : 'int',
                 '*frequency'    : 'int',
                 '*readable'     : 'bool' } }
+## @log-dirty-bitmap-cancel
+#
+# cancel the dirty bitmap logging process
+##
+{ 'command': 'log-dirty-bitmap-cancel' }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 33e7719..55b2251 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -3603,3 +3603,23 @@ value is 3 while that of frequency is 40 and readable defaults to false.
 
 EQMP
 
+	{
+        .name       = "log-dirty-bitmap-cancel",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_input_log_dirty_bitmap_cancel,
+    },
+
+SQMP
+log_bitmap_cancel
+--------------
+
+Cancel the current logging of the dirty bitmap.
+
+Arguments: None.
+
+Example:
+
+-> { "execute": "log-bitmap-cancel" }
+<- { "return": {} }
+
+EQMP
diff --git a/savevm.c b/savevm.c
index 25d399a..1859f57 100644
--- a/savevm.c
+++ b/savevm.c
@@ -1320,6 +1320,25 @@ void qmp_log_dirty_bitmap(const char *filename, bool has_epochs,
     return;
 }
 
+static void logging_bitmap_cancel(BitmapLogState *b)
+{
+    int old_state;
+    do {
+        old_state = b->state;
+        if (old_state != LOG_BITMAP_STATE_SETUP &&
+            old_state != LOG_BITMAP_STATE_ACTIVE) {
+            break;
+        }
+        logging_state_set_status(b, old_state,
+                                 LOG_BITMAP_STATE_CANCELING);
+    } while (b->state != LOG_BITMAP_STATE_CANCELING);
+}
+
+void qmp_log_dirty_bitmap_cancel(Error **errp)
+{
+    logging_bitmap_cancel(logging_current_state());
+}
+
 void qmp_xen_save_devices_state(const char *filename, Error **errp)
 {
     QEMUFile *f;
-- 
1.8.3.1