Migration: Generate the completed event only when we complete

The current migration-completed event is generated a bit too early,
which means that an eager libvirt that's ready to go as soon
as it sees the event ends up racing with the actual end of migration.

This corresponds to RH bug:
https://bugzilla.redhat.com/show_bug.cgi?id=1271145

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
xSigned-off-by: Juan Quintela <quintela@redhat.com>

diff --git a/migration/migration.c b/migration/migration.c
index b7de9b7b3f4664f78241acd602daee85f5fb3866..3d40f2455690c893e9f8516fd83e5d153e26bbad 100644 (file)
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -294,12 +294,12 @@ static void process_incoming_migration_co(void *opaque)
         migrate_decompress_threads_join();
         exit(EXIT_FAILURE);
     }
-    migrate_generate_event(MIGRATION_STATUS_COMPLETED);
     qemu_announce_self();
 
     /* Make sure all file formats flush their mutable metadata */
     bdrv_invalidate_cache_all(&local_err);
     if (local_err) {
+        migrate_generate_event(MIGRATION_STATUS_FAILED);
         error_report_err(local_err);
         migrate_decompress_threads_join();
         exit(EXIT_FAILURE);
@@ -320,6 +320,12 @@ static void process_incoming_migration_co(void *opaque)
         runstate_set(global_state_get_runstate());
     }
     migrate_decompress_threads_join();
+    /*
+     * This must happen after any state changes since as soon as an external
+     * observer sees this event they might start to prod at the VM assuming
+     * it's ready to use.
+     */
+    migrate_generate_event(MIGRATION_STATUS_COMPLETED);
 }
 
 void process_incoming_migration(QEMUFile *f)