migration: Take reference to migration state around bg_migration_vm_start_bh

We need to hold a reference to the current_migration object around
async calls to avoid it been freed while still in use.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240119233922.32588-3-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/migration/migration.c b/migration/migration.c
index cf17b68e57..b1213b59ce 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3382,6 +3382,7 @@ static void bg_migration_vm_start_bh(void *opaque)
 
     vm_resume(s->vm_old_state);
     migration_downtime_end(s);
+    object_unref(OBJECT(s));
 }
 
 /**
@@ -3486,6 +3487,7 @@ static void *bg_migration_thread(void *opaque)
      * writes to virtio VQs memory which is in write-protected region.
      */
     s->vm_start_bh = qemu_bh_new(bg_migration_vm_start_bh, s);
+    object_ref(OBJECT(s));
     qemu_bh_schedule(s->vm_start_bh);
 
     bql_unlock();