[qemu-xen master] migration/block-dirty-bitmap: cancel migration on shutdown

[patchbot@xxxxxxx]

commit 1499ab096950364d634418e7aefb562694d6c953
Author:     Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
AuthorDate: Mon Jul 27 22:42:31 2020 +0300
Commit:     Eric Blake <eblake@xxxxxxxxxx>
CommitDate: Mon Jul 27 15:41:34 2020 -0500

    migration/block-dirty-bitmap: cancel migration on shutdown
    
    If target is turned off prior to postcopy finished, target crashes
    because busy bitmaps are found at shutdown.
    Canceling incoming migration helps, as it removes all unfinished (and
    therefore busy) bitmaps.
    
    Similarly on source we crash in bdrv_close_all which asserts that all
    bdrv states are removed, because bdrv states involved into dirty bitmap
    migration are referenced by it. So, we need to cancel outgoing
    migration as well.
    
    Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
    Reviewed-by: Andrey Shinkevich <andrey.shinkevich@xxxxxxxxxxxxx>
    Message-Id: <20200727194236.19551-17-vsementsov@xxxxxxxxxxxxx>
    Signed-off-by: Eric Blake <eblake@xxxxxxxxxx>
---
 migration/block-dirty-bitmap.c | 16 ++++++++++++++++
 migration/migration.c          | 13 +++++++++++++
 migration/migration.h          |  2 ++
 3 files changed, 31 insertions(+)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index f91015a4f8..1f675b792f 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -657,6 +657,22 @@ static void cancel_incoming_locked(DBMLoadState *s)
     s->bitmaps = NULL;
 }
 
+void dirty_bitmap_mig_cancel_outgoing(void)
+{
+    dirty_bitmap_do_save_cleanup(&dbm_state.save);
+}
+
+void dirty_bitmap_mig_cancel_incoming(void)
+{
+    DBMLoadState *s = &dbm_state.load;
+
+    qemu_mutex_lock(&s->lock);
+
+    cancel_incoming_locked(s);
+
+    qemu_mutex_unlock(&s->lock);
+}
+
 static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
 {
     GSList *item;
diff --git a/migration/migration.c b/migration/migration.c
index 1c61428988..8fe36339db 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -188,6 +188,19 @@ void migration_shutdown(void)
      */
     migrate_fd_cancel(current_migration);
     object_unref(OBJECT(current_migration));
+
+    /*
+     * Cancel outgoing migration of dirty bitmaps. It should
+     * at least unref used block nodes.
+     */
+    dirty_bitmap_mig_cancel_outgoing();
+
+    /*
+     * Cancel incoming migration of dirty bitmaps. Dirty bitmaps
+     * are non-critical data, and their loss never considered as
+     * something serious.
+     */
+    dirty_bitmap_mig_cancel_incoming();
 }
 
 /* For outgoing */
diff --git a/migration/migration.h b/migration/migration.h
index ab20c756f5..6c6a931d0d 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -335,6 +335,8 @@ void migrate_send_rp_recv_bitmap(MigrationIncomingState 
*mis,
 void migrate_send_rp_resume_ack(MigrationIncomingState *mis, uint32_t value);
 
 void dirty_bitmap_mig_before_vm_start(void);
+void dirty_bitmap_mig_cancel_outgoing(void);
+void dirty_bitmap_mig_cancel_incoming(void);
 void migrate_add_address(SocketAddress *address);
 
 int foreach_not_ignored_block(RAMBlockIterFunc func, void *opaque);
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#master