Migration: fix missing iothread locking

[PATCH v1 2/2] migration: add missing qemu_mutex_lock_iothread in migration_completion

Posted by Emanuele Giuseppe Esposito 4 years, 4 months ago

qemu_savevm_state_complete_postcopy assumes the iothread lock (BQL)
to be held, but instead it isn't.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 migration/migration.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/migration/migration.c b/migration/migration.c
index 041b8451a6..215d5281f2 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3182,7 +3182,10 @@ static void migration_completion(MigrationState *s)
     } else if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) {
         trace_migration_completion_postcopy_end();
 
+        qemu_mutex_lock_iothread();
         qemu_savevm_state_complete_postcopy(s->to_dst_file);
+        qemu_mutex_unlock_iothread();
+
         trace_migration_completion_postcopy_end_after_complete();
     } else if (s->state == MIGRATION_STATUS_CANCELLING) {
         goto fail;
-- 
2.27.0

Re: [PATCH v1 2/2] migration: add missing qemu_mutex_lock_iothread in migration_completion

Posted by Dr. David Alan Gilbert 4 years, 4 months ago

* Emanuele Giuseppe Esposito (eesposit@redhat.com) wrote:
> qemu_savevm_state_complete_postcopy assumes the iothread lock (BQL)
> to be held, but instead it isn't.
> 
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>

Interesting, I think you're right - and I think it's been missing it
from the start.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  migration/migration.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 041b8451a6..215d5281f2 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -3182,7 +3182,10 @@ static void migration_completion(MigrationState *s)
>      } else if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) {
>          trace_migration_completion_postcopy_end();
>  
> +        qemu_mutex_lock_iothread();
>          qemu_savevm_state_complete_postcopy(s->to_dst_file);
> +        qemu_mutex_unlock_iothread();
> +
>          trace_migration_completion_postcopy_end_after_complete();
>      } else if (s->state == MIGRATION_STATUS_CANCELLING) {
>          goto fail;
> -- 
> 2.27.0
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

[PATCH v1 1/2] migration: block-dirty-bitmap: add missing qemu_mutex_lock_iothread
[PATCH v1 2/2] migration: add missing qemu_mutex_lock_iothread in migration_completion