* Peter Xu (pet...@redhat.com) wrote:
> Now at least migrate_incoming can be run in parallel. Let's provide a
> migration lock to protect it.
>
> Signed-off-by: Peter Xu <pet...@redhat.com>
> ---
> migration/migration.c | 6 ++++++
> migration/migration.h | 3 +++
> 2 files changed, 9 insertions(+)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index c3fe0ed..32058f7 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -145,6 +145,7 @@ MigrationIncomingState
> *migration_incoming_get_current(void)
> mis_current.state = MIGRATION_STATUS_NONE;
> memset(&mis_current, 0, sizeof(MigrationIncomingState));
> qemu_mutex_init(&mis_current.rp_mutex);
> + qemu_mutex_init(&mis_current.mgmt_mutex);
> qemu_event_init(&mis_current.main_thread_load_event, false);
> once = true;
> }
> @@ -1171,6 +1172,7 @@ void qmp_migrate_incoming(const char *uri, Error **errp)
> {
> Error *local_err = NULL;
> static bool once = true;
> + MigrationIncomingState *mis = migration_incoming_get_current();
migration_incoming_get_current isn't actually thread-safe itself unless
you can guarantee the initial allocation has happened - otherwise both
threads can race and do the 'once' code at the same time.
Similarly, these locks - they don't protect our 'once' - so a second
thread could come in here and both get past the !once check.
Dave
>
> if (!deferred_incoming) {
> error_setg(errp, "For use with '-incoming defer'");
> @@ -1180,8 +1182,12 @@ void qmp_migrate_incoming(const char *uri, Error
> **errp)
> error_setg(errp, "The incoming migration has already been started");
> }
>
> + qemu_mutex_lock(&mis->mgmt_mutex);
> +
> qemu_start_incoming_migration(uri, &local_err);
>
> + qemu_mutex_unlock(&mis->mgmt_mutex);
> +
> if (local_err) {
> error_propagate(errp, local_err);
> return;
> diff --git a/migration/migration.h b/migration/migration.h
> index 148c9fa..95f077b 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -58,6 +58,9 @@ struct MigrationIncomingState {
> /* The coroutine we should enter (back) after failover */
> Coroutine *migration_incoming_co;
> QemuSemaphore colo_incoming_sem;
> +
> + /* Migration incoming management lock */
> + QemuMutex mgmt_mutex;
> };
>
> MigrationIncomingState *migration_incoming_get_current(void);
> --
> 2.7.4
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
