Re: [Qemu-devel] [PATCH v3] vhost: Cancel migration when vhost-user process restarted during migration

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Ying Fang (fangying1@huawei.com) wrote:
> 
> On 2017/11/28 18:18, Dr. David Alan Gilbert wrote:
> > * fangying (fangying1@huawei.com) wrote:
> >> QEMU will abort when vhost-user process is restarted during migration
> >> and vhost_log_global_start/stop is called. The reason is clear that
> >> vhost_dev_set_log returns -1 because network connection is temporarily
> >> lost. To handle this situation, let's cancel migration here.
> >>
> >> Signed-off-by: Ying Fang <fangying1@huawei.com>
> > 
> > I thought we had agreed not to use migrate_fd_cancel here - that's for
> > cancelling not erroring.
> > 
> > Dave
> We can not use migrate_fd_error(migrate_get_current(),...) here,
> since it will touch the assertion of "s->to_dst_file",
> Is there any better solution ?  Thanks.

How about:
  error_report(....)
  qemu_file_set_error(migrate_get_current()->to_dst_file, -ECHILD);

  But please, don't use cancel.

Dave

> void migrate_fd_error(MigrationState *s, const Error *error)
> {
>     trace_migrate_fd_error(error_get_pretty(error));
> --> assert(s->to_dst_file == NULL);
>     migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
>                       MIGRATION_STATUS_FAILED);
>     migrate_set_error(s, error);
>     notifier_list_notify(&migration_state_notifiers, s);
>     block_cleanup_parameters(s);
> }
> 
> > 
> >> ---
> >>  hw/virtio/vhost.c     | 15 +++++++++++++--
> >>  migration/migration.c |  2 +-
> >>  migration/migration.h |  2 +-
> >>  3 files changed, 15 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> >> index ddc42f0..e2ade93 100644
> >> --- a/hw/virtio/vhost.c
> >> +++ b/hw/virtio/vhost.c
> >> @@ -26,6 +26,7 @@
> >>  #include "hw/virtio/virtio-bus.h"
> >>  #include "hw/virtio/virtio-access.h"
> >>  #include "migration/blocker.h"
> >> +#include "migration/migration.h"
> >>  #include "sysemu/dma.h"
> >>  
> >>  /* enabled until disconnected backend stabilizes */
> >> @@ -882,20 +883,30 @@ static int vhost_migration_log(MemoryListener *listener, int enable)
> >>  static void vhost_log_global_start(MemoryListener *listener)
> >>  {
> >>      int r;
> >> +    MigrationState *s = NULL;
> >>  
> >>      r = vhost_migration_log(listener, true);
> >>      if (r < 0) {
> >> -        abort();
> >> +        error_report("Failed to start vhost dirty log");
> >> +        s = migrate_get_current();
> >> +        if (s->migration_thread_running) {
> >> +            migrate_fd_cancel(s);
> >> +        }
> >>      }
> >>  }
> >>  
> >>  static void vhost_log_global_stop(MemoryListener *listener)
> >>  {
> >>      int r;
> >> +    MigrationState *s = NULL;
> >>  
> >>      r = vhost_migration_log(listener, false);
> >>      if (r < 0) {
> >> -        abort();
> >> +        error_report("Failed to stop vhost dirty log");
> >> +        s = migrate_get_current();
> >> +        if (s->migration_thread_running) {
> >> +            migrate_fd_cancel(s);
> >> +        }
> >>      }
> >>  }
> >>  
> >> diff --git a/migration/migration.c b/migration/migration.c
> >> index 4de3b55..6d2b7df 100644
> >> --- a/migration/migration.c
> >> +++ b/migration/migration.c
> >> @@ -1131,7 +1131,7 @@ void migrate_fd_error(MigrationState *s, const Error *error)
> >>      block_cleanup_parameters(s);
> >>  }
> >>  
> >> -static void migrate_fd_cancel(MigrationState *s)
> >> +void migrate_fd_cancel(MigrationState *s)
> >>  {
> >>      int old_state ;
> >>      QEMUFile *f = migrate_get_current()->to_dst_file;
> >> diff --git a/migration/migration.h b/migration/migration.h
> >> index 663415f..f0261e3 100644
> >> --- a/migration/migration.h
> >> +++ b/migration/migration.h
> >> @@ -167,7 +167,7 @@ uint64_t migrate_max_downtime(void);
> >>  
> >>  void migrate_set_error(MigrationState *s, const Error *error);
> >>  void migrate_fd_error(MigrationState *s, const Error *error);
> >> -
> >> +void migrate_fd_cancel(MigrationState *s);
> >>  void migrate_fd_connect(MigrationState *s);
> >>  
> >>  MigrationState *migrate_init(void);
> >> -- 
> >> 1.8.3.1
> >>
> >>
> >>
> > --
> > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> > 
> > .
> > 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK