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

[Ying Fang]

On 2017/11/28 18:18, Dr. David Alan Gilbert wrote:
> * fangying (address@hidden) 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 <address@hidden>
> 
> 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.

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 / address@hidden / Manchester, UK
> 
> .
>