Re: [Qemu-devel] [PATCH 09/36] migration: don't "write" when migration is not active

[Juan Quintela]

Anthony Liguori <address@hidden> wrote:
> On 10/11/2011 05:00 AM, Juan Quintela wrote:
>> If migration is not active, just ignore writes.
>>
>> Signed-off-by: Juan Quintela<address@hidden>
>> ---
>>   migration.c |    4 ++++
>>   1 files changed, 4 insertions(+), 0 deletions(-)
>>
>> diff --git a/migration.c b/migration.c
>> index 7ac1fc2..090c925 100644
>> --- a/migration.c
>> +++ b/migration.c
>> @@ -323,6 +323,10 @@ ssize_t migrate_fd_put_buffer(void *opaque, const void 
>> *data, size_t size)
>>       FdMigrationState *s = opaque;
>>       ssize_t ret;
>>
>> +    if (s->state != MIG_STATE_ACTIVE) {
>> +        return -EIO;
>> +    }
>> +
>
> Buffered file is buffered.  The migration may complete before the
> buffer is completely drained.  That means additional put_buffer calls
> may come after the migration state has moved to complete.

static void migrate_fd_completed(MigrationState *s)
{
    DPRINTF("setting completed state\n");
    if (migrate_fd_cleanup(s) < 0) {
        s->state = MIG_STATE_ERROR;
    } else {
        s->state = MIG_STATE_COMPLETED;
        runstate_set(RUN_STATE_POSTMIGRATE);
    }
    notifier_list_notify(&migration_state_notifiers, s);
}

After all the changes in this thread, that is the only place that can
change s->state to "MIG_STATE_COMPLETED", as you can see, we do that
after doing a migrate_fd_cleanup(), and that just flush + close the fd.

So, I still think that everything is done as expected. (testing confirms
that both migrate_cancel after one error don't hang and migration
without errors ends as expected.

Later, Juan.

> Regards,
> Anthony Liguori
>
>>       do {
>>           ret = s->write(s, data, size);
>>       } while (ret == -1&&  ((s->get_error(s)) == EINTR));