Re: [Qemu-devel] [PATCH v11 14/15] rdma: introduce MIG_STATE_NONE and change MIG_STATE_SETUP state transition

[Juan Quintela <quintela@redhat.com>]

mrhines@linux.vnet.ibm.com wrote:
> From: "Michael R. Hines" <mrhines@us.ibm.com>
>
> As described in the previous patch, until now, the MIG_STATE_SETUP
> state was not really a 'formal' state. It has been used as a 'zero' state
> (what we're calling 'NONE' here) and QEMU has been unconditionally transitioning
> into this state when the QMP migration command was called. Instead we want to
> introduce MIG_STATE_NONE, which is our starting state in the state machine, and
> then immediately transition into the MIG_STATE_SETUP state when the QMP migrate
> command is issued.
>
> In order to do this, we must delay the transition into MIG_STATE_ACTIVE until
> later in the migration_thread(). This is done to be able to timestamp the amount of
> time spent in the SETUP state for proper accounting to the user during
> an RDMA migration.
>
> Furthermore, the management software, until now, has never been aware of the
> existence of the SETUP state whatsoever. This must change, because, timing of this
> state implies that the state actually exists.
>
> These two patches cannot be separated because the 'query_migrate' QMP
> switch statement needs to know how to handle this new state transition.
>
> Tested-by: Michael R. Hines <mrhines@us.ibm.com>
> Signed-off-by: Michael R. Hines <mrhines@us.ibm.com>

> @@ -316,6 +321,7 @@ static void migrate_fd_cancel(MigrationState *s)
>  {
>      DPRINTF("cancelling migration\n");
>  
> +    migrate_set_state(s, MIG_STATE_SETUP, MIG_STATE_CANCELLED);
>      migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_CANCELLED);
>  }

This chunk is wrong.

we can call qme_migrate_cancel() at any point,  and it is going to be
called normally from MIG_STATE_ACTIVE.


    migrate_set_satet(s, s->state,  MIG_STATE_CANCELLED)

should do the trick.  Or something like that,  what do you think?

Later,  Juan.