Re: [Qemu-devel] [PATCH COLO-Frame (Base) v21 05/17] COLO: Establish a new communicating path for COLO

[Hailiang Zhang]

On 2016/10/27 11:57, Amit Shah wrote:
> On (Wed) 26 Oct 2016 [22:05:22], Hailiang Zhang wrote:
> > On 2016/10/26 13:06, Amit Shah wrote:
> > > On (Tue) 18 Oct 2016 [20:10:01], zhanghailiang wrote:
> > > > This new communication path will be used for returning messages
> > > >from Secondary side to Primary side.
> > > > Signed-off-by: zhanghailiang <address@hidden>
> > > > Signed-off-by: Li Zhijian <address@hidden>
> > > > Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> > >
> > > Reviewed-by: Amit Shah <address@hidden>
> > >
> > > > @@ -63,8 +75,24 @@ void *colo_process_incoming_thread(void *opaque)
> > > >       migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
> > > >                         MIGRATION_STATUS_COLO);
> > > >
> > > > +    mis->to_src_file = qemu_file_get_return_path(mis->from_src_file);
> > > > +    if (!mis->to_src_file) {
> > > > +        error_report("COLO incoming thread: Open QEMUFile to_src_file failed");
> > > > +        goto out;
> > > > +    }
> > > > +    /*
> > > > +     * Note: We set the fd to unblocked in migration incoming coroutine,
> > > > +     * But here we are in the COLO incoming thread, so it is ok to set the
> > > > +     * fd back to blocked.
> > > > +     */
> > > > +    qemu_file_set_blocking(mis->from_src_file, true);
> > >
> > > Why does it need to be blocking?
> >
> > Because, the communication/action between Primary side and Secondary side 
> > should be
> > sequential. Just as postcopy does. :)
>
> Yea - I mean please include that in the comment too so it's obvious
> why it's done.

OK, i will add this in next version, thanks.

>                 Amit
>
> .