Re: [Qemu-devel] [RFC 15/15] qmp: let migrate-incoming allow out-of-band

[Peter Xu <peterx@redhat.com>]

On Fri, Sep 15, 2017 at 05:09:28PM +0100, Dr. David Alan Gilbert wrote:
> * Peter Xu (peterx@redhat.com) wrote:
> > So it can get rid of being run on main thread.
> > 
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> > ---
> >  qapi/migration.json | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/qapi/migration.json b/qapi/migration.json
> > index ee2b3b8..dedc4f8 100644
> > --- a/qapi/migration.json
> > +++ b/qapi/migration.json
> > @@ -986,7 +986,8 @@
> >  # <- { "return": {} }
> >  #
> >  ##
> > -{ 'command': 'migrate-incoming', 'data': {'uri': 'str' } }
> > +{ 'command': 'migrate-incoming', 'data': {'uri': 'str' },
> > +  'allow-oob': true }
> 
> Are you completely convinced migrate-incoming is non-blocking?
> What about during the tls handshake if tls is enabled?
> (We only set non-blocking on the fd later)

IIUC after socket_start_incoming_migration() we are done in
qmp_migrate_incoming(), then all the rest of the socket work will all
be done in main thread.

Note: g_source_attach() along the way in the whole
qmp_migrate_incoming() should be using NULL as the second parameter,
which means they'll attach the objects all to the default gcontext,
which targets to the main thread.

> 
> I don't understand in this structure on which thread
> process_incoming_migration_co gets run.

IIUC it should be the main thread as well.

Thanks,

-- 
Peter Xu