Re: [Qemu-devel] [PATCH v5 17/45] Add wrappers and handlers for sending/receiving the postcopy-ram migration messages.

[Dr. David Alan Gilbert]

* Paolo Bonzini (address@hidden) wrote:
> 
> 
> On 25/02/2015 17:51, Dr. David Alan Gilbert (git) wrote:
> > +PostcopyState  postcopy_state_get(MigrationIncomingState *mis)
> > +{
> > +    return atomic_fetch_add(&mis->postcopy_state, 0);
> > +}
> > +
> > +/* Set the state and return the old state */
> > +PostcopyState postcopy_state_set(MigrationIncomingState *mis,
> > +                                 PostcopyState new_state)
> > +{
> > +    return atomic_xchg(&mis->postcopy_state, new_state);
> > +}
> 
> Which are the (multiple) threads are calling these functions?

The main thread receiving the migration and the postcopy ram_listen_thread
receiving the RAM pages.
It's not actually racy between multiple threads updating it,
it's sequenced so that the main thread initialises it and then
hands over to the listen thread that takes it over from that point.

Dave

> 
> Paolo
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK