Re: [Qemu-devel] [PATCH 13/41] migration: prepare to access s->state outside critical sections

[Paolo Bonzini]

Il 21/02/2013 18:42, Juan Quintela ha scritto:
> Paolo Bonzini <address@hidden> wrote:
>> Accessing s->state outside the big QEMU lock will simplify a bit the
>> locking/unlocking of the iothread lock.
>>
>> Signed-off-by: Paolo Bonzini <address@hidden>
> 
> Reviewed-by: Juan Quintela <address@hidden>
> 
> We compensate the locking removal you did on the previous patch.

I thought this was thread-safe at any step (and it took a while to reach
that state :)), did I miss something?

>> +    __sync_val_compare_and_swap(&s->state, MIG_STATE_ACTIVE, 
>> MIG_STATE_ERROR);
> 
> This can be done later, but can we change this to a macro/inline
> function:
> 
> inline void migration_set_state(int state)
> {
>     __sync_val_compare_and_swap(&s->state, MIG_STATE_ACTIVE, state);
> }
> 
> or something like that?

Yes, especially so that we can add a tracepoint as in the
recently-posted series.

Paolo