Re: [Qemu-devel] [PATCH 2/3] AioContext: acquire/release AioContext during aio_poll

[Paolo Bonzini <pbonzini@redhat.com>]

On 08/07/2015 04:18, Fam Zheng wrote:
>> > @@ -267,7 +268,13 @@ bool aio_poll(AioContext *ctx, bool blocking)
>> >      timeout = blocking ? aio_compute_timeout(ctx) : 0;
>> >  
>> >      /* wait until next event */
>> > +    if (timeout) {
>> > +        aio_context_release(ctx);
>> > +    }
>> >      ret = qemu_poll_ns((GPollFD *)pollfds, npfd, timeout);
> If two threads poll concurrently on this ctx, they will get the same set of
> events, is that safe? Doesn't that lead to double dispatch?

Yes, but handlers should be okay with spurious wakeup.  They will just
get EAGAIN.

Paolo