Re: [PATCH 6/6] aiopool: protect with a mutex

[Paolo Bonzini]

On 10/05/21 13:56, Vladimir Sementsov-Ogievskiy wrote:
> > +    }
> > -    if (task->ret < 0 && pool->status == 0) {
> > -        pool->status = task->ret;
> > +    if (ret < 0) {
> > +        qatomic_cmpxchg(&pool->status, 0, ret);
> >       }
>
> Can we just do it inside critical section above and avoid extra cmpxchg? 
> We'll need just qatomic_set as a pair to qatomic_read()

Good idea.

> >       g_free(task);
> > -    if (pool->waiting) {
> > -        pool->waiting = false;
> > -        aio_co_wake(pool->main_co);
> > -    }
> > +    qemu_co_queue_next(&pool->queue);
>
> this call doesn't need mutex protection?

It does indeed.

I second the idea of "stealing" Denis's two patches to block/aio_task 
and only adding the mutex (plus qatomic_read/set) here.

Paolo

> Then we should modify comment 
> insid AioTaskPool structure.
>
> Anyway, I think it's simpler to just have one QEMU_MUTEX_GUARD() for the 
> whole function.