Re: [Qemu-block] [Qemu-devel] [PATCH v2 4/8] qcow2-threads: split out generic path

[Paolo Bonzini]

On 11/12/18 17:43, Vladimir Sementsov-Ogievskiy wrote:
> +    ThreadPool *pool = aio_get_thread_pool(bdrv_get_aio_context(bs));
> +
> +    while (s->nb_threads >= QCOW2_MAX_THREADS) {
> +        qemu_co_queue_wait(&s->thread_task_queue, NULL);
> +    }
> +
> +    s->nb_threads++;
> +    ret = thread_pool_submit_co(pool, func, arg);
> +    s->nb_threads--;
> +
> +    qemu_co_queue_next(&s->thread_task_queue);

What lock is protecting this manipulation?  I'd rather avoid adding more
users of the AioContext lock, especially manipulation of CoQueues.

One possibility is to do the s->lock unlock/lock here, and then also
rely on that in patch 8.

Paolo