On 12/08/2017 12:12 PM, Paolo Bonzini wrote:
> On 08/12/2017 16:13, Stefan Hajnoczi wrote:
>>> - qemu_mutex_lock(&pool->lock);
>>> + QEMU_LOCK_GUARD(QemuMutex, pool_guard, &pool->lock);
>>> if (pool->idle_threads == 0 && pool->cur_threads < pool->max_threads) {
>>> spawn_thread(pool);
>>> }
>>> QTAILQ_INSERT_TAIL(&pool->request_list, req, reqs);
>>> - qemu_mutex_unlock(&pool->lock);
>>> + qemu_lock_guard_unlock(&pool_guard);
>> Why not QEMU_WITH_LOCK()? Then you can get rid of the explicit unlock.
>
> I agree that QEMU_WITH_LOCK_GUARD is better in this case. (IIRC I wrote
> this patch before coming up with the is_taken trick!).
>
> My main question for the series is what you think the balance should be
> between a more widely applicable API and a simpler one.
If you require the user to provide the scope, this could be:
@@ -258,12 +254,12 @@ BlockAIOCB *thread_pool_submit_aio(ThreadPool *pool,
trace_thread_pool_submit(pool, req, arg);
- qemu_mutex_lock(&pool->lock);
- if (pool->idle_threads == 0 && pool->cur_threads < pool->max_threads) {
- spawn_thread(pool);
- QTAILQ_INSERT_TAIL(&pool->request_list, req, reqs);
+ {
+ QEMU_LOCK_GUARD(QemuMutex, pool_guard, &pool->lock);
+ if (pool->idle_threads == 0 && pool->cur_threads <
pool->max_threads) {
+ spawn_thread(pool);
+ }
+ QTAILQ_INSERT_TAIL(&pool->request_list, req, reqs);
}
- qemu_mutex_unlock(&pool->lock);
qemu_sem_post(&pool->sem);
return &req->common;
}
In other words, I don't see what 'QEMU_WITH_LOCK_GUARD() {}' buys us
over '{ QEMU_LOCK_GUARD() }'.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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