static void thread_pool_cancel(BlockAIOCB *acb) { ThreadPoolElement *elem = (ThreadPoolElement *)acb; ThreadPool *pool = elem->pool; trace_thread_pool_cancel(elem, elem->common.opaque); qemu_mutex_lock(&pool->lock); if (elem->state == THREAD_QUEUED && /* No thread has yet started working on elem. we can try to "steal" * the item from the worker if we can get a signal from the * semaphore. Because this is non-blocking, we can do it with * the lock taken and ensure that elem will remain THREAD_QUEUED. */ qemu_sem_timedwait(&pool->sem, 0) == 0) { QTAILQ_REMOVE(&pool->request_list, elem, reqs); qemu_bh_schedule(pool->completion_bh); elem->state = THREAD_DONE; elem->ret = -ECANCELED; } qemu_mutex_unlock(&pool->lock); }