From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Thierry Subject: [PATCH kvmtool 11/13] threadpool: Add cancel() function Date: Tue, 4 Dec 2018 11:08:44 +0000 Message-ID: <1543921726-54571-12-git-send-email-julien.thierry@arm.com> References: <1543921726-54571-1-git-send-email-julien.thierry@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B1C3E4A357 for ; Tue, 4 Dec 2018 06:09:08 -0500 (EST) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id F-bdOx45WNKn for ; Tue, 4 Dec 2018 06:09:07 -0500 (EST) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 5D0854A37E for ; Tue, 4 Dec 2018 06:09:06 -0500 (EST) In-Reply-To: <1543921726-54571-1-git-send-email-julien.thierry@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Cc: will.deacon@arm.com List-Id: kvmarm@lists.cs.columbia.edu From: Jean-Philippe Brucker When resetting a virtqueue, it is often necessary to make sure that the associated threadpool job isn't running anymore. Add a function to cancel a job. A threadpool job has three states: idle, queued and running. A job is queued when it is in the job list. It is running when it is out the list, but its signal count is greater than zero. It is idle when it is both out of the list and its signal count is zero. The cancel() function simply waits for the job to be idle. It is up to the caller to make sure that the job isn't queued concurrently. Signed-off-by: Jean-Philippe Brucker Signed-off-by: Julien Thierry --- include/kvm/threadpool.h | 2 ++ util/threadpool.c | 25 ++++++++++++++++++++++++- 2 files changed, 26 insertions(+), 1 deletion(-) diff --git a/include/kvm/threadpool.h b/include/kvm/threadpool.h index bacb243..880487a 100644 --- a/include/kvm/threadpool.h +++ b/include/kvm/threadpool.h @@ -28,11 +28,13 @@ static inline void thread_pool__init_job(struct thread_pool__job *job, struct kv .data = data, .mutex = MUTEX_INITIALIZER, }; + INIT_LIST_HEAD(&job->queue); } int thread_pool__init(struct kvm *kvm); int thread_pool__exit(struct kvm *kvm); void thread_pool__do_job(struct thread_pool__job *job); +void thread_pool__cancel_job(struct thread_pool__job *job); #endif diff --git a/util/threadpool.c b/util/threadpool.c index e64aa26..1dc3bf7 100644 --- a/util/threadpool.c +++ b/util/threadpool.c @@ -25,7 +25,7 @@ static struct thread_pool__job *thread_pool__job_pop_locked(void) return NULL; job = list_first_entry(&head, struct thread_pool__job, queue); - list_del(&job->queue); + list_del_init(&job->queue); return job; } @@ -173,3 +173,26 @@ void thread_pool__do_job(struct thread_pool__job *job) pthread_cond_signal(&job_cond); mutex_unlock(&job_mutex); } + +void thread_pool__cancel_job(struct thread_pool__job *job) +{ + bool running; + + /* + * If the job is queued but not running, remove it. Otherwise, wait for + * the signalcount to drop to 0, indicating that it has finished + * running. We assume that nobody is queueing this job - + * thread_pool__do_job() isn't called - while this function is running. + */ + do { + mutex_lock(&job_mutex); + if (list_empty(&job->queue)) { + running = job->signalcount > 0; + } else { + list_del_init(&job->queue); + job->signalcount = 0; + running = false; + } + mutex_unlock(&job_mutex); + } while (running); +} -- 1.9.1