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Commit 8cca0eea authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: add find_worker_executing_work() and track current_cwq 



Now that all the workers are tracked by gcwq, we can find which worker
is executing a work from gcwq.  Implement find_worker_executing_work()
and make worker track its current_cwq so that we can find things the
other way around.  This will be used to implement non-reentrant wqs.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 502ca9d8

kernel/workqueue.c

+56 −0
Original line number Diff line number Diff line
@@ -82,6 +82,7 @@ struct worker { 
	};



	struct work_struct	*current_work;	/* L: work being processed */

	struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */

	struct list_head	scheduled;	/* L: scheduled works */

	struct task_struct	*task;		/* I: worker task */

	struct global_cwq	*gcwq;		/* I: the associated gcwq */
@@ -372,6 +373,59 @@ static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, 
	return &gcwq->busy_hash[v];

}



/**

 * __find_worker_executing_work - find worker which is executing a work

 * @gcwq: gcwq of interest

 * @bwh: hash head as returned by busy_worker_head()

 * @work: work to find worker for

 *

 * Find a worker which is executing @work on @gcwq.  @bwh should be

 * the hash head obtained by calling busy_worker_head() with the same

 * work.

 *

 * CONTEXT:

 * spin_lock_irq(gcwq->lock).

 *

 * RETURNS:

 * Pointer to worker which is executing @work if found, NULL

 * otherwise.

 */

static struct worker *__find_worker_executing_work(struct global_cwq *gcwq,

						   struct hlist_head *bwh,

						   struct work_struct *work)

{

	struct worker *worker;

	struct hlist_node *tmp;



	hlist_for_each_entry(worker, tmp, bwh, hentry)

		if (worker->current_work == work)

			return worker;

	return NULL;

}



/**

 * find_worker_executing_work - find worker which is executing a work

 * @gcwq: gcwq of interest

 * @work: work to find worker for

 *

 * Find a worker which is executing @work on @gcwq.  This function is

 * identical to __find_worker_executing_work() except that this

 * function calculates @bwh itself.

 *

 * CONTEXT:

 * spin_lock_irq(gcwq->lock).

 *

 * RETURNS:

 * Pointer to worker which is executing @work if found, NULL

 * otherwise.

 */

static struct worker *find_worker_executing_work(struct global_cwq *gcwq,

						 struct work_struct *work)

{

	return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work),

					    work);

}



/**

 * insert_work - insert a work into cwq

 * @cwq: cwq @work belongs to
@@ -914,6 +968,7 @@ static void process_one_work(struct worker *worker, struct work_struct *work) 
	debug_work_deactivate(work);

	hlist_add_head(&worker->hentry, bwh);

	worker->current_work = work;

	worker->current_cwq = cwq;

	work_color = get_work_color(work);

	list_del_init(&work->entry);
@@ -942,6 +997,7 @@ static void process_one_work(struct worker *worker, struct work_struct *work) 
	/* we're done with it, release */

	hlist_del_init(&worker->hentry);

	worker->current_work = NULL;

	worker->current_cwq = NULL;

	cwq_dec_nr_in_flight(cwq, work_color);

}