Commit a2d812a2 authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: Make worker_attach/detach_pool() update worker->pool 



For historical reasons, the worker attach/detach functions don't
currently manage worker->pool and the callers are manually and
inconsistently updating it.

This patch moves worker->pool updates into the worker attach/detach
functions.  This makes worker->pool consistent and clearly defines how
worker->pool updates are synchronized.

This will help later workqueue visibility improvements by allowing
safe access to workqueue information from worker->task.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 1258fae7

kernel/workqueue.c

+8 −8
Original line number Diff line number Diff line
@@ -1741,6 +1741,7 @@ static void worker_attach_to_pool(struct worker *worker, 
		worker->flags |= WORKER_UNBOUND;



	list_add_tail(&worker->node, &pool->workers);

	worker->pool = pool;



	mutex_unlock(&wq_pool_attach_mutex);

}
@@ -1748,19 +1749,21 @@ static void worker_attach_to_pool(struct worker *worker, 
/**

 * worker_detach_from_pool() - detach a worker from its pool

 * @worker: worker which is attached to its pool

 * @pool: the pool @worker is attached to

 *

 * Undo the attaching which had been done in worker_attach_to_pool().  The

 * caller worker shouldn't access to the pool after detached except it has

 * other reference to the pool.

 */

static void worker_detach_from_pool(struct worker *worker,

				    struct worker_pool *pool)

static void worker_detach_from_pool(struct worker *worker)

{

	struct worker_pool *pool = worker->pool;

	struct completion *detach_completion = NULL;



	mutex_lock(&wq_pool_attach_mutex);



	list_del(&worker->node);

	worker->pool = NULL;



	if (list_empty(&pool->workers))

		detach_completion = pool->detach_completion;

	mutex_unlock(&wq_pool_attach_mutex);
@@ -1799,7 +1802,6 @@ static struct worker *create_worker(struct worker_pool *pool) 
	if (!worker)

		goto fail;



	worker->pool = pool;

	worker->id = id;



	if (pool->cpu >= 0)
@@ -2236,7 +2238,7 @@ woke_up: 


		set_task_comm(worker->task, "kworker/dying");

		ida_simple_remove(&pool->worker_ida, worker->id);

		worker_detach_from_pool(worker, pool);

		worker_detach_from_pool(worker);

		kfree(worker);

		return 0;

	}
@@ -2367,7 +2369,6 @@ repeat: 
		worker_attach_to_pool(rescuer, pool);



		spin_lock_irq(&pool->lock);

		rescuer->pool = pool;



		/*

		 * Slurp in all works issued via this workqueue and
@@ -2417,10 +2418,9 @@ repeat: 
		if (need_more_worker(pool))

			wake_up_worker(pool);



		rescuer->pool = NULL;

		spin_unlock_irq(&pool->lock);



		worker_detach_from_pool(rescuer, pool);

		worker_detach_from_pool(rescuer);



		spin_lock_irq(&wq_mayday_lock);

	}

kernel/workqueue_internal.h

+1 −1
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ struct worker { 
	/* 64 bytes boundary on 64bit, 32 on 32bit */



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

	struct worker_pool	*pool;		/* I: the associated pool */

	struct worker_pool	*pool;		/* A: the associated pool */

						/* L: for rescuers */

	struct list_head	node;		/* A: anchored at pool->workers */

						/* A: runs through worker->node */

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