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Commit 7cda9aae authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Tejun Heo
Browse files

workqueue: convert worker_idr to worker_ida 



We no longer iterate workers via worker_idr and worker_idr is used
only for allocating/freeing ID, so we can convert it to worker_ida.

By using ida_simple_get/remove(), worker_ida doesn't require external
synchronization, so we don't need manager_mutex to protect it and the
ID-removal code is allowed to be moved out from
worker_detach_from_pool().

In a later patch, worker_detach_from_pool() will be used in rescuers
which don't have IDs, so we move the ID-removal code out from
worker_detach_from_pool() into worker_thread().

tj: Minor description updates.

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent da028469

kernel/workqueue.c

+8 −12
Original line number Diff line number Diff line
@@ -161,10 +161,11 @@ struct worker_pool { 
	/* see manage_workers() for details on the two manager mutexes */

	struct mutex		manager_arb;	/* manager arbitration */

	struct mutex		manager_mutex;	/* manager exclusion */

	struct idr		worker_idr;	/* M: worker IDs */

	struct list_head	workers;	/* M: attached workers */

	struct completion	*detach_completion; /* all workers detached */



	struct ida		worker_ida;	/* worker IDs for task name */



	struct workqueue_attrs	*attrs;		/* I: worker attributes */

	struct hlist_node	hash_node;	/* PL: unbound_pool_hash node */

	int			refcnt;		/* PL: refcnt for unbound pools */
@@ -1696,7 +1697,6 @@ static void worker_detach_from_pool(struct worker *worker, 
	struct completion *detach_completion = NULL;



	mutex_lock(&pool->manager_mutex);

	idr_remove(&pool->worker_idr, worker->id);

	list_del(&worker->node);

	if (list_empty(&pool->workers))

		detach_completion = pool->detach_completion;
@@ -1727,11 +1727,8 @@ static struct worker *create_worker(struct worker_pool *pool) 


	lockdep_assert_held(&pool->manager_mutex);



	/*

	 * ID is needed to determine kthread name.  Allocate ID first

	 * without installing the pointer.

	 */

	id = idr_alloc(&pool->worker_idr, NULL, 0, 0, GFP_KERNEL);

	/* ID is needed to determine kthread name */

	id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL);

	if (id < 0)

		goto fail;
@@ -1772,8 +1769,6 @@ static struct worker *create_worker(struct worker_pool *pool) 
	if (pool->flags & POOL_DISASSOCIATED)

		worker->flags |= WORKER_UNBOUND;



	/* successful, commit the pointer to idr */

	idr_replace(&pool->worker_idr, worker, worker->id);

	/* successful, attach the worker to the pool */

	list_add_tail(&worker->node, &pool->workers);
@@ -1781,7 +1776,7 @@ static struct worker *create_worker(struct worker_pool *pool) 


fail:

	if (id >= 0)

		idr_remove(&pool->worker_idr, id);

		ida_simple_remove(&pool->worker_ida, id);

	kfree(worker);

	return NULL;

}
@@ -2250,6 +2245,7 @@ woke_up: 
		worker->task->flags &= ~PF_WQ_WORKER;



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

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

		worker_detach_from_pool(worker, pool);

		kfree(worker);

		return 0;
@@ -3486,9 +3482,9 @@ static int init_worker_pool(struct worker_pool *pool) 


	mutex_init(&pool->manager_arb);

	mutex_init(&pool->manager_mutex);

	idr_init(&pool->worker_idr);

	INIT_LIST_HEAD(&pool->workers);



	ida_init(&pool->worker_ida);

	INIT_HLIST_NODE(&pool->hash_node);

	pool->refcnt = 1;
@@ -3503,7 +3499,7 @@ static void rcu_free_pool(struct rcu_head *rcu) 
{

	struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu);



	idr_destroy(&pool->worker_idr);

	ida_destroy(&pool->worker_ida);

	free_workqueue_attrs(pool->attrs);

	kfree(pool);

}