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Commit a892cacc authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: move pwq_pool_locking outside of get/put_unbound_pool() 



The scheduled NUMA affinity support for unbound workqueues would need
to walk workqueues list and pool related operations on each workqueue.

Move wq_pool_mutex locking out of get/put_unbound_pool() to their
callers so that pool operations can be performed while walking the
workqueues list, which is also protected by wq_pool_mutex.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
parent 4862125b

kernel/workqueue.c

+22 −14
Original line number Diff line number Diff line
@@ -3395,31 +3395,28 @@ static void rcu_free_pool(struct rcu_head *rcu) 
 * safe manner.  get_unbound_pool() calls this function on its failure path

 * and this function should be able to release pools which went through,

 * successfully or not, init_worker_pool().

 *

 * Should be called with wq_pool_mutex held.

 */

static void put_unbound_pool(struct worker_pool *pool)

{

	struct worker *worker;



	mutex_lock(&wq_pool_mutex);

	if (--pool->refcnt) {

		mutex_unlock(&wq_pool_mutex);

	lockdep_assert_held(&wq_pool_mutex);



	if (--pool->refcnt)

		return;

	}



	/* sanity checks */

	if (WARN_ON(!(pool->flags & POOL_DISASSOCIATED)) ||

	    WARN_ON(!list_empty(&pool->worklist))) {

		mutex_unlock(&wq_pool_mutex);

	    WARN_ON(!list_empty(&pool->worklist)))

		return;

	}



	/* release id and unhash */

	if (pool->id >= 0)

		idr_remove(&worker_pool_idr, pool->id);

	hash_del(&pool->hash_node);



	mutex_unlock(&wq_pool_mutex);



	/*

	 * Become the manager and destroy all workers.  Grabbing

	 * manager_arb prevents @pool's workers from blocking on
@@ -3453,13 +3450,15 @@ static void put_unbound_pool(struct worker_pool *pool) 
 * reference count and return it.  If there already is a matching

 * worker_pool, it will be used; otherwise, this function attempts to

 * create a new one.  On failure, returns NULL.

 *

 * Should be called with wq_pool_mutex held.

 */

static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs)

{

	u32 hash = wqattrs_hash(attrs);

	struct worker_pool *pool;



	mutex_lock(&wq_pool_mutex);

	lockdep_assert_held(&wq_pool_mutex);



	/* do we already have a matching pool? */

	hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) {
@@ -3490,10 +3489,8 @@ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) 
	/* install */

	hash_add(unbound_pool_hash, &pool->hash_node, hash);

out_unlock:

	mutex_unlock(&wq_pool_mutex);

	return pool;

fail:

	mutex_unlock(&wq_pool_mutex);

	if (pool)

		put_unbound_pool(pool);

	return NULL;
@@ -3530,7 +3527,10 @@ static void pwq_unbound_release_workfn(struct work_struct *work) 
	is_last = list_empty(&wq->pwqs);

	mutex_unlock(&wq->mutex);



	mutex_lock(&wq_pool_mutex);

	put_unbound_pool(pool);

	mutex_unlock(&wq_pool_mutex);



	call_rcu_sched(&pwq->rcu, rcu_free_pwq);



	/*
@@ -3654,13 +3654,21 @@ int apply_workqueue_attrs(struct workqueue_struct *wq, 
	copy_workqueue_attrs(new_attrs, attrs);

	cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);



	mutex_lock(&wq_pool_mutex);



	pwq = kmem_cache_zalloc(pwq_cache, GFP_KERNEL);

	if (!pwq)

	if (!pwq) {

		mutex_unlock(&wq_pool_mutex);

		goto enomem;

	}



	pool = get_unbound_pool(new_attrs);

	if (!pool)

	if (!pool) {

		mutex_unlock(&wq_pool_mutex);

		goto enomem;

	}



	mutex_unlock(&wq_pool_mutex);



	init_and_link_pwq(pwq, wq, pool, &last_pwq);

	if (last_pwq) {