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workqueue: move pwq_pool_locking outside of get/put_unbound_pool()

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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: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
This commit is contained in:
Tejun Heo 2013-04-01 11:23:32 -07:00
parent 4862125b02
commit a892cacc7f
1 changed files with 22 additions and 14 deletions
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36
kernel/workqueue.c
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@ -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) {