From a892cacc7f4960a39c0fad7bbdf04c5cbf7c229e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 1 Apr 2013 11:23:32 -0700 Subject: [PATCH] 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: Tejun Heo Reviewed-by: Lai Jiangshan --- kernel/workqueue.c | 36 ++++++++++++++++++++++-------------- 1 file changed, 22 insertions(+), 14 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 89480fc..2bf3d8c 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -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) { -- 2.7.4