workqueue: break out gcwq->lock locking from gcwq_claim/release_management_and_[un...

Releasing management and unlocking gcwq->lock need to be done
separately for the scheduled fix of a subtle idle worker depletion
issue during CPU_ONLINE.  Break out gcwq->lock handling from these
functions.

This patch doesn't introduce any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index dc7b8458e275f73a38278974676c22d1a5c84d2a..63ede1fc00a1d263814610485bb6a72ac29b9af1 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3394,21 +3394,19 @@ EXPORT_SYMBOL_GPL(work_busy);
  */
 
 /* claim manager positions of all pools */
-static void gcwq_claim_management_and_lock(struct global_cwq *gcwq)
+static void gcwq_claim_management(struct global_cwq *gcwq)
 {
        struct worker_pool *pool;
 
        for_each_worker_pool(pool, gcwq)
                mutex_lock_nested(&pool->manager_mutex, pool - gcwq->pools);
-       spin_lock_irq(&gcwq->lock);
 }
 
 /* release manager positions */
-static void gcwq_release_management_and_unlock(struct global_cwq *gcwq)
+static void gcwq_release_management(struct global_cwq *gcwq)
 {
        struct worker_pool *pool;
 
-       spin_unlock_irq(&gcwq->lock);
        for_each_worker_pool(pool, gcwq)
                mutex_unlock(&pool->manager_mutex);
 }
@@ -3423,7 +3421,8 @@ static void gcwq_unbind_fn(struct work_struct *work)
 
        BUG_ON(gcwq->cpu != smp_processor_id());
 
-       gcwq_claim_management_and_lock(gcwq);
+       gcwq_claim_management(gcwq);
+       spin_lock_irq(&gcwq->lock);
 
        /*
         * We've claimed all manager positions.  Make all workers unbound
@@ -3440,7 +3439,8 @@ static void gcwq_unbind_fn(struct work_struct *work)
 
        gcwq->flags |= GCWQ_DISASSOCIATED;
 
-       gcwq_release_management_and_unlock(gcwq);
+       spin_unlock_irq(&gcwq->lock);
+       gcwq_release_management(gcwq);
 
        /*
         * Call schedule() so that we cross rq->lock and thus can guarantee
@@ -3496,10 +3496,12 @@ static int __devinit workqueue_cpu_up_callback(struct notifier_block *nfb,
 
        case CPU_DOWN_FAILED:
        case CPU_ONLINE:
-               gcwq_claim_management_and_lock(gcwq);
+               gcwq_claim_management(gcwq);
+               spin_lock_irq(&gcwq->lock);
                gcwq->flags &= ~GCWQ_DISASSOCIATED;
                rebind_workers(gcwq);
-               gcwq_release_management_and_unlock(gcwq);
+               spin_unlock_irq(&gcwq->lock);
+               gcwq_release_management(gcwq);
                break;
        }
        return NOTIFY_OK;