From 038366c5cf23ae737b9f72169dd8ade2d105755b Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Wed, 6 Feb 2013 18:04:53 -0800 Subject: [PATCH] workqueue: make work_busy() test WORK_STRUCT_PENDING first Currently, work_busy() first tests whether the work has a pool associated with it and if not, considers it idle. This works fine even for delayed_work.work queued on timer, as __queue_delayed_work() sets cwq on delayed_work.work - a queued delayed_work always has its cwq and thus pool associated with it. However, we're about to update delayed_work queueing and this won't hold. Update work_busy() such that it tests WORK_STRUCT_PENDING before the associated pool. This doesn't make any noticeable behavior difference now. With work_pending() test moved, the function read a lot better with "if (!pool)" test flipped to positive. Flip it. While at it, lose the comment about now non-existent reentrant workqueues. tj: Reorganized the function and rewrote the description. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo --- kernel/workqueue.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 7e11334a119f..a229a56f3a32 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3443,8 +3443,6 @@ EXPORT_SYMBOL_GPL(workqueue_congested); * Test whether @work is currently pending or running. There is no * synchronization around this function and the test result is * unreliable and only useful as advisory hints or for debugging. - * Especially for reentrant wqs, the pending state might hide the - * running state. * * RETURNS: * OR'd bitmask of WORK_BUSY_* bits. @@ -3455,17 +3453,15 @@ unsigned int work_busy(struct work_struct *work) unsigned long flags; unsigned int ret = 0; - if (!pool) - return 0; - - spin_lock_irqsave(&pool->lock, flags); - if (work_pending(work)) ret |= WORK_BUSY_PENDING; - if (find_worker_executing_work(pool, work)) - ret |= WORK_BUSY_RUNNING; - spin_unlock_irqrestore(&pool->lock, flags); + if (pool) { + spin_lock_irqsave(&pool->lock, flags); + if (find_worker_executing_work(pool, work)) + ret |= WORK_BUSY_RUNNING; + spin_unlock_irqrestore(&pool->lock, flags); + } return ret; }