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authorTejun Heo <tj@kernel.org>2010-10-11 11:51:57 +0200
committerTejun Heo <tj@kernel.org>2010-10-11 12:09:30 +0200
commit30310045dd20a286cf3800f063f79b468e132fb1 (patch)
tree535dd3273332f18b245afd6a4142fcc49ada8e61 /kernel/workqueue.c
parentcdadf0097cdca06c497ffaeb5982e028c6e4ed38 (diff)
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workqueue: fix HIGHPRI handling in keep_working()
The policy function keep_working() didn't check GCWQ_HIGHPRI_PENDING and could return %false with highpri work pending. This could lead to late execution of a highpri work which was delayed due to @max_active throttling if other works are actively consuming CPU cycles. For example, the following could happen. 1. Work W0 which burns CPU cycles. 2. Two works W1 and W2 are queued to a highpri wq w/ @max_active of 1. 3. W1 starts executing and W2 is put to delayed queue. W0 and W1 are both runnable. 4. W1 finishes which puts W2 to pending queue but keep_working() incorrectly returns %false and the worker goes to sleep. 5. W0 finishes and W2 starts execution. With this patch applied, W2 starts execution as soon as W1 finishes. Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/workqueue.c')
-rw-r--r--kernel/workqueue.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index cb2ccfbed0c6..b57a8babdec3 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -604,7 +604,9 @@ static bool keep_working(struct global_cwq *gcwq)
{
atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
- return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1;
+ return !list_empty(&gcwq->worklist) &&
+ (atomic_read(nr_running) <= 1 ||
+ gcwq->flags & GCWQ_HIGHPRI_PENDING);
}
/* Do we need a new worker? Called from manager. */