kthread_work: wake up worker only when the worker is idle
If the worker is already executing a work item when another is queued,
we can safely skip wakeup without worrying about stalling queue thus
avoiding waking up the busy worker spuriously. Spurious wakeups
should be fine but still isn't nice and avoiding it is trivial here.
tj: Updated description.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/kernel/kthread.c b/kernel/kthread.c
index c2390f4..ef48322 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -591,7 +591,7 @@
list_add_tail(&work->node, pos);
work->worker = worker;
- if (likely(worker->task))
+ if (!worker->current_work && likely(worker->task))
wake_up_process(worker->task);
}