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workqueue: Change the comments of the synchronization about the idle_list

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The access to idle_list in wq_worker_sleeping() is changed to be
protected by pool->lock, so the comments above idle_list can be changed
to "L:" which is the meaning of "access with pool->lock held".

And the outdated comments in wq_worker_sleeping() is removed since
the function is not called with rq lock held any more, idle_list is
dereferenced with pool lock now.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Lai Jiangshan 2021-12-23 20:31:38 +08:00 committed by Tejun Heo
parent 21b195c05c
commit 2c1f1a9180
1 changed files with 2 additions and 9 deletions
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11
kernel/workqueue.c
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@ -162,7 +162,7 @@ struct worker_pool {
int nr_workers; /* L: total number of workers */
int nr_idle; /* L: currently idle workers */
struct list_head idle_list; /* X: list of idle workers */
struct list_head idle_list; /* L: list of idle workers */
struct timer_list idle_timer; /* L: worker idle timeout */
struct timer_list mayday_timer; /* L: SOS timer for workers */
@ -826,7 +826,7 @@ static bool too_many_workers(struct worker_pool *pool)
* Wake up functions.
*/
/* Return the first idle worker. Safe with preemption disabled */
/* Return the first idle worker. Called with pool->lock held. */
static struct worker *first_idle_worker(struct worker_pool *pool)
{
if (unlikely(list_empty(&pool->idle_list)))
@ -917,13 +917,6 @@ void wq_worker_sleeping(struct task_struct *task)
return;
}
/*
* NOT_RUNNING is clear. This means that we're bound to and
* running on the local cpu w/ rq lock held and preemption
* disabled, which in turn means that none else could be
* manipulating idle_list, so dereferencing idle_list without pool
* lock is safe.
*/
if (atomic_dec_and_test(&pool->nr_running) &&
!list_empty(&pool->worklist)) {
next = first_idle_worker(pool);