diff options
| -rw-r--r-- | kernel/workqueue.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index ff97b705f25e..eda756556341 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -7702,13 +7702,14 @@ static void wq_watchdog_timer_fn(struct timer_list *unused) /* * Did we stall? * - * Do a lockless check first. On weakly ordered - * architectures, the lockless check can observe a - * reordering between worklist insert_work() and - * last_progress_ts update from __queue_work(). Since - * __queue_work() is a much hotter path than the timer - * function, we handle false positive here by reading - * last_progress_ts again with pool->lock held. + * Do a lockless check first to do not disturb the system. + * + * Prevent false positives by double checking the timestamp + * under pool->lock. The lock makes sure that the check reads + * an updated pool->last_progress_ts when this CPU saw + * an already updated pool->worklist above. It seems better + * than adding another barrier into __queue_work() which + * is a hotter path. */ if (time_after(now, ts + thresh)) { scoped_guard(raw_spinlock_irqsave, &pool->lock) { |