Now rescuer checks pwq->nr_active before requeues the pwq, it is a more robust check and the rescuer must be still valid.
Signed-off-by: Lai Jiangshan <[email protected]> --- kernel/workqueue.c | 23 +++++++++-------------- 1 file changed, 9 insertions(+), 14 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index b2b15f1f0c8d..8d017727bfbc 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -248,7 +248,7 @@ struct workqueue_struct { struct list_head flusher_overflow; /* WQ: flush overflow list */ struct list_head maydays; /* MD: pwqs requesting rescue */ - struct worker *rescuer; /* MD: rescue worker */ + struct worker *rescuer; /* I: rescue worker */ int nr_drainers; /* WQ: drain in progress */ int saved_max_active; /* WQ: saved pwq max_active */ @@ -2532,12 +2532,13 @@ static int rescuer_thread(void *__rescuer) if (pwq->nr_active && need_to_create_worker(pool)) { spin_lock(&wq_mayday_lock); /* - * Queue iff we aren't racing destruction - * and somebody else hasn't queued it already. + * Queue iff somebody else hasn't queued it + * already. */ - if (wq->rescuer && list_empty(&pwq->mayday_node)) { + if (list_empty(&pwq->mayday_node)) { get_pwq(pwq); - list_add_tail(&pwq->mayday_node, &wq->maydays); + list_add_tail(&pwq->mayday_node, + &wq->maydays); } spin_unlock(&wq_mayday_lock); } @@ -4356,16 +4357,10 @@ void destroy_workqueue(struct workqueue_struct *wq) /* kill rescuer, if sanity checks fail, leave it w/o rescuer */ if (wq->rescuer) { - struct worker *rescuer = wq->rescuer; - - /* this prevents new queueing */ - spin_lock_irq(&wq_mayday_lock); - wq->rescuer = NULL; - spin_unlock_irq(&wq_mayday_lock); - /* rescuer will empty maydays list before exiting */ - kthread_stop(rescuer->task); - kfree(rescuer); + kthread_stop(wq->rescuer->task); + kfree(wq->rescuer); + wq->rescuer = NULL; } /* -- 2.20.1
