diff options
Diffstat (limited to 'kernel/workqueue.c')
| -rw-r--r-- | kernel/workqueue.c | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 85bd3409b9f5..b394df8beaee 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1048,16 +1048,14 @@ static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color, * for arbitrarily long * * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting - * preempted while holding PENDING and @work off queue, preemption must be - * disabled on entry. This ensures that we don't return -EAGAIN while - * another task is preempted in this function. + * interrupted while holding PENDING and @work off queue, irq must be + * disabled on entry. This, combined with delayed_work->timer being + * irqsafe, ensures that we return -EAGAIN for finite short period of time. * * On successful return, >= 0, irq is disabled and the caller is * responsible for releasing it using local_irq_restore(*@flags). * - * This function is safe to call from any context other than IRQ handler. - * An IRQ handler may run on top of delayed_work_timer_fn() which can make - * this function return -EAGAIN perpetually. + * This function is safe to call from any context including IRQ handler. */ static int try_to_grab_pending(struct work_struct *work, bool is_dwork, unsigned long *flags) @@ -1072,6 +1070,11 @@ static int try_to_grab_pending(struct work_struct *work, bool is_dwork, if (is_dwork) { struct delayed_work *dwork = to_delayed_work(work); + /* + * dwork->timer is irqsafe. If del_timer() fails, it's + * guaranteed that the timer is not queued anywhere and not + * running on the local CPU. + */ if (likely(del_timer(&dwork->timer))) return 1; } @@ -1327,9 +1330,8 @@ void delayed_work_timer_fn(unsigned long __data) struct delayed_work *dwork = (struct delayed_work *)__data; struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); - local_irq_disable(); + /* should have been called from irqsafe timer with irq already off */ __queue_work(dwork->cpu, cwq->wq, &dwork->work); - local_irq_enable(); } EXPORT_SYMBOL_GPL(delayed_work_timer_fn); @@ -1444,7 +1446,7 @@ EXPORT_SYMBOL_GPL(queue_delayed_work); * Returns %false if @dwork was idle and queued, %true if @dwork was * pending and its timer was modified. * - * This function is safe to call from any context other than IRQ handler. + * This function is safe to call from any context including IRQ handler. * See try_to_grab_pending() for details. */ bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, |
