Commit 419c21a3 authored Jun 02, 2015 by Akinobu Mita Committed by Jens Axboe Jun 01, 2015

null_blk: prevent timer handler running on a different CPU where started



When irqmode=2 (IRQ completion handler is timer), timer handler should
be called on the same CPU where the timer has been started.

Since completion_queues are per-cpu and the completion handler only
touches completion_queue for local CPU, we need to prevent the handler
from running on a different CPU where the timer has been started.
Otherwise, the IO cannot be completed until another completion handler
is executed on that CPU.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

parent 42483228

drivers/block/null_blk.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -257,7 +257,7 @@ static void null_cmd_end_timer(struct nullb_cmd *cmd)
		if (llist_add(&cmd->ll_list, &cq->list)) {
		ktime_t kt = ktime_set(0, completion_nsec);

		hrtimer_start(&cq->timer, kt, HRTIMER_MODE_REL);
		hrtimer_start(&cq->timer, kt, HRTIMER_MODE_REL_PINNED);
		}

		put_cpu();