From 24f5a90f0d13a97b51aa79f468143fafea4246bb Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sat, 6 Jan 2018 16:27:38 +0800 Subject: blk-mq: quiesce queue during switching io sched and updating nr_requests Dispatch may still be in-progress after queue is frozen, so we have to quiesce queue before switching IO scheduler and updating nr_requests. Also when switching io schedulers, blk_mq_run_hw_queue() may still be called somewhere(such as from nvme_reset_work()), and io scheduler's per-hctx data may not be setup yet, so cause oops even inside blk_mq_hctx_has_pending(), such as it can be run just between: ret = e->ops.mq.init_sched(q, e); AND ret = e->ops.mq.init_hctx(hctx, i) inside blk_mq_init_sched(). This reverts commit 7a148c2fcff8330(block: don't call blk_mq_quiesce_queue() after queue is frozen) basically, and makes sure blk_mq_hctx_has_pending won't be called if queue is quiesced. Reviewed-by: Christoph Hellwig Fixes: 7a148c2fcff83309(block: don't call blk_mq_quiesce_queue() after queue is frozen) Reported-by: Yi Zhang Tested-by: Yi Zhang Signed-off-by: Ming Lei Signed-off-by: Jens Axboe --- block/elevator.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'block/elevator.c') diff --git a/block/elevator.c b/block/elevator.c index 7bda083d59684..138faeb08a7c3 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -968,6 +968,7 @@ static int elevator_switch_mq(struct request_queue *q, int ret; blk_mq_freeze_queue(q); + blk_mq_quiesce_queue(q); if (q->elevator) { if (q->elevator->registered) @@ -994,6 +995,7 @@ static int elevator_switch_mq(struct request_queue *q, blk_add_trace_msg(q, "elv switch: none"); out: + blk_mq_unquiesce_queue(q); blk_mq_unfreeze_queue(q); return ret; } -- cgit v1.2.3