Ensure that all ongoing dm_mq_queue_rq() and dm_mq_requeue_request() calls have stopped before setting the "queue stopped" flag. This allows to remove the "queue stopped" test from dm_mq_queue_rq() and dm_mq_requeue_request(). Use BLK_MQ_S_STOPPED instead of QUEUE_FLAG_STOPPED.
Signed-off-by: Bart Van Assche <[email protected]> --- drivers/md/dm-rq.c | 29 +++++++---------------------- 1 file changed, 7 insertions(+), 22 deletions(-) diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 8dc8cfb..b5db523 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -78,7 +78,6 @@ void dm_start_queue(struct request_queue *q) if (!q->mq_ops) dm_old_start_queue(q); else { - queue_flag_clear_unlocked(QUEUE_FLAG_STOPPED, q); blk_mq_start_stopped_hw_queues(q, true); blk_mq_kick_requeue_list(q); } @@ -98,13 +97,13 @@ void dm_stop_queue(struct request_queue *q) { if (!q->mq_ops) dm_old_stop_queue(q); - else { - spin_lock_irq(q->queue_lock); - queue_flag_set(QUEUE_FLAG_STOPPED, q); - spin_unlock_irq(q->queue_lock); - + else if (!blk_mq_queue_stopped(q)) { + /* Wait until dm_mq_queue_rq() has finished. */ + blk_mq_freeze_queue(q); + /* Avoid that requeuing could restart the queue. */ blk_mq_cancel_requeue_work(q); blk_mq_stop_hw_queues(q); + blk_mq_unfreeze_queue(q); } } @@ -318,13 +317,10 @@ static void dm_old_requeue_request(struct request *rq) static void dm_mq_requeue_request(struct request *rq) { struct request_queue *q = rq->q; - unsigned long flags; blk_mq_requeue_request(rq); - spin_lock_irqsave(q->queue_lock, flags); - if (!blk_queue_stopped(q)) - blk_mq_kick_requeue_list(q); - spin_unlock_irqrestore(q->queue_lock, flags); + WARN_ON_ONCE(blk_mq_queue_stopped(q)); + blk_mq_kick_requeue_list(q); } static void dm_requeue_original_request(struct mapped_device *md, @@ -867,17 +863,6 @@ static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx, dm_put_live_table(md, srcu_idx); } - /* - * On suspend dm_stop_queue() handles stopping the blk-mq - * request_queue BUT: even though the hw_queues are marked - * BLK_MQ_S_STOPPED at that point there is still a race that - * is allowing block/blk-mq.c to call ->queue_rq against a - * hctx that it really shouldn't. The following check guards - * against this rarity (albeit _not_ race-free). - */ - if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state))) - return BLK_MQ_RQ_QUEUE_BUSY; - if (ti->type->busy && ti->type->busy(ti)) return BLK_MQ_RQ_QUEUE_BUSY; -- 2.9.3 -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
