From cf96a6c88c48687a85c81fbbb37e68db678cae81 Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Sat, 13 Aug 2016 07:45:12 -0400 Subject: [PATCH] dm rq: fix the starting and stopping of blk-mq queues Orabug: 25308141 [ Upstream commit 7d9595d848cdff5c7939f68eec39e0c5d36a1d67 ] Improve dm_stop_queue() to cancel any requeue_work. Also, have dm_start_queue() and dm_stop_queue() clear/set the QUEUE_FLAG_STOPPED for the blk-mq request_queue. 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. Add a check to dm_mq_queue_rq() that guards against this rarity (albeit _not_ race-free). Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org # must patch dm.c on < 4.8 kernels Signed-off-by: Sasha Levin (cherry picked from commit 655fe78746d0b9141fe763535fc16d6652665c13) Signed-off-by: Dhaval Giani --- drivers/md/dm.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 848d85339271..8594a0992e6a 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1200,8 +1200,14 @@ static void stop_queue(struct request_queue *q) { if (!q->mq_ops) old_stop_queue(q); - else + else { + spin_lock_irq(q->queue_lock); + queue_flag_set(QUEUE_FLAG_STOPPED, q); + spin_unlock_irq(q->queue_lock); + + blk_mq_cancel_requeue_work(q); blk_mq_stop_hw_queues(q); + } } static void old_start_queue(struct request_queue *q) @@ -1218,8 +1224,10 @@ static void start_queue(struct request_queue *q) { if (!q->mq_ops) old_start_queue(q); - else + else { + queue_flag_clear_unlocked(QUEUE_FLAG_STOPPED, q); blk_mq_start_stopped_hw_queues(q, true); + } } static void dm_done(struct request *clone, int error, bool mapped) @@ -2731,6 +2739,17 @@ 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; -- 2.50.1