dm: fix a couple locking issues with use of block interfaces

old_stop_queue() was checking blk_queue_stopped() without holding the
q->queue_lock.

dm_requeue_original_request() needed to check blk_queue_stopped(), with
q->queue_lock held, before calling blk_mq_kick_requeue_list().  And a
side-effect of that change is start_queue() must also call
blk_mq_kick_requeue_list().

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index e9035959f9049a72ff16c91dc62c4730460cfabd..8a62e43fbff505e78fa30cc9c2789469e1c6e7fe 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1215,6 +1215,18 @@ static void old_requeue_request(struct request *rq)
        spin_unlock_irqrestore(q->queue_lock, flags);
 }
 
+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);
+}
+
 static void dm_requeue_original_request(struct mapped_device *md,
                                        struct request *rq)
 {
@@ -1225,10 +1237,8 @@ static void dm_requeue_original_request(struct mapped_device *md,
        rq_end_stats(md, rq);
        if (!rq->q->mq_ops)
                old_requeue_request(rq);
-       else {
-               blk_mq_requeue_request(rq);
-               blk_mq_kick_requeue_list(rq->q);
-       }
+       else
+               dm_mq_requeue_request(rq);
 
        rq_completed(md, rw, false);
 }
@@ -1237,10 +1247,12 @@ static void old_stop_queue(struct request_queue *q)
 {
        unsigned long flags;
 
-       if (blk_queue_stopped(q))
+       spin_lock_irqsave(q->queue_lock, flags);
+       if (blk_queue_stopped(q)) {
+               spin_unlock_irqrestore(q->queue_lock, flags);
                return;
+       }
 
-       spin_lock_irqsave(q->queue_lock, flags);
        blk_stop_queue(q);
        spin_unlock_irqrestore(q->queue_lock, flags);
 }
@@ -1267,8 +1279,10 @@ static void start_queue(struct request_queue *q)
 {
        if (!q->mq_ops)
                old_start_queue(q);
-       else
+       else {
                blk_mq_start_stopped_hw_queues(q, true);
+               blk_mq_kick_requeue_list(q);
+       }
 }
 
 static void dm_done(struct request *clone, int error, bool mapped)