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 <bart.vanassche@xxxxxxxxxxx>
---
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
--
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