BLK_MQ_S_STOPPED may not be observed in other concurrent I/O paths,
we can't guarantee that dispatching won't happen after returning
from the APIs of stopping queue.
So clarify the fact and avoid potential misuse.
Signed-off-by: Ming Lei <ming....@redhat.com>
---
block/blk-mq.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index bcff1b184bbb..352aaaf0bcf9 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1187,6 +1187,11 @@ static void __blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx, bool sync)
set_bit(BLK_MQ_S_STOPPED, &hctx->state);
}
+/*
+ * We do not guarantee that dispatch can be drained or blocked
+ * after blk_mq_stop_hw_queue() returns. Please use
+ * blk_mq_quiesce_queue() for that requirement.
+ */
void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
{
__blk_mq_stop_hw_queue(hctx, false);
@@ -1202,6 +1207,11 @@ static void __blk_mq_stop_hw_queues(struct request_queue
*q, bool sync)
__blk_mq_stop_hw_queue(hctx, sync);
}
+/*
+ * We do not guarantee that dispatch can be drained or blocked
+ * after blk_mq_stop_hw_queues() returns. Please use
+ * blk_mq_quiesce_queue() for that requirement.
+ */
void blk_mq_stop_hw_queues(struct request_queue *q)
{
__blk_mq_stop_hw_queues(q, false);
--
2.9.4
