From: Jens Axboe <axboe@fb.com>
Date: Thu, 20 Apr 2017 23:23:13 +0000 (-0600)
Subject: blk-mq: add might_sleep check to blk_mq_get_driver_tag()
X-Git-Tag: v4.12-rc1~175^2~21
X-Git-Url: https://git.kernelconcepts.de/?p=karo-tx-linux.git;a=commitdiff_plain;h=5feeacdd4a75bc6e5c6c613ae09ef07bc5dfd05a

blk-mq: add might_sleep check to blk_mq_get_driver_tag()

If the caller passes in wait=true, it has to be able to block
for a driver tag. We just had a bug where flush insertion
would block on tag allocation, while we had preempt disabled.
Ensure that we catch cases like that earlier next time.

Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/block/blk-mq.c b/block/blk-mq.c
index b6dc9ba38e35..fa7d86f59687 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -864,6 +864,8 @@ bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
 		.flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
 	};
 
+	might_sleep_if(wait);
+
 	if (rq->tag != -1)
 		goto done;