block: do not put mq context in blk_mq_alloc_request_hctx

In blk_mq_alloc_request_hctx, blk_mq_sched_get_request doesn't get sw context so we don't need to put the context with blk_mq_put_ctx. Unless, we will see preempt counter underflow.

---

Maybe, it would be fixed by someone but I have noticed preempt counter undeflow problem a few weeks ago and still see the problem with linux-next.

 block/blk-mq.c | 1 -
 1 file changed, 1 deletion(-)

index a4546f060e80..a6f3998dc4ee 100644
@@ -321,7 +321,6 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
 
 	rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
 
-	blk_mq_put_ctx(alloc_data.ctx);
 	blk_queue_exit(q);
 
 	if (!rq)

2.7.4

Looks good,

Good catch, that's definitely a bug. I have applied your patch for 4.11.

Jens Axboe