blk-mq: Fix queue usage on failed request allocation

blk_mq_get_request() does not release the callers queue usage counter when allocation fails. The caller still needs to account for its own queue usage when it is unable to allocate a request. Fixes: 1ad43c0 ("blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed") Reported-by: Max Gurtovoy <[email protected]> Reviewed-by: Ming Lei <[email protected]> Reviewed-by: Sagi Grimberg <[email protected]> Tested-by: Max Gurtovoy <[email protected]> Signed-off-by: Keith Busch <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
cail · Aug 15, 2017 · 3280d66 · 3280d66
1 parent ef95484
commit 3280d66
Showing 1 changed file with 2 additions and 3 deletions.
diff --git a/block/blk-mq.c b/block/blk-mq.c
@@ -360,12 +360,12 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
 		return ERR_PTR(ret);
 
 	rq = blk_mq_get_request(q, NULL, op, &alloc_data);
+	blk_queue_exit(q);
 
 	if (!rq)
 		return ERR_PTR(-EWOULDBLOCK);
 
 	blk_mq_put_ctx(alloc_data.ctx);
-	blk_queue_exit(q);
 
 	rq->__data_len = 0;
 	rq->__sector = (sector_t) -1;
@@ -411,12 +411,11 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
 	alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
 
 	rq = blk_mq_get_request(q, NULL, op, &alloc_data);
+	blk_queue_exit(q);
 
 	if (!rq)
 		return ERR_PTR(-EWOULDBLOCK);
 
-	blk_queue_exit(q);
-
 	return rq;
 }
 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);