[PATCH] blk-mq: Fix blk_mq_get_request() error path
From: Bart Van Assche <hidden>
Date: 2017-09-20 18:47:04
Also in:
stable
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
blk_mq_get_tag() can modify data->ctx. This means that in the
error path of blk_mq_get_request() data->ctx should be passed to
blk_mq_put_ctx() instead of local_ctx.
Fixes: commit 1ad43c0078b7 ("blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed")
Signed-off-by: Bart Van Assche <redacted>
Cc: Ming Lei <redacted>
Cc: <redacted> # v4.13+
---
block/blk-mq.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 3f18cff80050..fc20016f8a9a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c@@ -336,12 +336,14 @@ static struct request *blk_mq_get_request(struct request_queue *q, struct elevator_queue *e = q->elevator; struct request *rq; unsigned int tag; - struct blk_mq_ctx *local_ctx = NULL; + bool put_ctx_on_error = false; blk_queue_enter_live(q); data->q = q; - if (likely(!data->ctx)) - data->ctx = local_ctx = blk_mq_get_ctx(q); + if (likely(!data->ctx)) { + data->ctx = blk_mq_get_ctx(q); + put_ctx_on_error = true; + } if (likely(!data->hctx)) data->hctx = blk_mq_map_queue(q, data->ctx->cpu); if (op & REQ_NOWAIT)
@@ -360,8 +362,8 @@ static struct request *blk_mq_get_request(struct request_queue *q, tag = blk_mq_get_tag(data); if (tag == BLK_MQ_TAG_FAIL) { - if (local_ctx) { - blk_mq_put_ctx(local_ctx); + if (put_ctx_on_error) { + blk_mq_put_ctx(data->ctx); data->ctx = NULL; } blk_queue_exit(q);
--
2.14.1