[PATCH V2] blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed
From: Ming Lei <hidden>
Date: 2017-08-02 00:01:56
From: Ming Lei <redacted>
When blk_mq_get_request() failed, preempt counter isn't
released, and blk_mq_make_request() doesn't release the counter
too.
This patch fixes the issue, and makes sure that preempt counter
is only held if rq is allocated successfully. The same policy is
applied on .q_usage_counter too.
Signed-off-by: Ming Lei <redacted>
---
V2: use local_ctx, and clear data->ctx if allocation fails, as
suggested by Jens.
block/blk-mq.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 041f7b7fa0d6..211ef367345f 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c@@ -301,11 +301,12 @@ 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; blk_queue_enter_live(q); data->q = q; if (likely(!data->ctx)) - data->ctx = blk_mq_get_ctx(q); + data->ctx = local_ctx = blk_mq_get_ctx(q); if (likely(!data->hctx)) data->hctx = blk_mq_map_queue(q, data->ctx->cpu); if (op & REQ_NOWAIT)
@@ -324,6 +325,10 @@ 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); + data->ctx = NULL; + } blk_queue_exit(q); return NULL; }
@@ -356,12 +361,12 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op, rq = blk_mq_get_request(q, NULL, op, &alloc_data); - blk_mq_put_ctx(alloc_data.ctx); - 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; rq->bio = rq->biotail = NULL;
@@ -407,11 +412,11 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, 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);
--
2.9.4