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authorBart Van Assche <bart.vanassche@wdc.com>2017-10-16 16:32:26 -0700
committerJens Axboe <axboe@kernel.dk>2017-11-03 12:33:56 -0600
commit21e768b442bb587123ea924620e74d6e5655d717 (patch)
tree85982dcf7d7e98c8e22f5f0addc32796273f536c /block
parentc2e82a234873d905260a3bd0aca9577e85619bda (diff)
downloadlinux-stericsson-21e768b442bb587123ea924620e74d6e5655d717.tar.gz
blk-mq: Make blk_mq_get_request() error path less confusing
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. Note: since blk_mq_put_ctx() ignores its argument, this patch does not change any functionality. References: commit 1ad43c0078b7 ("blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed") Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Cc: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9eea67ce82d9..13cdccef543c 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -337,12 +337,14 @@ 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)
@@ -361,8 +363,8 @@ 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);