Commit 21e768b4 authored by Bart Van Assche's avatar Bart Van Assche Committed by Jens Axboe

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 1ad43c00 ("blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed")
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c2e82a23
...@@ -337,12 +337,14 @@ static struct request *blk_mq_get_request(struct request_queue *q, ...@@ -337,12 +337,14 @@ static struct request *blk_mq_get_request(struct request_queue *q,
struct elevator_queue *e = q->elevator; struct elevator_queue *e = q->elevator;
struct request *rq; struct request *rq;
unsigned int tag; unsigned int tag;
struct blk_mq_ctx *local_ctx = NULL; bool put_ctx_on_error = false;
blk_queue_enter_live(q); blk_queue_enter_live(q);
data->q = q; data->q = q;
if (likely(!data->ctx)) if (likely(!data->ctx)) {
data->ctx = local_ctx = blk_mq_get_ctx(q); data->ctx = blk_mq_get_ctx(q);
put_ctx_on_error = true;
}
if (likely(!data->hctx)) if (likely(!data->hctx))
data->hctx = blk_mq_map_queue(q, data->ctx->cpu); data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
if (op & REQ_NOWAIT) if (op & REQ_NOWAIT)
...@@ -361,8 +363,8 @@ static struct request *blk_mq_get_request(struct request_queue *q, ...@@ -361,8 +363,8 @@ static struct request *blk_mq_get_request(struct request_queue *q,
tag = blk_mq_get_tag(data); tag = blk_mq_get_tag(data);
if (tag == BLK_MQ_TAG_FAIL) { if (tag == BLK_MQ_TAG_FAIL) {
if (local_ctx) { if (put_ctx_on_error) {
blk_mq_put_ctx(local_ctx); blk_mq_put_ctx(data->ctx);
data->ctx = NULL; data->ctx = NULL;
} }
blk_queue_exit(q); blk_queue_exit(q);
......
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