blk-mq: Document locking assumptions
Document the locking assumptions in functions that modify
blk_mq_ctx.rq_list to make it easier for humans to verify
this code.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 9f02528..191bf82 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -150,6 +150,8 @@ static bool blk_mq_attempt_merge(struct request_queue *q,
struct request *rq;
int checked = 8;
+ lockdep_assert_held(&ctx->lock);
+
list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
bool merged = false;