[17/19] blk-mq: Document locking assumptions
diff mbox

Message ID 20170525184327.23570-18-bart.vanassche@sandisk.com
State New
Headers show

Commit Message

Bart Van Assche May 25, 2017, 6:43 p.m. UTC
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>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
---
 block/blk-mq.c | 6 ++++++
 1 file changed, 6 insertions(+)

Patch
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diff --git a/block/blk-mq.c b/block/blk-mq.c
index b230038eba1d..4b1b2c7b4344 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -785,6 +785,8 @@  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;
 
@@ -1338,6 +1340,8 @@  static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
 {
 	struct blk_mq_ctx *ctx = rq->mq_ctx;
 
+	lockdep_assert_held(&ctx->lock);
+
 	trace_block_rq_insert(hctx->queue, rq);
 
 	if (at_head)
@@ -1351,6 +1355,8 @@  void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 {
 	struct blk_mq_ctx *ctx = rq->mq_ctx;
 
+	lockdep_assert_held(&ctx->lock);
+
 	__blk_mq_insert_req_list(hctx, rq, at_head);
 	blk_mq_hctx_mark_pending(hctx, ctx);
 }