[v2,09/12] blk-mq: Document locking assumptions
diff mbox

Message ID 20170531225246.26261-10-bart.vanassche@sandisk.com
State New
Headers show

Commit Message

Bart Van Assche May 31, 2017, 10:52 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-sched.c | 2 ++
 block/blk-mq.c       | 4 ++++
 2 files changed, 6 insertions(+)

Comments

Christoph Hellwig June 1, 2017, 6:11 a.m. UTC | #1
On Wed, May 31, 2017 at 03:52:43PM -0700, Bart Van Assche wrote:
> 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>

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

Patch
diff mbox

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index c4e2afb9d12d..88aa460b2e8a 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -232,6 +232,8 @@  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;
 
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 488c6ca2ad91..b56cb3d9060f 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1274,6 +1274,8 @@  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)
@@ -1287,6 +1289,8 @@  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);
 }