blk-mq: Document locking assumptions (7b607814) · Commits · 戴 / test

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>

block/blk-mq-sched.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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;

block/blk-mq.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -1317,6 +1317,8 @@ 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)
		@@ -1330,6 +1332,8 @@ 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);
		}

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