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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>
This commit is contained in:
Bart Van Assche 2017-06-20 11:15:47 -07:00 committed by Jens Axboe
parent 332ebbf7f9
commit 7b6078146c
2 changed files with 6 additions and 0 deletions
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2
block/blk-mq-sched.c
View File

@ -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;

4
block/blk-mq.c
View File

@ -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);
}