Blk-iolatency: warn on negative inflight IO counter

[ Upstream commit 391f552af213985d3d324c60004475759a7030c5 ] This is to catch any unexpected negative value of inflight IO counter. Signed-off-by: Liu Bo <[email protected]> Signed-off-by: Jens Axboe <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
akeromi · Sep 16, 2019 · 5f33e81 · 5f33e81
1 parent 91a71a6
commit 5f33e81
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
@@ -560,6 +560,7 @@ static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio)
 	u64 now = ktime_to_ns(ktime_get());
 	bool issue_as_root = bio_issue_as_root_blkg(bio);
 	bool enabled = false;
+	int inflight = 0;
 
 	blkg = bio->bi_blkg;
 	if (!blkg)
@@ -585,7 +586,8 @@ static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio)
 		}
 		rqw = &iolat->rq_wait;
 
-		atomic_dec(&rqw->inflight);
+		inflight = atomic_dec_return(&rqw->inflight);
+		WARN_ON_ONCE(inflight < 0);
 		if (iolat->min_lat_nsec == 0)
 			goto next;
 		iolatency_record_time(iolat, &bio->bi_issue, now,