From: Yu Kuai <yukuai3@huawei.com>
Date: Thu, 5 Aug 2021 12:46:45 +0000 (+0800)
Subject: blk-iolatency: error out if blk_get_queue() failed in iolatency_set_limit()
X-Git-Tag: v5.15~504^2~13
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8d75d0eff6887bcac7225e12b9c75595e523d92d;p=platform%2Fkernel%2Flinux-starfive.git

blk-iolatency: error out if blk_get_queue() failed in iolatency_set_limit()

If queue is dying while iolatency_set_limit() is in progress,
blk_get_queue() won't increment the refcount of the queue. However,
blk_put_queue() will still decrement the refcount later, which will
cause the refcout to be unbalanced.

Thus error out in such case to fix the problem.

Fixes: 8c772a9bfc7c ("blk-iolatency: fix IO hang due to negative inflight counter")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20210805124645.543797-1-yukuai3@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index 81be009..d8b0d8b 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -833,7 +833,11 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf,
 
 	enable = iolatency_set_min_lat_nsec(blkg, lat_val);
 	if (enable) {
-		WARN_ON_ONCE(!blk_get_queue(blkg->q));
+		if (!blk_get_queue(blkg->q)) {
+			ret = -ENODEV;
+			goto out;
+		}
+
 		blkg_get(blkg);
 	}