From 580c10a40cc76a206e18c424a114195160a69ddd Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Thu, 5 Aug 2021 20:46:45 +0800 Subject: [PATCH] blk-iolatency: error out if blk_get_queue() failed in iolatency_set_limit() [ Upstream commit 8d75d0eff6887bcac7225e12b9c75595e523d92d ] 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 Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20210805124645.543797-1-yukuai3@huawei.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-iolatency.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index c128d50cb410..71a82528d4bf 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -832,7 +832,11 @@ 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); }