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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, gi-oh.kim@ionos.com,
        Md Haris Iqbal <haris.iqbal@ionos.com>,
        Jack Wang <jinpu.wang@ionos.com>, Jens Axboe <axboe@kernel.dk>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 547/779] block/rnbd-srv: Set keep_id to true after mutex_trylock
Date:   Mon, 15 Aug 2022 20:03:11 +0200
Message-Id: <20220815180400.696262812@linuxfoundation.org>
In-Reply-To: <20220815180337.130757997@linuxfoundation.org>
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From: Md Haris Iqbal <haris.iqbal@ionos.com>

[ Upstream commit 4bc14f3101364877dd59085f39e068a2a7ec9f2d ]

After setting keep_id if the mutex trylock fails, the keep_id stays set
for the rest of the sess_dev lifetime.

Therefore, set keep_id to true after mutex_trylock succeeds, so that a
failure of trylock does'nt touch keep_id.

Fixes: b168e1d85cf3 ("block/rnbd-srv: Prevent a deadlock generated by accessing sysfs in parallel")
Cc: gi-oh.kim@ionos.com
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Link: https://lore.kernel.org/r/20220707143122.460362-2-haris.iqbal@ionos.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/rnbd/rnbd-srv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/block/rnbd/rnbd-srv.c b/drivers/block/rnbd/rnbd-srv.c
index 1ba1a93a6fe7..1896cde8135e 100644
--- a/drivers/block/rnbd/rnbd-srv.c
+++ b/drivers/block/rnbd/rnbd-srv.c
@@ -333,10 +333,11 @@ void rnbd_srv_sess_dev_force_close(struct rnbd_srv_sess_dev *sess_dev,
 {
 	struct rnbd_srv_session	*sess = sess_dev->sess;
 
-	sess_dev->keep_id = true;
 	/* It is already started to close by client's close message. */
 	if (!mutex_trylock(&sess->lock))
 		return;
+
+	sess_dev->keep_id = true;
 	/* first remove sysfs itself to avoid deadlock */
 	sysfs_remove_file_self(&sess_dev->kobj, &attr->attr);
 	rnbd_srv_destroy_dev_session_sysfs(sess_dev);
-- 
2.35.1