[PATCH 4.9 087/310] md-cluster: fix potential lock issue in add_new_disk

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Guoqing Jiang <gqji...@suse.com>


[ Upstream commit 2dffdc0724004f38f5e39907747b53e4b0d80e59 ]

The add_new_disk returns with communication locked if
__sendmsg returns failure, fix it with call unlock_comm
before return.

Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
CC: Goldwyn Rodrigues <rgold...@suse.com>
Signed-off-by: Guoqing Jiang <gqji...@suse.com>
Signed-off-by: Shaohua Li <s...@fb.com>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/md/md-cluster.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/md/md-cluster.c
+++ b/drivers/md/md-cluster.c
@@ -1122,8 +1122,10 @@ static int add_new_disk(struct mddev *md
        cmsg.raid_slot = cpu_to_le32(rdev->desc_nr);
        lock_comm(cinfo);
        ret = __sendmsg(cinfo, &cmsg);
-       if (ret)
+       if (ret) {
+               unlock_comm(cinfo);
                return ret;
+       }
        cinfo->no_new_dev_lockres->flags |= DLM_LKF_NOQUEUE;
        ret = dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_EX);
        cinfo->no_new_dev_lockres->flags &= ~DLM_LKF_NOQUEUE;