From c7355827b27c550824bbcc1f0586cf993bf83d94 Mon Sep 17 00:00:00 2001
From: "tsutomu.owa@toshiba.co.jp" <tsutomu.owa@toshiba.co.jp>
Date: Tue, 12 Sep 2017 08:56:00 +0000
Subject: [PATCH 07/19] DLM: fix to use sock_mutex correctly in
 xxx_accept_from_sock
Git-commit: c7355827b27c550824bbcc1f0586cf993bf83d94
Patch-mainline: v4.15-rc1
References: bsc#1074590

In the current implementation, we think that exclusion control
for othercon in tcp_accept_from_sock() and sctp_accept_from_sock()
was not enough. We fix them.

Signed-off-by: Tadashi Miyauchi <miyauchi@toshiba-tops.co.jp>
Signed-off-by: Tsutomu Owa <tsutomu.owa@toshiba.co.jp>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Gang He <ghe@suse.com>
---
 fs/dlm/lowcomms.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 420946d..b275813 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -801,16 +801,19 @@ static int tcp_accept_from_sock(struct connection *con)
 			INIT_WORK(&othercon->rwork, process_recv_sockets);
 			set_bit(CF_IS_OTHERCON, &othercon->flags);
 		}
+		mutex_lock_nested(&othercon->sock_mutex, 2);
 		if (!othercon->sock) {
 			newcon->othercon = othercon;
 			othercon->sock = newsock;
 			newsock->sk->sk_user_data = othercon;
 			add_sock(newsock, othercon);
 			addcon = othercon;
+			mutex_unlock(&othercon->sock_mutex);
 		}
 		else {
 			printk("Extra connection from node %d attempted\n", nodeid);
 			result = -EAGAIN;
+			mutex_unlock(&othercon->sock_mutex);
 			mutex_unlock(&newcon->sock_mutex);
 			goto accept_err;
 		}
@@ -918,15 +921,18 @@ static int sctp_accept_from_sock(struct connection *con)
 			INIT_WORK(&othercon->rwork, process_recv_sockets);
 			set_bit(CF_IS_OTHERCON, &othercon->flags);
 		}
+		mutex_lock_nested(&othercon->sock_mutex, 2);
 		if (!othercon->sock) {
 			newcon->othercon = othercon;
 			othercon->sock = newsock;
 			newsock->sk->sk_user_data = othercon;
 			add_sock(newsock, othercon);
 			addcon = othercon;
+			mutex_unlock(&othercon->sock_mutex);
 		} else {
 			printk("Extra connection from node %d attempted\n", nodeid);
 			ret = -EAGAIN;
+			mutex_unlock(&othercon->sock_mutex);
 			mutex_unlock(&newcon->sock_mutex);
 			goto accept_err;
 		}
-- 
1.8.5.6