netdev - [PATCH v2] net: bridge: Fix a warning when del bridge sysfs

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Date:   Fri, 11 Dec 2020 20:29:21 +0800
From:   Wang Hai <wanghai38@...wei.com>
To:     <kuba@...nel.org>, <nikolay@...dia.com>, <davem@...emloft.net>,
        <roopa@...dia.com>
CC:     <bridge@...ts.linux-foundation.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] net: bridge: Fix a warning when del bridge sysfs

I got a warining report:

br_sysfs_addbr: can't create group bridge4/bridge
------------[ cut here ]------------
sysfs group 'bridge' not found for kobject 'bridge4'
WARNING: CPU: 2 PID: 9004 at fs/sysfs/group.c:279 sysfs_remove_group fs/sysfs/group.c:279 [inline]
WARNING: CPU: 2 PID: 9004 at fs/sysfs/group.c:279 sysfs_remove_group+0x153/0x1b0 fs/sysfs/group.c:270
Modules linked in: iptable_nat
...
Call Trace:
  br_dev_delete+0x112/0x190 net/bridge/br_if.c:384
  br_dev_newlink net/bridge/br_netlink.c:1381 [inline]
  br_dev_newlink+0xdb/0x100 net/bridge/br_netlink.c:1362
  __rtnl_newlink+0xe11/0x13f0 net/core/rtnetlink.c:3441
  rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3500
  rtnetlink_rcv_msg+0x385/0x980 net/core/rtnetlink.c:5562
  netlink_rcv_skb+0x134/0x3d0 net/netlink/af_netlink.c:2494
  netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
  netlink_unicast+0x4a0/0x6a0 net/netlink/af_netlink.c:1330
  netlink_sendmsg+0x793/0xc80 net/netlink/af_netlink.c:1919
  sock_sendmsg_nosec net/socket.c:651 [inline]
  sock_sendmsg+0x139/0x170 net/socket.c:671
  ____sys_sendmsg+0x658/0x7d0 net/socket.c:2353
  ___sys_sendmsg+0xf8/0x170 net/socket.c:2407
  __sys_sendmsg+0xd3/0x190 net/socket.c:2440
  do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
  entry_SYSCALL_64_after_hwframe+0x44/0xa9

In br_device_event(), if the bridge sysfs fails to be added,
br_device_event() should return error. This can prevent warining
when removing bridge sysfs that do not exist.

Fixes: bb900b27a2f4 ("bridge: allow creating bridge devices with netlink")
Reported-by: Hulk Robot <hulkci@...wei.com>
Signed-off-by: Wang Hai <wanghai38@...wei.com>
---
v1->v2: Fix this by check br_sysfs_addbr() return value as Nik's suggestion
 net/bridge/br.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br.c b/net/bridge/br.c
index 401eeb9142eb..1b169f8e7491 100644
--- a/net/bridge/br.c
+++ b/net/bridge/br.c
@@ -43,7 +43,10 @@ static int br_device_event(struct notifier_block *unused, unsigned long event, v
 
 		if (event == NETDEV_REGISTER) {
 			/* register of bridge completed, add sysfs entries */
-			br_sysfs_addbr(dev);
+			err = br_sysfs_addbr(dev);
+			if (err)
+				return notifier_from_errno(err);
+
 			return NOTIFY_DONE;
 		}
 	}
-- 
2.17.1