From: Eric W. Biederman <ebiederm@xmission.com>
Date: Wed, 13 May 2009 16:59:21 +0000 (+0000)
Subject: net: Fix devinet_sysctl_forward
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=9b8adb5ea005fe73acd5dd58f9bd47eafa74c9d1;p=mv-sheeva.git

net: Fix devinet_sysctl_forward

sysctls are unregistered with the rntl_lock held making
it unsafe to unconditionally grab the the rtnl_lock.  Instead
we need to call rtnl_trylock and restart the system call
if we can not grab it.  Otherwise we could deadlock at unregistration
time.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 126bb911880..3863c3a4223 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1347,7 +1347,8 @@ static int devinet_sysctl_forward(ctl_table *ctl, int write,
 		struct net *net = ctl->extra2;
 
 		if (valp != &IPV4_DEVCONF_DFLT(net, FORWARDING)) {
-			rtnl_lock();
+			if (!rtnl_trylock())
+				return restart_syscall();
 			if (valp == &IPV4_DEVCONF_ALL(net, FORWARDING)) {
 				inet_forward_change(net);
 			} else if (*valp) {