net: Fix devinet_sysctl_forward
authorEric W. Biederman <ebiederm@xmission.com>
Wed, 13 May 2009 16:59:21 +0000 (16:59 +0000)
committerDavid S. Miller <davem@davemloft.net>
Tue, 19 May 2009 05:15:58 +0000 (22:15 -0700)
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>
net/ipv4/devinet.c

index 126bb911880fa675861f4b1940655e18fcbe1774..3863c3a4223f45f84167b9a50c708049822f1ce4 100644 (file)
@@ -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) {