ipv6: Fix sysctl unregistration deadlock

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 6 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index f9afb452249c..40fabdee42ae 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -493,15 +493,17 @@ static void addrconf_forward_change(struct net *net, __s32 newf)
         read_unlock(&dev_base_lock);
 }
 
-static void addrconf_fixup_forwarding(struct ctl_table *table, int *p, int old)
+static int addrconf_fixup_forwarding(struct ctl_table *table, int *p, int old)
 {
         struct net *net;
 
         net = (struct net *)table->extra2;
         if (p == &net->ipv6.devconf_dflt->forwarding)
-                return;
+                return 0;
+
+        if (!rtnl_trylock())
+                return -ERESTARTSYS;
 
-        rtnl_lock();
         if (p == &net->ipv6.devconf_all->forwarding) {
                 __s32 newf = net->ipv6.devconf_all->forwarding;
                 net->ipv6.devconf_dflt->forwarding = newf;
@@ -512,6 +514,7 @@ static void addrconf_fixup_forwarding(struct ctl_table *table, int *p, int old)
 
         if (*p)
                 rt6_purge_dflt_routers(net);
+        return 1;
 }
 #endif
 
@@ -3983,7 +3986,7 @@ int addrconf_sysctl_forward(ctl_table *ctl, int write, struct file * filp,
         ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
 
         if (write)
-                addrconf_fixup_forwarding(ctl, valp, val);
+                ret = addrconf_fixup_forwarding(ctl, valp, val);
         return ret;
 }
 
@@ -4019,8 +4022,7 @@ static int addrconf_sysctl_forward_strategy(ctl_table *table,
         }
 
         *valp = new;
-        addrconf_fixup_forwarding(table, valp, val);
-        return 1;
+        return addrconf_fixup_forwarding(table, valp, val);
 }
 
 static struct addrconf_sysctl_table