[IPV6]: Eliminate difference in actions of sysctl and proc handler for conf.all.forwarding

The only difference in this case is that updating all.forwarding
causes the update in default.forwarding when done via proc, but
not via the system call.

Besides, this consolidates a good portion of code.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -476,6 +476,21 @@ static void addrconf_forward_change(void)
 	}
 	read_unlock(&dev_base_lock);
 }
+
+static void addrconf_fixup_forwarding(struct ctl_table *table, int *p, int old)
+{
+	if (p == &ipv6_devconf_dflt.forwarding)
+		return;
+
+	if (p == &ipv6_devconf.forwarding) {
+		ipv6_devconf_dflt.forwarding = ipv6_devconf.forwarding;
+		addrconf_forward_change();
+	} else if ((!*p) ^ (!old))
+		dev_forward_change((struct inet6_dev *)table->extra1);
+
+	if (*p)
+		rt6_purge_dflt_routers();
+}
 #endif
 
 /* Nobody refers to this ifaddr, destroy it */
@@ -3771,22 +3786,8 @@ int addrconf_sysctl_forward(ctl_table *ctl, int write, struct file * filp,
 
 	ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
 
-	if (write && valp != &ipv6_devconf_dflt.forwarding) {
-		if (valp != &ipv6_devconf.forwarding) {
-			if ((!*valp) ^ (!val)) {
-				struct inet6_dev *idev = (struct inet6_dev *)ctl->extra1;
-				if (idev == NULL)
-					return ret;
-				dev_forward_change(idev);
-			}
-		} else {
-			ipv6_devconf_dflt.forwarding = ipv6_devconf.forwarding;
-			addrconf_forward_change();
-		}
-		if (*valp)
-			rt6_purge_dflt_routers();
-	}
-
+	if (write)
+		addrconf_fixup_forwarding(ctl, valp, val);
 	return ret;
 }
 
@@ -3797,6 +3798,7 @@ static int addrconf_sysctl_forward_strategy(ctl_table *table,
 					    void __user *newval, size_t newlen)
 {
 	int *valp = table->data;
+	int val = *valp;
 	int new;
 
 	if (!newval || !newlen)
@@ -3821,26 +3823,8 @@ static int addrconf_sysctl_forward_strategy(ctl_table *table,
 		}
 	}
 
-	if (valp != &ipv6_devconf_dflt.forwarding) {
-		if (valp != &ipv6_devconf.forwarding) {
-			struct inet6_dev *idev = (struct inet6_dev *)table->extra1;
-			int changed;
-			if (unlikely(idev == NULL))
-				return -ENODEV;
-			changed = (!*valp) ^ (!new);
-			*valp = new;
-			if (changed)
-				dev_forward_change(idev);
-		} else {
-			*valp = new;
-			addrconf_forward_change();
-		}
-
-		if (*valp)
-			rt6_purge_dflt_routers();
-	} else
-		*valp = new;
-
+	*valp = new;
+	addrconf_fixup_forwarding(table, valp, val);
 	return 1;
 }