[PATCH net-2.6.25 2/2][INET] Eliminate difference in actions of sysctl and proc handler for conf.all.forwarding

[Pavel Emelyanov <xemul@openvz.org>]

AFAIS the net.ipv4.conf. <dev>, all and default sysctls should 
work like this when changed (besides changing the value itself):

<dev>   : optionally do smth else
all     : walk devices
default : walk devices

The proc handler for net.ipv4.conf.all works like this:

<dev>   : flush rt cache
all     : walk devices and flush rt cache
default : nothing

while the sysctl handler works like this:

<dev>   : nothing
all     : nothing
default : walk devices but don't flush the cache

All this looks strange. Am I right that regardless of whatever
handler (proc or syscall) is called the behavior should be:

<dev>   : flush rt cache
all     : walk the devices and flush the cache
default : walk the devices and flush the cache

?

If yes, then this patch should fix it up.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>

---

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 0b5f042..1934a06 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1282,6 +1282,17 @@ static void inet_forward_change(void)
 		rcu_read_unlock();
 	}
 	read_unlock(&dev_base_lock);
+}
+
+static void fixup_forward_change(struct ctl_table *table)
+{
+	struct ipv4_devconf *conf;
+
+	conf = table->extra1;
+	if (conf == &ipv4_devconf)
+		inet_forward_change();
+	else if (conf == &ipv4_devconf_dflt)
+		devinet_copy_dflt_conf(NET_IPV4_CONF_FORWARDING - 1);
 
 	rt_cache_flush(0);
 }
@@ -1305,9 +1316,9 @@ static int devinet_conf_proc(ctl_table *ctl, int write,
 	return ret;
 }
 
-static int devinet_conf_sysctl(ctl_table *table, int __user *name, int nlen,
+static int __devinet_conf_sysctl(ctl_table *table, int __user *name, int nlen,
 			       void __user *oldval, size_t __user *oldlenp,
-			       void __user *newval, size_t newlen)
+			       void __user *newval, size_t newlen, int *idx)
 {
 	struct ipv4_devconf *cnf;
 	int *valp = table->data;
@@ -1346,16 +1357,27 @@ static int devinet_conf_sysctl(ctl_table *table, int __user *name, int nlen,
 
 	cnf = table->extra1;
 	i = (int *)table->data - cnf->data;
-
 	set_bit(i, cnf->state);
+	*idx = i;
+	return 1;
+}
+
+static int devinet_conf_sysctl(ctl_table *table, int __user *name, int nlen,
+			       void __user *oldval, size_t __user *oldlenp,
+			       void __user *newval, size_t newlen)
+{
+	int ret, i;
 
-	if (cnf == &ipv4_devconf_dflt)
+	ret = __devinet_conf_sysctl(table, name, nlen, oldval, oldlenp,
+			newval, newlen, &i);
+
+	if (ret == 1 && table->extra1 == &ipv4_devconf_dflt)
 		devinet_copy_dflt_conf(i);
 
-	return 1;
+	return ret;
 }
 
-static int devinet_sysctl_forward(ctl_table *ctl, int write,
+static int devinet_forward_proc(ctl_table *ctl, int write,
 				  struct file* filp, void __user *buffer,
 				  size_t *lenp, loff_t *ppos)
 {
@@ -1363,16 +1385,25 @@ static int devinet_sysctl_forward(ctl_table *ctl, int write,
 	int val = *valp;
 	int ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
 
-	if (write && *valp != val) {
-		if (valp == &IPV4_DEVCONF_ALL(FORWARDING))
-			inet_forward_change();
-		else if (valp != &IPV4_DEVCONF_DFLT(FORWARDING))
-			rt_cache_flush(0);
-	}
+	if (write && *valp != val)
+		fixup_forward_change(ctl);
 
 	return ret;
 }
 
+static int devinet_forward_sysctl(ctl_table *table, int __user *name, int nlen,
+			       void __user *oldval, size_t __user *oldlenp,
+			       void __user *newval, size_t newlen)
+{
+	int ret, i;
+
+	ret = __devinet_conf_sysctl(table, name, nlen, oldval, oldlenp,
+			newval, newlen, &i);
+	if (ret == 1)
+		fixup_forward_change(table);
+	return ret;
+}
+
 int ipv4_doint_and_flush(ctl_table *ctl, int write,
 			 struct file* filp, void __user *buffer,
 			 size_t *lenp, loff_t *ppos)
@@ -1436,8 +1467,8 @@ static struct devinet_sysctl_table {
 } devinet_sysctl = {
 	.devinet_vars = {
 		DEVINET_SYSCTL_COMPLEX_ENTRY(FORWARDING, "forwarding",
-					     devinet_sysctl_forward,
-					     devinet_conf_sysctl),
+					     devinet_forward_proc,
+					     devinet_forward_sysctl),
 		DEVINET_SYSCTL_RO_ENTRY(MC_FORWARDING, "mc_forwarding"),
 
 		DEVINET_SYSCTL_RW_ENTRY(ACCEPT_REDIRECTS, "accept_redirects"),
@@ -1545,8 +1576,8 @@ static struct ctl_table ctl_forward_entry[] = {
 					NET_IPV4_CONF_FORWARDING - 1],
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= devinet_sysctl_forward,
-		.strategy	= devinet_conf_sysctl,
+		.proc_handler	= devinet_forward_proc,
+		.strategy	= devinet_forward_sysctl,
 		.extra1		= &ipv4_devconf,
 	},
 	{ },