[IPV4]: Flush routing cache on sysctl_ip_default_ttl changes.

include/net/ip.h

@@ -298,4 +298,15 @@ extern void	ip_local_error(struct sock *sk, int err, u32 daddr, u16 dport,
 extern int ip_seq_release(struct inode *inode, struct file *file);
 extern int ipv4_proc_init(void);
 
+/* sysctl helpers - any sysctl which holds a value that ends up being
+ * fed into the routing cache should use these handlers.
+ */
+int ipv4_doint_and_flush(ctl_table *ctl, int write,
+			 struct file* filp, void *buffer,
+			 size_t *lenp);
+int ipv4_doint_and_flush_strategy(ctl_table *table, int *name, int nlen,
+				  void *oldval, size_t *oldlenp,
+				  void *newval, size_t newlen, 
+				  void **context);
+
 #endif	/* _IP_H */

net/ipv4/devinet.c

@@ -1065,9 +1065,9 @@ static int devinet_sysctl_forward(ctl_table *ctl, int write,
 	return ret;
 }
 
-static int ipv4_doint_and_flush(ctl_table *ctl, int write,
-				struct file* filp, void *buffer,
-				size_t *lenp)
+int ipv4_doint_and_flush(ctl_table *ctl, int write,
+			 struct file* filp, void *buffer,
+			 size_t *lenp)
 {
 	int *valp = ctl->data;
 	int val = *valp;
@@ -1079,10 +1079,10 @@ static int ipv4_doint_and_flush(ctl_table *ctl, int write,
 	return ret;
 }
 
-static int ipv4_doint_and_flush_strategy(ctl_table *table, int *name, int nlen,
-					 void *oldval, size_t *oldlenp,
-					 void *newval, size_t newlen, 
-					 void **context)
+int ipv4_doint_and_flush_strategy(ctl_table *table, int *name, int nlen,
+				  void *oldval, size_t *oldlenp,
+				  void *newval, size_t newlen, 
+				  void **context)
 {
 	int *valp = table->data;
 	int new;

net/ipv4/sysctl_net_ipv4.c

@@ -160,7 +160,8 @@ ctl_table ipv4_table[] = {
  		.data		= &sysctl_ip_default_ttl,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= &proc_dointvec
+		.proc_handler	= &ipv4_doint_and_flush,
+		.strategy	= &ipv4_doint_and_flush_strategy,
 	},
         {
 		.ctl_name	= NET_IPV4_AUTOCONFIG,