net: Make ip_ra_chain per struct net

This is optimization, which makes ip_call_ra_chain()
iterate less sockets to find the sockets it's looking for.

Signed-off-by: Kirill Tkhai <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/ip.h

···
 	return 0;
 }
 
+/* Special input handler for packets caught by router alert option.
+   They are selected only by protocol field, and then processed likely
+   local ones; but only if someone wants them! Otherwise, router
+   not running rsvpd will kill RSVP.
+
+   It is user level problem, what it will make with them.
+   I have no idea, how it will masquearde or NAT them (it is joke, joke :-)),
+   but receiver should be enough clever f.e. to forward mtrace requests,
+   sent to multicast group to reach destination designated router.
+ */
+
 struct ip_ra_chain {
 	struct ip_ra_chain __rcu *next;
 	struct sock		*sk;
···
 	};
 	struct rcu_head		rcu;
 };
-
-extern struct ip_ra_chain __rcu *ip_ra_chain;
 
 /* IP flags. */
 #define IP_CE		0x8000		/* Flag: "Congestion"		*/

include/net/netns/ipv4.h

···
 #endif
 	struct ipv4_devconf	*devconf_all;
 	struct ipv4_devconf	*devconf_dflt;
+	struct ip_ra_chain __rcu *ra_chain;
 #ifdef CONFIG_IP_MULTIPLE_TABLES
 	struct fib_rules_ops	*rules_ops;
 	bool			fib_has_custom_rules;

net/ipv4/ip_input.c

···
 	struct net_device *dev = skb->dev;
 	struct net *net = dev_net(dev);
 
-	for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
+	for (ra = rcu_dereference(net->ipv4.ra_chain); ra; ra = rcu_dereference(ra->next)) {
 		struct sock *sk = ra->sk;
 
 		/* If socket is bound to an interface, only report
···
 		 */
 		if (sk && inet_sk(sk)->inet_num == protocol &&
 		    (!sk->sk_bound_dev_if ||
-		     sk->sk_bound_dev_if == dev->ifindex) &&
-		    net_eq(sock_net(sk), net)) {
+		     sk->sk_bound_dev_if == dev->ifindex)) {
 			if (ip_is_fragment(ip_hdr(skb))) {
 				if (ip_defrag(net, skb, IP_DEFRAG_CALL_RA_CHAIN))
 					return true;

net/ipv4/ip_sockglue.c

···
 	return 0;
 }
 
-
-/* Special input handler for packets caught by router alert option.
-   They are selected only by protocol field, and then processed likely
-   local ones; but only if someone wants them! Otherwise, router
-   not running rsvpd will kill RSVP.
-
-   It is user level problem, what it will make with them.
-   I have no idea, how it will masquearde or NAT them (it is joke, joke :-)),
-   but receiver should be enough clever f.e. to forward mtrace requests,
-   sent to multicast group to reach destination designated router.
- */
-struct ip_ra_chain __rcu *ip_ra_chain;
 static DEFINE_SPINLOCK(ip_ra_lock);
 
 
···
 {
 	struct ip_ra_chain *ra, *new_ra;
 	struct ip_ra_chain __rcu **rap;
+	struct net *net = sock_net(sk);
 
 	if (sk->sk_type != SOCK_RAW || inet_sk(sk)->inet_num == IPPROTO_RAW)
 		return -EINVAL;
···
 	new_ra = on ? kmalloc(sizeof(*new_ra), GFP_KERNEL) : NULL;
 
 	spin_lock_bh(&ip_ra_lock);
-	for (rap = &ip_ra_chain;
+	for (rap = &net->ipv4.ra_chain;
 	     (ra = rcu_dereference_protected(*rap,
 			lockdep_is_held(&ip_ra_lock))) != NULL;
 	     rap = &ra->next) {