inet: Don't lookup the socket if there's a socket attached to the skb

Use the socket cached in the skb if it's present.
Signed-off-by: KOVACS Krisztian <hidden@sch.bme.hu>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet6_hashtables.h

@@ -96,7 +96,11 @@ static inline struct sock *__inet6_lookup_skb(struct inet_hashinfo *hashinfo,
 					      const __be16 sport,
 					      const __be16 dport)
 {
-	return __inet6_lookup(dev_net(skb->dst->dev), hashinfo,
+	struct sock *sk;
+
+	if (unlikely(sk = skb_steal_sock(skb)))
+		return sk;
+	else return __inet6_lookup(dev_net(skb->dst->dev), hashinfo,
 				   &ipv6_hdr(skb)->saddr, sport,
 				   &ipv6_hdr(skb)->daddr, ntohs(dport),
 				   inet6_iif(skb));

include/net/inet_hashtables.h

@@ -378,8 +378,12 @@ static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
 					     const __be16 sport,
 					     const __be16 dport)
 {
+	struct sock *sk;
 	const struct iphdr *iph = ip_hdr(skb);
 
+	if (unlikely(sk = skb_steal_sock(skb)))
+		return sk;
+	else
 		return __inet_lookup(dev_net(skb->dst->dev), hashinfo,
 				     iph->saddr, sport,
 				     iph->daddr, dport, inet_iif(skb));

include/net/sock.h

@@ -1324,6 +1324,18 @@ static inline void sk_change_net(struct sock *sk, struct net *net)
 	sock_net_set(sk, hold_net(net));
 }
 
+static inline struct sock *skb_steal_sock(struct sk_buff *skb)
+{
+	if (unlikely(skb->sk)) {
+		struct sock *sk = skb->sk;
+
+		skb->destructor = NULL;
+		skb->sk = NULL;
+		return sk;
+	}
+	return NULL;
+}
+
 extern void sock_enable_timestamp(struct sock *sk);
 extern int sock_get_timestamp(struct sock *, struct timeval __user *);
 extern int sock_get_timestampns(struct sock *, struct timespec __user *);

net/ipv4/udp.c

@@ -306,8 +306,12 @@ static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
 						 __be16 sport, __be16 dport,
 						 struct hlist_head udptable[])
 {
+	struct sock *sk;
 	const struct iphdr *iph = ip_hdr(skb);
 
+	if (unlikely(sk = skb_steal_sock(skb)))
+		return sk;
+	else
 		return __udp4_lib_lookup(dev_net(skb->dst->dev), iph->saddr, sport,
 					 iph->daddr, dport, inet_iif(skb),
 					 udptable);

net/ipv6/udp.c

@@ -111,8 +111,12 @@ static struct sock *__udp6_lib_lookup_skb(struct sk_buff *skb,
 					  __be16 sport, __be16 dport,
 					  struct hlist_head udptable[])
 {
+	struct sock *sk;
 	struct ipv6hdr *iph = ipv6_hdr(skb);
 
+	if (unlikely(sk = skb_steal_sock(skb)))
+		return sk;
+	else
 		return __udp6_lib_lookup(dev_net(skb->dst->dev), &iph->saddr, sport,
 					 &iph->daddr, dport, inet6_iif(skb),
 					 udptable);