udp: Add GRO functions to UDP socket

This patch adds GRO functions (gro_receive and gro_complete) to UDP
sockets. udp_gro_receive is changed to perform socket lookup on a
packet. If a socket is found the related GRO functions are called.

This features obsoletes using UDP offload infrastructure for GRO
(udp_offload). This has the advantage of not being limited to provide
offload on a per port basis, GRO is now applied to whatever individual
UDP sockets are bound to. This also allows the possbility of
"application defined GRO"-- that is we can attach something like
a BPF program to a UDP socket to perfrom GRO on an application
layer protocol.

Signed-off-by: Tom Herbert <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/udp.h

···
 	 */
 	int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
 	void (*encap_destroy)(struct sock *sk);
+
+	/* GRO functions for UDP socket */
+	struct sk_buff **	(*gro_receive)(struct sock *sk,
+					       struct sk_buff **head,
+					       struct sk_buff *skb);
+	int			(*gro_complete)(struct sock *sk,
+						struct sk_buff *skb,
+						int nhoff);
 };
 
 static inline struct udp_sock *udp_sk(const struct sock *sk)

include/net/udp.h

···
 	UDP_SKB_CB(skb)->cscov -= sizeof(struct udphdr);
 }
 
+typedef struct sock *(*udp_lookup_t)(struct sk_buff *skb, __be16 sport,
+				     __be16 dport);
+
 struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
-				 struct udphdr *uh);
-int udp_gro_complete(struct sk_buff *skb, int nhoff);
+				 struct udphdr *uh, udp_lookup_t lookup);
+int udp_gro_complete(struct sk_buff *skb, int nhoff, udp_lookup_t lookup);
 
 static inline struct udphdr *udp_gro_udphdr(struct sk_buff *skb)
 {

net/ipv4/udp_offload.c

···
 
 	return segs;
 }
+EXPORT_SYMBOL(skb_udp_tunnel_segment);
 
 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
 					 netdev_features_t features)
···
 EXPORT_SYMBOL(udp_del_offload);
 
 struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
-				 struct udphdr *uh)
+				 struct udphdr *uh, udp_lookup_t lookup)
 {
-	struct udp_offload_priv *uo_priv;
 	struct sk_buff *p, **pp = NULL;
 	struct udphdr *uh2;
 	unsigned int off = skb_gro_offset(skb);
 	int flush = 1;
+	struct sock *sk;
 
 	if (NAPI_GRO_CB(skb)->encap_mark ||
 	    (skb->ip_summed != CHECKSUM_PARTIAL &&
···
 	NAPI_GRO_CB(skb)->encap_mark = 1;
 
 	rcu_read_lock();
-	uo_priv = rcu_dereference(udp_offload_base);
-	for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
-		if (net_eq(read_pnet(&uo_priv->net), dev_net(skb->dev)) &&
-		    uo_priv->offload->port == uh->dest &&
-		    uo_priv->offload->callbacks.gro_receive)
-			goto unflush;
-	}
+	sk = (*lookup)(skb, uh->source, uh->dest);
+
+	if (sk && udp_sk(sk)->gro_receive)
+		goto unflush;
+
 	goto out_unlock;
 
 unflush:
···
 
 	skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
 	skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
-	NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
-	pp = uo_priv->offload->callbacks.gro_receive(head, skb,
-						     uo_priv->offload);
+	pp = udp_sk(sk)->gro_receive(sk, head, skb);
 
 out_unlock:
 	rcu_read_unlock();
···
 	NAPI_GRO_CB(skb)->flush |= flush;
 	return pp;
 }
+EXPORT_SYMBOL(udp_gro_receive);
 
 static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
 					 struct sk_buff *skb)
···
 					     inet_gro_compute_pseudo);
 skip:
 	NAPI_GRO_CB(skb)->is_ipv6 = 0;
-	return udp_gro_receive(head, skb, uh);
+	return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb);
 
 flush:
 	NAPI_GRO_CB(skb)->flush = 1;
 	return NULL;
 }
 
-int udp_gro_complete(struct sk_buff *skb, int nhoff)
+int udp_gro_complete(struct sk_buff *skb, int nhoff,
+		     udp_lookup_t lookup)
 {
-	struct udp_offload_priv *uo_priv;
 	__be16 newlen = htons(skb->len - nhoff);
 	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 	int err = -ENOSYS;
+	struct sock *sk;
 
 	uh->len = newlen;
 
 	rcu_read_lock();
-
-	uo_priv = rcu_dereference(udp_offload_base);
-	for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
-		if (net_eq(read_pnet(&uo_priv->net), dev_net(skb->dev)) &&
-		    uo_priv->offload->port == uh->dest &&
-		    uo_priv->offload->callbacks.gro_complete)
-			break;
-	}
-
-	if (uo_priv) {
-		NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
-		err = uo_priv->offload->callbacks.gro_complete(skb,
-				nhoff + sizeof(struct udphdr),
-				uo_priv->offload);
-	}
-
+	sk = (*lookup)(skb, uh->source, uh->dest);
+	if (sk && udp_sk(sk)->gro_complete)
+		err = udp_sk(sk)->gro_complete(sk, skb,
+				nhoff + sizeof(struct udphdr));
 	rcu_read_unlock();
 
 	if (skb->remcsum_offload)
···
 
 	return err;
 }
+EXPORT_SYMBOL(udp_gro_complete);
 
 static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
 {
···
 		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 	}
 
-	return udp_gro_complete(skb, nhoff);
+	return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
 }
 
 static const struct net_offload udpv4_offload = {

net/ipv6/Makefile

···
 		addrlabel.o \
 		route.o ip6_fib.o ipv6_sockglue.o ndisc.o udp.o udplite.o \
 		raw.o icmp.o mcast.o reassembly.o tcp_ipv6.o ping.o \
-		exthdrs.o datagram.o ip6_flowlabel.o inet6_connection_sock.o
+		exthdrs.o datagram.o ip6_flowlabel.o inet6_connection_sock.o \
+		udp_offload.o
 
-ipv6-offload :=	ip6_offload.o tcpv6_offload.o udp_offload.o exthdrs_offload.o
+ipv6-offload :=	ip6_offload.o tcpv6_offload.o exthdrs_offload.o
 
 ipv6-$(CONFIG_SYSCTL) = sysctl_net_ipv6.o
 ipv6-$(CONFIG_IPV6_MROUTE) += ip6mr.o

net/ipv6/af_inet6.c

···
 #include <asm/uaccess.h>
 #include <linux/mroute6.h>
 
+#include "ip6_offload.h"
+
 MODULE_AUTHOR("Cast of dozens");
 MODULE_DESCRIPTION("IPv6 protocol stack for Linux");
 MODULE_LICENSE("GPL");
···
 	if (err)
 		goto udplitev6_fail;
 
+	err = udpv6_offload_init();
+	if (err)
+		goto udpv6_offload_fail;
+
 	err = tcpv6_init();
 	if (err)
 		goto tcpv6_fail;
···
 ipv6_packet_fail:
 	tcpv6_exit();
 tcpv6_fail:
+	udpv6_offload_exit();
+udpv6_offload_fail:
 	udplitev6_exit();
 udplitev6_fail:
 	udpv6_exit();

net/ipv6/ip6_offload.c

···
 
 	if (tcpv6_offload_init() < 0)
 		pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
-	if (udp_offload_init() < 0)
-		pr_crit("%s: Cannot add UDP protocol offload\n", __func__);
 	if (ipv6_exthdrs_offload_init() < 0)
 		pr_crit("%s: Cannot add EXTHDRS protocol offload\n", __func__);
 

net/ipv6/ip6_offload.h

···
 #define __ip6_offload_h
 
 int ipv6_exthdrs_offload_init(void);
-int udp_offload_init(void);
+int udpv6_offload_init(void);
+int udpv6_offload_exit(void);
 int tcpv6_offload_init(void);
 
 #endif

net/ipv6/udp_offload.c

···
 
 skip:
 	NAPI_GRO_CB(skb)->is_ipv6 = 1;
-	return udp_gro_receive(head, skb, uh);
+	return udp_gro_receive(head, skb, uh, udp6_lib_lookup_skb);
 
 flush:
 	NAPI_GRO_CB(skb)->flush = 1;
···
 		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 	}
 
-	return udp_gro_complete(skb, nhoff);
+	return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb);
 }
 
 static const struct net_offload udpv6_offload = {
···
 	},
 };
 
-int __init udp_offload_init(void)
+int udpv6_offload_init(void)
 {
 	return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
+}
+
+int udpv6_offload_exit(void)
+{
+	return inet6_del_offload(&udpv6_offload, IPPROTO_UDP);
 }