net: tcp: move GRO/GSO functions to tcp_offload
authorDaniel Borkmann <dborkman@redhat.com>
Fri, 7 Jun 2013 05:11:46 +0000 (05:11 +0000)
committerDavid S. Miller <davem@davemloft.net>
Fri, 7 Jun 2013 21:39:05 +0000 (14:39 -0700)
Would be good to make things explicit and move those functions to
a new file called tcp_offload.c, thus make this similar to tcpv6_offload.c.
While moving all related functions into tcp_offload.c, we can also
make some of them static, since they are only used there. Also, add
an explicit registration function.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/net/tcp.h
net/ipv4/Makefile
net/ipv4/af_inet.c
net/ipv4/tcp.c
net/ipv4/tcp_ipv4.c
net/ipv4/tcp_offload.c [new file with mode: 0644]

index bf1cc3dced5ecdb571cecd9738ea30fc3aef5927..0d637e9403a54cfd6896f9282871e20168383cff 100644 (file)
@@ -1541,15 +1541,14 @@ extern struct request_sock_ops tcp6_request_sock_ops;
 
 extern void tcp_v4_destroy_sock(struct sock *sk);
 
-extern int tcp_v4_gso_send_check(struct sk_buff *skb);
 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
                                       netdev_features_t features);
 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
                                        struct sk_buff *skb);
-extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
-                                        struct sk_buff *skb);
 extern int tcp_gro_complete(struct sk_buff *skb);
-extern int tcp4_gro_complete(struct sk_buff *skb);
+
+extern void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr,
+                               __be32 daddr);
 
 #ifdef CONFIG_PROC_FS
 extern int tcp4_proc_init(void);
@@ -1584,6 +1583,8 @@ struct tcp_request_sock_ops {
 #endif
 };
 
+extern int tcpv4_offload_init(void);
+
 extern void tcp_v4_init(void);
 extern void tcp_init(void);
 
index 089cb9f363871327b027d8ce9246c830256cd456..4d3e138c564fb93d6771de1a310a458e05f7c84a 100644 (file)
@@ -8,7 +8,7 @@ obj-y     := route.o inetpeer.o protocol.o \
             inet_timewait_sock.o inet_connection_sock.o \
             tcp.o tcp_input.o tcp_output.o tcp_timer.o tcp_ipv4.o \
             tcp_minisocks.o tcp_cong.o tcp_metrics.o tcp_fastopen.o \
-            datagram.o raw.o udp.o udplite.o \
+            tcp_offload.o datagram.o raw.o udp.o udplite.o \
             arp.o icmp.o devinet.o af_inet.o  igmp.o \
             fib_frontend.o fib_semantics.o fib_trie.o \
             inet_fragment.o ping.o
index 9c090c7daea1d12a1a5babbca388f4f7741948b6..7b514290efc6bc68ccb46341facdf937ee813ce2 100644 (file)
@@ -1559,15 +1559,6 @@ static const struct net_protocol tcp_protocol = {
        .netns_ok       =       1,
 };
 
-static const struct net_offload tcp_offload = {
-       .callbacks = {
-               .gso_send_check =       tcp_v4_gso_send_check,
-               .gso_segment    =       tcp_tso_segment,
-               .gro_receive    =       tcp4_gro_receive,
-               .gro_complete   =       tcp4_gro_complete,
-       },
-};
-
 static const struct net_protocol udp_protocol = {
        .handler =      udp_rcv,
        .err_handler =  udp_err,
@@ -1683,8 +1674,8 @@ static int __init ipv4_offload_init(void)
         */
        if (inet_add_offload(&udp_offload, IPPROTO_UDP) < 0)
                pr_crit("%s: Cannot add UDP protocol offload\n", __func__);
-       if (inet_add_offload(&tcp_offload, IPPROTO_TCP) < 0)
-               pr_crit("%s: Cannot add TCP protocol offlaod\n", __func__);
+       if (tcpv4_offload_init() < 0)
+               pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
 
        dev_add_offload(&ip_packet_offload);
        return 0;
index 6a1cf95abc987ddd335f879c7a567c34769c83c7..bc4246940f6c22d4952ead8858211c7a0f4f7619 100644 (file)
@@ -2877,247 +2877,6 @@ int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
 EXPORT_SYMBOL(compat_tcp_getsockopt);
 #endif
 
-struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
-       netdev_features_t features)
-{
-       struct sk_buff *segs = ERR_PTR(-EINVAL);
-       struct tcphdr *th;
-       unsigned int thlen;
-       unsigned int seq;
-       __be32 delta;
-       unsigned int oldlen;
-       unsigned int mss;
-       struct sk_buff *gso_skb = skb;
-       __sum16 newcheck;
-       bool ooo_okay, copy_destructor;
-
-       if (!pskb_may_pull(skb, sizeof(*th)))
-               goto out;
-
-       th = tcp_hdr(skb);
-       thlen = th->doff * 4;
-       if (thlen < sizeof(*th))
-               goto out;
-
-       if (!pskb_may_pull(skb, thlen))
-               goto out;
-
-       oldlen = (u16)~skb->len;
-       __skb_pull(skb, thlen);
-
-       mss = tcp_skb_mss(skb);
-       if (unlikely(skb->len <= mss))
-               goto out;
-
-       if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
-               /* Packet is from an untrusted source, reset gso_segs. */
-               int type = skb_shinfo(skb)->gso_type;
-
-               if (unlikely(type &
-                            ~(SKB_GSO_TCPV4 |
-                              SKB_GSO_DODGY |
-                              SKB_GSO_TCP_ECN |
-                              SKB_GSO_TCPV6 |
-                              SKB_GSO_GRE |
-                              SKB_GSO_MPLS |
-                              SKB_GSO_UDP_TUNNEL |
-                              0) ||
-                            !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
-                       goto out;
-
-               skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
-
-               segs = NULL;
-               goto out;
-       }
-
-       copy_destructor = gso_skb->destructor == tcp_wfree;
-       ooo_okay = gso_skb->ooo_okay;
-       /* All segments but the first should have ooo_okay cleared */
-       skb->ooo_okay = 0;
-
-       segs = skb_segment(skb, features);
-       if (IS_ERR(segs))
-               goto out;
-
-       /* Only first segment might have ooo_okay set */
-       segs->ooo_okay = ooo_okay;
-
-       delta = htonl(oldlen + (thlen + mss));
-
-       skb = segs;
-       th = tcp_hdr(skb);
-       seq = ntohl(th->seq);
-
-       newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
-                                              (__force u32)delta));
-
-       do {
-               th->fin = th->psh = 0;
-               th->check = newcheck;
-
-               if (skb->ip_summed != CHECKSUM_PARTIAL)
-                       th->check =
-                            csum_fold(csum_partial(skb_transport_header(skb),
-                                                   thlen, skb->csum));
-
-               seq += mss;
-               if (copy_destructor) {
-                       skb->destructor = gso_skb->destructor;
-                       skb->sk = gso_skb->sk;
-                       /* {tcp|sock}_wfree() use exact truesize accounting :
-                        * sum(skb->truesize) MUST be exactly be gso_skb->truesize
-                        * So we account mss bytes of 'true size' for each segment.
-                        * The last segment will contain the remaining.
-                        */
-                       skb->truesize = mss;
-                       gso_skb->truesize -= mss;
-               }
-               skb = skb->next;
-               th = tcp_hdr(skb);
-
-               th->seq = htonl(seq);
-               th->cwr = 0;
-       } while (skb->next);
-
-       /* Following permits TCP Small Queues to work well with GSO :
-        * The callback to TCP stack will be called at the time last frag
-        * is freed at TX completion, and not right now when gso_skb
-        * is freed by GSO engine
-        */
-       if (copy_destructor) {
-               swap(gso_skb->sk, skb->sk);
-               swap(gso_skb->destructor, skb->destructor);
-               swap(gso_skb->truesize, skb->truesize);
-       }
-
-       delta = htonl(oldlen + (skb_tail_pointer(skb) -
-                               skb_transport_header(skb)) +
-                     skb->data_len);
-       th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
-                               (__force u32)delta));
-       if (skb->ip_summed != CHECKSUM_PARTIAL)
-               th->check = csum_fold(csum_partial(skb_transport_header(skb),
-                                                  thlen, skb->csum));
-
-out:
-       return segs;
-}
-EXPORT_SYMBOL(tcp_tso_segment);
-
-struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
-{
-       struct sk_buff **pp = NULL;
-       struct sk_buff *p;
-       struct tcphdr *th;
-       struct tcphdr *th2;
-       unsigned int len;
-       unsigned int thlen;
-       __be32 flags;
-       unsigned int mss = 1;
-       unsigned int hlen;
-       unsigned int off;
-       int flush = 1;
-       int i;
-
-       off = skb_gro_offset(skb);
-       hlen = off + sizeof(*th);
-       th = skb_gro_header_fast(skb, off);
-       if (skb_gro_header_hard(skb, hlen)) {
-               th = skb_gro_header_slow(skb, hlen, off);
-               if (unlikely(!th))
-                       goto out;
-       }
-
-       thlen = th->doff * 4;
-       if (thlen < sizeof(*th))
-               goto out;
-
-       hlen = off + thlen;
-       if (skb_gro_header_hard(skb, hlen)) {
-               th = skb_gro_header_slow(skb, hlen, off);
-               if (unlikely(!th))
-                       goto out;
-       }
-
-       skb_gro_pull(skb, thlen);
-
-       len = skb_gro_len(skb);
-       flags = tcp_flag_word(th);
-
-       for (; (p = *head); head = &p->next) {
-               if (!NAPI_GRO_CB(p)->same_flow)
-                       continue;
-
-               th2 = tcp_hdr(p);
-
-               if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
-                       NAPI_GRO_CB(p)->same_flow = 0;
-                       continue;
-               }
-
-               goto found;
-       }
-
-       goto out_check_final;
-
-found:
-       flush = NAPI_GRO_CB(p)->flush;
-       flush |= (__force int)(flags & TCP_FLAG_CWR);
-       flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
-                 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
-       flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
-       for (i = sizeof(*th); i < thlen; i += 4)
-               flush |= *(u32 *)((u8 *)th + i) ^
-                        *(u32 *)((u8 *)th2 + i);
-
-       mss = tcp_skb_mss(p);
-
-       flush |= (len - 1) >= mss;
-       flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
-
-       if (flush || skb_gro_receive(head, skb)) {
-               mss = 1;
-               goto out_check_final;
-       }
-
-       p = *head;
-       th2 = tcp_hdr(p);
-       tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
-
-out_check_final:
-       flush = len < mss;
-       flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
-                                       TCP_FLAG_RST | TCP_FLAG_SYN |
-                                       TCP_FLAG_FIN));
-
-       if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
-               pp = head;
-
-out:
-       NAPI_GRO_CB(skb)->flush |= flush;
-
-       return pp;
-}
-EXPORT_SYMBOL(tcp_gro_receive);
-
-int tcp_gro_complete(struct sk_buff *skb)
-{
-       struct tcphdr *th = tcp_hdr(skb);
-
-       skb->csum_start = skb_transport_header(skb) - skb->head;
-       skb->csum_offset = offsetof(struct tcphdr, check);
-       skb->ip_summed = CHECKSUM_PARTIAL;
-
-       skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
-
-       if (th->cwr)
-               skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
-
-       return 0;
-}
-EXPORT_SYMBOL(tcp_gro_complete);
-
 #ifdef CONFIG_TCP_MD5SIG
 static struct tcp_md5sig_pool __percpu *tcp_md5sig_pool __read_mostly;
 static DEFINE_MUTEX(tcp_md5sig_mutex);
index d20ede0c9593c2b918fd5224661aa92b9bae8c46..289039b4d8deeaacbff8de87c353bf09a3299da4 100644 (file)
@@ -545,8 +545,7 @@ out:
        sock_put(sk);
 }
 
-static void __tcp_v4_send_check(struct sk_buff *skb,
-                               __be32 saddr, __be32 daddr)
+void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr)
 {
        struct tcphdr *th = tcp_hdr(skb);
 
@@ -571,23 +570,6 @@ void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)
 }
 EXPORT_SYMBOL(tcp_v4_send_check);
 
-int tcp_v4_gso_send_check(struct sk_buff *skb)
-{
-       const struct iphdr *iph;
-       struct tcphdr *th;
-
-       if (!pskb_may_pull(skb, sizeof(*th)))
-               return -EINVAL;
-
-       iph = ip_hdr(skb);
-       th = tcp_hdr(skb);
-
-       th->check = 0;
-       skb->ip_summed = CHECKSUM_PARTIAL;
-       __tcp_v4_send_check(skb, iph->saddr, iph->daddr);
-       return 0;
-}
-
 /*
  *     This routine will send an RST to the other tcp.
  *
@@ -2795,52 +2777,6 @@ void tcp4_proc_exit(void)
 }
 #endif /* CONFIG_PROC_FS */
 
-struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
-{
-       const struct iphdr *iph = skb_gro_network_header(skb);
-       __wsum wsum;
-       __sum16 sum;
-
-       switch (skb->ip_summed) {
-       case CHECKSUM_COMPLETE:
-               if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
-                                 skb->csum)) {
-                       skb->ip_summed = CHECKSUM_UNNECESSARY;
-                       break;
-               }
-flush:
-               NAPI_GRO_CB(skb)->flush = 1;
-               return NULL;
-
-       case CHECKSUM_NONE:
-               wsum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
-                                         skb_gro_len(skb), IPPROTO_TCP, 0);
-               sum = csum_fold(skb_checksum(skb,
-                                            skb_gro_offset(skb),
-                                            skb_gro_len(skb),
-                                            wsum));
-               if (sum)
-                       goto flush;
-
-               skb->ip_summed = CHECKSUM_UNNECESSARY;
-               break;
-       }
-
-       return tcp_gro_receive(head, skb);
-}
-
-int tcp4_gro_complete(struct sk_buff *skb)
-{
-       const struct iphdr *iph = ip_hdr(skb);
-       struct tcphdr *th = tcp_hdr(skb);
-
-       th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb),
-                                 iph->saddr, iph->daddr, 0);
-       skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
-
-       return tcp_gro_complete(skb);
-}
-
 struct proto tcp_prot = {
        .name                   = "TCP",
        .owner                  = THIS_MODULE,
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
new file mode 100644 (file)
index 0000000..3a7525e
--- /dev/null
@@ -0,0 +1,332 @@
+/*
+ *     IPV4 GSO/GRO offload support
+ *     Linux INET implementation
+ *
+ *     This program is free software; you can redistribute it and/or
+ *     modify it under the terms of the GNU General Public License
+ *     as published by the Free Software Foundation; either version
+ *     2 of the License, or (at your option) any later version.
+ *
+ *     TCPv4 GSO/GRO support
+ */
+
+#include <linux/skbuff.h>
+#include <net/tcp.h>
+#include <net/protocol.h>
+
+struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
+                               netdev_features_t features)
+{
+       struct sk_buff *segs = ERR_PTR(-EINVAL);
+       struct tcphdr *th;
+       unsigned int thlen;
+       unsigned int seq;
+       __be32 delta;
+       unsigned int oldlen;
+       unsigned int mss;
+       struct sk_buff *gso_skb = skb;
+       __sum16 newcheck;
+       bool ooo_okay, copy_destructor;
+
+       if (!pskb_may_pull(skb, sizeof(*th)))
+               goto out;
+
+       th = tcp_hdr(skb);
+       thlen = th->doff * 4;
+       if (thlen < sizeof(*th))
+               goto out;
+
+       if (!pskb_may_pull(skb, thlen))
+               goto out;
+
+       oldlen = (u16)~skb->len;
+       __skb_pull(skb, thlen);
+
+       mss = tcp_skb_mss(skb);
+       if (unlikely(skb->len <= mss))
+               goto out;
+
+       if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
+               /* Packet is from an untrusted source, reset gso_segs. */
+               int type = skb_shinfo(skb)->gso_type;
+
+               if (unlikely(type &
+                            ~(SKB_GSO_TCPV4 |
+                              SKB_GSO_DODGY |
+                              SKB_GSO_TCP_ECN |
+                              SKB_GSO_TCPV6 |
+                              SKB_GSO_GRE |
+                              SKB_GSO_MPLS |
+                              SKB_GSO_UDP_TUNNEL |
+                              0) ||
+                            !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
+                       goto out;
+
+               skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
+
+               segs = NULL;
+               goto out;
+       }
+
+       copy_destructor = gso_skb->destructor == tcp_wfree;
+       ooo_okay = gso_skb->ooo_okay;
+       /* All segments but the first should have ooo_okay cleared */
+       skb->ooo_okay = 0;
+
+       segs = skb_segment(skb, features);
+       if (IS_ERR(segs))
+               goto out;
+
+       /* Only first segment might have ooo_okay set */
+       segs->ooo_okay = ooo_okay;
+
+       delta = htonl(oldlen + (thlen + mss));
+
+       skb = segs;
+       th = tcp_hdr(skb);
+       seq = ntohl(th->seq);
+
+       newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
+                                              (__force u32)delta));
+
+       do {
+               th->fin = th->psh = 0;
+               th->check = newcheck;
+
+               if (skb->ip_summed != CHECKSUM_PARTIAL)
+                       th->check =
+                            csum_fold(csum_partial(skb_transport_header(skb),
+                                                   thlen, skb->csum));
+
+               seq += mss;
+               if (copy_destructor) {
+                       skb->destructor = gso_skb->destructor;
+                       skb->sk = gso_skb->sk;
+                       /* {tcp|sock}_wfree() use exact truesize accounting :
+                        * sum(skb->truesize) MUST be exactly be gso_skb->truesize
+                        * So we account mss bytes of 'true size' for each segment.
+                        * The last segment will contain the remaining.
+                        */
+                       skb->truesize = mss;
+                       gso_skb->truesize -= mss;
+               }
+               skb = skb->next;
+               th = tcp_hdr(skb);
+
+               th->seq = htonl(seq);
+               th->cwr = 0;
+       } while (skb->next);
+
+       /* Following permits TCP Small Queues to work well with GSO :
+        * The callback to TCP stack will be called at the time last frag
+        * is freed at TX completion, and not right now when gso_skb
+        * is freed by GSO engine
+        */
+       if (copy_destructor) {
+               swap(gso_skb->sk, skb->sk);
+               swap(gso_skb->destructor, skb->destructor);
+               swap(gso_skb->truesize, skb->truesize);
+       }
+
+       delta = htonl(oldlen + (skb_tail_pointer(skb) -
+                               skb_transport_header(skb)) +
+                     skb->data_len);
+       th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
+                               (__force u32)delta));
+       if (skb->ip_summed != CHECKSUM_PARTIAL)
+               th->check = csum_fold(csum_partial(skb_transport_header(skb),
+                                                  thlen, skb->csum));
+out:
+       return segs;
+}
+EXPORT_SYMBOL(tcp_tso_segment);
+
+struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
+{
+       struct sk_buff **pp = NULL;
+       struct sk_buff *p;
+       struct tcphdr *th;
+       struct tcphdr *th2;
+       unsigned int len;
+       unsigned int thlen;
+       __be32 flags;
+       unsigned int mss = 1;
+       unsigned int hlen;
+       unsigned int off;
+       int flush = 1;
+       int i;
+
+       off = skb_gro_offset(skb);
+       hlen = off + sizeof(*th);
+       th = skb_gro_header_fast(skb, off);
+       if (skb_gro_header_hard(skb, hlen)) {
+               th = skb_gro_header_slow(skb, hlen, off);
+               if (unlikely(!th))
+                       goto out;
+       }
+
+       thlen = th->doff * 4;
+       if (thlen < sizeof(*th))
+               goto out;
+
+       hlen = off + thlen;
+       if (skb_gro_header_hard(skb, hlen)) {
+               th = skb_gro_header_slow(skb, hlen, off);
+               if (unlikely(!th))
+                       goto out;
+       }
+
+       skb_gro_pull(skb, thlen);
+
+       len = skb_gro_len(skb);
+       flags = tcp_flag_word(th);
+
+       for (; (p = *head); head = &p->next) {
+               if (!NAPI_GRO_CB(p)->same_flow)
+                       continue;
+
+               th2 = tcp_hdr(p);
+
+               if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
+                       NAPI_GRO_CB(p)->same_flow = 0;
+                       continue;
+               }
+
+               goto found;
+       }
+
+       goto out_check_final;
+
+found:
+       flush = NAPI_GRO_CB(p)->flush;
+       flush |= (__force int)(flags & TCP_FLAG_CWR);
+       flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
+                 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
+       flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
+       for (i = sizeof(*th); i < thlen; i += 4)
+               flush |= *(u32 *)((u8 *)th + i) ^
+                        *(u32 *)((u8 *)th2 + i);
+
+       mss = tcp_skb_mss(p);
+
+       flush |= (len - 1) >= mss;
+       flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
+
+       if (flush || skb_gro_receive(head, skb)) {
+               mss = 1;
+               goto out_check_final;
+       }
+
+       p = *head;
+       th2 = tcp_hdr(p);
+       tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
+
+out_check_final:
+       flush = len < mss;
+       flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
+                                       TCP_FLAG_RST | TCP_FLAG_SYN |
+                                       TCP_FLAG_FIN));
+
+       if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
+               pp = head;
+
+out:
+       NAPI_GRO_CB(skb)->flush |= flush;
+
+       return pp;
+}
+EXPORT_SYMBOL(tcp_gro_receive);
+
+int tcp_gro_complete(struct sk_buff *skb)
+{
+       struct tcphdr *th = tcp_hdr(skb);
+
+       skb->csum_start = skb_transport_header(skb) - skb->head;
+       skb->csum_offset = offsetof(struct tcphdr, check);
+       skb->ip_summed = CHECKSUM_PARTIAL;
+
+       skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+
+       if (th->cwr)
+               skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
+
+       return 0;
+}
+EXPORT_SYMBOL(tcp_gro_complete);
+
+static int tcp_v4_gso_send_check(struct sk_buff *skb)
+{
+       const struct iphdr *iph;
+       struct tcphdr *th;
+
+       if (!pskb_may_pull(skb, sizeof(*th)))
+               return -EINVAL;
+
+       iph = ip_hdr(skb);
+       th = tcp_hdr(skb);
+
+       th->check = 0;
+       skb->ip_summed = CHECKSUM_PARTIAL;
+       __tcp_v4_send_check(skb, iph->saddr, iph->daddr);
+       return 0;
+}
+
+static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
+{
+       const struct iphdr *iph = skb_gro_network_header(skb);
+       __wsum wsum;
+       __sum16 sum;
+
+       switch (skb->ip_summed) {
+       case CHECKSUM_COMPLETE:
+               if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
+                                 skb->csum)) {
+                       skb->ip_summed = CHECKSUM_UNNECESSARY;
+                       break;
+               }
+flush:
+               NAPI_GRO_CB(skb)->flush = 1;
+               return NULL;
+
+       case CHECKSUM_NONE:
+               wsum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
+                                         skb_gro_len(skb), IPPROTO_TCP, 0);
+               sum = csum_fold(skb_checksum(skb,
+                                            skb_gro_offset(skb),
+                                            skb_gro_len(skb),
+                                            wsum));
+               if (sum)
+                       goto flush;
+
+               skb->ip_summed = CHECKSUM_UNNECESSARY;
+               break;
+       }
+
+       return tcp_gro_receive(head, skb);
+}
+
+static int tcp4_gro_complete(struct sk_buff *skb)
+{
+       const struct iphdr *iph = ip_hdr(skb);
+       struct tcphdr *th = tcp_hdr(skb);
+
+       th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb),
+                                 iph->saddr, iph->daddr, 0);
+       skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
+
+       return tcp_gro_complete(skb);
+}
+
+static const struct net_offload tcpv4_offload = {
+       .callbacks = {
+               .gso_send_check =       tcp_v4_gso_send_check,
+               .gso_segment    =       tcp_tso_segment,
+               .gro_receive    =       tcp4_gro_receive,
+               .gro_complete   =       tcp4_gro_complete,
+       },
+};
+
+int __init tcpv4_offload_init(void)
+{
+       return inet_add_offload(&tcpv4_offload, IPPROTO_TCP);
+}