tcpv6: combine tcp_v6_send_(reset|ack)

$ codiff tcp_ipv6.o.old tcp_ipv6.o.new
net/ipv6/tcp_ipv6.c:
  tcp_v6_md5_hash_hdr | -144
  tcp_v6_send_ack     | -585
  tcp_v6_send_reset   | -540
 3 functions changed, 1269 bytes removed, diff: -1269

net/ipv6/tcp_ipv6.c:
  tcp_v6_send_response | +791
 1 function changed, 791 bytes added, diff: +791

tcp_ipv6.o.new:
 4 functions changed, 791 bytes added, 1269 bytes removed, diff: -478

I choose to leave the reset related netns comment in place (not
the one that is killed) as I cannot understand its English so
it's a bit hard for me to evaluate its usefulness :-).

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 40 insertions, 99 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 1941c5c888d3..13c65144a00a 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -942,7 +942,8 @@ static int tcp_v6_gso_send_check(struct sk_buff *skb)
         return 0;
 }
 
-static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
+static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
+                                 u32 ts, struct tcp_md5sig_key *key, int rst)
 {
         struct tcphdr *th = tcp_hdr(skb), *t1;
         struct sk_buff *buff;
@@ -951,31 +952,14 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
         struct sock *ctl_sk = net->ipv6.tcp_sk;
         unsigned int tot_len = sizeof(struct tcphdr);
         __be32 *topt;
-#ifdef CONFIG_TCP_MD5SIG
-        struct tcp_md5sig_key *key;
-#endif
-
-        if (th->rst)
-                return;
-
-        if (!ipv6_unicast_destination(skb))
-                return;
 
+        if (ts)
+                tot_len += TCPOLEN_TSTAMP_ALIGNED;
 #ifdef CONFIG_TCP_MD5SIG
-        if (sk)
-                key = tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr);
-        else
-                key = NULL;
-
         if (key)
                 tot_len += TCPOLEN_MD5SIG_ALIGNED;
 #endif
 
-        /*
-         * We need to grab some memory, and put together an RST,
-         * and then put it into the queue to be sent.
-         */
-
         buff = alloc_skb(MAX_HEADER + sizeof(struct ipv6hdr) + tot_len,
                          GFP_ATOMIC);
         if (buff == NULL)
@@ -990,18 +974,21 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
         t1->dest = th->source;
         t1->source = th->dest;
         t1->doff = tot_len / 4;
-        t1->rst = 1;
-
-        if(th->ack) {
-                t1->seq = th->ack_seq;
-        } else {
-                t1->ack = 1;
-                t1->ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin
-                                    + skb->len - (th->doff<<2));
-        }
+        t1->seq = htonl(seq);
+        t1->ack_seq = htonl(ack);
+        t1->ack = !rst || !th->ack;
+        t1->rst = rst;
+        t1->window = htons(win);
 
         topt = (__be32 *)(t1 + 1);
 
+        if (ts) {
+                *topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
+                                (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
+                *topt++ = htonl(tcp_time_stamp);
+                *topt++ = htonl(ts);
+        }
+
 #ifdef CONFIG_TCP_MD5SIG
         if (key) {
                 *topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
@@ -1036,7 +1023,8 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
                 if (xfrm_lookup(&buff->dst, &fl, NULL, 0) >= 0) {
                         ip6_xmit(ctl_sk, buff, &fl, NULL, 0);
                         TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
-                        TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
+                        if (rst)
+                                TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
                         return;
                 }
         }
@@ -1044,87 +1032,40 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
         kfree_skb(buff);
 }
 
-static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack, u32 win, u32 ts,
-                            struct tcp_md5sig_key *key)
+static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
 {
-        struct tcphdr *th = tcp_hdr(skb), *t1;
-        struct sk_buff *buff;
-        struct flowi fl;
-        struct net *net = dev_net(skb->dst->dev);
-        struct sock *ctl_sk = net->ipv6.tcp_sk;
-        unsigned int tot_len = sizeof(struct tcphdr);
-        __be32 *topt;
-
-        if (ts)
-                tot_len += TCPOLEN_TSTAMP_ALIGNED;
+        struct tcphdr *th = tcp_hdr(skb);
+        u32 seq = 0, ack_seq = 0;
 #ifdef CONFIG_TCP_MD5SIG
-        if (key)
-                tot_len += TCPOLEN_MD5SIG_ALIGNED;
+        struct tcp_md5sig_key *key;
 #endif
 
-        buff = alloc_skb(MAX_HEADER + sizeof(struct ipv6hdr) + tot_len,
-                         GFP_ATOMIC);
-        if (buff == NULL)
+        if (th->rst)
                 return;
 
-        skb_reserve(buff, MAX_HEADER + sizeof(struct ipv6hdr) + tot_len);
-
-        t1 = (struct tcphdr *) skb_push(buff, tot_len);
-
-        /* Swap the send and the receive. */
-        memset(t1, 0, sizeof(*t1));
-        t1->dest = th->source;
-        t1->source = th->dest;
-        t1->doff = tot_len / 4;
-        t1->seq = htonl(seq);
-        t1->ack_seq = htonl(ack);
-        t1->ack = 1;
-        t1->window = htons(win);
-
-        topt = (__be32 *)(t1 + 1);
-
-        if (ts) {
-                *topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
-                                (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
-                *topt++ = htonl(tcp_time_stamp);
-                *topt++ = htonl(ts);
-        }
+        if (!ipv6_unicast_destination(skb))
+                return;
 
 #ifdef CONFIG_TCP_MD5SIG
-        if (key) {
-                *topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
-                                (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG);
-                tcp_v6_md5_hash_hdr((__u8 *)topt, key,
-                                    &ipv6_hdr(skb)->saddr,
-                                    &ipv6_hdr(skb)->daddr, t1);
-        }
+        if (sk)
+                key = tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr);
+        else
+                key = NULL;
 #endif
 
-        buff->csum = csum_partial((char *)t1, tot_len, 0);
-
-        memset(&fl, 0, sizeof(fl));
-        ipv6_addr_copy(&fl.fl6_dst, &ipv6_hdr(skb)->saddr);
-        ipv6_addr_copy(&fl.fl6_src, &ipv6_hdr(skb)->daddr);
-
-        t1->check = csum_ipv6_magic(&fl.fl6_src, &fl.fl6_dst,
-                                    tot_len, IPPROTO_TCP,
-                                    buff->csum);
-
-        fl.proto = IPPROTO_TCP;
-        fl.oif = inet6_iif(skb);
-        fl.fl_ip_dport = t1->dest;
-        fl.fl_ip_sport = t1->source;
-        security_skb_classify_flow(skb, &fl);
+        if (th->ack)
+                seq = ntohl(th->ack_seq);
+        else
+                ack_seq = ntohl(th->seq) + th->syn + th->fin + skb->len -
+                          (th->doff << 2);
 
-        if (!ip6_dst_lookup(ctl_sk, &buff->dst, &fl)) {
-                if (xfrm_lookup(&buff->dst, &fl, NULL, 0) >= 0) {
-                        ip6_xmit(ctl_sk, buff, &fl, NULL, 0);
-                        TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
-                        return;
-                }
-        }
+        tcp_v6_send_response(skb, seq, ack_seq, 0, 0, key, 1);
+}
 
-        kfree_skb(buff);
+static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack, u32 win, u32 ts,
+                            struct tcp_md5sig_key *key)
+{
+        tcp_v6_send_response(skb, seq, ack, win, ts, key, 0);
 }
 
 static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)