syncookies: remove last_synq_overflow from struct tcp_sock

last_synq_overflow eats 4 or 8 bytes in struct tcp_sock, even
though it is only used when a listening sockets syn queue
is full.

We can (ab)use rx_opt.ts_recent_stamp to store the same information;
it is not used otherwise as long as a socket is in listen state.

Move linger2 around to avoid splitting struct mtu_probe
across cacheline boundary on 32 bit arches.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 3 deletions

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index b35a950d2e06..cd2b97f1b6e1 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -161,13 +161,12 @@ static __u16 const msstab[] = {
  */
 __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp)
 {
-        struct tcp_sock *tp = tcp_sk(sk);
         const struct iphdr *iph = ip_hdr(skb);
         const struct tcphdr *th = tcp_hdr(skb);
         int mssind;
         const __u16 mss = *mssp;
 
-        tp->last_synq_overflow = jiffies;
+        tcp_synq_overflow(sk);
 
         /* XXX sort msstab[] by probability?  Binary search? */
         for (mssind = 0; mss > msstab[mssind + 1]; mssind++)
@@ -268,7 +267,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
         if (!sysctl_tcp_syncookies || !th->ack)
                 goto out;
 
-        if (time_after(jiffies, tp->last_synq_overflow + TCP_TIMEOUT_INIT) ||
+        if (tcp_synq_no_recent_overflow(sk) ||
             (mss = cookie_check(skb, cookie)) == 0) {
                 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESFAILED);
                 goto out;