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, 1 insertions, 3 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 9d5078bd23a3..8afac76cd748 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -377,7 +377,7 @@ struct tcp_sock {
         unsigned int            keepalive_time;   /* time before keep alive takes place */
         unsigned int            keepalive_intvl;  /* time interval between keep alive probes */
 
-        unsigned long last_synq_overflow; 
+        int                     linger2;
 
 /* Receiver side RTT estimation */
         struct {
@@ -406,8 +406,6 @@ struct tcp_sock {
 /* TCP MD5 Signagure Option information */
         struct tcp_md5sig_info  *md5sig_info;
 #endif
-
-        int                     linger2;
 };
 
 static inline struct tcp_sock *tcp_sk(const struct sock *sk)