tcp: shrink tcp6_timewait_sock by one cache line

While working on tcp listener refactoring, I found that it
would really make things easier if sock_common could include
the IPv6 addresses needed in the lookups, instead of doing
very complex games to get their values (depending on sock
being SYN_RECV, ESTABLISHED, TIME_WAIT)

For this to happen, I need to be sure that tcp6_timewait_sock
and tcp_timewait_sock consume same number of cache lines.

This is possible if we only use 32bits for tw_ttd, as we remove
one 32bit hole in inet_timewait_sock

inet_tw_time_stamp() is defined and used, even if its current
implementation looks like tcp_time_stamp : We might need finer
resolution for tcp_time_stamp in the future.

Before patch : sizeof(struct tcp6_timewait_sock) = 0xc8

After patch : sizeof(struct tcp6_timewait_sock) = 0xc0

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 5c71501fc917..dde8bad04481 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1811,7 +1811,7 @@ static void get_timewait6_sock(struct seq_file *seq,
         const struct in6_addr *dest, *src;
         __u16 destp, srcp;
         const struct inet6_timewait_sock *tw6 = inet6_twsk((struct sock *)tw);
-        long delta = tw->tw_ttd - jiffies;
+        s32 delta = tw->tw_ttd - inet_tw_time_stamp();
 
         dest = &tw6->tw_v6_daddr;
         src  = &tw6->tw_v6_rcv_saddr;