[PATCH] [RFC] tcp: add ability to set a timestamp offset (v2)

Andrey Vagin
2013-01-23T15:02:59Z

If a TCP socket will get live-migrated from one box to another the
timestamps (which are typically ON) will get screwed up -- the new
kernel will generate TS values that has nothing to do with what they
were on dump. The solution is to yet again fix the kernel and put a
"timestamp offset" on a socket.

v2: We can't adjust tcp_time_stamp only for output packets, because
echoed timestamp values will also no longer have a meaningful
relationship to tcp_time_stamp. That violates assumptions made in
several places in the code, which assumes that we can compare echoed
timestamp values to tcp_time_stamp; //Neal Cardwell

This version is a "bit more" radical. It makes tcp_time_stamp dependent
on tcp_sock. The idea of this patch is in the next two lines:

-#define tcp_time_stamp ((__u32)(jiffies))
+#define tcp_time_stamp(tp) ((__u32)(jiffies) + tp->tsoffset)

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>

Andrey Vagin (2):
tcp: make tcp_timestamp dependent on tcp_sock
tcp: add ability to set a timestamp offset (v2)

include/linux/tcp.h | 2 ++
include/net/tcp.h | 15 +++++++++-----
include/uapi/linux/tcp.h | 1 +
net/ipv4/syncookies.c | 4 ++--
net/ipv4/tcp.c | 9 +++++++-
net/ipv4/tcp_bic.c | 10 ++++-----
net/ipv4/tcp_cubic.c | 14 ++++++-------
net/ipv4/tcp_htcp.c | 2 +-
net/ipv4/tcp_input.c | 53 +++++++++++++++++++++++++-----------------------
net/ipv4/tcp_ipv4.c | 19 +++++++++--------
net/ipv4/tcp_lp.c | 10 ++++-----
net/ipv4/tcp_metrics.c | 2 +-
net/ipv4/tcp_output.c | 35 +++++++++++++++++---------------
net/ipv4/tcp_timer.c | 9 ++++----
net/ipv4/tcp_westwood.c | 8 +++++---
net/ipv6/tcp_ipv6.c | 22 ++++++++++++--------
16 files changed, 123 insertions(+), 92 deletions(-)

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1.7.11.7