[PATCH RFC 0/3] tcp: allow to repair a tcp connections in closing states

[Andrey Vagin <avagin@openvz.org>]

Currently connections only in the TCP_ESTABLISHED state can be dumped and
restored. This series allows to restore connections in the FIN_WAIT_1,
FIN_WAIT_2, LAST_ACK, CLOSE_WAIT or CLOSING states.

For restoring closing states we need an ability to restore a fin packet
in a queue. In this series I suggest to use the interface of control
messages for that.

Here is an example of user-space code:

msg.msg_control = buf;
msg.msg_controllen = sizeof buf;
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = SOL_TCP;
cmsg->cmsg_type = TCP_CMSG_SEND_FIN;
cmsg->cmsg_len = CMSG_LEN(0);
msg.msg_controllen = cmsg->cmsg_len;
if (sendmsg(sk, &msg, 0) < 0) {
	pr_perror("sendmsg");
	return -1;
}

Andrey Vagin (3):
  tcp: allow to enable repair mode for sockets in any state
  tcp: check repair before fastopen in tcp_sendmsg
  tcp: add ability to restore a fin packet

 include/net/tcp.h        |  1 +
 include/uapi/linux/tcp.h |  3 +++
 net/ipv4/tcp.c           | 69 +++++++++++++++++++++++++++++++++++++-----------
 net/ipv4/tcp_input.c     |  2 +-
 4 files changed, 59 insertions(+), 16 deletions(-)

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: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrey Vagin <avagin@openvz.org>

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