[CRIU] [PATCH 1/2] tcp: allow to enable repair mode for sockets in closing states

Andrey Vagin avagin at openvz.org
Thu Apr 10 13:25:38 PDT 2014

The repair mode is used for dumping state of tcp connections
(sequence numbers, queues, options, etc).

Currently the repair mode can be enalbed only for sockets in the
TCP_ESTABLISHED state. If a socket in another state, its internal
state can not be dumped.

Same time there is no guarantee that a connection won't be in other
states when we are dumping it, thus to be able to dump and restore
such states we need to get rid of CLOSE,ESTABLISHED in-kernel

I see nothing wrong to allow enabling of the repair mode for connected
sockets in any states.

Cc: "David S. Miller" <davem at davemloft.net>
Cc: Alexey Kuznetsov <kuznet at ms2.inr.ac.ru>
Cc: James Morris <jmorris at namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji at linux-ipv6.org>
Cc: Patrick McHardy <kaber at trash.net>
Cc: Eric Dumazet <edumazet at google.com>
Cc: Pavel Emelyanov <xemul at parallels.com>
Cc: Cyrill Gorcunov <gorcunov at openvz.org>
Signed-off-by: Andrey Vagin <avagin at openvz.org>
 net/ipv4/tcp.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2c7e326..bcb1d59 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1106,15 +1106,18 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	if (unlikely(tp->repair)) {
+		err = -EINVAL;
+		if (tp->repair_queue == TCP_NO_QUEUE)
+			goto out_err;
+		if (sk->sk_state != TCP_ESTABLISHED)
+			goto out_err;
 		if (tp->repair_queue == TCP_RECV_QUEUE) {
 			copied = tcp_send_rcvq(sk, msg, size);
 			goto out;
-		err = -EINVAL;
-		if (tp->repair_queue == TCP_NO_QUEUE)
-			goto out_err;
 		/* 'common' sending to sendq */
@@ -2375,7 +2378,8 @@ void tcp_sock_destruct(struct sock *sk)
 static inline bool tcp_can_repair_sock(const struct sock *sk)
 	return ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN) &&
-		((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_ESTABLISHED));
+		!((1 << sk->sk_state) & (TCPF_LISTEN |
 static int tcp_repair_options_est(struct tcp_sock *tp,

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