[CRIU] [PATCH 2/2] tcp: refresh a data about tcp connection after blocking it (v4)

[Andrey Vagin]

We have a window between getting info about tcp connections
and blocking them. States of tcp connections can be changes,
so they should be refreshed after blocking.

https://bugzilla.openvz.org/show_bug.cgi?id=2419

v2: clean up
v3: don't update lengthes of queues for listen sockets,
    they don't used.
v4: check that a state of a tcp connection is ESTABLISHED or CLOSE

Signed-off-by: Andrey Vagin <avagin at openvz.org>
---
 sk-tcp.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/sk-tcp.c b/sk-tcp.c
index cc1af80..ca14f47 100644
--- a/sk-tcp.c
+++ b/sk-tcp.c
@@ -51,6 +51,38 @@ static int tcp_repair_on(int fd)
 	return ret;
 }
 
+static int refresh_inet_sk(int fd, struct inet_sk_desc *sk)
+{
+	int size;
+	struct tcp_info info;
+
+	if (sk->state == TCP_CLOSE)
+		return 0;
+
+	if (dump_opt(fd, SOL_TCP, TCP_INFO, &info)) {
+		pr_perror("Failt to obtain TCP_INFO");
+		return -1;
+	}
+
+	sk->state = info.tcpi_state;
+
+	if (ioctl(fd, SIOCOUTQ, &size) == -1) {
+		pr_perror("Unable to get size of snd queue");
+		return -1;
+	}
+
+	sk->wqlen = size;
+
+	if (ioctl(fd, SIOCINQ, &size) == -1) {
+		pr_perror("Unable to get size of recv queue");
+		return -1;
+	}
+
+	sk->rqlen = size;
+
+	return 0;
+}
+
 static int tcp_repair_establised(int fd, struct inet_sk_desc *sk)
 {
 	int ret;
@@ -298,6 +330,21 @@ int dump_one_tcp(int fd, struct inet_sk_desc *sk)
 		ret = nf_lock_connection(sk);
 		if (ret < 0)
 			return -1;
+
+		/* A state of a tcp connection could be changed */
+		ret = refresh_inet_sk(fd, sk);
+		if (ret < 0)
+			goto err;
+
+		if (sk->state == TCP_CLOSE) {
+			nf_unlock_connection(sk);
+			return 0;
+		}
+
+		if (sk->state != TCP_ESTABLISHED) {
+			pr_err("Unknown state %d\n", sk->state);
+			goto err;
+		}
 	}
 
 	pr_info("Dumping TCP connection\n");
-- 
1.7.11.7