4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jason Xing <kernelxing@xxxxxxxxxxx>
[ Upstream commit a46d0ea5c94205f40ecf912d1bb7806a8a64704f ]
According to RFC 1213, we should also take CLOSE-WAIT sockets into
consideration:
"tcpCurrEstab OBJECT-TYPE
...
The number of TCP connections for which the current state
is either ESTABLISHED or CLOSE- WAIT."
After this, CurrEstab counter will display the total number of
ESTABLISHED and CLOSE-WAIT sockets.
The logic of counting
When we increment the counter?
a) if we change the state to ESTABLISHED.
b) if we change the state from SYN-RECEIVED to CLOSE-WAIT.
When we decrement the counter?
a) if the socket leaves ESTABLISHED and will never go into CLOSE-WAIT,
say, on the client side, changing from ESTABLISHED to FIN-WAIT-1.
b) if the socket leaves CLOSE-WAIT, say, on the server side, changing
from CLOSE-WAIT to LAST-ACK.
Please note: there are two chances that old state of socket can be changed
to CLOSE-WAIT in tcp_fin(). One is SYN-RECV, the other is ESTABLISHED.
So we have to take care of the former case.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jason Xing <kernelxing@xxxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/ipv4/tcp.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index e3475f833f8fe..0cbfb57de0f07 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2242,6 +2242,10 @@ void tcp_set_state(struct sock *sk, int state)
if (oldstate != TCP_ESTABLISHED)
TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
break;
+ case TCP_CLOSE_WAIT:
+ if (oldstate == TCP_SYN_RECV)
+ TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
+ break;
case TCP_CLOSE:
if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
@@ -2253,7 +2257,7 @@ void tcp_set_state(struct sock *sk, int state)
inet_put_port(sk);
/* fall through */
default:
- if (oldstate == TCP_ESTABLISHED)
+ if (oldstate == TCP_ESTABLISHED || oldstate == TCP_CLOSE_WAIT)
TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
}
--
2.43.0
