diff mbox series

[net,v3,1/2] tcp: count CLOSE-WAIT sockets for TCP_MIB_CURRESTAB

Message ID 20240530131308.59737-2-kerneljasonxing@gmail.com (mailing list archive)
State Superseded, archived
Delegated to: Matthieu Baerts
Headers show
Series tcp/mptcp: count CLOSE-WAIT for CurrEstab | expand

Checks

Context Check Description
matttbe/build success Build and static analysis OK
matttbe/checkpatch success total: 0 errors, 0 warnings, 0 checks, 18 lines checked
matttbe/shellcheck success MPTCP selftests files have not been modified
matttbe/KVM_Validation__normal success Success! ✅
matttbe/KVM_Validation__debug success Success! ✅
matttbe/KVM_Validation__btf__only_bpftest_all_ success Success! ✅

Commit Message

Jason Xing May 30, 2024, 1:13 p.m. UTC 
From: Jason Xing <kernelxing@tencent.com>

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@tencent.com>
---
previous discussion
Link: https://lore.kernel.org/all/20240529033104.33882-1-kerneljasonxing@gmail.com/
1. Chose to fix CurrEstab instead of introduing a new counter (Eric, Neal)
---
 net/ipv4/tcp.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Comments

Eric Dumazet May 31, 2024, 6:23 a.m. UTC | #1 
On Thu, May 30, 2024 at 3:13 PM Jason Xing <kerneljasonxing@gmail.com> wrote:
>
> From: Jason Xing <kernelxing@tencent.com>
>
> 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@tencent.com>

Reviewed-by: Eric Dumazet <edumazet@google.com>

Thanks.
diff mbox series

Patch

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 5fa68e7f6ddb..902266146d0e 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2646,6 +2646,10 @@  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)
@@ -2657,7 +2661,7 @@  void tcp_set_state(struct sock *sk, int state)
 			inet_put_port(sk);
 		fallthrough;
 	default:
-		if (oldstate == TCP_ESTABLISHED)
+		if (oldstate == TCP_ESTABLISHED || oldstate == TCP_CLOSE_WAIT)
 			TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
 	}