Patchwork [2/2] tcp: fix FIN_WAIT2 timer expression in /proc/net/tcp

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Submitter Toshiaki Makita
Date Feb. 12, 2013, 12:54 p.m.
Message ID <1360673668.10638.14.camel@ubuntu-vm-makita>
Download mbox | patch
Permalink /patch/219853/
State Changes Requested
Delegated to: David Miller
Headers show

Comments

Toshiaki Makita - Feb. 12, 2013, 12:54 p.m.
When tcp_fin_timeout is greater than 60, /proc/net/tcp shows
FIN_WAIT2 keepalive timer as expires in (tcp_fin_timeout - 60)
sec. This is confusing because the timer is not for keepalive
and the socket needs another timewait timer to disappear.

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
---
 net/ipv4/tcp_ipv4.c |   23 +++++++++++++++--------
 net/ipv6/tcp_ipv6.c |   23 +++++++++++++++--------
 2 files changed, 30 insertions(+), 16 deletions(-)
Eric Dumazet - Feb. 12, 2013, 2:57 p.m.
On Tue, 2013-02-12 at 21:54 +0900, Toshiaki Makita wrote:
> When tcp_fin_timeout is greater than 60, /proc/net/tcp shows
> FIN_WAIT2 keepalive timer as expires in (tcp_fin_timeout - 60)
> sec. This is confusing because the timer is not for keepalive
> and the socket needs another timewait timer to disappear.
> 
> Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
> ---
>  net/ipv4/tcp_ipv4.c |   23 +++++++++++++++--------
>  net/ipv6/tcp_ipv6.c |   23 +++++++++++++++--------
>  2 files changed, 30 insertions(+), 16 deletions(-)
> 
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index 629937d..32bde0e 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -2656,17 +2656,24 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
>  	int rx_queue;
>  
>  	if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
> -		timer_active	= 1;
> -		timer_expires	= icsk->icsk_timeout;
> +		timer_active		= 1;
> +		timer_expires		= icsk->icsk_timeout;
>  	} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
> -		timer_active	= 4;
> -		timer_expires	= icsk->icsk_timeout;
> +		timer_active		= 4;
> +		timer_expires		= icsk->icsk_timeout;
>  	} else if (timer_pending(&sk->sk_timer)) {
> -		timer_active	= 2;
> -		timer_expires	= sk->sk_timer.expires;
> +		if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) {
> +			timer_active	= 3;
> +			timer_expires	= sk->sk_timer.expires +
> +					  (tp->linger2 >= 0 ?
> +					   TCP_TIMEWAIT_LEN : 0);
> +		} else {
> +			timer_active	= 2;
> +			timer_expires	= sk->sk_timer.expires;
> +		}
>  	} else {
> -		timer_active	= 0;
> -		timer_expires = jiffies;
> +		timer_active		= 0;
> +		timer_expires		= jiffies;
>  	}
>  

I find this patch confusing :

1) Please don't change the indentation for a bug fix

2) You add a new 'active=3' field, that some user space
reading /proc/net/tcp wont expect.

So the changelog is not matching the changes.




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Eric Dumazet - Feb. 12, 2013, 3:13 p.m.
On Tue, 2013-02-12 at 06:57 -0800, Eric Dumazet wrote:

> I find this patch confusing :
> 
> 1) Please don't change the indentation for a bug fix
> 
> 2) You add a new 'active=3' field, that some user space
> reading /proc/net/tcp wont expect.
> 
> So the changelog is not matching the changes.

Also, net/ipv4/inet_diag.c was not changed


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Toshiaki Makita - Feb. 15, 2013, 8:26 a.m.
On Tue, 2013-02-12 at 07:13 -0800, Eric Dumazet wrote:
> On Tue, 2013-02-12 at 06:57 -0800, Eric Dumazet wrote:
> 
> > I find this patch confusing :
> > 
> > 1) Please don't change the indentation for a bug fix

OK, I will separate changes of indentation to another patch.

> > 
> > 2) You add a new 'active=3' field, that some user space
> > reading /proc/net/tcp wont expect.

I think, at least, it's harmless and beneficial for netstat.
Even without this change, a keepalive timer of an orphaned
FIN_WAIT2 socket will eventually turn to a timewait timer, 
and by default, or when tcp_fin_timeout is 60, there will be
only timewait timers for orphaned FIN_WAIT2.
If the socket is not closed and SO_KEEPALIVE is set, 
a keepalive timer of FIN_WAIT2 will also be shown in
/proc/net/tcp, whose state isn't equal to above one.
I don't know any application that will be damaged with this
change, and I think the possibility that this change affects
a bad influence to userspace is low.
Please advise.

> > 
> > So the changelog is not matching the changes.
> 
> Also, net/ipv4/inet_diag.c was not changed
> 

thank you for pointing out my mistake.
I will correct it, too.


Toshiaki Makita


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Patch

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 629937d..32bde0e 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2656,17 +2656,24 @@  static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
 	int rx_queue;
 
 	if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
-		timer_active	= 1;
-		timer_expires	= icsk->icsk_timeout;
+		timer_active		= 1;
+		timer_expires		= icsk->icsk_timeout;
 	} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
-		timer_active	= 4;
-		timer_expires	= icsk->icsk_timeout;
+		timer_active		= 4;
+		timer_expires		= icsk->icsk_timeout;
 	} else if (timer_pending(&sk->sk_timer)) {
-		timer_active	= 2;
-		timer_expires	= sk->sk_timer.expires;
+		if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) {
+			timer_active	= 3;
+			timer_expires	= sk->sk_timer.expires +
+					  (tp->linger2 >= 0 ?
+					   TCP_TIMEWAIT_LEN : 0);
+		} else {
+			timer_active	= 2;
+			timer_expires	= sk->sk_timer.expires;
+		}
 	} else {
-		timer_active	= 0;
-		timer_expires = jiffies;
+		timer_active		= 0;
+		timer_expires		= jiffies;
 	}
 
 	if (sk->sk_state == TCP_LISTEN)
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 93825dd..3af4f9d 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1795,17 +1795,24 @@  static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
 	srcp  = ntohs(inet->inet_sport);
 
 	if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
-		timer_active	= 1;
-		timer_expires	= icsk->icsk_timeout;
+		timer_active		= 1;
+		timer_expires		= icsk->icsk_timeout;
 	} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
-		timer_active	= 4;
-		timer_expires	= icsk->icsk_timeout;
+		timer_active		= 4;
+		timer_expires		= icsk->icsk_timeout;
 	} else if (timer_pending(&sp->sk_timer)) {
-		timer_active	= 2;
-		timer_expires	= sp->sk_timer.expires;
+		if (sp->sk_state == TCP_FIN_WAIT2 && sock_flag(sp, SOCK_DEAD)) {
+			timer_active	= 3;
+			timer_expires	= sp->sk_timer.expires +
+					  (tp->linger2 >= 0 ?
+					   TCP_TIMEWAIT_LEN : 0);
+		} else {
+			timer_active	= 2;
+			timer_expires	= sp->sk_timer.expires;
+		}
 	} else {
-		timer_active	= 0;
-		timer_expires = jiffies;
+		timer_active		= 0;
+		timer_expires		= jiffies;
 	}
 
 	seq_printf(seq,