netdev - Re: ax25 rose Re: kernel panic linux-2.6.27-rc7

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Message-ID: <20081003074351.GB5235@ff.dom.local>
Date:	Fri, 3 Oct 2008 07:43:51 +0000
From:	Jarek Poplawski <jarkao2@...il.com>
To:	"Bernard, f6bvp" <f6bvp@...e.fr>
Cc:	Linux Netdev List <netdev@...r.kernel.org>,
	Ralf Baechle DL5RB <ralf@...ux-mips.org>
Subject: Re: ax25 rose Re: kernel panic linux-2.6.27-rc7

On Fri, Oct 03, 2008 at 07:34:18AM +0000, Jarek Poplawski wrote:
> On 02-10-2008 21:48, Jarek Poplawski wrote:
> > On Thu, Oct 02, 2008 at 08:20:18PM +0200, Bernard, f6bvp wrote:
> ...
> >> Although I did not change anything, and contrarily to my previous
> >> observation, the system instability as shown above occurs
> >> systematically.
> >> There was no problem with Kernel 2.6.25-10 I was using before (with
> >> patches for AX25 and ROSE that are now included in 2.6.27-rc7).
> 
> Then it could be useful to try our luck with reverting some other
> "suspicious" changes added in the meantime. My first candidate is
> attached below. (So you could test this with vanilla 2.6.27-rc7 or
> later, with or without any of the patches in this thread, and the
> patch below reverted.)

Hmm... Of course, you could do this other way as well: 2.6.25-10 etc.
with this patch applied.

Jarek P.

> 
> >> I did not try 2.6.26 on this machine, thus I cannot tell if the bug was
> >> already present.
> >> Would it be worth to test 2.6.26 ?   
> > 
> > Yes, but only if you think you can do it safely.
> 
> This is still valid (it can wait).
> 
> Jarek P.
> 
> -------->
> 
> commit 30902dc3cb0ea1cfc7ac2b17bcf478ff98420d74
> Author: David S. Miller <davem@...emloft.net>
> Date:   Tue Jun 17 21:26:37 2008 -0700
> 
>     ax25: Fix std timer socket destroy handling.
>     
>     Tihomir Heidelberg - 9a4gl, reports:
>     
>     --------------------
>     I would like to direct you attention to one problem existing in ax.25
>     kernel since 2.4. If listening socket is closed and its SKB queue is
>     released but those sockets get weird. Those "unAccepted()" sockets
>     should be destroyed in ax25_std_heartbeat_expiry, but it will not
>     happen. And there is also a note about that in ax25_std_timer.c:
>     /* Magic here: If we listen() and a new link dies before it
>     is accepted() it isn't 'dead' so doesn't get removed. */
>     
>     This issue cause ax25d to stop accepting new connections and I had to
>     restarted ax25d approximately each day and my services were unavailable.
>     Also netstat -n -l shows invalid source and device for those listening
>     sockets. It is strange why ax25d's listening socket get weird because of
>     this issue, but definitely when I solved this bug I do not have problems
>     with ax25d anymore and my ax25d can run for months without problems.
>     --------------------
>     
>     Actually as far as I can see, this problem is even in releases
>     as far back as 2.2.x as well.
>     
>     It seems senseless to special case this test on TCP_LISTEN state.
>     Anything still stuck in state 0 has no external references and
>     we can just simply kill it off directly.
>     
>     Signed-off-by: David S. Miller <davem@...emloft.net>
> 
> diff --git a/net/ax25/ax25_std_timer.c b/net/ax25/ax25_std_timer.c
> index 96e4b92..cdc7e75 100644
> --- a/net/ax25/ax25_std_timer.c
> +++ b/net/ax25/ax25_std_timer.c
> @@ -39,11 +39,9 @@ void ax25_std_heartbeat_expiry(ax25_cb *ax25)
>  
>  	switch (ax25->state) {
>  	case AX25_STATE_0:
> -		/* Magic here: If we listen() and a new link dies before it
> -		   is accepted() it isn't 'dead' so doesn't get removed. */
> -		if (!sk || sock_flag(sk, SOCK_DESTROY) ||
> -		    (sk->sk_state == TCP_LISTEN &&
> -		     sock_flag(sk, SOCK_DEAD))) {
> +		if (!sk ||
> +		    sock_flag(sk, SOCK_DESTROY) ||
> +		    sock_flag(sk, SOCK_DEAD)) {
>  			if (sk) {
>  				sock_hold(sk);
>  				ax25_destroy_socket(ax25);
--
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