From: James Chapman <jchapman@katalix•com>
To: Jarek Poplawski <jarkao2@gmail•com>
Cc: David Miller <davem@davemloft•net>, netdev@vger•kernel.org
Subject: Re: [PATCH][PPPOL2TP]: Fix SMP oops in pppol2tp driver
Date: Tue, 26 Feb 2008 12:14:26 +0000 [thread overview]
Message-ID: <47C402A2.8040401@katalix.com> (raw)
In-Reply-To: <20080225215837.GA3281@ami.dom.local>
Jarek Poplawski wrote:
> Jarek Poplawski wrote, On 02/25/2008 02:39 PM:
> ...
>> Hmm... Wait a minute! But on the other hand David has written about
>> his cons here, and it looks reasonable: this place would be fixed,
>> but some others can start reports like this. Maybe, it's better to
>> analyze yet if it's really so hard to eliminate taking this lock
>> on the xmit path?
>
> James, I wonder if you could try to test this patch below?
> ip_queue_xmit() seems to do proper things with __sk_dst_check(), and
> if some other functions don't behave similarly lockdep should tell.
> I think, you could test it with your "locks to _bh" patch (without
> pppol2tp_xmit() part), and maybe with my sock.c lockdep patch (it
> should help lockdep to see these locks a bit more distinctly).
I found the same thing and was running a variant of your patch last
night; rather than set skb->dst to NULL though, I use __sk_dst_get() and
let ip_queue_xmit() do the route lookup if it returns NULL. But this has
the same symptoms as the code I tried a few days ago - no lockdep errors
but a system lockup after up to several hours. Nothing is logged in the
syslog.
Luckily, I'm in the lab where my two borrowed servers are today so I
have access to their consoles. Hopefully I'll be able to find out why
there are hanging. Btw, they don't hang if I disable irqs around the
ppp_input() call.
Will update you later.
/james
> PS: Since ppp_generic isn't endangered for now I removed Paul from CC.
>
> ---
>
> diff --git a/drivers/net/pppol2tp.c b/drivers/net/pppol2tp.c
> index e0b072d..b94659a 100644
> --- a/drivers/net/pppol2tp.c
> +++ b/drivers/net/pppol2tp.c
> @@ -1058,7 +1058,7 @@ static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
>
> /* Get routing info from the tunnel socket */
> dst_release(skb->dst);
> - skb->dst = sk_dst_get(sk_tun);
> + skb->dst = NULL;
> skb_orphan(skb);
> skb->sk = sk_tun;
>
> --
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>
--
James Chapman
Katalix Systems Ltd
http://www.katalix.com
Catalysts for your Embedded Linux software development
next prev parent reply other threads:[~2008-02-26 12:14 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-11 9:22 [PATCH][PPPOL2TP]: Fix SMP oops in pppol2tp driver James Chapman
2008-02-11 18:57 ` Jarek Poplawski
2008-02-11 22:19 ` James Chapman
2008-02-11 22:49 ` Jarek Poplawski
2008-02-11 22:55 ` Jarek Poplawski
2008-02-11 23:42 ` James Chapman
2008-02-12 10:42 ` Jarek Poplawski
2008-02-11 23:41 ` James Chapman
2008-02-12 5:30 ` David Miller
2008-02-12 10:58 ` James Chapman
2008-02-12 13:24 ` Jarek Poplawski
2008-02-13 6:00 ` David Miller
2008-02-13 7:29 ` Jarek Poplawski
2008-02-14 13:00 ` Jarek Poplawski
2008-02-18 22:09 ` James Chapman
2008-02-18 23:01 ` Jarek Poplawski
2008-02-19 9:09 ` James Chapman
2008-02-19 4:29 ` David Miller
2008-02-19 9:03 ` James Chapman
2008-02-19 10:30 ` Jarek Poplawski
2008-02-19 10:36 ` Jarek Poplawski
2008-02-19 14:37 ` James Chapman
2008-02-19 23:06 ` Jarek Poplawski
2008-02-19 23:28 ` Jarek Poplawski
2008-02-20 16:02 ` James Chapman
2008-02-20 18:38 ` Jarek Poplawski
2008-02-20 22:37 ` James Chapman
2008-02-21 8:59 ` Jarek Poplawski
2008-02-21 9:53 ` James Chapman
2008-02-21 12:08 ` Jarek Poplawski
2008-02-21 17:09 ` Jarek Poplawski
2008-02-25 12:19 ` James Chapman
2008-02-25 13:05 ` Jarek Poplawski
2008-02-25 13:39 ` Jarek Poplawski
2008-02-25 14:02 ` Jarek Poplawski
2008-02-25 21:58 ` Jarek Poplawski
2008-02-26 12:14 ` James Chapman [this message]
2008-02-26 13:03 ` Jarek Poplawski
2008-02-26 13:18 ` Jarek Poplawski
2008-02-26 20:00 ` Jarek Poplawski
2008-03-02 20:29 ` James Chapman
2008-03-03 8:22 ` Jarek Poplawski
2008-03-03 9:35 ` Jarek Poplawski
2008-02-27 10:54 ` [PATCH][PPPOL2TP] add missing sock_put() in pppol2tp_recv_dequeue() Jarek Poplawski
2008-03-02 20:31 ` James Chapman
2008-03-04 4:49 ` David Miller
2008-02-27 11:48 ` [PATCH][PPPOL2TP] add missing sock_put() in pppol2tp_tunnel_closeall() Jarek Poplawski
2008-03-02 20:32 ` James Chapman
2008-03-04 4:49 ` David Miller
2008-02-22 14:16 ` [PATCH][NET] sock.c: sk_dst_lock lockdep keys and names per af_family Jarek Poplawski
2008-02-12 7:19 ` [PATCH][PPPOL2TP]: Fix SMP oops in pppol2tp driver Jarek Poplawski
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