From: "François Cachereul" <f.cachereul@alphalink•fr>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: James Chapman <jchapman@katalix•com>,
"David S. Miller" <davem@davemloft•net>,
netdev@vger•kernel.org
Subject: Re: BUG in net/l2tp/l2tp_core.c
Date: Thu, 10 Oct 2013 09:37:18 +0200 [thread overview]
Message-ID: <5256592E.3080600@alphalink.fr> (raw)
In-Reply-To: <1381316730.4971.16.camel@edumazet-glaptop.roam.corp.google.com>
On 10/09/2013 01:05 PM, Eric Dumazet wrote:
> On Wed, 2013-10-09 at 12:11 +0200, François Cachereul wrote:
>> Hi,
>>
>> I got the following BUG when using l2tp modules with smp kernel.
>> I noticed that l2tp_xmit_skb uses bh_lock_sock/bh_unlok_sock which
>> doesn't seem to be correct because it does a lot of stuff and probably
>> sleep before releasing the lock. I try replacing
>> bh_lock_sock/bh_unlock_sock with lock_sock/release_sock and the BUG
>> doesn't happened anymore. Is it correct ?
>>
>> Regards
>> François
>>
>
> At first glance, you might read commit
> 6af88da14ee284aaad6e4326da09a89191ab6165
> ("l2tp: Fix locking in l2tp_core.c")
>
> l2tp_eth_dev_xmit() is called from BH context, so you cannot use
> lock_sock()
>
> Try the following patch instead :
>
> diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
> index f0a7ada..ffda81e 100644
> --- a/net/l2tp/l2tp_ppp.c
> +++ b/net/l2tp/l2tp_ppp.c
> @@ -353,7 +353,9 @@ static int pppol2tp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msgh
> goto error_put_sess_tun;
> }
>
> + local_bh_disable();
> l2tp_xmit_skb(session, skb, session->hdr_len);
> + local_bh_enable();
>
> sock_put(ps->tunnel_sock);
> sock_put(sk);
> @@ -422,7 +424,9 @@ static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
> skb->data[0] = ppph[0];
> skb->data[1] = ppph[1];
>
> + local_bh_disable();
> l2tp_xmit_skb(session, skb, session->hdr_len);
> + local_bh_enable();
>
> sock_put(sk_tun);
> sock_put(sk);
>
>
That works. Thanks
François
next prev parent reply other threads:[~2013-10-10 7:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-09 10:11 BUG in net/l2tp/l2tp_core.c François Cachereul
2013-10-09 11:05 ` Eric Dumazet
2013-10-10 7:37 ` François Cachereul [this message]
2013-10-10 13:30 ` [PATCH] l2tp: must disable bh before calling l2tp_xmit_skb() Eric Dumazet
2013-10-11 21:20 ` David Miller
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