netdev - Re: kernel panic in latest vanilla stable, while using nameif with "alive" pppoe interfaces

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Date:	Tue, 20 Oct 2009 09:17:59 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Michal Ostrowski <mostrows@...il.com>,
	Denys Fedoryschenko <denys@...p.net.lb>,
	netdev <netdev@...r.kernel.org>, linux-ppp@...r.kernel.org,
	paulus@...ba.org, mostrows@...thlink.net
Subject: Re: kernel panic in latest vanilla stable, while using nameif with 
	"alive" pppoe interfaces

On 10/20/09, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Cyrill Gorcunov a écrit :
>> On 10/20/09, Eric Dumazet <eric.dumazet@...il.com> wrote:
>>> Michal Ostrowski a écrit :
>>>> Access of po->pppoe_dev is guarded by sk->sk_state & PPPOX_CONNECTED,
>>>> and all use cases now rely on the socket lock.  Because of this, the
>>>> ref-count on the namespace held by the socket object suffices to hold
>>>> the namespace in existence and so we don't need to ref-count the
>>>> namespace in PPPoE. The flush_lock is gone.
>>>>
>>> Seems good !
>>>
>>> But can we use lock_sock() in __pppoe_xmit() context ?
>>>
>>
>> Eric, most probably i miss something, but how lock sock protect us
>> from mtu changed via sysfs. This action calls change mtu notifier
>> which doesn't care about sockets at all...
>
> This ultimately calls pppoe_flush_dev() and this function
> takes care of taking appropriate sock_locks() on each sockets ?
>
This hold and lock socks but set pppoe_dev to null as well. I'll back
later. And i need to reread the code.
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