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

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Message-ID: <4ADC9DE2.5010308@gmail.com>
Date:	Mon, 19 Oct 2009 19:12:02 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Michal Ostrowski <mostrows@...il.com>
CC:	Cyrill Gorcunov <gorcunov@...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

Michal Ostrowski a écrit :
> Here's a bigger patch that just gets rid of flush_lock altogether.
> 
> We were seeing oopses due to net namespaces going away while we were using
> them, which turns out is simply due to the fact that pppoew wasn't claiming ref
> counts properly.
> 
> Fixing this requires that adding and removing entries to the per-net hash-table
> requires incrementing and decrementing the ref count.  This also allows us to
> get rid of the flush_lock since we can now depend on the existence of
> "pn->hash_lock".
> 
> We also have to be careful when flushing devices that removal of a hash table
> entry may bring the net namespace refcount to 0.
> 

Your patch is mangled (tabulation -> white spaces),

and I dont believe namespace refcount can reach 0 inside pppoe_flush_dev(),
it would be a bug from core network code.


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