netdev - Re: tun netns BUG()

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Message-ID: <20090703152547.GA28755@gondor.apana.org.au>
Date:	Fri, 3 Jul 2009 23:25:47 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	davem@...emloft.net, dwmw2@...radead.org, netdev@...r.kernel.org,
	johannes@...solutions.net
Subject: Re: tun netns BUG()

Eric W. Biederman <ebiederm@...ssion.com> wrote:
> 
> Not so.
> 
> unregister_netdevice
>  rollback_registered
>    tun_net_unit
>      __tun_detach.
> 
> 
> Further we need rtnl_lock around __tun_detach.

No we don't, tfile->count prevents this from occuring.  The async
path will only __tun_detach if the count hits zero, in which case
the first if clause in tun_chr_close will fail.  Conversely, if
we're in the first if clause in tun_chr_close, then the async
path either didn't execute at all or did not call __tun_detach.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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