Subject: Re: [RFC][PATCH 2/9] deadlock prevention core
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: David Miller <davem@davemloft.net>
Cc: tgraf@suug.ch, phillips@google.com, linux-mm@kvack.org,
       linux-kernel@vger.kernel.org, netdev@vger.kernel.org
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	 <20060809.165846.107940575.davem@davemloft.net>
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Date: Thu, 10 Aug 2006 08:25:59 +0200
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On Wed, 2006-08-09 at 16:58 -0700, David Miller wrote:
> From: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Date: Wed, 09 Aug 2006 16:07:20 +0200
> 
> > Hmm, what does sk_buff::input_dev do? That seems to store the initial
> > device?
> 
> You can run grep on the tree just as easily as I can which is what I
> did to answer this question.  It only takes a few seconds of your
> time to grep the source tree for things like "skb->input_dev", so
> would you please do that before asking more questions like this?

That is exactly what I did, but I wanted a bit of confirmation. Sorry if
it 
offends you, but I'm a bit new to this network thing.

> It does store the initial device, but as Thomas tried so hard to
> explain to you guys these device pointers in the skb are transient and
> you cannot refer to them outside of packet receive processing.

Yes, I understood that after Thomas' last mail.

> The reason is that there is no refcounting performed on these devices
> when they are attached to the skb, for performance reasons, and thus
> the device can be downed, the module for it removed, etc. long before
> the skb is freed up.

I understood that, thanks.

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