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Date: Sun, 23 Feb 2003 00:15:50 -0300
From: Werner Almesberger <wa@almesberger.net>
To: chas williams <chas@locutus.cmf.nrl.navy.mil>
Cc: Mitchell Blank Jr <mitch@sfgoth.com>, "David S. Miller" <davem@redhat.com>,
       linux-kernel@vger.kernel.org
Subject: Re: [ATM] who 'owns' the skb created by drivers/atm?
Message-ID: <20030223001550.I2791@almesberger.net>
References: <20030220222404.B11525@sfgoth.com> <200302211608.h1LG8tGi014271@locutus.cmf.nrl.navy.mil>
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In-Reply-To: <200302211608.h1LG8tGi014271@locutus.cmf.nrl.navy.mil>; from chas@locutus.cmf.nrl.navy.mil on Fri, Feb 21, 2003 at 11:08:55AM -0500
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chas williams wrote:
> In message <20030220222404.B11525@sfgoth.com>,Mitchell Blank Jr writes:
>>Hmmmm.. I guess we've just been getting lucky before in that case - we've
>>always just left the ATM_SKB() stuff in there.

The "cb must be in virgin state" rule is indeed news to me. But
maybe the rule has always been there, and nobody really noticed :-)

> this is one option.  the other would be to clone the skb and pass the
> clone to the ip layer.  the last option, and the one i prefer, would
> be to make the atm drivers not modify skb->cb (or reset it) when passing
> up the skb.  the atm socket layer doesnt rely on it, and it would keep
> the 'extra' processing to a minimum.

I'm not sure this is the problem: as far as I remember, the ATM stack
doesn't assume that other layers leave skb->cb intact. In fact, it
shouldn't even touch an skb once it has been passed on.

BTW, I'm happy that ATM finally has a maintainer again. Thanks, Chas !

- Werner

-- 
  _________________________________________________________________________
 / Werner Almesberger, Buenos Aires, Argentina         wa@almesberger.net /
/_http://www.almesberger.net/____________________________________________/
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