From mboxrd@z Thu Jan  1 00:00:00 1970
From: Neil Booth <neil@daikokuya.co.uk>
Subject: Re: sparse preprocessing confused
Date: Thu, 26 Apr 2007 23:38:52 +0900
Message-ID: <20070426143852.GB13111@daikokuya.co.uk>
References: <20070425164355.2c250388.rdunlap@xenotime.net> <118833cc0704251652r28f2431cs145a993e783a58bc@mail.gmail.com>
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To: Morten Welinder <mwelinder@gmail.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>, linux-sparse@vger.kernel.org

Morten Welinder wrote:-

> On 4/25/07, Randy Dunlap <rdunlap@xenotime.net> wrote:
> >Although this may just be a case of "it's fugly, kill it".
> >
> >In net/core/skbuff.c (2.6.21-rc7-mm1), we have:
> >
> >        memcpy(data + nhead, skb->head,
> >#ifdef NET_SKBUFF_DATA_USES_OFFSET
> >                skb->tail);
> >#else
> >                skb->tail - skb->head);
> >#endif
> 
> If memcpy happens to be a macro, that is not valid C.

It's undefined rather than invalid.  GCC makes an effort to
do "what you'd expect".

Neil.