netdev - Re: [RFC] skbuff: skb_mac_header_was

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Message-ID: <20090617163716.GA21530@ghostprotocols.net>
Date:	Wed, 17 Jun 2009 13:37:16 -0300
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Stephen Hemminger <shemminger@...tta.com>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [RFC] skbuff: skb_mac_header_was_set is always true on >32 bit

Em Wed, Jun 17, 2009 at 08:23:27AM -0700, Stephen Hemminger escreveu:
> Looking at the crash in log_martians(), one suspect is that the check for
> mac header being set is not correct.  The value of mac_header defaults to
> 0 on allocation, therefore skb_mac_header_was_set will always be true on
> platforms using NET_SKBUFF_USES_OFFSET.
> 
> Arnaldo, is this correct?
> 
> Signed-off-by: Stephen Hemminger <shemminger@...tta.com>

Yeah, looks right, I forgot to initialize it to the value I changed the
test in skb_mac_header_was_set when doing the offset patch :-\

Thanks!

Acked-by: Arnaldo Carvalho de Melo <acme@...hat.com>

> --- a/net/core/skbuff.c	2009-06-17 08:16:46.235188728 -0700
> +++ b/net/core/skbuff.c	2009-06-17 08:17:25.810314332 -0700
> @@ -201,6 +201,10 @@ struct sk_buff *__alloc_skb(unsigned int
>  	skb->data = data;
>  	skb_reset_tail_pointer(skb);
>  	skb->end = skb->tail + size;
> +#ifdef NET_SKBUFF_DATA_USES_OFFSET
> +	skb->mac_header = ~0U;
> +#endif
> +
>  	/* make sure we initialize shinfo sequentially */
>  	shinfo = skb_shinfo(skb);
>  	atomic_set(&shinfo->dataref, 1);
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