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Date: Tue, 10 Apr 2001 08:07:13 +0200
From: Andi Kleen <ak@suse.de>
To: Imran.Patel@nokia.com
Cc: netfilter-devel@us5.samba.org, netdev@oss.sgi.com,
        linux-kernel@vger.kernel.org
Subject: Re: skb allocation problems
Message-ID: <20010410080713.B9549@gruyere.muc.suse.de>
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In-Reply-To: <2D6CADE9B0C6D411A27500508BB3CBD063CF07@eseis15nok>; from Imran.Patel@nokia.com on Mon, Apr 09, 2001 at 07:03:46PM +0300
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On Mon, Apr 09, 2001 at 07:03:46PM +0300, Imran.Patel@nokia.com wrote:
> I have written a test module which closely mirrors what my code tries to
> do(attached below). This is what i get:
> 
> PRE_R: old skb:c371ee40  new skb:c371ee30 

I guess oldskb->len is <=0xc, and the slab allocator packs them near together
in the same zone.

>         printk("\nPRE_R: old skb:%p", (*pskb)->data);
> 
> /* translation happens in the real code here */
> 
>         skb = alloc_skb((*pskb)->len, GFP_ATOMIC);
>         if(!skb)
>                 printk("alloc failed");

I guess you want a return here.

>         skb_reserve(skb, 16);

You cannot do that if you didn't make sure that the old skb had enough
room for it (or rather it'll sometimes panic) 


-Andi
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