Re: Change in alloc_skb() behavior in 3.2+ kernels?

On 2012-06-06, David Miller [off-list ref] wrote:

From: Grant Edwards <redacted>
Date: Wed, 6 Jun 2012 18:59:19 +0000 (UTC)

quoted

At the time it was written (probably 10+ years ago) it was relying on
the documented API for alloc_skb() that stated alloc_skb() either
returned an sk_buff of the requested size or it failed.

It was never a formal API that we would only allocate 'size'
amount of tailroom.

How can you say that?

From skbuff.c:

    /**
    *__alloc_skb-allocate a network buffer
    *@size: size to allocate
    *@gfp_mask: allocation mask
    *@fclone: allocate from fclone cache instead of head cache
    *and allocate a cloned (child) skb
    *@node: numa node to allocate memory on
    *

quoted

quoted

*Allocate a new &sk_buff. The returned buffer has no headroom and a
*tail room of size bytes. The object has a reference count of one.

    *The return is the buffer. On a failure the return is %NULL.
    *
    *Buffers may only be allocated from interrupts using a @gfp_mask of
    *%GFP_ATOMIC.
    */

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