Re: [ 074/167] [PATCH 14/26] tcp: fix tcp_trim_head()

David Miller
2012-05-11T03:07:56Z

From: Ben Hutchings <ben@decadent.org.uk>
Date: Fri, 11 May 2012 04:00:15 +0100

> On Wed, 2012-05-09 at 03:16 -0500, Jonathan Nieder wrote:
>> Ben Hutchings wrote:
>>
>> > 3.2-stable review patch. If anyone has any objections, please let me know.
>> [...]
>> > [ Upstream commit 4fa48bf3c75069d636fc8830743c929a062e80dc ]
>> >
>> > commit f07d960df3 (tcp: avoid frag allocation for small frames)
>> > breaked assumption in tcp stack that skb is either linear (skb->data_len
>> > == 0), or fully fragged (skb->data_len == skb->len)
>> >
>> > tcp_trim_head() made this assumption, we must fix it.
>>
>> Is this needed in the context of 3.2.y (which does not include
>> f07d960df3)?
> [...]
>
> The code being replaced really didn't make sense, but unless there is
> some other case that breaks the assumption described then I don't think
> this meets the stable rules. David?

It's a prerequisite for cleanly applying the patch that comes right
afterwards.