netdev - Re: [PATCH] can-raw: Fix skb_orphan

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Date:	Tue, 03 Aug 2010 17:22:47 +0200
From:	Oliver Hartkopp <socketcan@...tkopp.net>
To:	David Miller <davem@...emloft.net>
CC:	eric.dumazet@...il.com, patrick.ohly@...el.com,
	netdev@...r.kernel.org, socketcan-core@...ts.berlios.de,
	matthias.fuchs@....eu
Subject: Re: [PATCH] can-raw: Fix skb_orphan_try handling

On 03.08.2010 09:30, David Miller wrote:
> From: Oliver Hartkopp <socketcan@...tkopp.net>
> Date: Sun, 01 Aug 2010 12:50:16 +0200
> 
>> On 01.08.2010 10:03, David Miller wrote:
>>> From: Oliver Hartkopp <socketcan@...tkopp.net>
>>> Date: Fri, 30 Jul 2010 11:44:27 +0200
>>>
>>>> Hello Eric, hello Patrick,
>>>>
>>>> Commit fc6055a5ba31e2c14e36e8939f9bf2b6d586a7f5 (net: Introduce
>>>> skb_orphan_try()) allows an early orphan of the skb and takes care on
>>>> tx timestamping, which needs the sk-reference in the skb on driver level.
>>>> So does the can-raw socket, which has not been taken into account here.
>>>>
>>>> The patch below adds a 'prevent_sk_orphan' bit in the skb tx shared info,
>>>> which fixes the problem discovered by Matthias Fuchs here:
>>>>
>>>>       http://marc.info/?t=128030411900003&r=1&w=2
>>>
>>> Your patch sets this new value, but I never see it getting tested anywhere.
>>>
>>> How does this work?
>>
>>
>> The flags are tested all together in skb_orphan_try() ...
> 
> This is why I hate using unions in situations like this... it makes
> code impossible to audit easily.
> 
> This damn thing should just be a "u8 flags" and a bunch of bit mask
> CPP macro defines for the various boolean values.

Yep! I also felt like this.

Maybe Patrick Ohly can give some feedback, if he's ok with that kind of
change. So far there are only a few places that would need to be changed for
the flags bitops.

> Anyways, I'll apply your patch thanks.

Thanks!

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