Re: [PATCH 3/5] inet_diag: Extend the meminfo report

[David Miller <davem@davemloft.net>]

From: Pavel Emelyanov <xemul@parallels.com>
Date: Wed, 28 Dec 2011 22:58:57 +0400

> On 12/28/2011 10:45 PM, David Miller wrote:
>> From: Pavel Emelyanov <xemul@parallels.com>
>> Date: Wed, 28 Dec 2011 17:38:40 +0400
>> 
>>> Add the backlog length and wmem and rmem buffers limits.
>>> With this the TCP memory info is full and can be analyzed.
>>>
>>> Few words about extending the existing structure. The nla engine stores lengths of
>>> fields and the nla parser will parse the new format successfully (checked on the ss
>>> tool). But new apps will have to take this field's length into account. Hopefully
>>> this is acceptable price for not introducing another ext bit and structure.
>>>
>>> Singed-off-by: Pavel Emelyanov <xemul@parallels.com>
>> 
>> I think you'll need to add a new extension, rather than create this incompatability.
>> 
> 
> OK, I will, but I seem to misunderstand the NLA's length value then. My impression is
> that it was introduced to make it possible to put the payload of different length,
> probably adding more stuff at the end.

It's to validate that the object inside the attribute has the expected length.