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Reply-To: nicolas.dichtel@6wind.com
Subject: Re: [PATCH 01/14] resource limits: foundation for resource highwater
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To: Topi Miettinen <toiwoton@gmail.com>, linux-kernel@vger.kernel.org
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From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Organization: 6WIND
Message-ID: <578923F6.1070606@6wind.com>
Date: Fri, 15 Jul 2016 19:57:10 +0200
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Le 15/07/2016 18:27, Topi Miettinen a écrit :
[snip]
>> Why playing with version number? It complexifies the (userland) code and
>> existing applications break when the kernel is updated.
>> Goal of netlink is to be easily extensible. By adding a new attribute, existing
>> userspace tools won't break.
> 
> I just followed this text in taskstats.h. Does that give wrong advice?
> 
>  * The struct is versioned. Newer versions should only add fields to
>  * the bottom of the struct to maintain backward compatibility.
>  *
>  *
>  * To add new fields
>  *	a) bump up TASKSTATS_VERSION
>  *	b) add comment indicating new version number at end of struct
>  *	c) add new fields after version comment; maintain 64-bit alignment
I don't know taskstats well, but that is not how netlink works. There is no need
to manage a version with netlink, just add new attributes.


Regards,
Nicolas