linux-kernel - Re: [RFC][PATCH 2/2] efi_pstore: add a sequence counter to a variable name

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Date:	Thu, 18 Oct 2012 16:47:40 -0700
From:	Mike Waychison <mikew@...gle.com>
To:	Seiji Aguchi <seiji.aguchi@....com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"Luck, Tony (tony.luck@...el.com)" <tony.luck@...el.com>,
	"Matthew Garrett (mjg@...hat.com)" <mjg@...hat.com>,
	"dzickus@...hat.com" <dzickus@...hat.com>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	Satoru Moriya <satoru.moriya@....com>
Subject: Re: [RFC][PATCH 2/2] efi_pstore: add a sequence counter to a variable name

On Fri, Oct 5, 2012 at 12:02 PM, Seiji Aguchi <seiji.aguchi@....com> wrote:
> [Problem]
>
> Currently, a variable name, which distinguishes each entry, consists of type, id and ctime.
> But if multiple events happens in a short time, a second/third event may fail to log because
> efi_pstore can't distinguish each event with current variable name.
>
> [Solution]
>
>   A reasonable way to identify all events precisely is introducing a sequence counter to
>   the variable name.
>
> [Patch Description]
>
>   The sequence counter has already supported in a pstore layer with "oopscount".
>   So, this patch adds it to a variable name.
>   Also, it is passed to read/erase callbacks of platform drivers in accordance with
>   the modification of the variable name.
>
>   <before applying this patch>
>  a variable name of first event: dump-type0-1-12345678
>  a variable name of second event: dump-type0-1-12345678
>
>   type:0
>   id:1
>   ctime:12345678
>
>  If multiple events happen in a short time, efi_pstore can't distinguish them because
>  variable names are same among them.
>
>   <after applying this patch>
>
>  it can be distinguishable by adding a sequence counter as follows.
>
>  a variable name of first event: dump-type0-1-1-12345678
>  a variable name of Second event: dump-type0-1-2-12345678
>
>   type:0
>   id:1
>   sequence counter: 1(first event), 2(second event)
>   ctime:12345678

This patch plumbs the count through the same way as you plumbed the
ctime through in patch 1/2, so I'm going to hold off on commenting on
this patch until we better understand i_ctime use is resolved there.
I suspect that we don't want to continue adding more arguments through
pstore ops this way.
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