linux-kernel - Re: [PATCH v5 -next 2/2]efi_pstore: Introducing workqueue updating sysfs entries

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Date:	Sat, 09 Feb 2013 20:12:35 +0000
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Seiji Aguchi <seiji.aguchi@....com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"Luck, Tony (tony.luck@...el.com)" <tony.luck@...el.com>,
	"mikew@...gle.com" <mikew@...gle.com>,
	"cbouatmailru@...il.com" <cbouatmailru@...il.com>,
	"dzickus@...hat.com" <dzickus@...hat.com>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	Satoru Moriya <satoru.moriya@....com>
Subject: Re: [PATCH v5 -next 2/2]efi_pstore: Introducing workqueue updating
 sysfs entries

On Thu, 2013-01-24 at 00:41 +0000, Seiji Aguchi wrote:
> [Problem]
> efi_pstore creates sysfs entries, which enable users to access to NVRAM,
> in a write callback. If a kernel panic happens in an interrupt context,
> it may fail because it could sleep due to dynamic memory allocations during
> creating sysfs entries.
> 
> [Patch Description]
> This patch removes sysfs operations from a write callback by introducing 
> a workqueue updating sysfs entries which is scheduled after the write
> callback is called.
> 
> Also, the workqueue is kicked in a just oops case.
> A system will go down in other cases such as panic, clean shutdown and emergency 
> restart. And we don't need to create sysfs entries because there is no chance for 
> users to access to them.
> 
> efi_pstore will be robust against a kernel panic in an interrupt context with this patch.
> 
> Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>
> ---
>  drivers/firmware/efivars.c |   85 +++++++++++++++++++++++++++++++++++++++++---
>  include/linux/efi.h        |    3 +-
>  2 files changed, 82 insertions(+), 6 deletions(-)

Acked-by: Matt Fleming <matt.fleming@...el.com>

-- 
Matt Fleming, Intel Open Source Technology Center

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