Re: [PATCH v5 -next 2/2]efi_pstore: Introducing workqueue updatingsysfs entries

From: Matt Fleming
Date: Sat Feb 09 2013 - 15:12:43 EST

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@xxxxxxx>
> ---
> drivers/firmware/efivars.c | 85 +++++++++++++++++++++++++++++++++++++++++---
> include/linux/efi.h | 3 +-
> 2 files changed, 82 insertions(+), 6 deletions(-)

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

Matt Fleming, Intel Open Source Technology Center

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