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

[Matt Fleming <matt@console-pimps.org>]

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

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

-- 
Matt Fleming, Intel Open Source Technology Center