Re: [PATCH 0/2] Protect cpu map updates from ACPI processor

[Rafael J. Wysocki]

On Monday, August 12, 2013 09:45:52 AM Toshi Kani wrote:
> CPU system maps are protected with reader/writer locks.  The reader
> lock, put_online_cpus(), assures that the maps are not updated while
> holding the lock.  The writer lock, cpu_hotplug_begin(), is used to
> udpate the cpu maps along with cpu_maps_update_begin().
> 
> However, the ACPI processor handler updates the cpu maps without
> holding the the writer lock.  This patchset fixes this problem.
> 
> ---
> The patchset is based on linux-next of the pm tree.

Basically looks OK to me, but I'd just merge the patches together,
because the [2/2] is the very reason for the change made by [1/2].

Also it would be good to mention the actual scenario that may lead
to problems with that.

Thanks,
Rafael


> ---
> Toshi Kani (2):
>  CPU hotplug: Export cpu_hotplug_begin() interface
>  ACPI: Acquire writer lock to update cpu maps
> 
> ---
>  drivers/acpi/acpi_processor.c | 21 ++++++++++++++++-----
>  include/linux/cpu.h           |  2 ++
>  kernel/cpu.c                  |  4 ++--
>  3 files changed, 20 insertions(+), 7 deletions(-)
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/