Re: [PATCH] ARM: machine_power_off should not return

Ezequiel Garcia
2014-03-25T22:46:18Z

Let's Cc: LAKML, and To: Russell.

Russell, any comments on this?

Without this patch we got the heartbeat's reboot_notifier called twice while
testing the recent hibernation patches, which was unexpected and produced a
kernel panic: https://lkml.org/lkml/2014/3/19/363

Instead of fixing the heartbeat LED trigger, or the hibernation code, it
seems better to fix the ARM machine_power_off, as it's not supposed to return.

On Mar 24, Sebastian Capella wrote:
> Add loop to prevent return from machine_power_off if
> pm_power_off is null or does not halt the system.
> This caused a panic during hibernation testing on Kirkwood
> Openblocks A6 board.
>
> Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>
> Reported-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> ---
> arch/arm/kernel/process.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
> index f58b723..6ffdc2c 100644
> --- a/arch/arm/kernel/process.c
> +++ b/arch/arm/kernel/process.c
> @@ -217,6 +217,8 @@ void machine_power_off(void)
>
> if (pm_power_off)
> pm_power_off();
> + while (1)
> + cpu_relax();
> }
>
> /*
> --
> 1.7.9.5
>
> --
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--
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering