[PATCH 01/18] powerpc: Make decrementer interrupt robust against offlined CPUs

[Michael Ellerman]

On Tue, 2011-03-08 at 17:37 +1100, Benjamin Herrenschmidt wrote:
> With some implementations, it is possible that a timer interrupt
> occurs every few seconds on an offline CPU. In this case, just
> re-arm the decrementer and return immediately
> 
> Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> ---
>  arch/powerpc/kernel/time.c |   15 +++++++++++----
>  1 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
> index 09d31db..ecebc7c 100644
> --- a/arch/powerpc/kernel/time.c
> +++ b/arch/powerpc/kernel/time.c
> @@ -577,14 +577,21 @@ void timer_interrupt(struct pt_regs * regs)
>  	struct clock_event_device *evt = &decrementer->event;
>  	u64 now;
>  
> +	/* Ensure a positive value is written to the decrementer, or else
> +	 * some CPUs will continuue to take decrementer exceptions
                                  ^

Seeing as you're moving it anyway, and maybe a full-stop.

cheers

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