On Thu, 9 Feb 2012, Benjamin Herrenschmidt wrote:
> We use __get_cpu_var() which triggers a false positive warning
> in smp_processor_id() thinking interrupts are enabled (at this
> point, they are soft-enabled but hard-disabled).
>
> Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
> ---
>
> I was initially planning to fix that with a more in-depth rework
> of how we do lazy irq disabling on powerpc, but that patch is
> becoming too complex for this release so I'll apply this as a
> stop-gap and leave the full rework for -next
Okay, thanks for the update, that's equivalent to the get_cpu_var
plus put_cpu_var patch I had generally been running with successfully.
(I was not at all confident that it was a sufficient fix, and have
to say "generally" above because one time I got something that looked
like recursive calls overflowing the stack, and IIRC something "irq"
did appear in each frame of the trace. But probably no connection,
never seen again, and I don't recall even which -rc or -next it was.)
Hugh
>
> diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
> index 701d4ac..01e2877 100644
> --- a/arch/powerpc/kernel/irq.c
> +++ b/arch/powerpc/kernel/irq.c
> @@ -118,10 +118,14 @@ static inline notrace void set_soft_enabled(unsigned
> long enable)
> static inline notrace void decrementer_check_overflow(void)
> {
> u64 now = get_tb_or_rtc();
> - u64 *next_tb = &__get_cpu_var(decrementers_next_tb);
> + u64 *next_tb;
> +
> + preempt_disable();
> + next_tb = &__get_cpu_var(decrementers_next_tb);
>
> if (now >= *next_tb)
> set_dec(1);
> + preempt_enable();
> }
>
> notrace void arch_local_irq_restore(unsigned long en)
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
