Re: [PATCH v2] x86/platform/uv: Dont use smp_processor_id while preemptible

[Andy Shevchenko]

On Thu, Sep 22, 2022 at 11:01 PM Mike Travis <mike.travis@xxxxxxx> wrote:
>
> To avoid a "BUG: using smp_processor_id() in preemptible" debug warning
> message, disable preemption around use of the processor id.  This code
> sequence merely decides which portal that this CPU uses to read the RTC.
> It does this to avoid thrashing the cache but even if preempted it still
> reads the same time from the single RTC clock.

...

> Signed-off-by: Mike Travis <mike.travis@xxxxxxx>
> Reviewed-by: Steve Wahl <steve.wahl@xxxxxxx>
> Reviewed-by: Dimitri Sivanich <dimitri.sivanich@xxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx

No kernel version? No Fixes tag?

...

> -               offset = (uv_blade_processor_id() * L1_CACHE_BYTES) % PAGE_SIZE;
> +               offset = (uv_cpu_blade_processor_id(cpu) * L1_CACHE_BYTES) % PAGE_SIZE;

Perhaps it can be transformed to use offset_in_page() at the same time.

-- 
With Best Regards,
Andy Shevchenko