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

On Thu, Sep 22, 2022 at 11:01 PM Mike Travis mike.travis@hpe.com 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.

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Signed-off-by: Mike Travis mike.travis@hpe.com Reviewed-by: Steve Wahl steve.wahl@hpe.com Reviewed-by: Dimitri Sivanich dimitri.sivanich@hpe.com Cc: stable@vger.kernel.org

No kernel version? No Fixes tag?

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•           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.