Re: [PATCH v5 0/1] MR824: ntoskrnl: Implement KeGetCurrentProcessorNumberEx

[Jinoh Kang (＠iamahuman)]

Jinoh Kang (@iamahuman) commented about dlls/ntoskrnl.exe/ntoskrnl.c:
> +/***********************************************************************
> + *          KeGetCurrentProcessorNumberEx   (NTOSKRNL.EXE.@)
> + */
> +ULONG WINAPI KeGetCurrentProcessorNumberEx(PPROCESSOR_NUMBER process_number)
> +{
> +    FIXME("%p semi-stub\n", process_number);
> +
> +    if (process_number)
> +    {
> +        process_number->Group = 0;
> +        process_number->Reserved = 0;
> +        process_number->Number = NtGetCurrentProcessorNumber();
> +    }
> +
> +    return NtGetCurrentProcessorNumber();

You should only call `NtGetCurrentProcessorNumber()` once.  Otherwise, the processor number can change if the thread is preempted and then re-scheduled to another processor.  This leads to inconsistent values between the return value and the `process_number->Number` output.

In general, you should treat `NtGetCurrentProcessorNumber()` as being volatile.

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https://gitlab.winehq.org/wine/wine/-/merge_requests/824#note_8781