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    SubjectRe: [PATCH] locking/lock_events: Use this_cpu_add() when necessary
    On Wed, May 22, 2019 at 8:40 AM Waiman Long <longman@redhat.com> wrote:
    >
    > +#if defined(CONFIG_PREEMPT) && \
    > + (defined(CONFIG_DEBUG_PREEMPT) || !defined(CONFIG_X86))
    > +#define lockevent_percpu_inc(x) this_cpu_inc(x)
    > +#define lockevent_percpu_add(x, v) this_cpu_add(x, v)

    Why that CONFIG_X86 special case?

    On x86, the regular non-underscore versionm is perfectly fine, and the
    underscore is no faster or simpler.

    So just make it be

    #if defined(CONFIG_PREEMPT)
    .. non-underscore versions..
    #else
    .. underscore versions ..
    #endif

    and realize that x86 simply doesn't _care_. On x86, it will be one
    single instruction regardless.

    Non-x86 may prefer the underscore versions for the non-preempt case.

    Linus

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