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    SubjectRe: [PATCH 6/6] percpu: Add preemption checks to __this_cpu ops
    On Wed, Oct 16, 2013 at 12:52:38PM -0400, Steven Rostedt wrote:
    > On Wed, 16 Oct 2013 18:25:37 +0200
    > Peter Zijlstra <peterz@infradead.org> wrote:
    >
    > > But yes, the way its set-up an arch could indeed provide __this_cup_$op
    > > itself -- without providing the _$n variants; in which case the
    > > raw_cpu_$op provided by you is broken.
    > >
    > > Can't we have a 'simple' coccinelle script rename the entire __this_cpu*
    > > implementation over to raw_cpu* and then provide generic __this_cpu* ->
    > > raw_cpu maps?
    > >
    >
    > Perhaps we should match the way spinlocks are.
    >
    >
    > this_cpu*() be the normal use.
    >
    > raw_this_cpu() could perhaps not do the checks?
    >
    > arch_this_cpu() be the architecture specific version of this_cpu*

    In that case we'd need to do something like:

    this_cpu_$op -> this_cpu_$op_irq (disables irqs itself)
    __this_cpu_$op -> this_cpu_$op (with check)
    -> raw_cpu_$op (without the check)

    I don't think the arch bits feature heavily for percpu; normally an arch
    provides __this_cpu_$op_$n; raw_cpu_$op_$n in my latest proposal.


    Anyway; I don't think the spinlock pattern matches too good and I don't
    mind the proposed:

    this_cpu_$op (disables IRQs itself)
    __this_cpu_$op (with preemption check)
    raw_cpu_$op (without preemption check)




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