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    SubjectRe: [PATCH 10/43] stop_machine: reimplement without using workqueue
    On 03/02, Tejun Heo wrote:
    >
    > Hello, again.
    >
    > On 02/28/2010 11:34 PM, Oleg Nesterov wrote:
    > > On 02/26, Tejun Heo wrote:
    > >>
    > >> @@ -164,19 +259,18 @@ int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus)
    > >> idle.fn = chill;
    > >> idle.data = NULL;
    > >>
    > >> + smp_wmb(); /* -> stop_cpu()::set_current_state() */
    > >> ...
    > >> + for_each_online_cpu(i)
    > >> + wake_up_process(*per_cpu_ptr(stop_machine_threads, i));
    > >
    > > Afaics, this smp_wmb() is not needed, wake_up_process() (try_to_wake_up)
    > > should ensure we can't race with set_current_state() + check_condition.
    > > It does, note the wmb() in try_to_wake_up().
    >
    > Yeap, the initial version was like that and it was awkward to explain
    > in the comment in stop_cpu() so I basically put it there as a
    > documentation anchor.

    OK,

    > Do you think removing it would be better?

    No, I just wanted to understand what I have missed. This applies to all
    my questions in this thread ;)

    Thanks,

    Oleg.



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