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    SubjectRe: [PATCH 10/43] stop_machine: reimplement without using workqueue
    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. Do you think removing it would be better?

    Thanks.

    --
    tejun


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