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    SubjectRe: [PATCH 10/43] stop_machine: reimplement without using workqueue
    On 03/02, Tejun Heo wrote:
    >
    > Hello,
    >
    > On 03/02/2010 12:37 AM, Oleg Nesterov wrote:
    > >
    > > Suppose that, when stop_machine_cpu_callback(CPU_POST_DEAD) is called,
    > > that stop_cpu() thread T is still running and it is going to check state
    > > before schedule().
    >
    > Oh, I see. I was thinking get/put_online_cpus() block is exclusive
    > against cpu_maps_update_begin/done() instead of
    > cpu_hotplug_begin/done(). Will update and add comments.

    Agreed, a little comment can help.

    But, just in case, I forgot to repeat this case is not possible anyway.
    _cpu_down() ensures idle_cpu(cpu) == T after __stop_machine(), this means
    that this SCHED_FIFO thread we are going to kthread_stop() later can't
    be active.

    Oleg.



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