Messages in this thread | | | Date | Mon, 1 Mar 2010 17:50:38 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH 10/43] stop_machine: reimplement without using workqueue |
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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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