Messages in this thread | | | Date | Sun, 9 Dec 2012 20:48:26 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC PATCH v3 7/9] yield_to(), cpu-hotplug: Prevent offlining of other CPUs properly |
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On 12/07, Srivatsa S. Bhat wrote: > > Once stop_machine() is gone from the CPU offline path, we won't be able to > depend on local_irq_save() to prevent CPUs from going offline from under us.
OK, I guess we need to avoid resched_task()->smp_send_reschedule() after __cpu_disable() and before migrate_tasks().
But, whatever problem we have,
> Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, > while invoking from atomic context.
it should be solved, so...
> - if (preempt && rq != p_rq) > + if (preempt && rq != p_rq && cpu_online(task_cpu(p)))
Why do we need this change?
Afaics, you could add BUG_ON(!cpu_online(...)) instead?
I am just curious.
Oleg.
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