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SubjectRe: [PATCH 2/2] ptrace: fix set_task_blockstep()->update_debugctlmsr() logic
On 08/03/2012 07:38 PM, Oleg Nesterov wrote:
>>> update_debugctlmsr(debugctl);
>>> + local_irq_enable();
>>
>> wouldn't preempt_disable() be enough?
>
> preempt_disable() can't help if interrupt handler changes
> other bits in between?

So perf() uses this register as well. Since perf() uses the raw
primitives (raw_spin_lock()) shouldn't you do the same? If I recall
correctly (but it is Friday and late) local_irq_enable() wouldn't
disable irqs on RT and perf takes the raw lock so the irqs there should
be really disabled.

>
> Oleg.

Sebastian


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