Re: [PATCH] KVM: x86: Kick VCPU outside PIC lock again

Jan Kiszka
2010-02-24T09:54:45Z

Avi Kivity wrote:
> On 02/24/2010 11:41 AM, Jan Kiszka wrote:
>> Thomas Gleixner wrote:
>>
>>> On Tue, 23 Feb 2010, Jan Kiszka wrote:
>>>
>>>
>>>> Thomas Gleixner wrote:
>>>>
>>>>> The i8254/i8259 locks need to be real spinlocks on preempt-rt. Convert
>>>>> them to raw_spinlock. No change for !RT kernels.
>>>>>
>>>> Doesn't fly for -rt anymore: pic_irq_update runs under this raw lock and
>>>> calls kvm_vcpu_kick which tries to wake_up some thread -> scheduling
>>>> while atomic.
>>>>
>>> Hmm, a wakeup itself is fine. Is that code waking a wake queue ?
>>>
>> Yes, it's a wake queue.
>>
>
> So what's the core issue? Is the lock_t in the wait_queue a sleeping mutex?

Yep.

Jan

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