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

[Jan Kiszka]

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

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/