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Date: Wed, 20 Oct 2010 17:03:51 -0500
From: Anthony Liguori <aliguori@linux.vnet.ibm.com>
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Subject: [Qemu-devel] Re: [PATCH 08/10] MCE: Relay UCR MCE to guest
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>, qemu-devel@nongnu.org, kvm@vger.kernel.org, Avi Kivity <avi@redhat.com>

On 10/20/2010 04:56 PM, Paolo Bonzini wrote:
> On 10/20/2010 09:51 PM, Anthony Liguori wrote:
>> I don't understand why this loop is needed but we specifically wait for
>> a signal to get delivered that's either SIG_IPI or SIGBUS. We then check
>> whether a SIG_IPI or SIGBUS is pending and loop waiting for signals 
>> again.
>>
>> Shouldn't we be looping on just sigismember(SIGBUS)?
>
> You mean because SIG_IPI is a real-time signal and standard signals 
> are delivered first?  OTOH, real-time signals can be queued multiple 
> times so it makes sense to loop on SIG_IPI as well.
>
>> BTW, we're no longer respecting timeout because we're not adjusting ts
>> after each iteration.
>
> The timeout of qemu_kvm_eat_signal is always zero.

So then qemu_kvm_eat_signal purely polls and it will happily keep 
polling as long as there is a signal pending.

So what's the point of doing a sigtimedwait() and dropping qemu_mutex?  
Why not just check sigpending in a loop?

Regards,

Anthony Liguori

> Paolo