From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sasha Levin <levinsasha928@gmail.com>
Subject: Re: [PATCH 1/3] kvm tools: Make virtio-net kvm__irq_line thread
 safe
Date: Fri, 29 Apr 2011 10:53:26 +0300
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Cc: Pekka Enberg <penberg@kernel.org>,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	Ingo Molnar <mingo@elte.hu>,
	Prasad Joshi <prasadjoshi124@gmail.com>, kvm@vger.kernel.org
To: Asias He <asias.hejun@gmail.com>
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On Fri, 2011-04-29 at 15:13 +0800, Asias He wrote:
> On 04/29/2011 02:52 PM, Pekka Enberg wrote:
> > Please make that IRQ latency fix a separate patch. Don't we need to do
> > it for TX path as well, btw?
> > 
> 
> No. We only need it in RX path. Sasha's threadpool patch breaks this.
> I'm just moving it back.
> 

I've moved the kvm__irq_line() call out because what would happen
sometimes is the following:
 - Call kvm__irq_line() to signal completion.
 - virt_queue__available() would return true.
 - readv() call blocks.

I figured it happens because we catch virt_queue in while it's being
updated by the guest and use an erroneous state of it.

-- 

Sasha.