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From: Avi Kivity <avi@redhat.com>
To: Gregory Haskins <ghaskins@novell.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	mst@redhat.com, paulmck@linux.vnet.ibm.com,
	davidel@xmailserver.org, rusty@rustcorp.com.au
Subject: Re: [KVM PATCH v5 0/4] irqfd fixes and enhancements
Date: Sun, 28 Jun 2009 16:40:05 +0300	[thread overview]
Message-ID: <4A4772B5.5030008@redhat.com> (raw)
In-Reply-To: <4A476927.4010900@novell.com>

On 06/28/2009 03:59 PM, Gregory Haskins wrote:
>> I agree that we want POLLHUP support, it's better than holding on to
>> the eventfd.  But I think we can make it even cleaner by merging it
>> with deassign.  Basically, when we get POLLHUP, we launch a slow_work
>> (or something) that does a regular deassign.  That slow_work can grab
>> a ref to the vm, so we don't race with the VM disappearing.
>>
>> But given that the current slow_work does almost nothing, I'm not sure
>> it's worth it.
>>      
>
> Yeah, and also note that the algorithm to unhook each side is not quite
> symmetrical.  I think I've captured all the common parts (in things like
> irqfd_deactivate(), etc).  A minor change in kvm_irqfd_release() could
> technically use a deferred job to release instead of doing it inline,
> but I do not think it buys us very much to do so (as you pointed out,
> the defered part is actually fairly simple).  The important parts of the
> protocol lie outside of the work we can do in the work-item anyway.
>    

Is the case of deassign vs POLLHUP covered?

Reusing deassign in POLLHUP at least makes it easy to verify that it is.

-- 
error compiling committee.c: too many arguments to function


      reply	other threads:[~2009-06-28 13:38 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-06-25 13:28 [KVM PATCH v5 0/4] irqfd fixes and enhancements Gregory Haskins
2009-06-25 13:28 ` [KVM PATCH v5 1/4] kvm: prepare irqfd for having interrupts disabled during eventfd->release Gregory Haskins
2009-06-25 13:28 ` [KVM PATCH v5 2/4] eventfd - revised interface and cleanups (4th rev) Gregory Haskins
2009-06-25 13:28 ` [KVM PATCH v5 3/4] KVM: Fix races in irqfd using new eventfd_kref_get interface Gregory Haskins
2009-06-26 14:05   ` Gregory Haskins
2009-06-28 11:06   ` Michael S. Tsirkin
2009-06-28 12:50     ` Gregory Haskins
2009-06-28 13:18       ` Michael S. Tsirkin
2009-06-28 13:25         ` Avi Kivity
2009-06-25 13:28 ` [KVM PATCH v5 4/4] KVM: add irqfd DEASSIGN feature Gregory Haskins
2009-06-28 10:46   ` Michael S. Tsirkin
2009-06-28 12:39     ` Gregory Haskins
2009-06-25 13:59 ` [KVM PATCH v5 0/4] irqfd fixes and enhancements Gregory Haskins
2009-06-25 16:44   ` Davide Libenzi
2009-06-28 11:03   ` Avi Kivity
2009-06-28 12:59     ` Gregory Haskins
2009-06-28 13:40       ` Avi Kivity [this message]

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