linux-kernel - Re: [KVM PATCH v8 1/3] KVM: Fix races in irqfd using new eventfd_kref

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Message-ID: <4A4CC3B4.7060109@novell.com>
Date:	Thu, 02 Jul 2009 10:27:00 -0400
From:	Gregory Haskins <ghaskins@...ell.com>
To:	Avi Kivity <avi@...hat.com>
CC:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org, mst@...hat.com,
	davidel@...ilserver.org
Subject: Re: [KVM PATCH v8 1/3] KVM: Fix races in irqfd using new eventfd_kref_get
 interface

Avi Kivity wrote:
> On 07/01/2009 07:09 PM, Gregory Haskins wrote:
>> eventfd currently emits a POLLHUP wakeup on f_ops->release() to
>> generate a
>> "release" callback.  This lets eventfd clients know if the eventfd is
>> about
>> to go away and is very useful particularly for in-kernel clients. 
>> However,
>> until recently it is not possible to use this feature of eventfd in a
>> race-free way.
>>
>> This patch utilizes a new eventfd interface to rectify the problem. 
>> It also
>> converts the eventfd POLLHUP generation code to use the locked variant
>> of wakeup.
>>
>> Signed-off-by: Gregory Haskins<ghaskins@...ell.com>
>> CC: Davide Libenzi<davidel@...ilserver.org>
>> ---
>>
>>   fs/eventfd.c             |    7 --
>>   include/linux/kvm_host.h |    5 +
>>   virt/kvm/eventfd.c       |  187
>> ++++++++++++++++++++++++++++++++--------------
>>   3 files changed, 134 insertions(+), 65 deletions(-)
>>    
>
>
> Please split the eventfd.c hunk into a separate patch.  When preparing
> the 2.6.32 submission, I'll fold that into the patch into its
> antipatch and they'll disappear.
>
Ok, but note that that means I should probably split 1/3 back out into
1/5 (prepare), 2/5 (eventfd hunk), 3/5 (fix irqfd) again like I had in
v7 so that the series is bisectable.  Is that ok?

-Greg


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