linux-kernel - Re: [RFC PATCH 1/3] kvm: keep track of which task is running a KVM vcpu

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Message-ID: <4CFB8CC5.50902@redhat.com>
Date:	Sun, 05 Dec 2010 14:59:49 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Rik van Riel <riel@...hat.com>
CC:	vatsa@...ux.vnet.ibm.com, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>,
	Anthony Liguori <aliguori@...ux.vnet.ibm.com>
Subject: Re: [RFC PATCH 1/3] kvm: keep track of which task is running a KVM
 vcpu

On 12/03/2010 04:16 PM, Rik van Riel wrote:
> On 12/03/2010 07:17 AM, Srivatsa Vaddagiri wrote:
>> On Thu, Dec 02, 2010 at 02:43:24PM -0500, Rik van Riel wrote:
>>>       mutex_lock(&vcpu->mutex);
>>> +    vcpu->task = current;
>>
>> Shouldn't we grab reference to current task_struct before storing a 
>> pointer to
>> it?
>
> That should not be needed, since current cannot go away without
> setting vcpu->task back to NULL in vcpu_put.
>

However, you do reference vcpu->task from other contexts.  So some sort 
of safe reference is needed.

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

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