From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir@xensource.com>
Subject: Re: [PATCH] trivial fix for vcpu_set_affinity
Date: Thu, 11 Jan 2007 09:43:47 +0000
Message-ID: <C1CBB753.7748%keir@xensource.com>
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To: "Tian, Kevin" <kevin.tian@intel.com>, xen-devel@lists.xensource.com
List-Id: xen-devel@lists.xenproject.org

It's true that the vcpu_migrate() is a no-op if v==current, but the
vcpu_sleep_nosync() does have to be executed, otherwise current will not be
migrated before returning to guest context (because the schedule softirq
will not be asserted). This would mean that a dom0 vcpu could no longer
synchronously migrate itself. In any case this patch has no upside -- the
existing code works just fine.

 -- Keir

On 11/1/07 08:42, "Tian, Kevin" <kevin.tian@intel.com> wrote:

> No need to try migration in current context since self migrate
> will be handled by next vcpu after context switch.
> 
> Signed-off-by Kevin Tian <kevin.tian@intel.com>
> 
> diff -r e66f047bc97e xen/common/schedule.c
> --- a/xen/common/schedule.c Tue Jan 09 18:56:44 2007 -0800
> +++ b/xen/common/schedule.c Thu Jan 11 16:31:37 2007 +0800
> @@ -243,7 +243,7 @@ int vcpu_set_affinity(struct vcpu *v, cp
>  
>      vcpu_schedule_unlock_irqrestore(v, flags);
>  
> -    if ( test_bit(_VCPUF_migrating, &v->vcpu_flags) )
> +    if ( (v != current) && test_bit(_VCPUF_migrating, &v->vcpu_flags) )
>      {
>          vcpu_sleep_nosync(v);
>          vcpu_migrate(v);
> 
> Thanks,
> Kevin
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