linux-kernel - Re: [PATCH 2/2] xen/x86: Call cpu_startup_entry(CPUHP_AP_ONLINE_IDLE) from xen_play

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Date:	Fri, 25 Mar 2016 11:08:32 -0400
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	david.vrabel@...rix.com, xen-devel@...ts.xenproject.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] xen/x86: Call cpu_startup_entry(CPUHP_AP_ONLINE_IDLE)
 from xen_play_dead()

On 03/25/2016 10:53 AM, Konrad Rzeszutek Wilk wrote:
> On Thu, Mar 17, 2016 at 09:03:25AM -0400, Boris Ostrovsky wrote:
>> This call has always been missing from xen_play dead() but until
>> recently this was rather benign. With new cpu hotplug framework
>> however this call is required, otherwise a hot-plugged CPU will not
> Could you include the commit id of the 'new cpu hotplug' in case
> anybody wants to backport this?

Sure.

It's commit 8df3e07e7f21 ("cpu/hotplug: Let upcoming cpu bring itself 
fully up").

Do you (or David) want me to re-send it?

-boris



>
> Thanks!
>> be properly brough up (by never calling cpuhp_online_idle())
>>
>> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
>> ---
>>   arch/x86/xen/smp.c |    2 ++
>>   1 files changed, 2 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
>> index 3c6d17f..719cf29 100644
>> --- a/arch/x86/xen/smp.c
>> +++ b/arch/x86/xen/smp.c
>> @@ -545,6 +545,8 @@ static void xen_play_dead(void) /* used only with HOTPLUG_CPU */
>>   	 * data back is to call:
>>   	 */
>>   	tick_nohz_idle_enter();
>> +
>> +	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
>>   }
>>   
>>   #else /* !CONFIG_HOTPLUG_CPU */
>> -- 
>> 1.7.1
>>