From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S932205AbcHOPGc (ORCPT <rfc822;w@1wt.eu>);
	Mon, 15 Aug 2016 11:06:32 -0400
Received: from smtp02.citrix.com ([66.165.176.63]:62030 "EHLO
	SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753181AbcHOPGb (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 15 Aug 2016 11:06:31 -0400
X-IronPort-AV: E=Sophos;i="5.28,525,1464652800"; 
   d="scan'208";a="380183205"
Subject: Re: [Xen-devel] [PATCH 2/2] xen/events: Convert to hotplug state
 machine
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>, <david.vrabel@citrix.com>,
        <jgross@suse.com>
References: <1471272407-4292-1-git-send-email-boris.ostrovsky@oracle.com>
 <1471272407-4292-3-git-send-email-boris.ostrovsky@oracle.com>
CC: <xen-devel@lists.xenproject.org>, <bigeasy@linutronix.de>,
        <linux-kernel@vger.kernel.org>
From: David Vrabel <david.vrabel@citrix.com>
X-Enigmail-Draft-Status: N1110
Message-ID: <57B1DA71.3020806@citrix.com>
Date: Mon, 15 Aug 2016 16:06:25 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Icedove/38.5.0
MIME-Version: 1.0
In-Reply-To: <1471272407-4292-3-git-send-email-boris.ostrovsky@oracle.com>
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit
X-DLP: MIA2
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 15/08/16 15:46, Boris Ostrovsky wrote:
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> 
> Install the callbacks via the state machine.
[...]
> +static int xen_evtchn_cpu_dead(unsigned int cpu)
> +{
> +	__evtchn_fifo_handle_events(cpu, true);
> +	return 0;
> +}

I'm not familiar with the new state machine.  When this is called, what
state is the CPU in?

In particular, local interrupts must be disabled and all non-percpu irqs
must have been migrated to other CPUs.


>  int __init xen_evtchn_fifo_init(void)
>  {
> @@ -456,7 +444,9 @@ int __init xen_evtchn_fifo_init(void)
>  
>  	evtchn_ops = &evtchn_ops_fifo;
>  
> -	register_cpu_notifier(&evtchn_fifo_cpu_notifier);
> +	cpuhp_setup_state_nocalls(CPUHP_XEN_EVTCHN_PREPARE,
> +				  "CPUHP_XEN_EVTCHN_PREPARE",
> +				  xen_evtchn_cpu_prepare, xen_evtchn_cpu_dead);
>  out:
>  	put_cpu();
>  	return ret;
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index d6beeb9..c60a17c 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -22,6 +22,7 @@ enum cpuhp_state {
>  	CPUHP_SMPCFD_PREPARE,
>  	CPUHP_RCUTREE_PREP,
>  	CPUHP_XEN_PREPARE,
> +	CPUHP_XEN_EVTCHN_PREPARE,
>  	CPUHP_NOTIFY_PREPARE,
>  	CPUHP_TIMERS_DEAD,
>  	CPUHP_BRINGUP_CPU,
>