From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754539AbcCBXoE (ORCPT ); Wed, 2 Mar 2016 18:44:04 -0500 Received: from outgoing.csail.mit.edu ([128.30.2.149]:36511 "EHLO outgoing.csail.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752899AbcCBXoC (ORCPT ); Wed, 2 Mar 2016 18:44:02 -0500 Subject: Re: [tip:smp/hotplug] cpu/hotplug: Restructure FROZEN state handling To: tj@kernel.org, akpm@linux-foundation.org, rusty@rustcorp.com.au, linux-kernel@vger.kernel.org, rostedt@goodmis.org, paulmck@linux.vnet.ibm.com, peterz@infradead.org, mingo@kernel.org, arjan@linux.intel.com, tglx@linutronix.de, rafael.j.wysocki@intel.com, pjt@google.com, riel@redhat.com, bigeasy@linutronix.de, oleg@redhat.com, torvalds@linux-foundation.org, srivatsa@mit.edu, hpa@zytor.com, linux-tip-commits@vger.kernel.org References: <20160226182340.334912357@linutronix.de> From: "Srivatsa S. Bhat" Message-ID: <56D77AB7.4090902@csail.mit.edu> Date: Wed, 2 Mar 2016 18:43:51 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/1/16 2:51 PM, tip-bot for Thomas Gleixner wrote: > Commit-ID: 090e77c391dd983c8945b8e2e16d09f378d2e334 > Gitweb: http://git.kernel.org/tip/090e77c391dd983c8945b8e2e16d09f378d2e334 > Author: Thomas Gleixner > AuthorDate: Fri, 26 Feb 2016 18:43:23 +0000 > Committer: Thomas Gleixner > CommitDate: Tue, 1 Mar 2016 20:36:53 +0100 > > cpu/hotplug: Restructure FROZEN state handling > > There are only a few callbacks which really care about FROZEN > vs. !FROZEN. No need to have extra states for this. > > Publish the frozen state in an extra variable which is updated under > the hotplug lock and let the users interested deal with it w/o > imposing that extra state checks on everyone. > > Signed-off-by: Thomas Gleixner > Cc: linux-arch@vger.kernel.org > Cc: Rik van Riel > Cc: Rafael Wysocki > Cc: "Srivatsa S. Bhat" > Cc: Peter Zijlstra > Cc: Arjan van de Ven > Cc: Sebastian Siewior > Cc: Rusty Russell > Cc: Steven Rostedt > Cc: Oleg Nesterov > Cc: Tejun Heo > Cc: Andrew Morton > Cc: Paul McKenney > Cc: Linus Torvalds > Cc: Paul Turner > Link: http://lkml.kernel.org/r/20160226182340.334912357@linutronix.de > Signed-off-by: Thomas Gleixner > --- > include/linux/cpu.h | 2 ++ > kernel/cpu.c | 69 ++++++++++++++++++++++------------------------------- > 2 files changed, 31 insertions(+), 40 deletions(-) > > diff --git a/include/linux/cpu.h b/include/linux/cpu.h > index d2ca8c3..f2fb549 100644 > --- a/include/linux/cpu.h > +++ b/include/linux/cpu.h > @@ -118,6 +118,7 @@ enum { > > > #ifdef CONFIG_SMP > +extern bool cpuhp_tasks_frozen; > /* Need to know about CPUs going up/down? */ > #if defined(CONFIG_HOTPLUG_CPU) || !defined(MODULE) > #define cpu_notifier(fn, pri) { \ > @@ -177,6 +178,7 @@ extern void cpu_maps_update_done(void); > #define cpu_notifier_register_done cpu_maps_update_done > > #else /* CONFIG_SMP */ > +#define cpuhp_tasks_frozen 0 > > #define cpu_notifier(fn, pri) do { (void)(fn); } while (0) > #define __cpu_notifier(fn, pri) do { (void)(fn); } while (0) > diff --git a/kernel/cpu.c b/kernel/cpu.c > index 5b9d396..41a6cb8 100644 > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -29,6 +29,8 @@ > #ifdef CONFIG_SMP > /* Serializes the updates to cpu_online_mask, cpu_present_mask */ > static DEFINE_MUTEX(cpu_add_remove_lock); > +bool cpuhp_tasks_frozen; > +EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen); > One small nitpick though: we don't need to export this symbol yet; it can be deferred until the callbacks that need it are actually modified to use this value (presumably in a later patchset). Regards, Srivatsa S. Bhat