From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753820AbcCBXFO (ORCPT ); Wed, 2 Mar 2016 18:05:14 -0500 Received: from outgoing.csail.mit.edu ([128.30.2.149]:35901 "EHLO outgoing.csail.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751013AbcCBXFM (ORCPT ); Wed, 2 Mar 2016 18:05:12 -0500 Subject: Re: [tip:smp/hotplug] cpu/hotplug: Split out cpu down functions To: arjan@linux.intel.com, paulmck@linux.vnet.ibm.com, riel@redhat.com, peterz@infradead.org, tj@kernel.org, rusty@rustcorp.com.au, akpm@linux-foundation.org, pjt@google.com, torvalds@linux-foundation.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, srivatsa@mit.edu, rafael.j.wysocki@intel.com, bigeasy@linutronix.de, oleg@redhat.com, hpa@zytor.com, rostedt@goodmis.org, mingo@kernel.org, linux-tip-commits@vger.kernel.org References: <20160226182340.511796562@linutronix.de> From: "Srivatsa S. Bhat" Message-ID: <56D76B40.8040304@csail.mit.edu> Date: Wed, 2 Mar 2016 17:37:52 -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 2:52 PM, tip-bot for Thomas Gleixner wrote: > Commit-ID: 984581728eb4b2e10baed3d606f85a119795b207 > Gitweb: http://git.kernel.org/tip/984581728eb4b2e10baed3d606f85a119795b207 > Author: Thomas Gleixner > AuthorDate: Fri, 26 Feb 2016 18:43:25 +0000 > Committer: Thomas Gleixner > CommitDate: Tue, 1 Mar 2016 20:36:53 +0100 > > cpu/hotplug: Split out cpu down functions > > Split cpu_down in separate functions in preparation for state machine > conversion. > > 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/20160226182340.511796562@linutronix.de > Signed-off-by: Thomas Gleixner > --- Reviewed-by: Srivatsa S. Bhat Regards, Srivatsa S. Bhat > kernel/cpu.c | 83 ++++++++++++++++++++++++++++++++++++++---------------------- > 1 file changed, 53 insertions(+), 30 deletions(-) > > diff --git a/kernel/cpu.c b/kernel/cpu.c > index 15a4136..0b5d259 100644 > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -266,11 +266,6 @@ static int bringup_cpu(unsigned int cpu) > } > > #ifdef CONFIG_HOTPLUG_CPU > - > -static void cpu_notify_nofail(unsigned long val, unsigned int cpu) > -{ > - BUG_ON(cpu_notify(val, cpu)); > -} > EXPORT_SYMBOL(register_cpu_notifier); > EXPORT_SYMBOL(__register_cpu_notifier); > > @@ -353,6 +348,25 @@ static inline void check_for_tasks(int dead_cpu) > read_unlock(&tasklist_lock); > } > > +static void cpu_notify_nofail(unsigned long val, unsigned int cpu) > +{ > + BUG_ON(cpu_notify(val, cpu)); > +} > + > +static int notify_down_prepare(unsigned int cpu) > +{ > + int err, nr_calls = 0; > + > + err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls); > + if (err) { > + nr_calls--; > + __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL); > + pr_warn("%s: attempt to take down CPU %u failed\n", > + __func__, cpu); > + } > + return err; > +} > + > /* Take this CPU down. */ > static int take_cpu_down(void *_param) > { > @@ -371,29 +385,9 @@ static int take_cpu_down(void *_param) > return 0; > } > > -/* Requires cpu_add_remove_lock to be held */ > -static int _cpu_down(unsigned int cpu, int tasks_frozen) > +static int takedown_cpu(unsigned int cpu) > { > - int err, nr_calls = 0; > - > - if (num_online_cpus() == 1) > - return -EBUSY; > - > - if (!cpu_online(cpu)) > - return -EINVAL; > - > - cpu_hotplug_begin(); > - > - cpuhp_tasks_frozen = tasks_frozen; > - > - err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls); > - if (err) { > - nr_calls--; > - __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL); > - pr_warn("%s: attempt to take down CPU %u failed\n", > - __func__, cpu); > - goto out_release; > - } > + int err; > > /* > * By now we've cleared cpu_active_mask, wait for all preempt-disabled > @@ -426,7 +420,7 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen) > /* CPU didn't die: tell everyone. Can't complain. */ > cpu_notify_nofail(CPU_DOWN_FAILED, cpu); > irq_unlock_sparse(); > - goto out_release; > + return err; > } > BUG_ON(cpu_online(cpu)); > > @@ -449,11 +443,40 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen) > /* This actually kills the CPU. */ > __cpu_die(cpu); > > - /* CPU is completely dead: tell everyone. Too late to complain. */ > tick_cleanup_dead_cpu(cpu); > - cpu_notify_nofail(CPU_DEAD, cpu); > + return 0; > +} > > +static int notify_dead(unsigned int cpu) > +{ > + cpu_notify_nofail(CPU_DEAD, cpu); > check_for_tasks(cpu); > + return 0; > +} > + > +/* Requires cpu_add_remove_lock to be held */ > +static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) > +{ > + int err; > + > + if (num_online_cpus() == 1) > + return -EBUSY; > + > + if (!cpu_online(cpu)) > + return -EINVAL; > + > + cpu_hotplug_begin(); > + > + cpuhp_tasks_frozen = tasks_frozen; > + > + err = notify_down_prepare(cpu); > + if (err) > + goto out_release; > + err = takedown_cpu(cpu); > + if (err) > + goto out_release; > + > + notify_dead(cpu); > > out_release: > cpu_hotplug_done(); >