From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753507AbbKWQWf (ORCPT ); Mon, 23 Nov 2015 11:22:35 -0500 Received: from terminus.zytor.com ([198.137.202.10]:44426 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751166AbbKWQWd (ORCPT ); Mon, 23 Nov 2015 11:22:33 -0500 Date: Mon, 23 Nov 2015 08:21:48 -0800 From: tip-bot for Oleg Nesterov Message-ID: Cc: tj@kernel.org, tglx@linutronix.de, efault@gmx.de, peterz@infradead.org, prarit@redhat.com, oleg@redhat.com, milos@redhat.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, mingo@kernel.org, hpa@zytor.com Reply-To: torvalds@linux-foundation.org, mingo@kernel.org, hpa@zytor.com, tj@kernel.org, tglx@linutronix.de, efault@gmx.de, peterz@infradead.org, milos@redhat.com, prarit@redhat.com, oleg@redhat.com, linux-kernel@vger.kernel.org In-Reply-To: <20151115193314.GA8249@redhat.com> References: <20151115193314.GA8249@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] stop_machine: Don' t disable preemption in stop_two_cpus() Git-Commit-ID: 6a19005157c464b47b2082f2617d12bc11198a0d X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 6a19005157c464b47b2082f2617d12bc11198a0d Gitweb: http://git.kernel.org/tip/6a19005157c464b47b2082f2617d12bc11198a0d Author: Oleg Nesterov AuthorDate: Sun, 15 Nov 2015 20:33:14 +0100 Committer: Ingo Molnar CommitDate: Mon, 23 Nov 2015 09:48:18 +0100 stop_machine: Don't disable preemption in stop_two_cpus() Now that stop_two_cpus() path does not check cpu_active() we can remove preempt_disable(), it was only needed to ensure that stop_machine() can not be called after we observe cpu_active() == T and before we queue the new work. Also, turn the pointless and confusing ->executed check into WARN_ON(). We know that both works must be executed, otherwise we have a bug. And in fact I think that done->executed should die, see the next changes. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Cc: Linus Torvalds Cc: Mike Galbraith Cc: Milos Vyletel Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20151115193314.GA8249@redhat.com Signed-off-by: Ingo Molnar --- kernel/stop_machine.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 1a66a95..17f01a9 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -258,7 +258,6 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void * struct cpu_stop_work work1, work2; struct multi_stop_data msdata; - preempt_disable(); msdata = (struct multi_stop_data){ .fn = fn, .data = arg, @@ -277,16 +276,12 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void * if (cpu1 > cpu2) swap(cpu1, cpu2); - if (cpu_stop_queue_two_works(cpu1, &work1, cpu2, &work2)) { - preempt_enable(); + if (cpu_stop_queue_two_works(cpu1, &work1, cpu2, &work2)) return -ENOENT; - } - - preempt_enable(); wait_for_completion(&done.completion); - - return done.executed ? done.ret : -ENOENT; + WARN_ON(!done.executed); + return done.ret; } /**