From patchwork Sun Jun 23 13:39:02 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Srivatsa S. Bhat" X-Patchwork-Id: 253473 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 8D55D2C0532 for ; Sun, 23 Jun 2013 23:42:49 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751968Ab3FWNm3 (ORCPT ); Sun, 23 Jun 2013 09:42:29 -0400 Received: from e28smtp07.in.ibm.com ([122.248.162.7]:56587 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751953Ab3FWNmY (ORCPT ); Sun, 23 Jun 2013 09:42:24 -0400 Received: from /spool/local by e28smtp07.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sun, 23 Jun 2013 19:05:23 +0530 Received: from d28dlp02.in.ibm.com (9.184.220.127) by e28smtp07.in.ibm.com (192.168.1.137) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Sun, 23 Jun 2013 19:05:19 +0530 Received: from d28relay03.in.ibm.com (d28relay03.in.ibm.com [9.184.220.60]) by d28dlp02.in.ibm.com (Postfix) with ESMTP id F1F1C394004E; Sun, 23 Jun 2013 19:12:17 +0530 (IST) Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay03.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r5NDgUZg32768150; Sun, 23 Jun 2013 19:12:30 +0530 Received: from d28av04.in.ibm.com (loopback [127.0.0.1]) by d28av04.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r5NDgF6r008039; Sun, 23 Jun 2013 23:42:17 +1000 Received: from srivatsabhat.in.ibm.com ([9.79.195.141]) by d28av04.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id r5NDgERH008023; Sun, 23 Jun 2013 23:42:14 +1000 From: "Srivatsa S. Bhat" Subject: [PATCH 05/45] CPU hotplug: Protect set_cpu_online() to avoid false-positives To: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, walken@google.com, vincent.guittot@linaro.org, laijs@cn.fujitsu.com Cc: rostedt@goodmis.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, sbw@mit.edu, fweisbec@gmail.com, zhong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, srivatsa.bhat@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Andrew Morton , Yasuaki Ishimatsu , "Rafael J. Wysocki" Date: Sun, 23 Jun 2013 19:09:02 +0530 Message-ID: <20130623133858.19094.70477.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20130623133642.19094.16038.stgit@srivatsabhat.in.ibm.com> References: <20130623133642.19094.16038.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13062313-8878-0000-0000-000007A61883 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org When bringing a secondary CPU online, the task running on the CPU coming up sets itself in the cpu_online_mask. This is safe even though this task is not the hotplug writer task. But it is kinda hard to teach this to the CPU hotplug debug infrastructure, and if we get it wrong, we risk making the debug code too lenient, risking false-negatives. Luckily, all architectures use set_cpu_online() to manipulate the cpu_online_mask. So, to avoid false-positive warnings from the CPU hotplug debug code, encapsulate the body of set_cpu_online() within get/put_online_cpus_atomic(). Cc: Thomas Gleixner Cc: Andrew Morton Cc: Yasuaki Ishimatsu Cc: "Rafael J. Wysocki" Signed-off-by: Srivatsa S. Bhat --- kernel/cpu.c | 4 ++++ 1 file changed, 4 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/kernel/cpu.c b/kernel/cpu.c index e90d9d7..23df9ba 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -818,10 +818,14 @@ void set_cpu_present(unsigned int cpu, bool present) void set_cpu_online(unsigned int cpu, bool online) { + get_online_cpus_atomic(); + if (online) cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits)); else cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits)); + + put_online_cpus_atomic(); } void set_cpu_active(unsigned int cpu, bool active)