From patchwork Mon Mar 10 20:38:36 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Srivatsa S. Bhat" X-Patchwork-Id: 3806671 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A781CBF540 for ; Mon, 10 Mar 2014 20:53:50 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id D71B92022F for ; Mon, 10 Mar 2014 20:53:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 078252021C for ; Mon, 10 Mar 2014 20:53:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754962AbaCJUiw (ORCPT ); Mon, 10 Mar 2014 16:38:52 -0400 Received: from e28smtp04.in.ibm.com ([122.248.162.4]:57016 "EHLO e28smtp04.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754953AbaCJUis (ORCPT ); Mon, 10 Mar 2014 16:38:48 -0400 Received: from /spool/local by e28smtp04.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 11 Mar 2014 02:08:47 +0530 Received: from d28dlp02.in.ibm.com (9.184.220.127) by e28smtp04.in.ibm.com (192.168.1.134) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Tue, 11 Mar 2014 02:08:44 +0530 Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by d28dlp02.in.ibm.com (Postfix) with ESMTP id BC04F3940023; Tue, 11 Mar 2014 02:08:43 +0530 (IST) Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay05.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s2AKcmcs5308776; Tue, 11 Mar 2014 02:08:48 +0530 Received: from d28av04.in.ibm.com (localhost [127.0.0.1]) by d28av04.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s2AKcfDF009616; Tue, 11 Mar 2014 02:08:43 +0530 Received: from srivatsabhat.in.ibm.com ([9.79.217.186]) by d28av04.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id s2AKceF6009605; Tue, 11 Mar 2014 02:08:40 +0530 From: "Srivatsa S. Bhat" Subject: [PATCH v3 26/52] x86, hpet: Fix CPU hotplug callback registration To: paulus@samba.org, oleg@redhat.com, mingo@kernel.org, rjw@rjwysocki.net, rusty@rustcorp.com.au, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org Cc: paulmck@linux.vnet.ibm.com, tj@kernel.org, walken@google.com, ego@linux.vnet.ibm.com, linux@arm.linux.org.uk, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-pm@vger.kernel.org, linuxppc-dev@ozlabs.org, srivatsa.bhat@linux.vnet.ibm.com, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, "Srivatsa S. Bhat" Date: Tue, 11 Mar 2014 02:08:36 +0530 Message-ID: <20140310203836.10746.23134.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20140310203312.10746.310.stgit@srivatsabhat.in.ibm.com> References: <20140310203312.10746.310.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14031020-5564-0000-0000-00000C6C7463 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Subsystems that want to register CPU hotplug callbacks, as well as perform initialization for the CPUs that are already online, often do it as shown below: get_online_cpus(); for_each_online_cpu(cpu) init_cpu(cpu); register_cpu_notifier(&foobar_cpu_notifier); put_online_cpus(); This is wrong, since it is prone to ABBA deadlocks involving the cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently with CPU hotplug operations). Instead, the correct and race-free way of performing the callback registration is: cpu_notifier_register_begin(); for_each_online_cpu(cpu) init_cpu(cpu); /* Note the use of the double underscored version of the API */ __register_cpu_notifier(&foobar_cpu_notifier); cpu_notifier_register_done(); Fix the hpet code in x86 by using this latter form of callback registration. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: x86@kernel.org Signed-off-by: Srivatsa S. Bhat --- arch/x86/kernel/hpet.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pm" 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/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index da85a8e..d89382b 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -943,12 +943,14 @@ static __init int hpet_late_init(void) if (boot_cpu_has(X86_FEATURE_ARAT)) return 0; + cpu_notifier_register_begin(); for_each_online_cpu(cpu) { hpet_cpuhp_notify(NULL, CPU_ONLINE, (void *)(long)cpu); } /* This notifier should be called after workqueue is ready */ - hotcpu_notifier(hpet_cpuhp_notify, -20); + __hotcpu_notifier(hpet_cpuhp_notify, -20); + cpu_notifier_register_done(); return 0; }