From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp02.in.ibm.com (e28smtp02.in.ibm.com [122.248.162.2]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 57C102C02A3 for ; Tue, 11 Mar 2014 07:37:35 +1100 (EST) Received: from /spool/local by e28smtp02.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 11 Mar 2014 02:07:33 +0530 Received: from d28relay02.in.ibm.com (d28relay02.in.ibm.com [9.184.220.59]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id 2A856E003F for ; Tue, 11 Mar 2014 02:11:16 +0530 (IST) Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s2AKbQLB65274022 for ; Tue, 11 Mar 2014 02:07:26 +0530 Received: from d28av01.in.ibm.com (localhost [127.0.0.1]) by d28av01.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s2AKbRXN009150 for ; Tue, 11 Mar 2014 02:07:29 +0530 From: "Srivatsa S. Bhat" Subject: [PATCH v3 20/52] x86, therm_throt.c: 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 Date: Tue, 11 Mar 2014 02:07:21 +0530 Message-ID: <20140310203721.10746.47726.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> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Cc: linux-arch@vger.kernel.org, ego@linux.vnet.ibm.com, walken@google.com, linux@arm.linux.org.uk, linux-pm@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Tony Luck , Borislav Petkov , "Srivatsa S. Bhat" , "H. Peter Anvin" , tj@kernel.org, Thomas Gleixner , paulmck@linux.vnet.ibm.com, Ingo Molnar , linux-edac@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 thermal throttle code in x86 by using this latter form of callback registration. Cc: Tony Luck Cc: Borislav Petkov Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: linux-edac@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- arch/x86/kernel/cpu/mcheck/therm_throt.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c index 3eec7de..e05dfa3 100644 --- a/arch/x86/kernel/cpu/mcheck/therm_throt.c +++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c @@ -319,7 +319,7 @@ static __init int thermal_throttle_init_device(void) if (!atomic_read(&therm_throt_en)) return 0; - register_hotcpu_notifier(&thermal_throttle_cpu_notifier); + cpu_notifier_register_begin(); #ifdef CONFIG_HOTPLUG_CPU mutex_lock(&therm_cpu_lock); @@ -333,6 +333,9 @@ static __init int thermal_throttle_init_device(void) mutex_unlock(&therm_cpu_lock); #endif + __register_hotcpu_notifier(&thermal_throttle_cpu_notifier); + cpu_notifier_register_done(); + return 0; } device_initcall(thermal_throttle_init_device);