From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp08.au.ibm.com (e23smtp08.au.ibm.com [202.81.31.141]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id B00FE2C0610 for ; Tue, 11 Mar 2014 07:41:14 +1100 (EST) Received: from /spool/local by e23smtp08.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 11 Mar 2014 06:41:14 +1000 Received: from d23relay05.au.ibm.com (d23relay05.au.ibm.com [9.190.235.152]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 417B32BB0057 for ; Tue, 11 Mar 2014 07:41:11 +1100 (EST) Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay05.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s2AKL1qd12517702 for ; Tue, 11 Mar 2014 07:21:02 +1100 Received: from d23av04.au.ibm.com (localhost [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s2AKf9Q6009917 for ; Tue, 11 Mar 2014 07:41:10 +1100 From: "Srivatsa S. Bhat" Subject: [PATCH v3 43/52] thermal, x86-pkg-temp: 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 02:10:54 +0530 Message-ID: <20140310204054.10746.57627.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, linux-kernel@vger.kernel.org, Eduardo Valentin , linuxppc-dev@ozlabs.org, "Srivatsa S. Bhat" , tj@kernel.org, Zhang Rui , paulmck@linux.vnet.ibm.com, Ingo Molnar 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 x86-pkg-temp code by using this latter form of callback registration. Cc: Zhang Rui Cc: Eduardo Valentin Cc: Ingo Molnar Cc: linux-pm@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- drivers/thermal/x86_pkg_temp_thermal.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/thermal/x86_pkg_temp_thermal.c b/drivers/thermal/x86_pkg_temp_thermal.c index 081fd7e..9ea3d9d 100644 --- a/drivers/thermal/x86_pkg_temp_thermal.c +++ b/drivers/thermal/x86_pkg_temp_thermal.c @@ -590,12 +590,12 @@ static int __init pkg_temp_thermal_init(void) platform_thermal_package_rate_control = pkg_temp_thermal_platform_thermal_rate_control; - get_online_cpus(); + cpu_notifier_register_begin(); for_each_online_cpu(i) if (get_core_online(i)) goto err_ret; - register_hotcpu_notifier(&pkg_temp_thermal_notifier); - put_online_cpus(); + __register_hotcpu_notifier(&pkg_temp_thermal_notifier); + cpu_notifier_register_done(); pkg_temp_debugfs_init(); /* Don't care if fails */ @@ -604,7 +604,7 @@ static int __init pkg_temp_thermal_init(void) err_ret: for_each_online_cpu(i) put_core_offline(i); - put_online_cpus(); + cpu_notifier_register_done(); kfree(pkg_work_scheduled); platform_thermal_package_notify = NULL; platform_thermal_package_rate_control = NULL; @@ -617,8 +617,8 @@ static void __exit pkg_temp_thermal_exit(void) struct phy_dev_entry *phdev, *n; int i; - get_online_cpus(); - unregister_hotcpu_notifier(&pkg_temp_thermal_notifier); + cpu_notifier_register_begin(); + __unregister_hotcpu_notifier(&pkg_temp_thermal_notifier); mutex_lock(&phy_dev_list_mutex); list_for_each_entry_safe(phdev, n, &phy_dev_list, list) { /* Retore old MSR value for package thermal interrupt */ @@ -636,7 +636,7 @@ static void __exit pkg_temp_thermal_exit(void) for_each_online_cpu(i) cancel_delayed_work_sync( &per_cpu(pkg_temp_thermal_threshold_work, i)); - put_online_cpus(); + cpu_notifier_register_done(); kfree(pkg_work_scheduled);