Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756068AbaBEWRY (ORCPT ); Wed, 5 Feb 2014 17:17:24 -0500 Received: from e28smtp09.in.ibm.com ([122.248.162.9]:40816 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755328AbaBEWRS (ORCPT ); Wed, 5 Feb 2014 17:17:18 -0500 From: "Srivatsa S. Bhat" Subject: [PATCH 41/51] thermal, x86-pkg-temp: Fix CPU hotplug callback registration To: paulus@samba.org, oleg@redhat.com, rusty@rustcorp.com.au, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org Cc: mingo@kernel.org, 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, srivatsa.bhat@linux.vnet.ibm.com, Zhang Rui , Eduardo Valentin , linux-pm@vger.kernel.org, "Srivatsa S. Bhat" Date: Thu, 06 Feb 2014 03:41:57 +0530 Message-ID: <20140205221156.19080.83761.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20140205220251.19080.92336.stgit@srivatsabhat.in.ibm.com> References: <20140205220251.19080.92336.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14020522-2674-0000-0000-00000C94B1B7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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_maps_update_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_maps_update_done(); Fix the thermal x86-pkg-temp code by using this latter form of callback registration. Cc: Zhang Rui Cc: Eduardo Valentin 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 972e1c7..55f9eac 100644 --- a/drivers/thermal/x86_pkg_temp_thermal.c +++ b/drivers/thermal/x86_pkg_temp_thermal.c @@ -589,12 +589,12 @@ static int __init pkg_temp_thermal_init(void) platform_thermal_package_rate_control = pkg_temp_thermal_platform_thermal_rate_control; - get_online_cpus(); + cpu_maps_update_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_maps_update_done(); pkg_temp_debugfs_init(); /* Don't care if fails */ @@ -603,7 +603,7 @@ static int __init pkg_temp_thermal_init(void) err_ret: for_each_online_cpu(i) put_core_offline(i); - put_online_cpus(); + cpu_maps_update_done(); kfree(pkg_work_scheduled); platform_thermal_package_notify = NULL; platform_thermal_package_rate_control = NULL; @@ -616,8 +616,8 @@ 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_maps_update_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 */ @@ -635,7 +635,7 @@ 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_maps_update_done(); kfree(pkg_work_scheduled); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/