From cf0485a2ac70acb1bc83f6310a7ebef3070f0333 Mon Sep 17 00:00:00 2001 From: "Srivatsa S. Bhat" Date: Tue, 11 Mar 2014 02:10:54 +0530 Subject: [PATCH] thermal, x86-pkg-temp: Fix CPU hotplug callback registration 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 Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki --- 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 081fd7e6a9f0..9ea3d9d49ffc 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); -- 2.20.1