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 <rui.zhang@intel.com>
Cc: Eduardo Valentin <eduardo.valentin@ti.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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 @@
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 @@
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 @@
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 @@
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);