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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>
This commit is contained in:
Srivatsa S. Bhat 2014-03-11 02:10:54 +05:30 committed by Rafael J. Wysocki
parent 99c3bf361a
commit cf0485a2ac
1 changed files with 7 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/thermal/x86_pkg_temp_thermal.c
View File

@ -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);