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authorSilas Boyd-Wickizer <sbw@mit.edu>2012-09-23 20:27:32 +0200
committerJean Delvare <khali@endymion.delvare>2012-09-23 20:27:32 +0200
commit641f14560035bbb86500ea4b3a27ad27f034725b (patch)
treeacf190876e015304f959294c37b302e904380baa
parent1ec3ddfd27a77db55b8c0e80bcd27c656473fb96 (diff)
downloadlinux-stericsson-641f14560035bbb86500ea4b3a27ad27f034725b.tar.gz
hwmon: (coretemp) Use get_online_cpus to avoid races involving CPU hotplug
coretemp_init loops with for_each_online_cpu, adding platform_devices and sysfs interfaces, then calls register_hotcpu_notifier. There is a race if a CPU is offlined or onlined after the loop, but before register_hotcpu_notifier. The race might result in the absence of a platform_device+sysfs interface for an online CPU, or the presence of a platform_device+sysfs interface for an offline CPU. A similar race occurs during coretemp_exit, after the module calls unregister_hotcpu_notifier, but before it unregisters all devices, a CPU might offline and a device for an offline CPU will exist for a short while. This fix surrounds for_each_online_cpu and register_hotcpu_notifier with get_online_cpus+put_online_cpus; and surrounds unregister_hotcpu_notifier and device unregistering with get_online_cpus+put_online_cpus. Build tested. Signed-off-by: Silas Boyd-Wickizer <sbw@mit.edu> Signed-off-by: Jean Delvare <khali@linux-fr.org>
-rw-r--r--drivers/hwmon/coretemp.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index 0fa356fe82cc..984a3f13923b 100644
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -815,17 +815,20 @@ static int __init coretemp_init(void)
if (err)
goto exit;
+ get_online_cpus();
for_each_online_cpu(i)
get_core_online(i);
#ifndef CONFIG_HOTPLUG_CPU
if (list_empty(&pdev_list)) {
+ put_online_cpus();
err = -ENODEV;
goto exit_driver_unreg;
}
#endif
register_hotcpu_notifier(&coretemp_cpu_notifier);
+ put_online_cpus();
return 0;
#ifndef CONFIG_HOTPLUG_CPU
@@ -840,6 +843,7 @@ static void __exit coretemp_exit(void)
{
struct pdev_entry *p, *n;
+ get_online_cpus();
unregister_hotcpu_notifier(&coretemp_cpu_notifier);
mutex_lock(&pdev_list_mutex);
list_for_each_entry_safe(p, n, &pdev_list, list) {
@@ -848,6 +852,7 @@ static void __exit coretemp_exit(void)
kfree(p);
}
mutex_unlock(&pdev_list_mutex);
+ put_online_cpus();
platform_driver_unregister(&coretemp_driver);
}