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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
commit1ec3ddfd27a77db55b8c0e80bcd27c656473fb96 (patch)
treea23e97b565f6618f008244da29cea7a4e1a4b239
parente5e77cf9f9a275083f9a365a20d956fa8a67803e (diff)
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hwmon: (via-cputemp) Use get_online_cpus to avoid races involving CPU hotplug
via_cputemp_init loops with for_each_online_cpu, adding platform_devices, then calls register_hotcpu_notifier. If a CPU is offlined between the loop and register_hotcpu_notifier, then later onlined, via_cputemp_device_add will attempt to add platform devices with the same ID. A similar race occurs during via_cputemp_exit, after the module calls unregister_hotcpu_notifier, a CPU might offline and a device will exist for a CPU that is offline. 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> Acked-by: Harald Welte <laforge@gnumonks.org> Signed-off-by: Jean Delvare <khali@linux-fr.org>
-rw-r--r--drivers/hwmon/via-cputemp.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/hwmon/via-cputemp.c b/drivers/hwmon/via-cputemp.c
index ee4ebc198a9..2e56c6ce9fb 100644
--- a/drivers/hwmon/via-cputemp.c
+++ b/drivers/hwmon/via-cputemp.c
@@ -328,6 +328,7 @@ static int __init via_cputemp_init(void)
if (err)
goto exit;
+ get_online_cpus();
for_each_online_cpu(i) {
struct cpuinfo_x86 *c = &cpu_data(i);
@@ -347,12 +348,14 @@ static int __init via_cputemp_init(void)
#ifndef CONFIG_HOTPLUG_CPU
if (list_empty(&pdev_list)) {
+ put_online_cpus();
err = -ENODEV;
goto exit_driver_unreg;
}
#endif
register_hotcpu_notifier(&via_cputemp_cpu_notifier);
+ put_online_cpus();
return 0;
#ifndef CONFIG_HOTPLUG_CPU
@@ -367,6 +370,7 @@ static void __exit via_cputemp_exit(void)
{
struct pdev_entry *p, *n;
+ get_online_cpus();
unregister_hotcpu_notifier(&via_cputemp_cpu_notifier);
mutex_lock(&pdev_list_mutex);
list_for_each_entry_safe(p, n, &pdev_list, list) {
@@ -375,6 +379,7 @@ static void __exit via_cputemp_exit(void)
kfree(p);
}
mutex_unlock(&pdev_list_mutex);
+ put_online_cpus();
platform_driver_unregister(&via_cputemp_driver);
}