coretemp_init in drivers/hwmon/coretemp.c 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 <[email protected]> --- drivers/hwmon/coretemp.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c index 637c51c..9483e90 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); } -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
