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| author | Silas Boyd-Wickizer <sbw@mit.edu> | 2012-09-23 20:27:32 +0200 |
|---|---|---|
| committer | Jean Delvare <khali@endymion.delvare> | 2012-09-23 20:27:32 +0200 |
| commit | 641f14560035bbb86500ea4b3a27ad27f034725b (patch) | |
| tree | acf190876e015304f959294c37b302e904380baa /drivers/hwmon/coretemp.c | |
| parent | 1ec3ddfd27a77db55b8c0e80bcd27c656473fb96 (diff) | |
| download | op-kernel-dev-641f14560035bbb86500ea4b3a27ad27f034725b.zip op-kernel-dev-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>
Diffstat (limited to 'drivers/hwmon/coretemp.c')
| -rw-r--r-- | drivers/hwmon/coretemp.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c index 0fa356f..984a3f1 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); } |
