diff options
| author | Matthew Wilcox <mawilcox@microsoft.com> | 2017-03-10 18:33:28 +0000 |
|---|---|---|
| committer | Zhang Rui <rui.zhang@intel.com> | 2017-03-13 10:06:04 +0800 |
| commit | 088db931e065bd3b159fa2e588eab859ef0d9d23 (patch) | |
| tree | 7211f7bc220cfc430e37dc4fa37dec978efbe0f7 /drivers/thermal | |
| parent | 4495c08e84729385774601b5146d51d9e5849f81 (diff) | |
| download | linux-088db931e065bd3b159fa2e588eab859ef0d9d23.tar.bz2 | |
thermal: Fix potential deadlock in cpu_cooling
cooling_list_lock is covering not just cpufreq_dev_count, but also the
calls to cpufreq_register_notifier() and cpufreq_unregister_notifier().
Since cooling_list_lock is also used within cpufreq_thermal_notifier(),
lockdep reports a potential deadlock. Fix it by testing the condition
under cooling_list_lock and dropping the lock before calling
cpufreq_register_notifier(). And variable cpufreq_dev_count is removed
at the same time, because it's no longer needed after the fix.
Fixes: ae606089621e ("thermal: convert cpu_cooling to use an IDA")
Reported-and-Tested-by: Russell King <linux@armlinux.org.uk>
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Diffstat (limited to 'drivers/thermal')
| -rw-r--r-- | drivers/thermal/cpu_cooling.c | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c index 91048eeca28b..11b5ea685518 100644 --- a/drivers/thermal/cpu_cooling.c +++ b/drivers/thermal/cpu_cooling.c @@ -107,8 +107,6 @@ struct cpufreq_cooling_device { }; static DEFINE_IDA(cpufreq_ida); -static unsigned int cpufreq_dev_count; - static DEFINE_MUTEX(cooling_list_lock); static LIST_HEAD(cpufreq_dev_list); @@ -771,6 +769,7 @@ __cpufreq_cooling_register(struct device_node *np, unsigned int freq, i, num_cpus; int ret; struct thermal_cooling_device_ops *cooling_ops; + bool first; if (!alloc_cpumask_var(&temp_mask, GFP_KERNEL)) return ERR_PTR(-ENOMEM); @@ -874,13 +873,14 @@ __cpufreq_cooling_register(struct device_node *np, cpufreq_dev->cool_dev = cool_dev; mutex_lock(&cooling_list_lock); + /* Register the notifier for first cpufreq cooling device */ + first = list_empty(&cpufreq_dev_list); list_add(&cpufreq_dev->node, &cpufreq_dev_list); + mutex_unlock(&cooling_list_lock); - /* Register the notifier for first cpufreq cooling device */ - if (!cpufreq_dev_count++) + if (first) cpufreq_register_notifier(&thermal_cpufreq_notifier_block, CPUFREQ_POLICY_NOTIFIER); - mutex_unlock(&cooling_list_lock); goto put_policy; @@ -1021,6 +1021,7 @@ EXPORT_SYMBOL(of_cpufreq_power_cooling_register); void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev) { struct cpufreq_cooling_device *cpufreq_dev; + bool last; if (!cdev) return; @@ -1028,14 +1029,15 @@ void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev) cpufreq_dev = cdev->devdata; mutex_lock(&cooling_list_lock); + list_del(&cpufreq_dev->node); /* Unregister the notifier for the last cpufreq cooling device */ - if (!--cpufreq_dev_count) + last = list_empty(&cpufreq_dev_list); + mutex_unlock(&cooling_list_lock); + + if (last) cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block, CPUFREQ_POLICY_NOTIFIER); - list_del(&cpufreq_dev->node); - mutex_unlock(&cooling_list_lock); - thermal_cooling_device_unregister(cpufreq_dev->cool_dev); ida_simple_remove(&cpufreq_ida, cpufreq_dev->id); kfree(cpufreq_dev->dyn_power_table); |