thermal: cpu_cooling: Fix NULL dereference in cpufreq_state2power

Currently all CPU cooling devices share a
`struct thermal_cooling_device_ops` instance. The thermal core uses the
presence of functions in this struct to determine if a cooling device
has a power model (see cdev_is_power_actor). cpu_cooling.c adds the
power model functions to the shared struct when a device is registered
with a power model.

Therefore, if a CPU cooling device is registered using
[of_]cpufreq_power_cooling_register, _all_ devices will be determined to
have a power model, including any registered with
[of_]cpufreq_cooling_register. This can result in cpufreq_state2power
being called on a device where dyn_power_table is NULL.

With this commit, instead of having a shared thermal_cooling_device_ops
which is mutated, we have two versions: one with the power functions and
one without.

Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>
Cc: Amit Daniel Kachhap <amit.kachhap@gmail.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Javi Merino <javi.merino@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

1 files changed, 16 insertions, 5 deletions

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index 3788ed74c9ab..a32b41783b77 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -740,12 +740,22 @@ static int cpufreq_power2state(struct thermal_cooling_device *cdev,
 }
 
 /* Bind cpufreq callbacks to thermal cooling device ops */
+
 static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
         .get_max_state = cpufreq_get_max_state,
         .get_cur_state = cpufreq_get_cur_state,
         .set_cur_state = cpufreq_set_cur_state,
 };
 
+static struct thermal_cooling_device_ops cpufreq_power_cooling_ops = {
+        .get_max_state          = cpufreq_get_max_state,
+        .get_cur_state          = cpufreq_get_cur_state,
+        .set_cur_state          = cpufreq_set_cur_state,
+        .get_requested_power    = cpufreq_get_requested_power,
+        .state2power            = cpufreq_state2power,
+        .power2state            = cpufreq_power2state,
+};
+
 /* Notifier for cpufreq policy change */
 static struct notifier_block thermal_cpufreq_notifier_block = {
         .notifier_call = cpufreq_thermal_notifier,
@@ -795,6 +805,7 @@ __cpufreq_cooling_register(struct device_node *np,
         struct cpumask temp_mask;
         unsigned int freq, i, num_cpus;
         int ret;
+        struct thermal_cooling_device_ops *cooling_ops;
 
         cpumask_and(&temp_mask, clip_cpus, cpu_online_mask);
         policy = cpufreq_cpu_get(cpumask_first(&temp_mask));
@@ -850,10 +861,6 @@ __cpufreq_cooling_register(struct device_node *np,
         cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
 
         if (capacitance) {
-                cpufreq_cooling_ops.get_requested_power =
-                        cpufreq_get_requested_power;
-                cpufreq_cooling_ops.state2power = cpufreq_state2power;
-                cpufreq_cooling_ops.power2state = cpufreq_power2state;
                 cpufreq_dev->plat_get_static_power = plat_static_func;
 
                 ret = build_dyn_power_table(cpufreq_dev, capacitance);
@@ -861,6 +868,10 @@ __cpufreq_cooling_register(struct device_node *np,
                         cool_dev = ERR_PTR(ret);
                         goto free_table;
                 }
+
+                cooling_ops = &cpufreq_power_cooling_ops;
+        } else {
+                cooling_ops = &cpufreq_cooling_ops;
         }
 
         ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
@@ -885,7 +896,7 @@ __cpufreq_cooling_register(struct device_node *np,
                  cpufreq_dev->id);
 
         cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
-                                                      &cpufreq_cooling_ops);
+                                                      cooling_ops);
         if (IS_ERR(cool_dev))
                 goto remove_idr;