cpuidle: Fix cpuidle_driver_state_disabled()

It turns out that cpuidle_driver_state_disabled() can be called
before registering the cpufreq driver on some platforms, which
was not expected when it was introduced and which leads to a NULL
pointer dereference when trying to walk the CPUs associated with
the given cpuidle driver.

Fix the problem by making cpuidle_driver_state_disabled() check if
the driver's mask of CPUs associated with it is present and to set
CPUIDLE_FLAG_UNUSABLE for the given idle state in the driver's states
list if that is not the case to cause __cpuidle_register_device() to
set CPUIDLE_STATE_DISABLED_BY_DRIVER for that state for all cpuidle
devices registered by it later.

Fixes: cbda56d5fefc ("cpuidle: Introduce cpuidle_driver_state_disabled() for driver quirks")
Reported-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Tested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index c76423aaef4d7ebe1098ec63507752ecf0eb194a..ce6a5f80fb8384c810d8c0890e1a003d216cbed4 100644 (file)
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -403,6 +403,13 @@ void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx,
 
        mutex_lock(&cpuidle_lock);
 
+       spin_lock(&cpuidle_driver_lock);
+
+       if (!drv->cpumask) {
+               drv->states[idx].flags |= CPUIDLE_FLAG_UNUSABLE;
+               goto unlock;
+       }
+
        for_each_cpu(cpu, drv->cpumask) {
                struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
 
@@ -415,5 +422,8 @@ void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx,
                        dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER;
        }
 
+unlock:
+       spin_unlock(&cpuidle_driver_lock);
+
        mutex_unlock(&cpuidle_lock);
 }