[PATCH] cpuidle: Fix cpuidle_driver_state_disabled()

Rafael J. Wysocki
2019-12-10T11:48:42Z

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

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>
---
drivers/cpuidle/driver.c | 10 ++++++++++
1 file changed, 10 insertions(+)

Index: linux-pm/drivers/cpuidle/driver.c
===================================================================
--- linux-pm.orig/drivers/cpuidle/driver.c
+++ linux-pm/drivers/cpuidle/driver.c
@@ -403,6 +403,13 @@ void cpuidle_driver_state_disabled(struc

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(struc
dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER;
}

+unlock:
+ spin_unlock(&cpuidle_driver_lock);
+
mutex_unlock(&cpuidle_lock);
}