From: Viresh Kumar viresh.kumar@linaro.org
[ Upstream commit 46770be0cf94149ca48be87719bda1d951066644 ]
The cpufreq core heavily depends on the availability of the struct device for CPUs and if they aren't available at the time cpufreq driver is registered, we will never succeed in making cpufreq work.
This happens due to following sequence of events:
- cpufreq_register_driver() - subsys_interface_register() - return 0; //successful registration of driver
... at a later point of time
- register_cpu(); - device_register(); - bus_probe_device(); - sif->add_dev(); - cpufreq_add_dev(); - get_cpu_device(); //FAILS - per_cpu(cpu_sys_devices, num) = &cpu->dev; //used by get_cpu_device() - return 0; //CPU registered successfully
Because the per-cpu variable cpu_sys_devices is set only after the CPU device is regsitered, cpufreq will never be able to get it when cpufreq_add_dev() is called.
This patch avoids this failure by making sure device structure of at least CPU0 is available when the cpufreq driver is registered, else return -EPROBE_DEFER.
Reported-by: Bjorn Andersson bjorn.andersson@linaro.org Co-developed-by: Amit Kucheria amit.kucheria@linaro.org Signed-off-by: Viresh Kumar viresh.kumar@linaro.org Tested-by: Amit Kucheria amit.kucheria@linaro.org Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/cpufreq/cpufreq.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 2239d42bdadd9..49aa58e617db4 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -2426,6 +2426,13 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) if (cpufreq_disabled()) return -ENODEV;
+ /* + * The cpufreq core depends heavily on the availability of device + * structure, make sure they are available before proceeding further. + */ + if (!get_cpu_device(0)) + return -EPROBE_DEFER; + if (!driver_data || !driver_data->verify || !driver_data->init || !(driver_data->setpolicy || driver_data->target_index || driver_data->target) ||