From: Xiongfeng Wang wangxiongfeng2@huawei.com
commit 2c1b5a84669d2477d8fffe9136e86a2cff591729 upstream.
When I hot added a CPU, I found 'cpufreq' directory was not created below /sys/devices/system/cpu/cpuX/.
It is because get_cpu_device() failed in add_cpu_dev_symlink().
cpufreq_add_dev() is the .add_dev callback of a CPU subsys interface. It will be called when the CPU device registered into the system. The call chain is as follows:
register_cpu() ->device_register() ->device_add() ->bus_probe_device() ->cpufreq_add_dev()
But only after the CPU device has been registered, we can get the CPU device by get_cpu_device(), otherwise it will return NULL.
Since we already have the CPU device in cpufreq_add_dev(), pass it to add_cpu_dev_symlink().
I noticed that the 'kobj' of the CPU device has been added into the system before cpufreq_add_dev().
Fixes: 2f0ba790df51 ("cpufreq: Fix creation of symbolic links to policy directories") Signed-off-by: Xiongfeng Wang wangxiongfeng2@huawei.com Acked-by: Viresh Kumar viresh.kumar@linaro.org Cc: All applicable stable@vger.kernel.org Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/cpufreq/cpufreq.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)
--- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -995,10 +995,9 @@ static struct kobj_type ktype_cpufreq = .release = cpufreq_sysfs_release, };
-static void add_cpu_dev_symlink(struct cpufreq_policy *policy, unsigned int cpu) +static void add_cpu_dev_symlink(struct cpufreq_policy *policy, unsigned int cpu, + struct device *dev) { - struct device *dev = get_cpu_device(cpu); - if (unlikely(!dev)) return;
@@ -1384,7 +1383,7 @@ static int cpufreq_online(unsigned int c if (new_policy) { for_each_cpu(j, policy->related_cpus) { per_cpu(cpufreq_cpu_data, j) = policy; - add_cpu_dev_symlink(policy, j); + add_cpu_dev_symlink(policy, j, get_cpu_device(j)); }
policy->min_freq_req = kzalloc(2 * sizeof(*policy->min_freq_req), @@ -1547,7 +1546,7 @@ static int cpufreq_add_dev(struct device /* Create sysfs link on CPU registration */ policy = per_cpu(cpufreq_cpu_data, cpu); if (policy) - add_cpu_dev_symlink(policy, cpu); + add_cpu_dev_symlink(policy, cpu, dev);
return 0; }