Commit 97e7efbb authored Nov 27, 2021 by Xiongfeng Wang Committed by Yang Yingliang Nov 27, 2021

cpufreq: Fix get_cpu_device() failed in add_cpu_dev_symlink()

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4HYY4?from=project-issue


CVE: NA

-------------------------------------------------

When I hot added a CPU, I found 'cpufreq' directory is 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 stack
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().

Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: Keqian Zhu <zhukeqian1@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>

parent b8815fbb

drivers/cpufreq/cpufreq.c

+4 −5

Original line number	Diff line number	Diff line
		@@ -965,10 +965,9 @@ 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 (!dev)
		return;

		@@ -1241,7 +1240,7 @@ static int cpufreq_online(unsigned int cpu)

		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));
		}
		} else {
		policy->min = policy->user_policy.min;
		@@ -1366,7 +1365,7 @@ static int cpufreq_add_dev(struct device dev, struct subsys_interface sif)
		/* 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;
		}