[PATCH] cpufreq: Fix get_cpu_device() failed in add_cpu_dev_symlink()
From: Xiongfeng Wang <hidden>
Date: 2021-11-29 07:53:57
Also in:
lkml
Subsystem:
cpu frequency scaling framework, the rest · Maintainers:
"Rafael J. Wysocki", Viresh Kumar, Linus Torvalds
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(). I noticed that the 'kobj' of the cpu device has
been added into the system before cpufreq_add_dev().
Signed-off-by: Xiongfeng Wang <redacted>
---
drivers/cpufreq/cpufreq.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index e338d2f010fe..22aa2793e4d2 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c@@ -1004,10 +1004,9 @@ 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;
@@ -1391,7 +1390,7 @@ static int cpufreq_online(unsigned int cpu) 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),
@@ -1565,7 +1564,7 @@ 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; }
--
2.20.1