This is a note to let you know that I've just added the patch titled
cpufreq: Fix get_cpu_device() failure in add_cpu_dev_symlink()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cpufreq-fix-get_cpu_device-failure-in-add_cpu_dev_symlink.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2c1b5a84669d2477d8fffe9136e86a2cff591729 Mon Sep 17 00:00:00 2001
From: Xiongfeng Wang <wangxiongfeng2@xxxxxxxxxx>
Date: Mon, 29 Nov 2021 16:02:48 +0800
Subject: cpufreq: Fix get_cpu_device() failure in add_cpu_dev_symlink()
From: Xiongfeng Wang <wangxiongfeng2@xxxxxxxxxx>
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@xxxxxxxxxx>
Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Cc: All applicable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
Patches currently in stable-queue which might be from wangxiongfeng2@xxxxxxxxxx are
queue-5.4/cpufreq-fix-get_cpu_device-failure-in-add_cpu_dev_symlink.patch
