cpufreq: Don't create empty /sys/devices/system/cpu/cpufreq directory

When we don't have any file in cpu/cpufreq directory we shouldn't
create it. Specially with the introduction of per-policy governor
instance patchset, even governors are moved to
cpu/cpu*/cpufreq/governor-name directory and so this directory is
just not required.

Lets have it only when required.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

4 files changed, 56 insertions, 6 deletions

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 11b8b4b54ceb..8c02622b35a4 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -947,7 +947,7 @@ static void __init acpi_cpufreq_boost_init(void)
         /* We create the boost file in any case, though for systems without
          * hardware support it will be read-only and hardwired to return 0.
          */
-        if (sysfs_create_file(cpufreq_global_kobject, &(global_boost.attr)))
+        if (cpufreq_sysfs_create_file(&(global_boost.attr)))
                 pr_warn(PFX "could not register global boost sysfs file\n");
         else
                 pr_debug("registered global boost sysfs file\n");
@@ -955,7 +955,7 @@ static void __init acpi_cpufreq_boost_init(void)
 
 static void __exit acpi_cpufreq_boost_exit(void)
 {
-        sysfs_remove_file(cpufreq_global_kobject, &(global_boost.attr));
+        cpufreq_sysfs_remove_file(&(global_boost.attr));
 
         if (msrs) {
                 unregister_cpu_notifier(&boost_nb);
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index c6ab21880c07..ce9273a7b4e3 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -678,9 +678,6 @@ static struct attribute *default_attrs[] = {
         NULL
 };
 
-struct kobject *cpufreq_global_kobject;
-EXPORT_SYMBOL(cpufreq_global_kobject);
-
 #define to_policy(k) container_of(k, struct cpufreq_policy, kobj)
 #define to_attr(a) container_of(a, struct freq_attr, attr)
 
@@ -751,6 +748,49 @@ static struct kobj_type ktype_cpufreq = {
         .release        = cpufreq_sysfs_release,
 };
 
+struct kobject *cpufreq_global_kobject;
+EXPORT_SYMBOL(cpufreq_global_kobject);
+
+static int cpufreq_global_kobject_usage;
+
+int cpufreq_get_global_kobject(void)
+{
+        if (!cpufreq_global_kobject_usage++)
+                return kobject_add(cpufreq_global_kobject,
+                                &cpu_subsys.dev_root->kobj, "%s", "cpufreq");
+
+        return 0;
+}
+EXPORT_SYMBOL(cpufreq_get_global_kobject);
+
+void cpufreq_put_global_kobject(void)
+{
+        if (!--cpufreq_global_kobject_usage)
+                kobject_del(cpufreq_global_kobject);
+}
+EXPORT_SYMBOL(cpufreq_put_global_kobject);
+
+int cpufreq_sysfs_create_file(const struct attribute *attr)
+{
+        int ret = cpufreq_get_global_kobject();
+
+        if (!ret) {
+                ret = sysfs_create_file(cpufreq_global_kobject, attr);
+                if (ret)
+                        cpufreq_put_global_kobject();
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL(cpufreq_sysfs_create_file);
+
+void cpufreq_sysfs_remove_file(const struct attribute *attr)
+{
+        sysfs_remove_file(cpufreq_global_kobject, attr);
+        cpufreq_put_global_kobject();
+}
+EXPORT_SYMBOL(cpufreq_sysfs_remove_file);
+
 /* symlink affected CPUs */
 static int cpufreq_add_dev_symlink(unsigned int cpu,
                                    struct cpufreq_policy *policy)
@@ -2020,7 +2060,7 @@ static int __init cpufreq_core_init(void)
                 init_rwsem(&per_cpu(cpu_policy_rwsem, cpu));
         }
 
-        cpufreq_global_kobject = kobject_create_and_add("cpufreq", &cpu_subsys.dev_root->kobj);
+        cpufreq_global_kobject = kobject_create();
         BUG_ON(!cpufreq_global_kobject);
         register_syscore_ops(&cpufreq_syscore_ops);
 
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index b6cfd55d8266..7532570c42b4 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -231,6 +231,9 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                         return rc;
                 }
 
+                if (!have_governor_per_policy())
+                        WARN_ON(cpufreq_get_global_kobject());
+
                 rc = sysfs_create_group(get_governor_parent_kobj(policy),
                                 get_sysfs_attr(dbs_data));
                 if (rc) {
@@ -269,6 +272,9 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                         sysfs_remove_group(get_governor_parent_kobj(policy),
                                         get_sysfs_attr(dbs_data));
 
+                        if (!have_governor_per_policy())
+                                cpufreq_put_global_kobject();
+
                         if ((dbs_data->cdata->governor == GOV_CONSERVATIVE) &&
                                 (policy->governor->initialized == 1)) {
                                 struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index fbf392aaa02e..1b5b5efa3e3a 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -71,6 +71,10 @@ struct cpufreq_governor;
 
 /* /sys/devices/system/cpu/cpufreq: entry point for global variables */
 extern struct kobject *cpufreq_global_kobject;
+int cpufreq_get_global_kobject(void);
+void cpufreq_put_global_kobject(void);
+int cpufreq_sysfs_create_file(const struct attribute *attr);
+void cpufreq_sysfs_remove_file(const struct attribute *attr);
 
 #define CPUFREQ_ETERNAL                 (-1)
 struct cpufreq_cpuinfo {