Re: [PATCH 2/2] cpufreq: Don't create empty /sys/devices/system/cpu/cpufreqdirectory

[Viresh Kumar]

On 20 May 2013 00:13, Francesco Lavra <francescolavra.fl@xxxxxxxxx> wrote:
> On 05/17/2013 01:26 PM, Viresh Kumar wrote:
>> +EXPORT_SYMBOL(get_cpufreq_global_kobject);
>> +EXPORT_SYMBOL(put_cpufreq_global_kobject);
>
> Global symbol names should begin with a sensible prefix; in this case,
> it looks like cpufreq_get_global_kobject and cpufreq_put_global_kobject
> would be more appropriate names.

Please see if V2 looks fine. Attached too for applying.

------------x--------------------x------------------

From: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Date: Fri, 17 May 2013 16:09:09 +0530
Subject: [PATCH V2] 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@xxxxxxxxxx>
---
V1->V2: Replace: {get|put}_cpufreq_global_kobject with
cpufreq_{get|put}_global_kobject.

 drivers/cpufreq/acpi-cpufreq.c     |  4 ++--
 drivers/cpufreq/cpufreq.c          | 48 ++++++++++++++++++++++++++++++++++----
 drivers/cpufreq/cpufreq_governor.c |  6 +++++
 include/linux/cpufreq.h            |  4 ++++
 4 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index ce28c34..ae0918d 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 e3d7112..74a1a60 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)
@@ -2022,7 +2062,7 @@ 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 b6cfd55..7532570 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 cbdf5a4..b97d99b 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 {

Attachment: 0001-cpufreq-Don-t-create-empty-sys-devices-system-cpu-cp.patch
Description: Binary data