cpuidle: Make cpuidle's sysfs directory dynamically allocated

The cpuidle sysfs code is designed to have a single instance of per
CPU cpuidle directory.  It is not possible to remove the sysfs entry
and create it again.  This is not a problem with the current code but
future changes will add CPU hotplug support to enable/disable the
device, so it will need to remove the sysfs entry like other
subsystems do.  That won't be possible without this change, because
the kobj is a static object which can't be reused for
kobj_init_and_add().

Add cpuidle_device_kobj to be allocated dynamically when
adding/removing a sysfs entry which is consistent with the other
cpuidle's sysfs entries.

An added benefit is that the sysfs code is now more self-contained
and the includes needed for sysfs can be moved from cpuidle.h
directly into sysfs.c so as to reduce the total number of headers
dragged along with cpuidle.h.

[rjw: Changelog]
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpuidle/sysfs.c

@@ -11,8 +11,10 @@
 #include <linux/sysfs.h>
 #include <linux/slab.h>
 #include <linux/cpu.h>
+#include <linux/completion.h>
 #include <linux/capability.h>
 #include <linux/device.h>
+#include <linux/kobject.h>
 
 #include "cpuidle.h"
 
@@ -167,14 +169,27 @@ struct cpuidle_attr {
 #define define_one_rw(_name, show, store) \
 	static struct cpuidle_attr attr_##_name = __ATTR(_name, 0644, show, store)
 
-#define kobj_to_cpuidledev(k) container_of(k, struct cpuidle_device, kobj)
 #define attr_to_cpuidleattr(a) container_of(a, struct cpuidle_attr, attr)
 
+struct cpuidle_device_kobj {
+	struct cpuidle_device *dev;
+	struct completion kobj_unregister;
+	struct kobject kobj;
+};
+
+static inline struct cpuidle_device *to_cpuidle_device(struct kobject *kobj)
+{
+	struct cpuidle_device_kobj *kdev =
+		container_of(kobj, struct cpuidle_device_kobj, kobj);
+
+	return kdev->dev;
+}
+
 static ssize_t cpuidle_show(struct kobject *kobj, struct attribute *attr,
 			    char *buf)
 {
 	int ret = -EIO;
-	struct cpuidle_device *dev = kobj_to_cpuidledev(kobj);
+	struct cpuidle_device *dev = to_cpuidle_device(kobj);
 	struct cpuidle_attr *cattr = attr_to_cpuidleattr(attr);
 
 	if (cattr->show) {
@@ -189,7 +204,7 @@ static ssize_t cpuidle_store(struct kobject *kobj, struct attribute *attr,
 			     const char *buf, size_t count)
 {
 	int ret = -EIO;
-	struct cpuidle_device *dev = kobj_to_cpuidledev(kobj);
+	struct cpuidle_device *dev = to_cpuidle_device(kobj);
 	struct cpuidle_attr *cattr = attr_to_cpuidleattr(attr);
 
 	if (cattr->store) {
@@ -207,9 +222,10 @@ static const struct sysfs_ops cpuidle_sysfs_ops = {
 
 static void cpuidle_sysfs_release(struct kobject *kobj)
 {
-	struct cpuidle_device *dev = kobj_to_cpuidledev(kobj);
+	struct cpuidle_device_kobj *kdev =
+		container_of(kobj, struct cpuidle_device_kobj, kobj);
 
-	complete(&dev->kobj_unregister);
+	complete(&kdev->kobj_unregister);
 }
 
 static struct kobj_type ktype_cpuidle = {
@@ -377,6 +393,7 @@ static int cpuidle_add_state_sysfs(struct cpuidle_device *device)
 {
 	int i, ret = -ENOMEM;
 	struct cpuidle_state_kobj *kobj;
+	struct cpuidle_device_kobj *kdev = device->kobj_dev;
 	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(device);
 
 	/* state statistics */
@@ -389,7 +406,7 @@ static int cpuidle_add_state_sysfs(struct cpuidle_device *device)
 		init_completion(&kobj->kobj_unregister);
 
 		ret = kobject_init_and_add(&kobj->kobj, &ktype_state_cpuidle,
-					   &device->kobj, "state%d", i);
+					   &kdev->kobj, "state%d", i);
 		if (ret) {
 			kfree(kobj);
 			goto error_state;
@@ -506,6 +523,7 @@ static struct kobj_type ktype_driver_cpuidle = {
 static int cpuidle_add_driver_sysfs(struct cpuidle_device *dev)
 {
 	struct cpuidle_driver_kobj *kdrv;
+	struct cpuidle_device_kobj *kdev = dev->kobj_dev;
 	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 	int ret;
 
@@ -517,7 +535,7 @@ static int cpuidle_add_driver_sysfs(struct cpuidle_device *dev)
 	init_completion(&kdrv->kobj_unregister);
 
 	ret = kobject_init_and_add(&kdrv->kobj, &ktype_driver_cpuidle,
-				   &dev->kobj, "driver");
+				   &kdev->kobj, "driver");
 	if (ret) {
 		kfree(kdrv);
 		return ret;
@@ -586,16 +604,28 @@ void cpuidle_remove_device_sysfs(struct cpuidle_device *device)
  */
 int cpuidle_add_sysfs(struct cpuidle_device *dev)
 {
+	struct cpuidle_device_kobj *kdev;
 	struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
 	int error;
 
-	init_completion(&dev->kobj_unregister);
+	kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
+	if (!kdev)
+		return -ENOMEM;
+	kdev->dev = dev;
+	dev->kobj_dev = kdev;
 
-	error = kobject_init_and_add(&dev->kobj, &ktype_cpuidle, &cpu_dev->kobj,
-				     "cpuidle");
-	if (!error)
-		kobject_uevent(&dev->kobj, KOBJ_ADD);
-	return error;
+	init_completion(&kdev->kobj_unregister);
+
+	error = kobject_init_and_add(&kdev->kobj, &ktype_cpuidle, &cpu_dev->kobj,
+				   "cpuidle");
+	if (error) {
+		kfree(kdev);
+		return error;
+	}
+
+	kobject_uevent(&kdev->kobj, KOBJ_ADD);
+
+	return 0;
 }
 
 /**
@@ -604,6 +634,9 @@ int cpuidle_add_sysfs(struct cpuidle_device *dev)
  */
 void cpuidle_remove_sysfs(struct cpuidle_device *dev)
 {
-	kobject_put(&dev->kobj);
-	wait_for_completion(&dev->kobj_unregister);
+	struct cpuidle_device_kobj *kdev = dev->kobj_dev;
+
+	kobject_put(&kdev->kobj);
+	wait_for_completion(&kdev->kobj_unregister);
+	kfree(kdev);
 }

include/linux/cpuidle.h

@@ -13,8 +13,6 @@
 
 #include <linux/percpu.h>
 #include <linux/list.h>
-#include <linux/kobject.h>
-#include <linux/completion.h>
 #include <linux/hrtimer.h>
 
 #define CPUIDLE_STATE_MAX	10
@@ -61,6 +59,8 @@ struct cpuidle_state {
 
 #define CPUIDLE_DRIVER_FLAGS_MASK (0xFFFF0000)
 
+struct cpuidle_device_kobj;
+
 struct cpuidle_device {
 	unsigned int		registered:1;
 	unsigned int		enabled:1;
@@ -71,9 +71,8 @@ struct cpuidle_device {
 	struct cpuidle_state_usage	states_usage[CPUIDLE_STATE_MAX];
 	struct cpuidle_state_kobj *kobjs[CPUIDLE_STATE_MAX];
 	struct cpuidle_driver_kobj *kobj_driver;
+	struct cpuidle_device_kobj *kobj_dev;
 	struct list_head 	device_list;
-	struct kobject		kobj;
-	struct completion	kobj_unregister;
 
 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
 	int			safe_state_index;