driver core: class.c: convert to only use class_to_subsys

Now that class_to_subsys() can be used to get access to the internal
class private pointer, convert the remaining few places in class.c that
were accessing the pointer directly to use class_to_subsys() instead.

By doing this, the need for class_get() and class_put() goes away as no
one actually tries to increment the class structures anymore, only the
internal dynamic one.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230325194234.46588-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/class.c b/drivers/base/class.c
index c53d6f9..1f12bd5 100644 (file)
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -66,24 +66,6 @@ done:
        return sp;
 }
 
-static const struct class *class_get(const struct class *class)
-{
-       struct subsys_private *sp = class_to_subsys(class);
-
-       if (sp)
-               return class;
-       return NULL;
-}
-
-static void class_put(const struct class *class)
-{
-       struct subsys_private *sp = class_to_subsys(class);
-
-       /* two puts are required as the call to bus_to_subsys incremented it again */
-       subsys_put(sp);
-       subsys_put(sp);
-}
-
 static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
                               char *buf)
 {
@@ -148,13 +130,15 @@ static const struct kobj_type class_ktype = {
 int class_create_file_ns(const struct class *cls, const struct class_attribute *attr,
                         const void *ns)
 {
+       struct subsys_private *sp = class_to_subsys(cls);
        int error;
 
-       if (cls)
-               error = sysfs_create_file_ns(&cls->p->subsys.kobj,
-                                            &attr->attr, ns);
-       else
-               error = -EINVAL;
+       if (!sp)
+               return -EINVAL;
+
+       error = sysfs_create_file_ns(&sp->subsys.kobj, &attr->attr, ns);
+       subsys_put(sp);
+
        return error;
 }
 EXPORT_SYMBOL_GPL(class_create_file_ns);
@@ -162,8 +146,13 @@ EXPORT_SYMBOL_GPL(class_create_file_ns);
 void class_remove_file_ns(const struct class *cls, const struct class_attribute *attr,
                          const void *ns)
 {
-       if (cls)
-               sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns);
+       struct subsys_private *sp = class_to_subsys(cls);
+
+       if (!sp)
+               return;
+
+       sysfs_remove_file_ns(&sp->subsys.kobj, &attr->attr, ns);
+       subsys_put(sp);
 }
 EXPORT_SYMBOL_GPL(class_remove_file_ns);
 
@@ -187,18 +176,6 @@ static void klist_class_dev_put(struct klist_node *n)
        put_device(dev);
 }
 
-static int class_add_groups(const struct class *cls,
-                           const struct attribute_group **groups)
-{
-       return sysfs_create_groups(&cls->p->subsys.kobj, groups);
-}
-
-static void class_remove_groups(const struct class *cls,
-                               const struct attribute_group **groups)
-{
-       return sysfs_remove_groups(&cls->p->subsys.kobj, groups);
-}
-
 int class_register(struct class *cls)
 {
        struct subsys_private *cp;
@@ -235,8 +212,7 @@ int class_register(struct class *cls)
        if (error)
                goto err_out;
 
-       error = class_add_groups(class_get(cls), cls->class_groups);
-       class_put(cls);
+       error = sysfs_create_groups(&cp->subsys.kobj, cls->class_groups);
        if (error) {
                kobject_del(&cp->subsys.kobj);
                kfree_const(cp->subsys.kobj.name);
@@ -253,9 +229,16 @@ EXPORT_SYMBOL_GPL(class_register);
 
 void class_unregister(const struct class *cls)
 {
+       struct subsys_private *sp = class_to_subsys(cls);
+
+       if (!sp)
+               return;
+
        pr_debug("device class '%s': unregistering\n", cls->name);
-       class_remove_groups(cls, cls->class_groups);
-       kset_unregister(&cls->p->subsys);
+
+       sysfs_remove_groups(&sp->subsys.kobj, cls->class_groups);
+       kset_unregister(&sp->subsys);
+       subsys_put(sp);
 }
 EXPORT_SYMBOL_GPL(class_unregister);
 
@@ -334,11 +317,15 @@ EXPORT_SYMBOL_GPL(class_destroy);
 void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class,
                         const struct device *start, const struct device_type *type)
 {
+       struct subsys_private *sp = class_to_subsys(class);
        struct klist_node *start_knode = NULL;
 
+       if (!sp)
+               return;
+
        if (start)
                start_knode = &start->p->knode_class;
-       klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
+       klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
        iter->type = type;
 }
 EXPORT_SYMBOL_GPL(class_dev_iter_init);
@@ -405,13 +392,14 @@ EXPORT_SYMBOL_GPL(class_dev_iter_exit);
 int class_for_each_device(const struct class *class, const struct device *start,
                          void *data, int (*fn)(struct device *, void *))
 {
+       struct subsys_private *sp = class_to_subsys(class);
        struct class_dev_iter iter;
        struct device *dev;
        int error = 0;
 
        if (!class)
                return -EINVAL;
-       if (!class->p) {
+       if (!sp) {
                WARN(1, "%s called for class '%s' before it was initialized",
                     __func__, class->name);
                return -EINVAL;
@@ -424,6 +412,7 @@ int class_for_each_device(const struct class *class, const struct device *start,
                        break;
        }
        class_dev_iter_exit(&iter);
+       subsys_put(sp);
 
        return error;
 }
@@ -453,12 +442,13 @@ struct device *class_find_device(const struct class *class, const struct device
                                 const void *data,
                                 int (*match)(struct device *, const void *))
 {
+       struct subsys_private *sp = class_to_subsys(class);
        struct class_dev_iter iter;
        struct device *dev;
 
        if (!class)
                return NULL;
-       if (!class->p) {
+       if (!sp) {
                WARN(1, "%s called for class '%s' before it was initialized",
                     __func__, class->name);
                return NULL;
@@ -472,6 +462,7 @@ struct device *class_find_device(const struct class *class, const struct device
                }
        }
        class_dev_iter_exit(&iter);
+       subsys_put(sp);
 
        return dev;
 }
@@ -479,6 +470,7 @@ EXPORT_SYMBOL_GPL(class_find_device);
 
 int class_interface_register(struct class_interface *class_intf)
 {
+       struct subsys_private *sp;
        const struct class *parent;
        struct class_dev_iter iter;
        struct device *dev;
@@ -486,19 +478,25 @@ int class_interface_register(struct class_interface *class_intf)
        if (!class_intf || !class_intf->class)
                return -ENODEV;
 
-       parent = class_get(class_intf->class);
-       if (!parent)
+       parent = class_intf->class;
+       sp = class_to_subsys(parent);
+       if (!sp)
                return -EINVAL;
 
-       mutex_lock(&parent->p->mutex);
-       list_add_tail(&class_intf->node, &parent->p->interfaces);
+       /*
+        * Reference in sp is now incremented and will be dropped when
+        * the interface is removed in the call to class_interface_unregister()
+        */
+
+       mutex_lock(&sp->mutex);
+       list_add_tail(&class_intf->node, &sp->interfaces);
        if (class_intf->add_dev) {
                class_dev_iter_init(&iter, parent, NULL, NULL);
                while ((dev = class_dev_iter_next(&iter)))
                        class_intf->add_dev(dev, class_intf);
                class_dev_iter_exit(&iter);
        }
-       mutex_unlock(&parent->p->mutex);
+       mutex_unlock(&sp->mutex);
 
        return 0;
 }
@@ -506,6 +504,7 @@ EXPORT_SYMBOL_GPL(class_interface_register);
 
 void class_interface_unregister(struct class_interface *class_intf)
 {
+       struct subsys_private *sp;
        struct class *parent = class_intf->class;
        struct class_dev_iter iter;
        struct device *dev;
@@ -513,7 +512,11 @@ void class_interface_unregister(struct class_interface *class_intf)
        if (!parent)
                return;
 
-       mutex_lock(&parent->p->mutex);
+       sp = class_to_subsys(parent);
+       if (!sp)
+               return;
+
+       mutex_lock(&sp->mutex);
        list_del_init(&class_intf->node);
        if (class_intf->remove_dev) {
                class_dev_iter_init(&iter, parent, NULL, NULL);
@@ -521,9 +524,15 @@ void class_interface_unregister(struct class_interface *class_intf)
                        class_intf->remove_dev(dev, class_intf);
                class_dev_iter_exit(&iter);
        }
-       mutex_unlock(&parent->p->mutex);
+       mutex_unlock(&sp->mutex);
 
-       class_put(parent);
+       /*
+        * Decrement the reference count twice, once for the class_to_subsys()
+        * call in the start of this function, and the second one from the
+        * reference increment in class_interface_register()
+        */
+       subsys_put(sp);
+       subsys_put(sp);
 }
 EXPORT_SYMBOL_GPL(class_interface_unregister);