Merge tag 'driver-core-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the large set of driver core changes for 6.4-rc1.

  Once again, a busy development cycle, with lots of changes happening
  in the driver core in the quest to be able to move "struct bus" and
  "struct class" into read-only memory, a task now complete with these
  changes.

  This will make the future rust interactions with the driver core more
  "provably correct" as well as providing more obvious lifetime rules
  for all busses and classes in the kernel.

  The changes required for this did touch many individual classes and
  busses as many callbacks were changed to take const * parameters
  instead. All of these changes have been submitted to the various
  subsystem maintainers, giving them plenty of time to review, and most
  of them actually did so.

  Other than those changes, included in here are a small set of other
  things:

   - kobject logging improvements

   - cacheinfo improvements and updates

   - obligatory fw_devlink updates and fixes

   - documentation updates

   - device property cleanups and const * changes

   - firwmare loader dependency fixes.

  All of these have been in linux-next for a while with no reported
  problems"

* tag 'driver-core-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (120 commits)
  device property: make device_property functions take const device *
  driver core: update comments in device_rename()
  driver core: Don't require dynamic_debug for initcall_debug probe timing
  firmware_loader: rework crypto dependencies
  firmware_loader: Strip off \n from customized path
  zram: fix up permission for the hot_add sysfs file
  cacheinfo: Add use_arch[|_cache]_info field/function
  arch_topology: Remove early cacheinfo error message if -ENOENT
  cacheinfo: Check cache properties are present in DT
  cacheinfo: Check sib_leaf in cache_leaves_are_shared()
  cacheinfo: Allow early level detection when DT/ACPI info is missing/broken
  cacheinfo: Add arm64 early level initializer implementation
  cacheinfo: Add arch specific early level initializer
  tty: make tty_class a static const structure
  driver core: class: remove struct class_interface * from callbacks
  driver core: class: mark the struct class in struct class_interface constant
  driver core: class: make class_register() take a const *
  driver core: class: mark class_release() as taking a const *
  driver core: remove incorrect comment for device_create*
  MIPS: vpe-cmp: remove module owner pointer from struct class usage.
  ...

1 files changed, 156 insertions, 91 deletions

diff --git a/drivers/base/class.c b/drivers/base/class.c
index 2373b3e210d8..ac1808d1a2e8 100644
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -20,8 +20,52 @@
 #include <linux/mutex.h>
 #include "base.h"
 
+/* /sys/class */
+static struct kset *class_kset;
+
 #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
 
+/**
+ * class_to_subsys - Turn a struct class into a struct subsys_private
+ *
+ * @class: pointer to the struct bus_type to look up
+ *
+ * The driver core internals need to work on the subsys_private structure, not
+ * the external struct class pointer.  This function walks the list of
+ * registered classes in the system and finds the matching one and returns the
+ * internal struct subsys_private that relates to that class.
+ *
+ * Note, the reference count of the return value is INCREMENTED if it is not
+ * NULL.  A call to subsys_put() must be done when finished with the pointer in
+ * order for it to be properly freed.
+ */
+struct subsys_private *class_to_subsys(const struct class *class)
+{
+	struct subsys_private *sp = NULL;
+	struct kobject *kobj;
+
+	if (!class || !class_kset)
+		return NULL;
+
+	spin_lock(&class_kset->list_lock);
+
+	if (list_empty(&class_kset->list))
+		goto done;
+
+	list_for_each_entry(kobj, &class_kset->list, entry) {
+		struct kset *kset = container_of(kobj, struct kset, kobj);
+
+		sp = container_of_const(kset, struct subsys_private, subsys);
+		if (sp->class == class)
+			goto done;
+	}
+	sp = NULL;
+done:
+	sp = subsys_get(sp);
+	spin_unlock(&class_kset->list_lock);
+	return sp;
+}
+
 static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
 			       char *buf)
 {
@@ -49,25 +93,24 @@ static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
 static void class_release(struct kobject *kobj)
 {
 	struct subsys_private *cp = to_subsys_private(kobj);
-	struct class *class = cp->class;
+	const struct class *class = cp->class;
 
 	pr_debug("class '%s': release.\n", class->name);
 
-	class->p = NULL;
-
 	if (class->class_release)
 		class->class_release(class);
 	else
 		pr_debug("class '%s' does not have a release() function, "
 			 "be careful\n", class->name);
 
+	lockdep_unregister_key(&cp->lock_key);
 	kfree(cp);
 }
 
 static const struct kobj_ns_type_operations *class_child_ns_type(const struct kobject *kobj)
 {
 	const struct subsys_private *cp = to_subsys_private(kobj);
-	struct class *class = cp->class;
+	const struct class *class = cp->class;
 
 	return class->ns_type;
 }
@@ -83,44 +126,34 @@ static const struct kobj_type class_ktype = {
 	.child_ns_type	= class_child_ns_type,
 };
 
-/* Hotplug events for classes go to the class subsys */
-static struct kset *class_kset;
-
-
-int class_create_file_ns(struct class *cls, const struct class_attribute *attr,
+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);
 
-void class_remove_file_ns(struct class *cls, const struct class_attribute *attr,
+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);
-}
-EXPORT_SYMBOL_GPL(class_remove_file_ns);
+	struct subsys_private *sp = class_to_subsys(cls);
 
-static struct class *class_get(struct class *cls)
-{
-	if (cls)
-		kset_get(&cls->p->subsys);
-	return cls;
-}
+	if (!sp)
+		return;
 
-static void class_put(struct class *cls)
-{
-	if (cls)
-		kset_put(&cls->p->subsys);
+	sysfs_remove_file_ns(&sp->subsys.kobj, &attr->attr, ns);
+	subsys_put(sp);
 }
+EXPORT_SYMBOL_GPL(class_remove_file_ns);
 
 static struct device *klist_class_to_dev(struct klist_node *n)
 {
@@ -142,21 +175,10 @@ static void klist_class_dev_put(struct klist_node *n)
 	put_device(dev);
 }
 
-static int class_add_groups(struct class *cls,
-			    const struct attribute_group **groups)
-{
-	return sysfs_create_groups(&cls->p->subsys.kobj, groups);
-}
-
-static void class_remove_groups(struct class *cls,
-				const struct attribute_group **groups)
-{
-	return sysfs_remove_groups(&cls->p->subsys.kobj, groups);
-}
-
-int __class_register(struct class *cls, struct lock_class_key *key)
+int class_register(const struct class *cls)
 {
 	struct subsys_private *cp;
+	struct lock_class_key *key;
 	int error;
 
 	pr_debug("device class '%s': registering\n", cls->name);
@@ -167,6 +189,8 @@ int __class_register(struct class *cls, struct lock_class_key *key)
 	klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
 	INIT_LIST_HEAD(&cp->interfaces);
 	kset_init(&cp->glue_dirs);
+	key = &cp->lock_key;
+	lockdep_register_key(key);
 	__mutex_init(&cp->mutex, "subsys mutex", key);
 	error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
 	if (error) {
@@ -174,27 +198,15 @@ int __class_register(struct class *cls, struct lock_class_key *key)
 		return error;
 	}
 
-	/* set the default /sys/dev directory for devices of this class */
-	if (!cls->dev_kobj)
-		cls->dev_kobj = sysfs_dev_char_kobj;
-
-#if defined(CONFIG_BLOCK)
-	/* let the block class directory show up in the root of sysfs */
-	if (!sysfs_deprecated || cls != &block_class)
-		cp->subsys.kobj.kset = class_kset;
-#else
 	cp->subsys.kobj.kset = class_kset;
-#endif
 	cp->subsys.kobj.ktype = &class_ktype;
 	cp->class = cls;
-	cls->p = cp;
 
 	error = kset_register(&cp->subsys);
 	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);
@@ -204,30 +216,34 @@ int __class_register(struct class *cls, struct lock_class_key *key)
 
 err_out:
 	kfree(cp);
-	cls->p = NULL;
 	return error;
 }
-EXPORT_SYMBOL_GPL(__class_register);
+EXPORT_SYMBOL_GPL(class_register);
 
-void class_unregister(struct class *cls)
+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);
 
-static void class_create_release(struct class *cls)
+static void class_create_release(const struct class *cls)
 {
 	pr_debug("%s called for %s\n", __func__, cls->name);
 	kfree(cls);
 }
 
 /**
- * __class_create - create a struct class structure
- * @owner: pointer to the module that is to "own" this struct class
+ * class_create - create a struct class structure
  * @name: pointer to a string for the name of this class.
- * @key: the lock_class_key for this class; used by mutex lock debugging
  *
  * This is used to create a struct class pointer that can then be used
  * in calls to device_create().
@@ -237,8 +253,7 @@ static void class_create_release(struct class *cls)
  * Note, the pointer created here is to be destroyed when finished by
  * making a call to class_destroy().
  */
-struct class *__class_create(struct module *owner, const char *name,
-			     struct lock_class_key *key)
+struct class *class_create(const char *name)
 {
 	struct class *cls;
 	int retval;
@@ -250,10 +265,9 @@ struct class *__class_create(struct module *owner, const char *name,
 	}
 
 	cls->name = name;
-	cls->owner = owner;
 	cls->class_release = class_create_release;
 
-	retval = __class_register(cls, key);
+	retval = class_register(cls);
 	if (retval)
 		goto error;
 
@@ -263,7 +277,7 @@ error:
 	kfree(cls);
 	return ERR_PTR(retval);
 }
-EXPORT_SYMBOL_GPL(__class_create);
+EXPORT_SYMBOL_GPL(class_create);
 
 /**
  * class_destroy - destroys a struct class structure
@@ -272,7 +286,7 @@ EXPORT_SYMBOL_GPL(__class_create);
  * Note, the pointer to be destroyed must have been created with a call
  * to class_create().
  */
-void class_destroy(struct class *cls)
+void class_destroy(const struct class *cls)
 {
 	if (IS_ERR_OR_NULL(cls))
 		return;
@@ -293,14 +307,18 @@ EXPORT_SYMBOL_GPL(class_destroy);
  * otherwise if it is NULL, the iteration starts at the beginning of
  * the list.
  */
-void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
-			 struct device *start, const struct device_type *type)
+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);
@@ -364,16 +382,17 @@ EXPORT_SYMBOL_GPL(class_dev_iter_exit);
  * @fn is allowed to do anything including calling back into class
  * code.  There's no locking restriction.
  */
-int class_for_each_device(struct class *class, struct device *start,
+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;
@@ -386,6 +405,7 @@ int class_for_each_device(struct class *class, struct device *start,
 			break;
 	}
 	class_dev_iter_exit(&iter);
+	subsys_put(sp);
 
 	return error;
 }
@@ -411,16 +431,17 @@ EXPORT_SYMBOL_GPL(class_for_each_device);
  * @match is allowed to do anything including calling back into class
  * code.  There's no locking restriction.
  */
-struct device *class_find_device(struct class *class, struct device *start,
+struct device *class_find_device(const struct class *class, const struct device *start,
 				 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;
@@ -434,6 +455,7 @@ struct device *class_find_device(struct class *class, struct device *start,
 		}
 	}
 	class_dev_iter_exit(&iter);
+	subsys_put(sp);
 
 	return dev;
 }
@@ -441,26 +463,33 @@ EXPORT_SYMBOL_GPL(class_find_device);
 
 int class_interface_register(struct class_interface *class_intf)
 {
-	struct class *parent;
+	struct subsys_private *sp;
+	const struct class *parent;
 	struct class_dev_iter iter;
 	struct device *dev;
 
 	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_intf->add_dev(dev);
 		class_dev_iter_exit(&iter);
 	}
-	mutex_unlock(&parent->p->mutex);
+	mutex_unlock(&sp->mutex);
 
 	return 0;
 }
@@ -468,29 +497,40 @@ EXPORT_SYMBOL_GPL(class_interface_register);
 
 void class_interface_unregister(struct class_interface *class_intf)
 {
-	struct class *parent = class_intf->class;
+	struct subsys_private *sp;
+	const struct class *parent = class_intf->class;
 	struct class_dev_iter iter;
 	struct device *dev;
 
 	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);
 		while ((dev = class_dev_iter_next(&iter)))
-			class_intf->remove_dev(dev, class_intf);
+			class_intf->remove_dev(dev);
 		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);
 
-ssize_t show_class_attr_string(struct class *class,
-			       struct class_attribute *attr, char *buf)
+ssize_t show_class_attr_string(const struct class *class,
+			       const struct class_attribute *attr, char *buf)
 {
 	struct class_attribute_string *cs;
 
@@ -587,6 +627,31 @@ void class_compat_remove_link(struct class_compat *cls, struct device *dev,
 }
 EXPORT_SYMBOL_GPL(class_compat_remove_link);
 
+/**
+ * class_is_registered - determine if at this moment in time, a class is
+ *			 registered in the driver core or not.
+ * @class: the class to check
+ *
+ * Returns a boolean to state if the class is registered in the driver core
+ * or not.  Note that the value could switch right after this call is made,
+ * so only use this in places where you "know" it is safe to do so (usually
+ * to determine if the specific class has been registered yet or not).
+ *
+ * Be careful in using this.
+ */
+bool class_is_registered(const struct class *class)
+{
+	struct subsys_private *sp = class_to_subsys(class);
+	bool is_initialized = false;
+
+	if (sp) {
+		is_initialized = true;
+		subsys_put(sp);
+	}
+	return is_initialized;
+}
+EXPORT_SYMBOL_GPL(class_is_registered);
+
 int __init classes_init(void)
 {
 	class_kset = kset_create_and_add("class", NULL, NULL);