Merge tag 'driver-core-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the set of driver core and kernfs changes for 6.2-rc1.

  The "big" change in here is the addition of a new macro,
  container_of_const() that will preserve the "const-ness" of a pointer
  passed into it.

  The "problem" of the current container_of() macro is that if you pass
  in a "const *", out of it can comes a non-const pointer unless you
  specifically ask for it. For many usages, we want to preserve the
  "const" attribute by using the same call. For a specific example, this
  series changes the kobj_to_dev() macro to use it, allowing it to be
  used no matter what the const value is. This prevents every subsystem
  from having to declare 2 different individual macros (i.e.
  kobj_const_to_dev() and kobj_to_dev()) and having the compiler enforce
  the const value at build time, which having 2 macros would not do
  either.

  The driver for all of this have been discussions with the Rust kernel
  developers as to how to properly mark driver core, and kobject,
  objects as being "non-mutable". The changes to the kobject and driver
  core in this pull request are the result of that, as there are lots of
  paths where kobjects and device pointers are not modified at all, so
  marking them as "const" allows the compiler to enforce this.

  So, a nice side affect of the Rust development effort has been already
  to clean up the driver core code to be more obvious about object
  rules.

  All of this has been bike-shedded in quite a lot of detail on lkml
  with different names and implementations resulting in the tiny version
  we have in here, much better than my original proposal. Lots of
  subsystem maintainers have acked the changes as well.

  Other than this change, included in here are smaller stuff like:

   - kernfs fixes and updates to handle lock contention better

   - vmlinux.lds.h fixes and updates

   - sysfs and debugfs documentation updates

   - device property updates

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

* tag 'driver-core-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (58 commits)
  device property: Fix documentation for fwnode_get_next_parent()
  firmware_loader: fix up to_fw_sysfs() to preserve const
  usb.h: take advantage of container_of_const()
  device.h: move kobj_to_dev() to use container_of_const()
  container_of: add container_of_const() that preserves const-ness of the pointer
  driver core: fix up missed drivers/s390/char/hmcdrv_dev.c class.devnode() conversion.
  driver core: fix up missed scsi/cxlflash class.devnode() conversion.
  driver core: fix up some missing class.devnode() conversions.
  driver core: make struct class.devnode() take a const *
  driver core: make struct class.dev_uevent() take a const *
  cacheinfo: Remove of_node_put() for fw_token
  device property: Add a blank line in Kconfig of tests
  device property: Rename goto label to be more precise
  device property: Move PROPERTY_ENTRY_BOOL() a bit down
  device property: Get rid of __PROPERTY_ENTRY_ARRAY_EL*SIZE*()
  kernfs: fix all kernel-doc warnings and multiple typos
  driver core: pass a const * into of_device_uevent()
  kobject: kset_uevent_ops: make name() callback take a const *
  kobject: kset_uevent_ops: make filter() callback take a const *
  kobject: make kobject_namespace take a const *
  ...

1 files changed, 18 insertions, 11 deletions

diff --git a/lib/kobject.c b/lib/kobject.c
index af1f5f2954d4..985ee1c4f2c6 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -25,7 +25,7 @@
  * and thus @kobj should have a namespace tag associated with it.  Returns
  * %NULL otherwise.
  */
-const void *kobject_namespace(struct kobject *kobj)
+const void *kobject_namespace(const struct kobject *kobj)
 {
 	const struct kobj_ns_type_operations *ns_ops = kobj_ns_ops(kobj);
 
@@ -45,7 +45,7 @@ const void *kobject_namespace(struct kobject *kobj)
  * representation of given kobject. Normally used to adjust ownership of
  * objects in a container.
  */
-void kobject_get_ownership(struct kobject *kobj, kuid_t *uid, kgid_t *gid)
+void kobject_get_ownership(const struct kobject *kobj, kuid_t *uid, kgid_t *gid)
 {
 	*uid = GLOBAL_ROOT_UID;
 	*gid = GLOBAL_ROOT_GID;
@@ -94,10 +94,10 @@ static int create_dir(struct kobject *kobj)
 	return 0;
 }
 
-static int get_kobj_path_length(struct kobject *kobj)
+static int get_kobj_path_length(const struct kobject *kobj)
 {
 	int length = 1;
-	struct kobject *parent = kobj;
+	const struct kobject *parent = kobj;
 
 	/* walk up the ancestors until we hit the one pointing to the
 	 * root.
@@ -112,9 +112,9 @@ static int get_kobj_path_length(struct kobject *kobj)
 	return length;
 }
 
-static void fill_kobj_path(struct kobject *kobj, char *path, int length)
+static void fill_kobj_path(const struct kobject *kobj, char *path, int length)
 {
-	struct kobject *parent;
+	const struct kobject *parent;
 
 	--length;
 	for (parent = kobj; parent; parent = parent->parent) {
@@ -136,7 +136,7 @@ static void fill_kobj_path(struct kobject *kobj, char *path, int length)
  *
  * Return: The newly allocated memory, caller must free with kfree().
  */
-char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
+char *kobject_get_path(const struct kobject *kobj, gfp_t gfp_mask)
 {
 	char *path;
 	int len;
@@ -834,6 +834,9 @@ EXPORT_SYMBOL_GPL(kobj_sysfs_ops);
 /**
  * kset_register() - Initialize and add a kset.
  * @k: kset.
+ *
+ * NOTE: On error, the kset.kobj.name allocated by() kobj_set_name()
+ * is freed, it can not be used any more.
  */
 int kset_register(struct kset *k)
 {
@@ -844,8 +847,12 @@ int kset_register(struct kset *k)
 
 	kset_init(k);
 	err = kobject_add_internal(&k->kobj);
-	if (err)
+	if (err) {
+		kfree_const(k->kobj.name);
+		/* Set it to NULL to avoid accessing bad pointer in callers. */
+		k->kobj.name = NULL;
 		return err;
+	}
 	kobject_uevent(&k->kobj, KOBJ_ADD);
 	return 0;
 }
@@ -900,7 +907,7 @@ static void kset_release(struct kobject *kobj)
 	kfree(kset);
 }
 
-static void kset_get_ownership(struct kobject *kobj, kuid_t *uid, kgid_t *gid)
+static void kset_get_ownership(const struct kobject *kobj, kuid_t *uid, kgid_t *gid)
 {
 	if (kobj->parent)
 		kobject_get_ownership(kobj->parent, uid, gid);
@@ -1032,7 +1039,7 @@ int kobj_ns_type_registered(enum kobj_ns_type type)
 	return registered;
 }
 
-const struct kobj_ns_type_operations *kobj_child_ns_ops(struct kobject *parent)
+const struct kobj_ns_type_operations *kobj_child_ns_ops(const struct kobject *parent)
 {
 	const struct kobj_ns_type_operations *ops = NULL;
 
@@ -1042,7 +1049,7 @@ const struct kobj_ns_type_operations *kobj_child_ns_ops(struct kobject *parent)
 	return ops;
 }
 
-const struct kobj_ns_type_operations *kobj_ns_ops(struct kobject *kobj)
+const struct kobj_ns_type_operations *kobj_ns_ops(const struct kobject *kobj)
 {
 	return kobj_child_ns_ops(kobj->parent);
 }