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, 67 insertions, 39 deletions

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index f33b3baad07c..935ef8cb02b2 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -125,9 +125,9 @@ static struct kernfs_node *kernfs_common_ancestor(struct kernfs_node *a,
  * kn_to:   /n1/n2/n3         [depth=3]
  * result:  /../..
  *
- * [3] when @kn_to is NULL result will be "(null)"
+ * [3] when @kn_to is %NULL result will be "(null)"
  *
- * Returns the length of the full path.  If the full length is equal to or
+ * Return: the length of the full path.  If the full length is equal to or
  * greater than @buflen, @buf contains the truncated path with the trailing
  * '\0'.  On error, -errno is returned.
  */
@@ -185,10 +185,12 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to,
  * @buflen: size of @buf
  *
  * Copies the name of @kn into @buf of @buflen bytes.  The behavior is
- * similar to strlcpy().  It returns the length of @kn's name and if @buf
- * isn't long enough, it's filled upto @buflen-1 and nul terminated.
+ * similar to strlcpy().
  *
- * Fills buffer with "(null)" if @kn is NULL.
+ * Fills buffer with "(null)" if @kn is %NULL.
+ *
+ * Return: the length of @kn's name and if @buf isn't long enough,
+ * it's filled up to @buflen-1 and nul terminated.
  *
  * This function can be called from any context.
  */
@@ -215,7 +217,7 @@ int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
  * path (which includes '..'s) as needed to reach from @from to @to is
  * returned.
  *
- * Returns the length of the full path.  If the full length is equal to or
+ * Return: the length of the full path.  If the full length is equal to or
  * greater than @buflen, @buf contains the truncated path with the trailing
  * '\0'.  On error, -errno is returned.
  */
@@ -287,6 +289,8 @@ out:
  *
  * Determines @kn's parent, pins and returns it.  This function can be
  * called from any context.
+ *
+ * Return: parent node of @kn
  */
 struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
 {
@@ -302,11 +306,11 @@ struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
 }
 
 /**
- *	kernfs_name_hash
+ *	kernfs_name_hash - calculate hash of @ns + @name
  *	@name: Null terminated string to hash
  *	@ns:   Namespace tag to hash
  *
- *	Returns 31 bit hash of ns + name (so it fits in an off_t )
+ *	Return: 31-bit hash of ns + name (so it fits in an off_t)
  */
 static unsigned int kernfs_name_hash(const char *name, const void *ns)
 {
@@ -354,8 +358,8 @@ static int kernfs_sd_compare(const struct kernfs_node *left,
  *	Locking:
  *	kernfs_rwsem held exclusive
  *
- *	RETURNS:
- *	0 on susccess -EEXIST on failure.
+ *	Return:
+ *	%0 on success, -EEXIST on failure.
  */
 static int kernfs_link_sibling(struct kernfs_node *kn)
 {
@@ -394,8 +398,10 @@ static int kernfs_link_sibling(struct kernfs_node *kn)
  *	@kn: kernfs_node of interest
  *
  *	Try to unlink @kn from its sibling rbtree which starts from
- *	kn->parent->dir.children.  Returns %true if @kn was actually
- *	removed, %false if @kn wasn't on the rbtree.
+ *	kn->parent->dir.children.
+ *
+ *	Return: %true if @kn was actually removed,
+ *	%false if @kn wasn't on the rbtree.
  *
  *	Locking:
  *	kernfs_rwsem held exclusive
@@ -419,10 +425,10 @@ static bool kernfs_unlink_sibling(struct kernfs_node *kn)
  *	@kn: kernfs_node to get an active reference to
  *
  *	Get an active reference of @kn.  This function is noop if @kn
- *	is NULL.
+ *	is %NULL.
  *
- *	RETURNS:
- *	Pointer to @kn on success, NULL on failure.
+ *	Return:
+ *	Pointer to @kn on success, %NULL on failure.
  */
 struct kernfs_node *kernfs_get_active(struct kernfs_node *kn)
 {
@@ -442,7 +448,7 @@ struct kernfs_node *kernfs_get_active(struct kernfs_node *kn)
  *	@kn: kernfs_node to put an active reference to
  *
  *	Put an active reference to @kn.  This function is noop if @kn
- *	is NULL.
+ *	is %NULL.
  */
 void kernfs_put_active(struct kernfs_node *kn)
 {
@@ -464,7 +470,7 @@ void kernfs_put_active(struct kernfs_node *kn)
  * kernfs_drain - drain kernfs_node
  * @kn: kernfs_node to drain
  *
- * Drain existing usages and nuke all existing mmaps of @kn.  Mutiple
+ * Drain existing usages and nuke all existing mmaps of @kn.  Multiple
  * removers may invoke this function concurrently on @kn and all will
  * return after draining is complete.
  */
@@ -577,7 +583,7 @@ EXPORT_SYMBOL_GPL(kernfs_put);
  * kernfs_node_from_dentry - determine kernfs_node associated with a dentry
  * @dentry: the dentry in question
  *
- * Return the kernfs_node associated with @dentry.  If @dentry is not a
+ * Return: the kernfs_node associated with @dentry.  If @dentry is not a
  * kernfs one, %NULL is returned.
  *
  * While the returned kernfs_node will stay accessible as long as @dentry
@@ -684,8 +690,8 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
  * @id's lower 32bits encode ino and upper gen.  If the gen portion is
  * zero, all generations are matched.
  *
- * RETURNS:
- * NULL on failure. Return a kernfs node with reference counter incremented
+ * Return: %NULL on failure,
+ * otherwise a kernfs node with reference counter incremented.
  */
 struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root,
 						   u64 id)
@@ -733,8 +739,8 @@ err_unlock:
  *	function increments nlink of the parent's inode if @kn is a
  *	directory and link into the children list of the parent.
  *
- *	RETURNS:
- *	0 on success, -EEXIST if entry with the given name already
+ *	Return:
+ *	%0 on success, -EEXIST if entry with the given name already
  *	exists.
  */
 int kernfs_add_one(struct kernfs_node *kn)
@@ -797,8 +803,9 @@ out_unlock:
  * @name: name to look for
  * @ns: the namespace tag to use
  *
- * Look for kernfs_node with name @name under @parent.  Returns pointer to
- * the found kernfs_node on success, %NULL on failure.
+ * Look for kernfs_node with name @name under @parent.
+ *
+ * Return: pointer to the found kernfs_node on success, %NULL on failure.
  */
 static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent,
 					  const unsigned char *name,
@@ -871,8 +878,9 @@ static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent,
  * @ns: the namespace tag to use
  *
  * Look for kernfs_node with name @name under @parent and get a reference
- * if found.  This function may sleep and returns pointer to the found
- * kernfs_node on success, %NULL on failure.
+ * if found.  This function may sleep.
+ *
+ * Return: pointer to the found kernfs_node on success, %NULL on failure.
  */
 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
 					   const char *name, const void *ns)
@@ -896,8 +904,9 @@ EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
  * @ns: the namespace tag to use
  *
  * Look for kernfs_node with path @path under @parent and get a reference
- * if found.  This function may sleep and returns pointer to the found
- * kernfs_node on success, %NULL on failure.
+ * if found.  This function may sleep.
+ *
+ * Return: pointer to the found kernfs_node on success, %NULL on failure.
  */
 struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent,
 					   const char *path, const void *ns)
@@ -919,7 +928,7 @@ struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent,
  * @flags: KERNFS_ROOT_* flags
  * @priv: opaque data associated with the new directory
  *
- * Returns the root of the new hierarchy on success, ERR_PTR() value on
+ * Return: the root of the new hierarchy on success, ERR_PTR() value on
  * failure.
  */
 struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
@@ -991,6 +1000,8 @@ void kernfs_destroy_root(struct kernfs_root *root)
 /**
  * kernfs_root_to_node - return the kernfs_node associated with a kernfs_root
  * @root: root to use to lookup
+ *
+ * Return: @root's kernfs_node
  */
 struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root)
 {
@@ -1007,7 +1018,7 @@ struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root)
  * @priv: opaque data associated with the new directory
  * @ns: optional namespace tag of the directory
  *
- * Returns the created node on success, ERR_PTR() value on failure.
+ * Return: the created node on success, ERR_PTR() value on failure.
  */
 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
 					 const char *name, umode_t mode,
@@ -1041,7 +1052,7 @@ struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
  * @parent: parent in which to create a new directory
  * @name: name of the new directory
  *
- * Returns the created node on success, ERR_PTR() value on failure.
+ * Return: the created node on success, ERR_PTR() value on failure.
  */
 struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
 					    const char *name)
@@ -1083,20 +1094,30 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
 
 		/* If the kernfs parent node has changed discard and
 		 * proceed to ->lookup.
+		 *
+		 * There's nothing special needed here when getting the
+		 * dentry parent, even if a concurrent rename is in
+		 * progress. That's because the dentry is negative so
+		 * it can only be the target of the rename and it will
+		 * be doing a d_move() not a replace. Consequently the
+		 * dentry d_parent won't change over the d_move().
+		 *
+		 * Also kernfs negative dentries transitioning from
+		 * negative to positive during revalidate won't happen
+		 * because they are invalidated on containing directory
+		 * changes and the lookup re-done so that a new positive
+		 * dentry can be properly created.
 		 */
-		spin_lock(&dentry->d_lock);
+		root = kernfs_root_from_sb(dentry->d_sb);
+		down_read(&root->kernfs_rwsem);
 		parent = kernfs_dentry_node(dentry->d_parent);
 		if (parent) {
-			spin_unlock(&dentry->d_lock);
-			root = kernfs_root(parent);
-			down_read(&root->kernfs_rwsem);
 			if (kernfs_dir_changed(parent, dentry)) {
 				up_read(&root->kernfs_rwsem);
 				return 0;
 			}
-			up_read(&root->kernfs_rwsem);
-		} else
-			spin_unlock(&dentry->d_lock);
+		}
+		up_read(&root->kernfs_rwsem);
 
 		/* The kernfs parent node hasn't changed, leave the
 		 * dentry negative and return success.
@@ -1290,6 +1311,8 @@ static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos)
  * Find the next descendant to visit for post-order traversal of @root's
  * descendants.  @root is included in the iteration and the last node to be
  * visited.
+ *
+ * Return: the next descendant to visit or %NULL when done.
  */
 static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos,
 						       struct kernfs_node *root)
@@ -1553,6 +1576,8 @@ void kernfs_unbreak_active_protection(struct kernfs_node *kn)
  * the whole kernfs_ops which won the arbitration.  This can be used to
  * guarantee, for example, all concurrent writes to a "delete" file to
  * finish only after the whole operation is complete.
+ *
+ * Return: %true if @kn is removed by this call, otherwise %false.
  */
 bool kernfs_remove_self(struct kernfs_node *kn)
 {
@@ -1613,7 +1638,8 @@ bool kernfs_remove_self(struct kernfs_node *kn)
  * @ns: namespace tag of the kernfs_node to remove
  *
  * Look for the kernfs_node with @name and @ns under @parent and remove it.
- * Returns 0 on success, -ENOENT if such entry doesn't exist.
+ *
+ * Return: %0 on success, -ENOENT if such entry doesn't exist.
  */
 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
 			     const void *ns)
@@ -1651,6 +1677,8 @@ int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
  * @new_parent: new parent to put @sd under
  * @new_name: new name
  * @new_ns: new namespace tag
+ *
+ * Return: %0 on success, -errno on failure.
  */
 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
 		     const char *new_name, const void *new_ns)