Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 1111 insertions, 0 deletions

diff --git a/lib/kobject.c b/lib/kobject.c
new file mode 100644
index 000000000..e7b010a98
--- /dev/null
+++ b/lib/kobject.c
@@ -0,0 +1,1111 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * kobject.c - library routines for handling generic kernel objects
+ *
+ * Copyright (c) 2002-2003 Patrick Mochel <mochel@osdl.org>
+ * Copyright (c) 2006-2007 Greg Kroah-Hartman <greg@kroah.com>
+ * Copyright (c) 2006-2007 Novell Inc.
+ *
+ * Please see the file Documentation/core-api/kobject.rst for critical information
+ * about using the kobject interface.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kobject.h>
+#include <linux/string.h>
+#include <linux/export.h>
+#include <linux/stat.h>
+#include <linux/slab.h>
+#include <linux/random.h>
+
+/**
+ * kobject_namespace() - Return @kobj's namespace tag.
+ * @kobj: kobject in question
+ *
+ * Returns namespace tag of @kobj if its parent has namespace ops enabled
+ * and thus @kobj should have a namespace tag associated with it.  Returns
+ * %NULL otherwise.
+ */
+const struct ns_common *kobject_namespace(const struct kobject *kobj)
+{
+	const struct kobj_ns_type_operations *ns_ops = kobj_ns_ops(kobj);
+
+	if (!ns_ops || ns_ops->type == KOBJ_NS_TYPE_NONE)
+		return NULL;
+
+	return kobj->ktype->namespace(kobj);
+}
+
+/**
+ * kobject_get_ownership() - Get sysfs ownership data for @kobj.
+ * @kobj: kobject in question
+ * @uid: kernel user ID for sysfs objects
+ * @gid: kernel group ID for sysfs objects
+ *
+ * Returns initial uid/gid pair that should be used when creating sysfs
+ * representation of given kobject. Normally used to adjust ownership of
+ * objects in a container.
+ */
+void kobject_get_ownership(const struct kobject *kobj, kuid_t *uid, kgid_t *gid)
+{
+	*uid = GLOBAL_ROOT_UID;
+	*gid = GLOBAL_ROOT_GID;
+
+	if (kobj->ktype->get_ownership)
+		kobj->ktype->get_ownership(kobj, uid, gid);
+}
+
+static bool kobj_ns_type_is_valid(enum kobj_ns_type type)
+{
+	if ((type <= KOBJ_NS_TYPE_NONE) || (type >= KOBJ_NS_TYPES))
+		return false;
+
+	return true;
+}
+
+static int create_dir(struct kobject *kobj)
+{
+	const struct kobj_type *ktype = get_ktype(kobj);
+	const struct kobj_ns_type_operations *ops;
+	int error;
+
+	error = sysfs_create_dir_ns(kobj, kobject_namespace(kobj));
+	if (error)
+		return error;
+
+	if (ktype) {
+		error = sysfs_create_groups(kobj, ktype->default_groups);
+		if (error) {
+			sysfs_remove_dir(kobj);
+			return error;
+		}
+	}
+
+	/*
+	 * @kobj->sd may be deleted by an ancestor going away.  Hold an
+	 * extra reference so that it stays until @kobj is gone.
+	 */
+	sysfs_get(kobj->sd);
+
+	/*
+	 * If @kobj has ns_ops, its children need to be filtered based on
+	 * their namespace tags.  Enable namespace support on @kobj->sd.
+	 */
+	ops = kobj_child_ns_ops(kobj);
+	if (ops) {
+		BUG_ON(!kobj_ns_type_is_valid(ops->type));
+		BUG_ON(!kobj_ns_type_registered(ops->type));
+
+		sysfs_enable_ns(kobj->sd);
+	}
+
+	return 0;
+}
+
+static int get_kobj_path_length(const struct kobject *kobj)
+{
+	int length = 1;
+	const struct kobject *parent = kobj;
+
+	/* walk up the ancestors until we hit the one pointing to the
+	 * root.
+	 * Add 1 to strlen for leading '/' of each level.
+	 */
+	do {
+		if (kobject_name(parent) == NULL)
+			return 0;
+		length += strlen(kobject_name(parent)) + 1;
+		parent = parent->parent;
+	} while (parent);
+	return length;
+}
+
+static int fill_kobj_path(const struct kobject *kobj, char *path, int length)
+{
+	const struct kobject *parent;
+
+	--length;
+	for (parent = kobj; parent; parent = parent->parent) {
+		int cur = strlen(kobject_name(parent));
+		/* back up enough to print this name with '/' */
+		length -= cur;
+		if (length <= 0)
+			return -EINVAL;
+		memcpy(path + length, kobject_name(parent), cur);
+		*(path + --length) = '/';
+	}
+
+	pr_debug("'%s' (%p): %s: path = '%s'\n", kobject_name(kobj),
+		 kobj, __func__, path);
+
+	return 0;
+}
+
+/**
+ * kobject_get_path() - Allocate memory and fill in the path for @kobj.
+ * @kobj:	kobject in question, with which to build the path
+ * @gfp_mask:	the allocation type used to allocate the path
+ *
+ * Return: The newly allocated memory, caller must free with kfree().
+ */
+char *kobject_get_path(const struct kobject *kobj, gfp_t gfp_mask)
+{
+	char *path;
+	int len;
+
+retry:
+	len = get_kobj_path_length(kobj);
+	if (len == 0)
+		return NULL;
+	path = kzalloc(len, gfp_mask);
+	if (!path)
+		return NULL;
+	if (fill_kobj_path(kobj, path, len)) {
+		kfree(path);
+		goto retry;
+	}
+
+	return path;
+}
+EXPORT_SYMBOL_GPL(kobject_get_path);
+
+/* add the kobject to its kset's list */
+static void kobj_kset_join(struct kobject *kobj)
+{
+	if (!kobj->kset)
+		return;
+
+	kset_get(kobj->kset);
+	spin_lock(&kobj->kset->list_lock);
+	list_add_tail(&kobj->entry, &kobj->kset->list);
+	spin_unlock(&kobj->kset->list_lock);
+}
+
+/* remove the kobject from its kset's list */
+static void kobj_kset_leave(struct kobject *kobj)
+{
+	if (!kobj->kset)
+		return;
+
+	spin_lock(&kobj->kset->list_lock);
+	list_del_init(&kobj->entry);
+	spin_unlock(&kobj->kset->list_lock);
+	kset_put(kobj->kset);
+}
+
+static void kobject_init_internal(struct kobject *kobj)
+{
+	if (!kobj)
+		return;
+	kref_init(&kobj->kref);
+	INIT_LIST_HEAD(&kobj->entry);
+	kobj->state_in_sysfs = 0;
+	kobj->state_add_uevent_sent = 0;
+	kobj->state_remove_uevent_sent = 0;
+	kobj->state_initialized = 1;
+}
+
+
+static int kobject_add_internal(struct kobject *kobj)
+{
+	int error = 0;
+	struct kobject *parent;
+
+	if (!kobj)
+		return -ENOENT;
+
+	if (!kobj->name || !kobj->name[0]) {
+		WARN(1,
+		     "kobject: (%p): attempted to be registered with empty name!\n",
+		     kobj);
+		return -EINVAL;
+	}
+
+	parent = kobject_get(kobj->parent);
+
+	/* join kset if set, use it as parent if we do not already have one */
+	if (kobj->kset) {
+		if (!parent)
+			parent = kobject_get(&kobj->kset->kobj);
+		kobj_kset_join(kobj);
+		kobj->parent = parent;
+	}
+
+	pr_debug("'%s' (%p): %s: parent: '%s', set: '%s'\n",
+		 kobject_name(kobj), kobj, __func__,
+		 parent ? kobject_name(parent) : "<NULL>",
+		 kobj->kset ? kobject_name(&kobj->kset->kobj) : "<NULL>");
+
+	error = create_dir(kobj);
+	if (error) {
+		kobj_kset_leave(kobj);
+		kobject_put(parent);
+		kobj->parent = NULL;
+
+		/* be noisy on error issues */
+		if (error == -EEXIST)
+			pr_err("%s failed for %s with -EEXIST, don't try to register things with the same name in the same directory.\n",
+			       __func__, kobject_name(kobj));
+		else
+			pr_err("%s failed for %s (error: %d parent: %s)\n",
+			       __func__, kobject_name(kobj), error,
+			       parent ? kobject_name(parent) : "'none'");
+	} else
+		kobj->state_in_sysfs = 1;
+
+	return error;
+}
+
+/**
+ * kobject_set_name_vargs() - Set the name of a kobject.
+ * @kobj: struct kobject to set the name of
+ * @fmt: format string used to build the name
+ * @vargs: vargs to format the string.
+ */
+int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
+				  va_list vargs)
+{
+	const char *s;
+
+	if (kobj->name && !fmt)
+		return 0;
+
+	s = kvasprintf_const(GFP_KERNEL, fmt, vargs);
+	if (!s)
+		return -ENOMEM;
+
+	/*
+	 * ewww... some of these buggers have '/' in the name ... If
+	 * that's the case, we need to make sure we have an actual
+	 * allocated copy to modify, since kvasprintf_const may have
+	 * returned something from .rodata.
+	 */
+	if (strchr(s, '/')) {
+		char *t;
+
+		t = kstrdup(s, GFP_KERNEL);
+		kfree_const(s);
+		if (!t)
+			return -ENOMEM;
+		s = strreplace(t, '/', '!');
+	}
+	kfree_const(kobj->name);
+	kobj->name = s;
+
+	return 0;
+}
+
+/**
+ * kobject_set_name() - Set the name of a kobject.
+ * @kobj: struct kobject to set the name of
+ * @fmt: format string used to build the name
+ *
+ * This sets the name of the kobject.  If you have already added the
+ * kobject to the system, you must call kobject_rename() in order to
+ * change the name of the kobject.
+ */
+int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
+{
+	va_list vargs;
+	int retval;
+
+	va_start(vargs, fmt);
+	retval = kobject_set_name_vargs(kobj, fmt, vargs);
+	va_end(vargs);
+
+	return retval;
+}
+EXPORT_SYMBOL(kobject_set_name);
+
+/**
+ * kobject_init() - Initialize a kobject structure.
+ * @kobj: pointer to the kobject to initialize
+ * @ktype: pointer to the ktype for this kobject.
+ *
+ * This function will properly initialize a kobject such that it can then
+ * be passed to the kobject_add() call.
+ *
+ * After this function is called, the kobject MUST be cleaned up by a call
+ * to kobject_put(), not by a call to kfree directly to ensure that all of
+ * the memory is cleaned up properly.
+ */
+void kobject_init(struct kobject *kobj, const struct kobj_type *ktype)
+{
+	char *err_str;
+
+	if (!kobj) {
+		err_str = "invalid kobject pointer!";
+		goto error;
+	}
+	if (!ktype) {
+		err_str = "must have a ktype to be initialized properly!\n";
+		goto error;
+	}
+	if (kobj->state_initialized) {
+		/* do not error out as sometimes we can recover */
+		pr_err("kobject (%p): tried to init an initialized object, something is seriously wrong.\n",
+		       kobj);
+		dump_stack_lvl(KERN_ERR);
+	}
+
+	kobject_init_internal(kobj);
+	kobj->ktype = ktype;
+	return;
+
+error:
+	pr_err("kobject (%p): %s\n", kobj, err_str);
+	dump_stack_lvl(KERN_ERR);
+}
+EXPORT_SYMBOL(kobject_init);
+
+static __printf(3, 0) int kobject_add_varg(struct kobject *kobj,
+					   struct kobject *parent,
+					   const char *fmt, va_list vargs)
+{
+	int retval;
+
+	retval = kobject_set_name_vargs(kobj, fmt, vargs);
+	if (retval) {
+		pr_err("can not set name properly!\n");
+		return retval;
+	}
+	kobj->parent = parent;
+	return kobject_add_internal(kobj);
+}
+
+/**
+ * kobject_add() - The main kobject add function.
+ * @kobj: the kobject to add
+ * @parent: pointer to the parent of the kobject.
+ * @fmt: format to name the kobject with.
+ *
+ * The kobject name is set and added to the kobject hierarchy in this
+ * function.
+ *
+ * If @parent is set, then the parent of the @kobj will be set to it.
+ * If @parent is NULL, then the parent of the @kobj will be set to the
+ * kobject associated with the kset assigned to this kobject.  If no kset
+ * is assigned to the kobject, then the kobject will be located in the
+ * root of the sysfs tree.
+ *
+ * Note, no "add" uevent will be created with this call, the caller should set
+ * up all of the necessary sysfs files for the object and then call
+ * kobject_uevent() with the UEVENT_ADD parameter to ensure that
+ * userspace is properly notified of this kobject's creation.
+ *
+ * Return: If this function returns an error, kobject_put() must be
+ *         called to properly clean up the memory associated with the
+ *         object.  Under no instance should the kobject that is passed
+ *         to this function be directly freed with a call to kfree(),
+ *         that can leak memory.
+ *
+ *         If this function returns success, kobject_put() must also be called
+ *         in order to properly clean up the memory associated with the object.
+ *
+ *         In short, once this function is called, kobject_put() MUST be called
+ *         when the use of the object is finished in order to properly free
+ *         everything.
+ */
+int kobject_add(struct kobject *kobj, struct kobject *parent,
+		const char *fmt, ...)
+{
+	va_list args;
+	int retval;
+
+	if (!kobj)
+		return -EINVAL;
+
+	if (!kobj->state_initialized) {
+		pr_err("kobject '%s' (%p): tried to add an uninitialized object, something is seriously wrong.\n",
+		       kobject_name(kobj), kobj);
+		dump_stack_lvl(KERN_ERR);
+		return -EINVAL;
+	}
+	va_start(args, fmt);
+	retval = kobject_add_varg(kobj, parent, fmt, args);
+	va_end(args);
+
+	return retval;
+}
+EXPORT_SYMBOL(kobject_add);
+
+/**
+ * kobject_init_and_add() - Initialize a kobject structure and add it to
+ *                          the kobject hierarchy.
+ * @kobj: pointer to the kobject to initialize
+ * @ktype: pointer to the ktype for this kobject.
+ * @parent: pointer to the parent of this kobject.
+ * @fmt: the name of the kobject.
+ *
+ * This function combines the call to kobject_init() and kobject_add().
+ *
+ * If this function returns an error, kobject_put() must be called to
+ * properly clean up the memory associated with the object.  This is the
+ * same type of error handling after a call to kobject_add() and kobject
+ * lifetime rules are the same here.
+ */
+int kobject_init_and_add(struct kobject *kobj, const struct kobj_type *ktype,
+			 struct kobject *parent, const char *fmt, ...)
+{
+	va_list args;
+	int retval;
+
+	kobject_init(kobj, ktype);
+
+	va_start(args, fmt);
+	retval = kobject_add_varg(kobj, parent, fmt, args);
+	va_end(args);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(kobject_init_and_add);
+
+/**
+ * kobject_rename() - Change the name of an object.
+ * @kobj: object in question.
+ * @new_name: object's new name
+ *
+ * It is the responsibility of the caller to provide mutual
+ * exclusion between two different calls of kobject_rename
+ * on the same kobject and to ensure that new_name is valid and
+ * won't conflict with other kobjects.
+ */
+int kobject_rename(struct kobject *kobj, const char *new_name)
+{
+	int error = 0;
+	const char *devpath = NULL;
+	const char *dup_name = NULL, *name;
+	char *devpath_string = NULL;
+	char *envp[2];
+
+	kobj = kobject_get(kobj);
+	if (!kobj)
+		return -EINVAL;
+	if (!kobj->parent) {
+		kobject_put(kobj);
+		return -EINVAL;
+	}
+
+	devpath = kobject_get_path(kobj, GFP_KERNEL);
+	if (!devpath) {
+		error = -ENOMEM;
+		goto out;
+	}
+	devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
+	if (!devpath_string) {
+		error = -ENOMEM;
+		goto out;
+	}
+	sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
+	envp[0] = devpath_string;
+	envp[1] = NULL;
+
+	name = dup_name = kstrdup_const(new_name, GFP_KERNEL);
+	if (!name) {
+		error = -ENOMEM;
+		goto out;
+	}
+
+	error = sysfs_rename_dir_ns(kobj, new_name, kobject_namespace(kobj));
+	if (error)
+		goto out;
+
+	/* Install the new kobject name */
+	dup_name = kobj->name;
+	kobj->name = name;
+
+	/* This function is mostly/only used for network interface.
+	 * Some hotplug package track interfaces by their name and
+	 * therefore want to know when the name is changed by the user. */
+	kobject_uevent_env(kobj, KOBJ_MOVE, envp);
+
+out:
+	kfree_const(dup_name);
+	kfree(devpath_string);
+	kfree(devpath);
+	kobject_put(kobj);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(kobject_rename);
+
+/**
+ * kobject_move() - Move object to another parent.
+ * @kobj: object in question.
+ * @new_parent: object's new parent (can be NULL)
+ */
+int kobject_move(struct kobject *kobj, struct kobject *new_parent)
+{
+	int error;
+	struct kobject *old_parent;
+	const char *devpath = NULL;
+	char *devpath_string = NULL;
+	char *envp[2];
+
+	kobj = kobject_get(kobj);
+	if (!kobj)
+		return -EINVAL;
+	new_parent = kobject_get(new_parent);
+	if (!new_parent) {
+		if (kobj->kset)
+			new_parent = kobject_get(&kobj->kset->kobj);
+	}
+
+	/* old object path */
+	devpath = kobject_get_path(kobj, GFP_KERNEL);
+	if (!devpath) {
+		error = -ENOMEM;
+		goto out;
+	}
+	devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
+	if (!devpath_string) {
+		error = -ENOMEM;
+		goto out;
+	}
+	sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
+	envp[0] = devpath_string;
+	envp[1] = NULL;
+	error = sysfs_move_dir_ns(kobj, new_parent, kobject_namespace(kobj));
+	if (error)
+		goto out;
+	old_parent = kobj->parent;
+	kobj->parent = new_parent;
+	new_parent = NULL;
+	kobject_put(old_parent);
+	kobject_uevent_env(kobj, KOBJ_MOVE, envp);
+out:
+	kobject_put(new_parent);
+	kobject_put(kobj);
+	kfree(devpath_string);
+	kfree(devpath);
+	return error;
+}
+EXPORT_SYMBOL_GPL(kobject_move);
+
+static void __kobject_del(struct kobject *kobj)
+{
+	struct kernfs_node *sd;
+	const struct kobj_type *ktype;
+
+	sd = kobj->sd;
+	ktype = get_ktype(kobj);
+
+	if (ktype)
+		sysfs_remove_groups(kobj, ktype->default_groups);
+
+	/* send "remove" if the caller did not do it but sent "add" */
+	if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
+		pr_debug("'%s' (%p): auto cleanup 'remove' event\n",
+			 kobject_name(kobj), kobj);
+		kobject_uevent(kobj, KOBJ_REMOVE);
+	}
+
+	sysfs_remove_dir(kobj);
+	sysfs_put(sd);
+
+	kobj->state_in_sysfs = 0;
+	kobj_kset_leave(kobj);
+	kobj->parent = NULL;
+}
+
+/**
+ * kobject_del() - Unlink kobject from hierarchy.
+ * @kobj: object.
+ *
+ * This is the function that should be called to delete an object
+ * successfully added via kobject_add().
+ */
+void kobject_del(struct kobject *kobj)
+{
+	struct kobject *parent;
+
+	if (!kobj)
+		return;
+
+	parent = kobj->parent;
+	__kobject_del(kobj);
+	kobject_put(parent);
+}
+EXPORT_SYMBOL(kobject_del);
+
+/**
+ * kobject_get() - Increment refcount for object.
+ * @kobj: object.
+ */
+struct kobject *kobject_get(struct kobject *kobj)
+{
+	if (kobj) {
+		if (!kobj->state_initialized)
+			WARN(1, KERN_WARNING
+				"kobject: '%s' (%p): is not initialized, yet kobject_get() is being called.\n",
+			     kobject_name(kobj), kobj);
+		kref_get(&kobj->kref);
+	}
+	return kobj;
+}
+EXPORT_SYMBOL(kobject_get);
+
+struct kobject * __must_check kobject_get_unless_zero(struct kobject *kobj)
+{
+	if (!kobj)
+		return NULL;
+	if (!kref_get_unless_zero(&kobj->kref))
+		kobj = NULL;
+	return kobj;
+}
+EXPORT_SYMBOL(kobject_get_unless_zero);
+
+/*
+ * kobject_cleanup - free kobject resources.
+ * @kobj: object to cleanup
+ */
+static void kobject_cleanup(struct kobject *kobj)
+{
+	struct kobject *parent = kobj->parent;
+	const struct kobj_type *t = get_ktype(kobj);
+	const char *name = kobj->name;
+
+	pr_debug("'%s' (%p): %s, parent %p\n",
+		 kobject_name(kobj), kobj, __func__, kobj->parent);
+
+	if (t && !t->release)
+		pr_debug("'%s' (%p): does not have a release() function, it is broken and must be fixed. See Documentation/core-api/kobject.rst.\n",
+			 kobject_name(kobj), kobj);
+
+	/* remove from sysfs if the caller did not do it */
+	if (kobj->state_in_sysfs) {
+		pr_debug("'%s' (%p): auto cleanup kobject_del\n",
+			 kobject_name(kobj), kobj);
+		__kobject_del(kobj);
+	} else {
+		/* avoid dropping the parent reference unnecessarily */
+		parent = NULL;
+	}
+
+	if (t && t->release) {
+		pr_debug("'%s' (%p): calling ktype release\n",
+			 kobject_name(kobj), kobj);
+		t->release(kobj);
+	}
+
+	/* free name if we allocated it */
+	if (name) {
+		pr_debug("'%s': free name\n", name);
+		kfree_const(name);
+	}
+
+	kobject_put(parent);
+}
+
+#ifdef CONFIG_DEBUG_KOBJECT_RELEASE
+static void kobject_delayed_cleanup(struct work_struct *work)
+{
+	kobject_cleanup(container_of(to_delayed_work(work),
+				     struct kobject, release));
+}
+#endif
+
+static void kobject_release(struct kref *kref)
+{
+	struct kobject *kobj = container_of(kref, struct kobject, kref);
+#ifdef CONFIG_DEBUG_KOBJECT_RELEASE
+	unsigned long delay = HZ + HZ * get_random_u32_below(4);
+	pr_info("'%s' (%p): %s, parent %p (delayed %ld)\n",
+		kobject_name(kobj), kobj, __func__, kobj->parent, delay);
+	INIT_DELAYED_WORK(&kobj->release, kobject_delayed_cleanup);
+
+	schedule_delayed_work(&kobj->release, delay);
+#else
+	kobject_cleanup(kobj);
+#endif
+}
+
+/**
+ * kobject_put() - Decrement refcount for object.
+ * @kobj: object.
+ *
+ * Decrement the refcount, and if 0, call kobject_cleanup().
+ */
+void kobject_put(struct kobject *kobj)
+{
+	if (kobj) {
+		if (!kobj->state_initialized)
+			WARN(1, KERN_WARNING
+				"kobject: '%s' (%p): is not initialized, yet kobject_put() is being called.\n",
+			     kobject_name(kobj), kobj);
+		kref_put(&kobj->kref, kobject_release);
+	}
+}
+EXPORT_SYMBOL(kobject_put);
+
+static void dynamic_kobj_release(struct kobject *kobj)
+{
+	pr_debug("(%p): %s\n", kobj, __func__);
+	kfree(kobj);
+}
+
+static const struct kobj_type dynamic_kobj_ktype = {
+	.release	= dynamic_kobj_release,
+	.sysfs_ops	= &kobj_sysfs_ops,
+};
+
+/**
+ * kobject_create() - Create a struct kobject dynamically.
+ *
+ * This function creates a kobject structure dynamically and sets it up
+ * to be a "dynamic" kobject with a default release function set up.
+ *
+ * If the kobject was not able to be created, NULL will be returned.
+ * The kobject structure returned from here must be cleaned up with a
+ * call to kobject_put() and not kfree(), as kobject_init() has
+ * already been called on this structure.
+ */
+static struct kobject *kobject_create(void)
+{
+	struct kobject *kobj;
+
+	kobj = kzalloc_obj(*kobj);
+	if (!kobj)
+		return NULL;
+
+	kobject_init(kobj, &dynamic_kobj_ktype);
+	return kobj;
+}
+
+/**
+ * kobject_create_and_add() - Create a struct kobject dynamically and
+ *                            register it with sysfs.
+ * @name: the name for the kobject
+ * @parent: the parent kobject of this kobject, if any.
+ *
+ * This function creates a kobject structure dynamically and registers it
+ * with sysfs.  When you are finished with this structure, call
+ * kobject_put() and the structure will be dynamically freed when
+ * it is no longer being used.
+ *
+ * If the kobject was not able to be created, NULL will be returned.
+ */
+struct kobject *kobject_create_and_add(const char *name, struct kobject *parent)
+{
+	struct kobject *kobj;
+	int retval;
+
+	kobj = kobject_create();
+	if (!kobj)
+		return NULL;
+
+	retval = kobject_add(kobj, parent, "%s", name);
+	if (retval) {
+		pr_warn("%s: kobject_add error: %d\n", __func__, retval);
+		kobject_put(kobj);
+		kobj = NULL;
+	}
+	return kobj;
+}
+EXPORT_SYMBOL_GPL(kobject_create_and_add);
+
+/**
+ * kset_init() - Initialize a kset for use.
+ * @k: kset
+ */
+void kset_init(struct kset *k)
+{
+	kobject_init_internal(&k->kobj);
+	INIT_LIST_HEAD(&k->list);
+	spin_lock_init(&k->list_lock);
+}
+
+/* default kobject attribute operations */
+static ssize_t kobj_attr_show(struct kobject *kobj, struct attribute *attr,
+			      char *buf)
+{
+	struct kobj_attribute *kattr;
+	ssize_t ret = -EIO;
+
+	kattr = container_of_const(attr, struct kobj_attribute, attr);
+	if (kattr->show)
+		ret = kattr->show(kobj, kattr, buf);
+	else if (kattr->show_const)
+		ret = kattr->show_const(kobj, kattr, buf);
+	return ret;
+}
+
+static ssize_t kobj_attr_store(struct kobject *kobj, struct attribute *attr,
+			       const char *buf, size_t count)
+{
+	struct kobj_attribute *kattr;
+	ssize_t ret = -EIO;
+
+	kattr = container_of_const(attr, struct kobj_attribute, attr);
+	if (kattr->store)
+		ret = kattr->store(kobj, kattr, buf, count);
+	else if (kattr->store_const)
+		ret = kattr->store_const(kobj, kattr, buf, count);
+	return ret;
+}
+
+const struct sysfs_ops kobj_sysfs_ops = {
+	.show	= kobj_attr_show,
+	.store	= kobj_attr_store,
+};
+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)
+{
+	int err;
+
+	if (!k)
+		return -EINVAL;
+
+	if (!k->kobj.ktype) {
+		pr_err("must have a ktype to be initialized properly!\n");
+		return -EINVAL;
+	}
+
+	kset_init(k);
+	err = kobject_add_internal(&k->kobj);
+	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;
+}
+EXPORT_SYMBOL(kset_register);
+
+/**
+ * kset_unregister() - Remove a kset.
+ * @k: kset.
+ */
+void kset_unregister(struct kset *k)
+{
+	if (!k)
+		return;
+	kobject_del(&k->kobj);
+	kobject_put(&k->kobj);
+}
+EXPORT_SYMBOL(kset_unregister);
+
+/**
+ * kset_find_obj() - Search for object in kset.
+ * @kset: kset we're looking in.
+ * @name: object's name.
+ *
+ * Lock kset via @kset->subsys, and iterate over @kset->list,
+ * looking for a matching kobject. If matching object is found
+ * take a reference and return the object.
+ */
+struct kobject *kset_find_obj(struct kset *kset, const char *name)
+{
+	struct kobject *k;
+	struct kobject *ret = NULL;
+
+	spin_lock(&kset->list_lock);
+
+	list_for_each_entry(k, &kset->list, entry) {
+		if (kobject_name(k) && !strcmp(kobject_name(k), name)) {
+			ret = kobject_get_unless_zero(k);
+			break;
+		}
+	}
+
+	spin_unlock(&kset->list_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(kset_find_obj);
+
+static void kset_release(struct kobject *kobj)
+{
+	struct kset *kset = container_of(kobj, struct kset, kobj);
+	pr_debug("'%s' (%p): %s\n",
+		 kobject_name(kobj), kobj, __func__);
+	kfree(kset);
+}
+
+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);
+}
+
+static const struct kobj_type kset_ktype = {
+	.sysfs_ops	= &kobj_sysfs_ops,
+	.release	= kset_release,
+	.get_ownership	= kset_get_ownership,
+};
+
+/**
+ * kset_create() - Create a struct kset dynamically.
+ *
+ * @name: the name for the kset
+ * @uevent_ops: a struct kset_uevent_ops for the kset
+ * @parent_kobj: the parent kobject of this kset, if any.
+ *
+ * This function creates a kset structure dynamically.  This structure can
+ * then be registered with the system and show up in sysfs with a call to
+ * kset_register().  When you are finished with this structure, if
+ * kset_register() has been called, call kset_unregister() and the
+ * structure will be dynamically freed when it is no longer being used.
+ *
+ * If the kset was not able to be created, NULL will be returned.
+ */
+static struct kset *kset_create(const char *name,
+				const struct kset_uevent_ops *uevent_ops,
+				struct kobject *parent_kobj)
+{
+	struct kset *kset;
+	int retval;
+
+	kset = kzalloc_obj(*kset);
+	if (!kset)
+		return NULL;
+	retval = kobject_set_name(&kset->kobj, "%s", name);
+	if (retval) {
+		kfree(kset);
+		return NULL;
+	}
+	kset->uevent_ops = uevent_ops;
+	kset->kobj.parent = parent_kobj;
+
+	/*
+	 * The kobject of this kset will have a type of kset_ktype and belong to
+	 * no kset itself.  That way we can properly free it when it is
+	 * finished being used.
+	 */
+	kset->kobj.ktype = &kset_ktype;
+	kset->kobj.kset = NULL;
+
+	return kset;
+}
+
+/**
+ * kset_create_and_add() - Create a struct kset dynamically and add it to sysfs.
+ *
+ * @name: the name for the kset
+ * @uevent_ops: a struct kset_uevent_ops for the kset
+ * @parent_kobj: the parent kobject of this kset, if any.
+ *
+ * This function creates a kset structure dynamically and registers it
+ * with sysfs.  When you are finished with this structure, call
+ * kset_unregister() and the structure will be dynamically freed when it
+ * is no longer being used.
+ *
+ * If the kset was not able to be created, NULL will be returned.
+ */
+struct kset *kset_create_and_add(const char *name,
+				 const struct kset_uevent_ops *uevent_ops,
+				 struct kobject *parent_kobj)
+{
+	struct kset *kset;
+	int error;
+
+	kset = kset_create(name, uevent_ops, parent_kobj);
+	if (!kset)
+		return NULL;
+	error = kset_register(kset);
+	if (error) {
+		kfree(kset);
+		return NULL;
+	}
+	return kset;
+}
+EXPORT_SYMBOL_GPL(kset_create_and_add);
+
+
+static DEFINE_SPINLOCK(kobj_ns_type_lock);
+static const struct kobj_ns_type_operations *kobj_ns_ops_tbl[KOBJ_NS_TYPES];
+
+int kobj_ns_type_register(const struct kobj_ns_type_operations *ops)
+{
+	enum kobj_ns_type type = ops->type;
+	int error;
+
+	spin_lock(&kobj_ns_type_lock);
+
+	error = -EINVAL;
+	if (!kobj_ns_type_is_valid(type))
+		goto out;
+
+	error = -EBUSY;
+	if (kobj_ns_ops_tbl[type])
+		goto out;
+
+	error = 0;
+	kobj_ns_ops_tbl[type] = ops;
+
+out:
+	spin_unlock(&kobj_ns_type_lock);
+	return error;
+}
+
+int kobj_ns_type_registered(enum kobj_ns_type type)
+{
+	int registered = 0;
+
+	spin_lock(&kobj_ns_type_lock);
+	if (kobj_ns_type_is_valid(type))
+		registered = kobj_ns_ops_tbl[type] != NULL;
+	spin_unlock(&kobj_ns_type_lock);
+
+	return registered;
+}
+
+const struct kobj_ns_type_operations *kobj_child_ns_ops(const struct kobject *parent)
+{
+	const struct kobj_ns_type_operations *ops = NULL;
+
+	if (parent && parent->ktype && parent->ktype->child_ns_type)
+		ops = parent->ktype->child_ns_type(parent);
+
+	return ops;
+}
+
+const struct kobj_ns_type_operations *kobj_ns_ops(const struct kobject *kobj)
+{
+	return kobj_child_ns_ops(kobj->parent);
+}
+
+bool kobj_ns_current_may_mount(enum kobj_ns_type type)
+{
+	bool may_mount = true;
+
+	spin_lock(&kobj_ns_type_lock);
+	if (kobj_ns_type_is_valid(type) && kobj_ns_ops_tbl[type])
+		may_mount = kobj_ns_ops_tbl[type]->current_may_mount();
+	spin_unlock(&kobj_ns_type_lock);
+
+	return may_mount;
+}
+
+struct ns_common *kobj_ns_grab_current(enum kobj_ns_type type)
+{
+	struct ns_common *ns = NULL;
+
+	spin_lock(&kobj_ns_type_lock);
+	if (kobj_ns_type_is_valid(type) && kobj_ns_ops_tbl[type])
+		ns = kobj_ns_ops_tbl[type]->grab_current_ns();
+	spin_unlock(&kobj_ns_type_lock);
+
+	return ns;
+}
+EXPORT_SYMBOL_GPL(kobj_ns_grab_current);
+
+void kobj_ns_drop(enum kobj_ns_type type, struct ns_common *ns)
+{
+	spin_lock(&kobj_ns_type_lock);
+	if (kobj_ns_type_is_valid(type) &&
+	    kobj_ns_ops_tbl[type] && kobj_ns_ops_tbl[type]->drop_ns)
+		kobj_ns_ops_tbl[type]->drop_ns(ns);
+	spin_unlock(&kobj_ns_type_lock);
+}
+EXPORT_SYMBOL_GPL(kobj_ns_drop);