Merge tag 'trace-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:
"User visible changes:

- Added a way to easier filter with cpumasks:

# echo 'cpumask & CPUS{17-42}' > /sys/kernel/tracing/events/ipi_send_cpumask/filter

- Show actual size of ring buffer after modifying the ring buffer
size via buffer_size_kb.

Currently it just returns what was written, but the actual size
rounds up to the sub buffer size. Show that real size instead.

Major changes:

- Added "eventfs". This is the code that handles the inodes and
dentries of tracefs/events directory. As there are thousands of
events, and each event has several inodes and dentries that
currently exist even when tracing is never used, they take up
precious memory. Instead, eventfs will allocate the inodes and
dentries in a JIT way (similar to what procfs does). There is now
metadata that handles the events and subdirectories, and will
create the inodes and dentries when they are used.

Note, I also have patches that remove the subdirectory meta data,
but will wait till the next merge window before applying them. It's
a little more complex, and I want to make sure the dynamic code
works properly before adding more complexity, making it easier to
revert if need be.

Minor changes:

- Optimization to user event list traversal

- Remove intermediate permission of tracefs files (note the
intermediate permission removes all access to the files so it is
not a security concern, but just a clean up)

- Add the complex fix to FORTIFY_SOURCE to the kernel stack event
logic

- Other minor cleanups"

* tag 'trace-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (29 commits)
tracefs: Remove kerneldoc from struct eventfs_file
tracefs: Avoid changing i_mode to a temp value
tracing/user_events: Optimize safe list traversals
ftrace: Remove empty declaration ftrace_enable_daemon() and ftrace_disable_daemon()
tracing: Remove unused function declarations
tracing/filters: Document cpumask filtering
tracing/filters: Further optimise scalar vs cpumask comparison
tracing/filters: Optimise CPU vs cpumask filtering when the user mask is a single CPU
tracing/filters: Optimise scalar vs cpumask filtering when the user mask is a single CPU
tracing/filters: Optimise cpumask vs cpumask filtering when user mask is a single CPU
tracing/filters: Enable filtering the CPU common field by a cpumask
tracing/filters: Enable filtering a scalar field by a cpumask
tracing/filters: Enable filtering a cpumask field by another cpumask
tracing/filters: Dynamically allocate filter_pred.regex
test: ftrace: Fix kprobe test for eventfs
eventfs: Move tracing/events to eventfs
eventfs: Implement removal of meta data from eventfs
eventfs: Implement functions to create files and dirs when accessed
eventfs: Implement eventfs lookup, read, open functions
eventfs: Implement eventfs file add functions
...

Documentation/trace/events.rst

···
 The ".function" postfix can only be attached to values of size long, and can only
 be compared with "==" or "!=".
 
+Cpumask fields or scalar fields that encode a CPU number can be filtered using
+a user-provided cpumask in cpulist format. The format is as follows::
+
+  CPUS{$cpulist}
+
+Operators available to cpumask filtering are:
+
+& (intersection), ==, !=
+
+For example, this will filter events that have their .target_cpu field present
+in the given cpumask::
+
+  target_cpu & CPUS{17-42}
+
 5.2 Setting filters
 -------------------
 

fs/tracefs/Makefile

···
 # SPDX-License-Identifier: GPL-2.0-only
 tracefs-objs	:= inode.o
+tracefs-objs	+= event_inode.o
 
 obj-$(CONFIG_TRACING)	+= tracefs.o
 

fs/tracefs/event_inode.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  event_inode.c - part of tracefs, a pseudo file system for activating tracing
+ *
+ *  Copyright (C) 2020-23 VMware Inc, author: Steven Rostedt (VMware) <[e-mail]>
+ *  Copyright (C) 2020-23 VMware Inc, author: Ajay Kaher <[e-mail]>
+ *
+ *  eventfs is used to dynamically create inodes and dentries based on the
+ *  meta data provided by the tracing system.
+ *
+ *  eventfs stores the meta-data of files/dirs and holds off on creating
+ *  inodes/dentries of the files. When accessed, the eventfs will create the
+ *  inodes/dentries in a just-in-time (JIT) manner. The eventfs will clean up
+ *  and delete the inodes/dentries when they are no longer referenced.
+ */
+#include <linux/fsnotify.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/workqueue.h>
+#include <linux/security.h>
+#include <linux/tracefs.h>
+#include <linux/kref.h>
+#include <linux/delay.h>
+#include "internal.h"
+
+struct eventfs_inode {
+	struct list_head	e_top_files;
+};
+
+/*
+ * struct eventfs_file - hold the properties of the eventfs files and
+ *                       directories.
+ * @name:	the name of the file or directory to create
+ * @d_parent:   holds parent's dentry
+ * @dentry:     once accessed holds dentry
+ * @list:	file or directory to be added to parent directory
+ * @ei:		list of files and directories within directory
+ * @fop:	file_operations for file or directory
+ * @iop:	inode_operations for file or directory
+ * @data:	something that the caller will want to get to later on
+ * @mode:	the permission that the file or directory should have
+ */
+struct eventfs_file {
+	const char			*name;
+	struct dentry			*d_parent;
+	struct dentry			*dentry;
+	struct list_head		list;
+	struct eventfs_inode		*ei;
+	const struct file_operations	*fop;
+	const struct inode_operations	*iop;
+	/*
+	 * Union - used for deletion
+	 * @del_list:	list of eventfs_file to delete
+	 * @rcu:	eventfs_file to delete in RCU
+	 * @is_freed:	node is freed if one of the above is set
+	 */
+	union {
+		struct list_head	del_list;
+		struct rcu_head		rcu;
+		unsigned long		is_freed;
+	};
+	void				*data;
+	umode_t				mode;
+};
+
+static DEFINE_MUTEX(eventfs_mutex);
+DEFINE_STATIC_SRCU(eventfs_srcu);
+
+static struct dentry *eventfs_root_lookup(struct inode *dir,
+					  struct dentry *dentry,
+					  unsigned int flags);
+static int dcache_dir_open_wrapper(struct inode *inode, struct file *file);
+static int eventfs_release(struct inode *inode, struct file *file);
+
+static const struct inode_operations eventfs_root_dir_inode_operations = {
+	.lookup		= eventfs_root_lookup,
+};
+
+static const struct file_operations eventfs_file_operations = {
+	.open		= dcache_dir_open_wrapper,
+	.read		= generic_read_dir,
+	.iterate_shared	= dcache_readdir,
+	.llseek		= generic_file_llseek,
+	.release	= eventfs_release,
+};
+
+/**
+ * create_file - create a file in the tracefs filesystem
+ * @name: the name of the file to create.
+ * @mode: the permission that the file should have.
+ * @parent: parent dentry for this file.
+ * @data: something that the caller will want to get to later on.
+ * @fop: struct file_operations that should be used for this file.
+ *
+ * This is the basic "create a file" function for tracefs.  It allows for a
+ * wide range of flexibility in creating a file.
+ *
+ * This function will return a pointer to a dentry if it succeeds.  This
+ * pointer must be passed to the tracefs_remove() function when the file is
+ * to be removed (no automatic cleanup happens if your module is unloaded,
+ * you are responsible here.)  If an error occurs, %NULL will be returned.
+ *
+ * If tracefs is not enabled in the kernel, the value -%ENODEV will be
+ * returned.
+ */
+static struct dentry *create_file(const char *name, umode_t mode,
+				  struct dentry *parent, void *data,
+				  const struct file_operations *fop)
+{
+	struct tracefs_inode *ti;
+	struct dentry *dentry;
+	struct inode *inode;
+
+	if (!(mode & S_IFMT))
+		mode |= S_IFREG;
+
+	if (WARN_ON_ONCE(!S_ISREG(mode)))
+		return NULL;
+
+	dentry = eventfs_start_creating(name, parent);
+
+	if (IS_ERR(dentry))
+		return dentry;
+
+	inode = tracefs_get_inode(dentry->d_sb);
+	if (unlikely(!inode))
+		return eventfs_failed_creating(dentry);
+
+	inode->i_mode = mode;
+	inode->i_fop = fop;
+	inode->i_private = data;
+
+	ti = get_tracefs(inode);
+	ti->flags |= TRACEFS_EVENT_INODE;
+	d_instantiate(dentry, inode);
+	fsnotify_create(dentry->d_parent->d_inode, dentry);
+	return eventfs_end_creating(dentry);
+};
+
+/**
+ * create_dir - create a dir in the tracefs filesystem
+ * @name: the name of the file to create.
+ * @parent: parent dentry for this file.
+ * @data: something that the caller will want to get to later on.
+ *
+ * This is the basic "create a dir" function for eventfs.  It allows for a
+ * wide range of flexibility in creating a dir.
+ *
+ * This function will return a pointer to a dentry if it succeeds.  This
+ * pointer must be passed to the tracefs_remove() function when the file is
+ * to be removed (no automatic cleanup happens if your module is unloaded,
+ * you are responsible here.)  If an error occurs, %NULL will be returned.
+ *
+ * If tracefs is not enabled in the kernel, the value -%ENODEV will be
+ * returned.
+ */
+static struct dentry *create_dir(const char *name, struct dentry *parent, void *data)
+{
+	struct tracefs_inode *ti;
+	struct dentry *dentry;
+	struct inode *inode;
+
+	dentry = eventfs_start_creating(name, parent);
+	if (IS_ERR(dentry))
+		return dentry;
+
+	inode = tracefs_get_inode(dentry->d_sb);
+	if (unlikely(!inode))
+		return eventfs_failed_creating(dentry);
+
+	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
+	inode->i_op = &eventfs_root_dir_inode_operations;
+	inode->i_fop = &eventfs_file_operations;
+	inode->i_private = data;
+
+	ti = get_tracefs(inode);
+	ti->flags |= TRACEFS_EVENT_INODE;
+
+	inc_nlink(inode);
+	d_instantiate(dentry, inode);
+	inc_nlink(dentry->d_parent->d_inode);
+	fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
+	return eventfs_end_creating(dentry);
+}
+
+/**
+ * eventfs_set_ef_status_free - set the ef->status to free
+ * @dentry: dentry who's status to be freed
+ *
+ * eventfs_set_ef_status_free will be called if no more
+ * references remain
+ */
+void eventfs_set_ef_status_free(struct dentry *dentry)
+{
+	struct tracefs_inode *ti_parent;
+	struct eventfs_file *ef;
+
+	mutex_lock(&eventfs_mutex);
+	ti_parent = get_tracefs(dentry->d_parent->d_inode);
+	if (!ti_parent || !(ti_parent->flags & TRACEFS_EVENT_INODE))
+		goto out;
+
+	ef = dentry->d_fsdata;
+	if (!ef)
+		goto out;
+
+	/*
+	 * If ef was freed, then the LSB bit is set for d_fsdata.
+	 * But this should not happen, as it should still have a
+	 * ref count that prevents it. Warn in case it does.
+	 */
+	if (WARN_ON_ONCE((unsigned long)ef & 1))
+		goto out;
+
+	dentry->d_fsdata = NULL;
+	ef->dentry = NULL;
+out:
+	mutex_unlock(&eventfs_mutex);
+}
+
+/**
+ * eventfs_post_create_dir - post create dir routine
+ * @ef: eventfs_file of recently created dir
+ *
+ * Map the meta-data of files within an eventfs dir to their parent dentry
+ */
+static void eventfs_post_create_dir(struct eventfs_file *ef)
+{
+	struct eventfs_file *ef_child;
+	struct tracefs_inode *ti;
+
+	/* srcu lock already held */
+	/* fill parent-child relation */
+	list_for_each_entry_srcu(ef_child, &ef->ei->e_top_files, list,
+				 srcu_read_lock_held(&eventfs_srcu)) {
+		ef_child->d_parent = ef->dentry;
+	}
+
+	ti = get_tracefs(ef->dentry->d_inode);
+	ti->private = ef->ei;
+}
+
+/**
+ * create_dentry - helper function to create dentry
+ * @ef: eventfs_file of file or directory to create
+ * @parent: parent dentry
+ * @lookup: true if called from lookup routine
+ *
+ * Used to create a dentry for file/dir, executes post dentry creation routine
+ */
+static struct dentry *
+create_dentry(struct eventfs_file *ef, struct dentry *parent, bool lookup)
+{
+	bool invalidate = false;
+	struct dentry *dentry;
+
+	mutex_lock(&eventfs_mutex);
+	if (ef->is_freed) {
+		mutex_unlock(&eventfs_mutex);
+		return NULL;
+	}
+	if (ef->dentry) {
+		dentry = ef->dentry;
+		/* On dir open, up the ref count */
+		if (!lookup)
+			dget(dentry);
+		mutex_unlock(&eventfs_mutex);
+		return dentry;
+	}
+	mutex_unlock(&eventfs_mutex);
+
+	if (!lookup)
+		inode_lock(parent->d_inode);
+
+	if (ef->ei)
+		dentry = create_dir(ef->name, parent, ef->data);
+	else
+		dentry = create_file(ef->name, ef->mode, parent,
+				     ef->data, ef->fop);
+
+	if (!lookup)
+		inode_unlock(parent->d_inode);
+
+	mutex_lock(&eventfs_mutex);
+	if (IS_ERR_OR_NULL(dentry)) {
+		/* If the ef was already updated get it */
+		dentry = ef->dentry;
+		if (dentry && !lookup)
+			dget(dentry);
+		mutex_unlock(&eventfs_mutex);
+		return dentry;
+	}
+
+	if (!ef->dentry && !ef->is_freed) {
+		ef->dentry = dentry;
+		if (ef->ei)
+			eventfs_post_create_dir(ef);
+		dentry->d_fsdata = ef;
+	} else {
+		/* A race here, should try again (unless freed) */
+		invalidate = true;
+
+		/*
+		 * Should never happen unless we get here due to being freed.
+		 * Otherwise it means two dentries exist with the same name.
+		 */
+		WARN_ON_ONCE(!ef->is_freed);
+	}
+	mutex_unlock(&eventfs_mutex);
+	if (invalidate)
+		d_invalidate(dentry);
+
+	if (lookup || invalidate)
+		dput(dentry);
+
+	return invalidate ? NULL : dentry;
+}
+
+static bool match_event_file(struct eventfs_file *ef, const char *name)
+{
+	bool ret;
+
+	mutex_lock(&eventfs_mutex);
+	ret = !ef->is_freed && strcmp(ef->name, name) == 0;
+	mutex_unlock(&eventfs_mutex);
+
+	return ret;
+}
+
+/**
+ * eventfs_root_lookup - lookup routine to create file/dir
+ * @dir: in which a lookup is being done
+ * @dentry: file/dir dentry
+ * @flags: to pass as flags parameter to simple lookup
+ *
+ * Used to create a dynamic file/dir within @dir. Use the eventfs_inode
+ * list of meta data to find the information needed to create the file/dir.
+ */
+static struct dentry *eventfs_root_lookup(struct inode *dir,
+					  struct dentry *dentry,
+					  unsigned int flags)
+{
+	struct tracefs_inode *ti;
+	struct eventfs_inode *ei;
+	struct eventfs_file *ef;
+	struct dentry *ret = NULL;
+	int idx;
+
+	ti = get_tracefs(dir);
+	if (!(ti->flags & TRACEFS_EVENT_INODE))
+		return NULL;
+
+	ei = ti->private;
+	idx = srcu_read_lock(&eventfs_srcu);
+	list_for_each_entry_srcu(ef, &ei->e_top_files, list,
+				 srcu_read_lock_held(&eventfs_srcu)) {
+		if (!match_event_file(ef, dentry->d_name.name))
+			continue;
+		ret = simple_lookup(dir, dentry, flags);
+		create_dentry(ef, ef->d_parent, true);
+		break;
+	}
+	srcu_read_unlock(&eventfs_srcu, idx);
+	return ret;
+}
+
+/**
+ * eventfs_release - called to release eventfs file/dir
+ * @inode: inode to be released
+ * @file: file to be released (not used)
+ */
+static int eventfs_release(struct inode *inode, struct file *file)
+{
+	struct tracefs_inode *ti;
+	struct eventfs_inode *ei;
+	struct eventfs_file *ef;
+	struct dentry *dentry;
+	int idx;
+
+	ti = get_tracefs(inode);
+	if (!(ti->flags & TRACEFS_EVENT_INODE))
+		return -EINVAL;
+
+	ei = ti->private;
+	idx = srcu_read_lock(&eventfs_srcu);
+	list_for_each_entry_srcu(ef, &ei->e_top_files, list,
+				 srcu_read_lock_held(&eventfs_srcu)) {
+		mutex_lock(&eventfs_mutex);
+		dentry = ef->dentry;
+		mutex_unlock(&eventfs_mutex);
+		if (dentry)
+			dput(dentry);
+	}
+	srcu_read_unlock(&eventfs_srcu, idx);
+	return dcache_dir_close(inode, file);
+}
+
+/**
+ * dcache_dir_open_wrapper - eventfs open wrapper
+ * @inode: not used
+ * @file: dir to be opened (to create its child)
+ *
+ * Used to dynamically create the file/dir within @file. @file is really a
+ * directory and all the files/dirs of the children within @file will be
+ * created. If any of the files/dirs have already been created, their
+ * reference count will be incremented.
+ */
+static int dcache_dir_open_wrapper(struct inode *inode, struct file *file)
+{
+	struct tracefs_inode *ti;
+	struct eventfs_inode *ei;
+	struct eventfs_file *ef;
+	struct dentry *dentry = file_dentry(file);
+	struct inode *f_inode = file_inode(file);
+	int idx;
+
+	ti = get_tracefs(f_inode);
+	if (!(ti->flags & TRACEFS_EVENT_INODE))
+		return -EINVAL;
+
+	ei = ti->private;
+	idx = srcu_read_lock(&eventfs_srcu);
+	list_for_each_entry_rcu(ef, &ei->e_top_files, list) {
+		create_dentry(ef, dentry, false);
+	}
+	srcu_read_unlock(&eventfs_srcu, idx);
+	return dcache_dir_open(inode, file);
+}
+
+/**
+ * eventfs_prepare_ef - helper function to prepare eventfs_file
+ * @name: the name of the file/directory to create.
+ * @mode: the permission that the file should have.
+ * @fop: struct file_operations that should be used for this file/directory.
+ * @iop: struct inode_operations that should be used for this file/directory.
+ * @data: something that the caller will want to get to later on. The
+ *        inode.i_private pointer will point to this value on the open() call.
+ *
+ * This function allocates and fills the eventfs_file structure.
+ */
+static struct eventfs_file *eventfs_prepare_ef(const char *name, umode_t mode,
+					const struct file_operations *fop,
+					const struct inode_operations *iop,
+					void *data)
+{
+	struct eventfs_file *ef;
+
+	ef = kzalloc(sizeof(*ef), GFP_KERNEL);
+	if (!ef)
+		return ERR_PTR(-ENOMEM);
+
+	ef->name = kstrdup(name, GFP_KERNEL);
+	if (!ef->name) {
+		kfree(ef);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	if (S_ISDIR(mode)) {
+		ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL);
+		if (!ef->ei) {
+			kfree(ef->name);
+			kfree(ef);
+			return ERR_PTR(-ENOMEM);
+		}
+		INIT_LIST_HEAD(&ef->ei->e_top_files);
+	} else {
+		ef->ei = NULL;
+	}
+
+	ef->iop = iop;
+	ef->fop = fop;
+	ef->mode = mode;
+	ef->data = data;
+	return ef;
+}
+
+/**
+ * eventfs_create_events_dir - create the trace event structure
+ * @name: the name of the directory to create.
+ * @parent: parent dentry for this file.  This should be a directory dentry
+ *          if set.  If this parameter is NULL, then the directory will be
+ *          created in the root of the tracefs filesystem.
+ *
+ * This function creates the top of the trace event directory.
+ */
+struct dentry *eventfs_create_events_dir(const char *name,
+					 struct dentry *parent)
+{
+	struct dentry *dentry = tracefs_start_creating(name, parent);
+	struct eventfs_inode *ei;
+	struct tracefs_inode *ti;
+	struct inode *inode;
+
+	if (IS_ERR(dentry))
+		return dentry;
+
+	ei = kzalloc(sizeof(*ei), GFP_KERNEL);
+	if (!ei)
+		return ERR_PTR(-ENOMEM);
+	inode = tracefs_get_inode(dentry->d_sb);
+	if (unlikely(!inode)) {
+		kfree(ei);
+		tracefs_failed_creating(dentry);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	INIT_LIST_HEAD(&ei->e_top_files);
+
+	ti = get_tracefs(inode);
+	ti->flags |= TRACEFS_EVENT_INODE;
+	ti->private = ei;
+
+	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
+	inode->i_op = &eventfs_root_dir_inode_operations;
+	inode->i_fop = &eventfs_file_operations;
+
+	/* directory inodes start off with i_nlink == 2 (for "." entry) */
+	inc_nlink(inode);
+	d_instantiate(dentry, inode);
+	inc_nlink(dentry->d_parent->d_inode);
+	fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
+	return tracefs_end_creating(dentry);
+}
+
+/**
+ * eventfs_add_subsystem_dir - add eventfs subsystem_dir to list to create later
+ * @name: the name of the file to create.
+ * @parent: parent dentry for this dir.
+ *
+ * This function adds eventfs subsystem dir to list.
+ * And all these dirs are created on the fly when they are looked up,
+ * and the dentry and inodes will be removed when they are done.
+ */
+struct eventfs_file *eventfs_add_subsystem_dir(const char *name,
+					       struct dentry *parent)
+{
+	struct tracefs_inode *ti_parent;
+	struct eventfs_inode *ei_parent;
+	struct eventfs_file *ef;
+
+	if (!parent)
+		return ERR_PTR(-EINVAL);
+
+	ti_parent = get_tracefs(parent->d_inode);
+	ei_parent = ti_parent->private;
+
+	ef = eventfs_prepare_ef(name, S_IFDIR, NULL, NULL, NULL);
+	if (IS_ERR(ef))
+		return ef;
+
+	mutex_lock(&eventfs_mutex);
+	list_add_tail(&ef->list, &ei_parent->e_top_files);
+	ef->d_parent = parent;
+	mutex_unlock(&eventfs_mutex);
+	return ef;
+}
+
+/**
+ * eventfs_add_dir - add eventfs dir to list to create later
+ * @name: the name of the file to create.
+ * @ef_parent: parent eventfs_file for this dir.
+ *
+ * This function adds eventfs dir to list.
+ * And all these dirs are created on the fly when they are looked up,
+ * and the dentry and inodes will be removed when they are done.
+ */
+struct eventfs_file *eventfs_add_dir(const char *name,
+				     struct eventfs_file *ef_parent)
+{
+	struct eventfs_file *ef;
+
+	if (!ef_parent)
+		return ERR_PTR(-EINVAL);
+
+	ef = eventfs_prepare_ef(name, S_IFDIR, NULL, NULL, NULL);
+	if (IS_ERR(ef))
+		return ef;
+
+	mutex_lock(&eventfs_mutex);
+	list_add_tail(&ef->list, &ef_parent->ei->e_top_files);
+	ef->d_parent = ef_parent->dentry;
+	mutex_unlock(&eventfs_mutex);
+	return ef;
+}
+
+/**
+ * eventfs_add_events_file - add the data needed to create a file for later reference
+ * @name: the name of the file to create.
+ * @mode: the permission that the file should have.
+ * @parent: parent dentry for this file.
+ * @data: something that the caller will want to get to later on.
+ * @fop: struct file_operations that should be used for this file.
+ *
+ * This function is used to add the information needed to create a
+ * dentry/inode within the top level events directory. The file created
+ * will have the @mode permissions. The @data will be used to fill the
+ * inode.i_private when the open() call is done. The dentry and inodes are
+ * all created when they are referenced, and removed when they are no
+ * longer referenced.
+ */
+int eventfs_add_events_file(const char *name, umode_t mode,
+			 struct dentry *parent, void *data,
+			 const struct file_operations *fop)
+{
+	struct tracefs_inode *ti;
+	struct eventfs_inode *ei;
+	struct eventfs_file *ef;
+
+	if (!parent)
+		return -EINVAL;
+
+	if (!(mode & S_IFMT))
+		mode |= S_IFREG;
+
+	if (!parent->d_inode)
+		return -EINVAL;
+
+	ti = get_tracefs(parent->d_inode);
+	if (!(ti->flags & TRACEFS_EVENT_INODE))
+		return -EINVAL;
+
+	ei = ti->private;
+	ef = eventfs_prepare_ef(name, mode, fop, NULL, data);
+
+	if (IS_ERR(ef))
+		return -ENOMEM;
+
+	mutex_lock(&eventfs_mutex);
+	list_add_tail(&ef->list, &ei->e_top_files);
+	ef->d_parent = parent;
+	mutex_unlock(&eventfs_mutex);
+	return 0;
+}
+
+/**
+ * eventfs_add_file - add eventfs file to list to create later
+ * @name: the name of the file to create.
+ * @mode: the permission that the file should have.
+ * @ef_parent: parent eventfs_file for this file.
+ * @data: something that the caller will want to get to later on.
+ * @fop: struct file_operations that should be used for this file.
+ *
+ * This function is used to add the information needed to create a
+ * file within a subdirectory of the events directory. The file created
+ * will have the @mode permissions. The @data will be used to fill the
+ * inode.i_private when the open() call is done. The dentry and inodes are
+ * all created when they are referenced, and removed when they are no
+ * longer referenced.
+ */
+int eventfs_add_file(const char *name, umode_t mode,
+		     struct eventfs_file *ef_parent,
+		     void *data,
+		     const struct file_operations *fop)
+{
+	struct eventfs_file *ef;
+
+	if (!ef_parent)
+		return -EINVAL;
+
+	if (!(mode & S_IFMT))
+		mode |= S_IFREG;
+
+	ef = eventfs_prepare_ef(name, mode, fop, NULL, data);
+	if (IS_ERR(ef))
+		return -ENOMEM;
+
+	mutex_lock(&eventfs_mutex);
+	list_add_tail(&ef->list, &ef_parent->ei->e_top_files);
+	ef->d_parent = ef_parent->dentry;
+	mutex_unlock(&eventfs_mutex);
+	return 0;
+}
+
+static void free_ef(struct rcu_head *head)
+{
+	struct eventfs_file *ef = container_of(head, struct eventfs_file, rcu);
+
+	kfree(ef->name);
+	kfree(ef->ei);
+	kfree(ef);
+}
+
+/**
+ * eventfs_remove_rec - remove eventfs dir or file from list
+ * @ef: eventfs_file to be removed.
+ * @head: to create list of eventfs_file to be deleted
+ * @level: to check recursion depth
+ *
+ * The helper function eventfs_remove_rec() is used to clean up and free the
+ * associated data from eventfs for both of the added functions.
+ */
+static void eventfs_remove_rec(struct eventfs_file *ef, struct list_head *head, int level)
+{
+	struct eventfs_file *ef_child;
+
+	if (!ef)
+		return;
+	/*
+	 * Check recursion depth. It should never be greater than 3:
+	 * 0 - events/
+	 * 1 - events/group/
+	 * 2 - events/group/event/
+	 * 3 - events/group/event/file
+	 */
+	if (WARN_ON_ONCE(level > 3))
+		return;
+
+	if (ef->ei) {
+		/* search for nested folders or files */
+		list_for_each_entry_srcu(ef_child, &ef->ei->e_top_files, list,
+					 lockdep_is_held(&eventfs_mutex)) {
+			eventfs_remove_rec(ef_child, head, level + 1);
+		}
+	}
+
+	list_del_rcu(&ef->list);
+	list_add_tail(&ef->del_list, head);
+}
+
+/**
+ * eventfs_remove - remove eventfs dir or file from list
+ * @ef: eventfs_file to be removed.
+ *
+ * This function acquire the eventfs_mutex lock and call eventfs_remove_rec()
+ */
+void eventfs_remove(struct eventfs_file *ef)
+{
+	struct eventfs_file *tmp;
+	LIST_HEAD(ef_del_list);
+	struct dentry *dentry_list = NULL;
+	struct dentry *dentry;
+
+	if (!ef)
+		return;
+
+	mutex_lock(&eventfs_mutex);
+	eventfs_remove_rec(ef, &ef_del_list, 0);
+	list_for_each_entry_safe(ef, tmp, &ef_del_list, del_list) {
+		if (ef->dentry) {
+			unsigned long ptr = (unsigned long)dentry_list;
+
+			/* Keep the dentry from being freed yet */
+			dget(ef->dentry);
+
+			/*
+			 * Paranoid: The dget() above should prevent the dentry
+			 * from being freed and calling eventfs_set_ef_status_free().
+			 * But just in case, set the link list LSB pointer to 1
+			 * and have eventfs_set_ef_status_free() check that to
+			 * make sure that if it does happen, it will not think
+			 * the d_fsdata is an event_file.
+			 *
+			 * For this to work, no event_file should be allocated
+			 * on a odd space, as the ef should always be allocated
+			 * to be at least word aligned. Check for that too.
+			 */
+			WARN_ON_ONCE(ptr & 1);
+
+			ef->dentry->d_fsdata = (void *)(ptr | 1);
+			dentry_list = ef->dentry;
+			ef->dentry = NULL;
+		}
+		call_srcu(&eventfs_srcu, &ef->rcu, free_ef);
+	}
+	mutex_unlock(&eventfs_mutex);
+
+	while (dentry_list) {
+		unsigned long ptr;
+
+		dentry = dentry_list;
+		ptr = (unsigned long)dentry->d_fsdata & ~1UL;
+		dentry_list = (struct dentry *)ptr;
+		dentry->d_fsdata = NULL;
+		d_invalidate(dentry);
+		mutex_lock(&eventfs_mutex);
+		/* dentry should now have at least a single reference */
+		WARN_ONCE((int)d_count(dentry) < 1,
+			  "dentry %p less than one reference (%d) after invalidate\n",
+			  dentry, d_count(dentry));
+		mutex_unlock(&eventfs_mutex);
+		dput(dentry);
+	}
+}
+
+/**
+ * eventfs_remove_events_dir - remove eventfs dir or file from list
+ * @dentry: events's dentry to be removed.
+ *
+ * This function remove events main directory
+ */
+void eventfs_remove_events_dir(struct dentry *dentry)
+{
+	struct tracefs_inode *ti;
+	struct eventfs_inode *ei;
+
+	if (!dentry || !dentry->d_inode)
+		return;
+
+	ti = get_tracefs(dentry->d_inode);
+	if (!ti || !(ti->flags & TRACEFS_EVENT_INODE))
+		return;
+
+	ei = ti->private;
+	d_invalidate(dentry);
+	dput(dentry);
+	kfree(ei);
+}

fs/tracefs/inode.c

···
 #include <linux/parser.h>
 #include <linux/magic.h>
 #include <linux/slab.h>
+#include "internal.h"
 
 #define TRACEFS_DEFAULT_MODE	0700
+static struct kmem_cache *tracefs_inode_cachep __ro_after_init;
 
 static struct vfsmount *tracefs_mount;
 static int tracefs_mount_count;
 static bool tracefs_registered;
+
+static struct inode *tracefs_alloc_inode(struct super_block *sb)
+{
+	struct tracefs_inode *ti;
+
+	ti = kmem_cache_alloc(tracefs_inode_cachep, GFP_KERNEL);
+	if (!ti)
+		return NULL;
+
+	ti->flags = 0;
+
+	return &ti->vfs_inode;
+}
+
+static void tracefs_free_inode(struct inode *inode)
+{
+	kmem_cache_free(tracefs_inode_cachep, get_tracefs(inode));
+}
 
 static ssize_t default_read_file(struct file *file, char __user *buf,
 				 size_t count, loff_t *ppos)
···
 	.rmdir		= tracefs_syscall_rmdir,
 };
 
-static struct inode *tracefs_get_inode(struct super_block *sb)
+struct inode *tracefs_get_inode(struct super_block *sb)
 {
 	struct inode *inode = new_inode(sb);
 	if (inode) {
···
 	struct tracefs_fs_info *fsi = sb->s_fs_info;
 	struct inode *inode = d_inode(sb->s_root);
 	struct tracefs_mount_opts *opts = &fsi->mount_opts;
+	umode_t tmp_mode;
 
 	/*
 	 * On remount, only reset mode/uid/gid if they were provided as mount
···
 	 */
 
 	if (!remount || opts->opts & BIT(Opt_mode)) {
-		inode->i_mode &= ~S_IALLUGO;
-		inode->i_mode |= opts->mode;
+		tmp_mode = READ_ONCE(inode->i_mode) & ~S_IALLUGO;
+		tmp_mode |= opts->mode;
+		WRITE_ONCE(inode->i_mode, tmp_mode);
 	}
 
 	if (!remount || opts->opts & BIT(Opt_uid))
···
 }
 
 static const struct super_operations tracefs_super_operations = {
+	.alloc_inode    = tracefs_alloc_inode,
+	.free_inode     = tracefs_free_inode,
+	.drop_inode     = generic_delete_inode,
 	.statfs		= simple_statfs,
 	.remount_fs	= tracefs_remount,
 	.show_options	= tracefs_show_options,
+};
+
+static void tracefs_dentry_iput(struct dentry *dentry, struct inode *inode)
+{
+	struct tracefs_inode *ti;
+
+	if (!dentry || !inode)
+		return;
+
+	ti = get_tracefs(inode);
+	if (ti && ti->flags & TRACEFS_EVENT_INODE)
+		eventfs_set_ef_status_free(dentry);
+	iput(inode);
+}
+
+static const struct dentry_operations tracefs_dentry_operations = {
+	.d_iput = tracefs_dentry_iput,
 };
 
 static int trace_fill_super(struct super_block *sb, void *data, int silent)
···
 		goto fail;
 
 	sb->s_op = &tracefs_super_operations;
+	sb->s_d_op = &tracefs_dentry_operations;
 
 	tracefs_apply_options(sb, false);
 
···
 };
 MODULE_ALIAS_FS("tracefs");
 
-static struct dentry *start_creating(const char *name, struct dentry *parent)
+struct dentry *tracefs_start_creating(const char *name, struct dentry *parent)
 {
 	struct dentry *dentry;
 	int error;
···
 	return dentry;
 }
 
-static struct dentry *failed_creating(struct dentry *dentry)
+struct dentry *tracefs_failed_creating(struct dentry *dentry)
 {
 	inode_unlock(d_inode(dentry->d_parent));
 	dput(dentry);
···
 	return NULL;
 }
 
-static struct dentry *end_creating(struct dentry *dentry)
+struct dentry *tracefs_end_creating(struct dentry *dentry)
 {
 	inode_unlock(d_inode(dentry->d_parent));
+	return dentry;
+}
+
+/**
+ * eventfs_start_creating - start the process of creating a dentry
+ * @name: Name of the file created for the dentry
+ * @parent: The parent dentry where this dentry will be created
+ *
+ * This is a simple helper function for the dynamically created eventfs
+ * files. When the directory of the eventfs files are accessed, their
+ * dentries are created on the fly. This function is used to start that
+ * process.
+ */
+struct dentry *eventfs_start_creating(const char *name, struct dentry *parent)
+{
+	struct dentry *dentry;
+	int error;
+
+	error = simple_pin_fs(&trace_fs_type, &tracefs_mount,
+			      &tracefs_mount_count);
+	if (error)
+		return ERR_PTR(error);
+
+	/*
+	 * If the parent is not specified, we create it in the root.
+	 * We need the root dentry to do this, which is in the super
+	 * block. A pointer to that is in the struct vfsmount that we
+	 * have around.
+	 */
+	if (!parent)
+		parent = tracefs_mount->mnt_root;
+
+	if (unlikely(IS_DEADDIR(parent->d_inode)))
+		dentry = ERR_PTR(-ENOENT);
+	else
+		dentry = lookup_one_len(name, parent, strlen(name));
+
+	if (!IS_ERR(dentry) && dentry->d_inode) {
+		dput(dentry);
+		dentry = ERR_PTR(-EEXIST);
+	}
+
+	if (IS_ERR(dentry))
+		simple_release_fs(&tracefs_mount, &tracefs_mount_count);
+
+	return dentry;
+}
+
+/**
+ * eventfs_failed_creating - clean up a failed eventfs dentry creation
+ * @dentry: The dentry to clean up
+ *
+ * If after calling eventfs_start_creating(), a failure is detected, the
+ * resources created by eventfs_start_creating() needs to be cleaned up. In
+ * that case, this function should be called to perform that clean up.
+ */
+struct dentry *eventfs_failed_creating(struct dentry *dentry)
+{
+	dput(dentry);
+	simple_release_fs(&tracefs_mount, &tracefs_mount_count);
+	return NULL;
+}
+
+/**
+ * eventfs_end_creating - Finish the process of creating a eventfs dentry
+ * @dentry: The dentry that has successfully been created.
+ *
+ * This function is currently just a place holder to match
+ * eventfs_start_creating(). In case any synchronization needs to be added,
+ * this function will be used to implement that without having to modify
+ * the callers of eventfs_start_creating().
+ */
+struct dentry *eventfs_end_creating(struct dentry *dentry)
+{
 	return dentry;
 }
 
···
 	if (!(mode & S_IFMT))
 		mode |= S_IFREG;
 	BUG_ON(!S_ISREG(mode));
-	dentry = start_creating(name, parent);
+	dentry = tracefs_start_creating(name, parent);
 
 	if (IS_ERR(dentry))
 		return NULL;
 
 	inode = tracefs_get_inode(dentry->d_sb);
 	if (unlikely(!inode))
-		return failed_creating(dentry);
+		return tracefs_failed_creating(dentry);
 
 	inode->i_mode = mode;
 	inode->i_fop = fops ? fops : &tracefs_file_operations;
···
 	inode->i_gid = d_inode(dentry->d_parent)->i_gid;
 	d_instantiate(dentry, inode);
 	fsnotify_create(d_inode(dentry->d_parent), dentry);
-	return end_creating(dentry);
+	return tracefs_end_creating(dentry);
 }
 
 static struct dentry *__create_dir(const char *name, struct dentry *parent,
 				   const struct inode_operations *ops)
 {
-	struct dentry *dentry = start_creating(name, parent);
+	struct dentry *dentry = tracefs_start_creating(name, parent);
 	struct inode *inode;
 
 	if (IS_ERR(dentry))
···
 
 	inode = tracefs_get_inode(dentry->d_sb);
 	if (unlikely(!inode))
-		return failed_creating(dentry);
+		return tracefs_failed_creating(dentry);
 
 	/* Do not set bits for OTH */
 	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUSR| S_IRGRP | S_IXUSR | S_IXGRP;
···
 	d_instantiate(dentry, inode);
 	inc_nlink(d_inode(dentry->d_parent));
 	fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
-	return end_creating(dentry);
+	return tracefs_end_creating(dentry);
 }
 
 /**
···
 	return tracefs_registered;
 }
 
+static void init_once(void *foo)
+{
+	struct tracefs_inode *ti = (struct tracefs_inode *) foo;
+
+	inode_init_once(&ti->vfs_inode);
+}
+
 static int __init tracefs_init(void)
 {
 	int retval;
+
+	tracefs_inode_cachep = kmem_cache_create("tracefs_inode_cache",
+						 sizeof(struct tracefs_inode),
+						 0, (SLAB_RECLAIM_ACCOUNT|
+						     SLAB_MEM_SPREAD|
+						     SLAB_ACCOUNT),
+						 init_once);
+	if (!tracefs_inode_cachep)
+		return -ENOMEM;
 
 	retval = sysfs_create_mount_point(kernel_kobj, "tracing");
 	if (retval)

fs/tracefs/internal.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TRACEFS_INTERNAL_H
+#define _TRACEFS_INTERNAL_H
+
+enum {
+	TRACEFS_EVENT_INODE     = BIT(1),
+};
+
+struct tracefs_inode {
+	unsigned long           flags;
+	void                    *private;
+	struct inode            vfs_inode;
+};
+
+static inline struct tracefs_inode *get_tracefs(const struct inode *inode)
+{
+	return container_of(inode, struct tracefs_inode, vfs_inode);
+}
+
+struct dentry *tracefs_start_creating(const char *name, struct dentry *parent);
+struct dentry *tracefs_end_creating(struct dentry *dentry);
+struct dentry *tracefs_failed_creating(struct dentry *dentry);
+struct inode *tracefs_get_inode(struct super_block *sb);
+struct dentry *eventfs_start_creating(const char *name, struct dentry *parent);
+struct dentry *eventfs_failed_creating(struct dentry *dentry);
+struct dentry *eventfs_end_creating(struct dentry *dentry);
+void eventfs_set_ef_status_free(struct dentry *dentry);
+
+#endif /* _TRACEFS_INTERNAL_H */

include/linux/ftrace.h

···
 extern void ftrace_module_init(struct module *mod);
 extern void ftrace_module_enable(struct module *mod);
 extern void ftrace_release_mod(struct module *mod);
-
-extern void ftrace_disable_daemon(void);
-extern void ftrace_enable_daemon(void);
 #else /* CONFIG_DYNAMIC_FTRACE */
 static inline int skip_trace(unsigned long ip) { return 0; }
-static inline void ftrace_disable_daemon(void) { }
-static inline void ftrace_enable_daemon(void) { }
 static inline void ftrace_module_init(struct module *mod) { }
 static inline void ftrace_module_enable(struct module *mod) { }
 static inline void ftrace_release_mod(struct module *mod) { }

include/linux/trace_events.h

···
 	struct list_head		list;
 	struct trace_event_call		*event_call;
 	struct event_filter __rcu	*filter;
+	struct eventfs_file             *ef;
 	struct dentry			*dir;
 	struct trace_array		*tr;
 	struct trace_subsystem_dir	*system;
···
 	FILTER_RDYN_STRING,
 	FILTER_PTR_STRING,
 	FILTER_TRACE_FN,
+	FILTER_CPUMASK,
 	FILTER_COMM,
 	FILTER_CPU,
 	FILTER_STACKTRACE,

include/linux/tracefs.h

···
 
 #ifdef CONFIG_TRACING
 
+struct eventfs_file;
+
+struct dentry *eventfs_create_events_dir(const char *name,
+					 struct dentry *parent);
+
+struct eventfs_file *eventfs_add_subsystem_dir(const char *name,
+					       struct dentry *parent);
+
+struct eventfs_file *eventfs_add_dir(const char *name,
+				     struct eventfs_file *ef_parent);
+
+int eventfs_add_file(const char *name, umode_t mode,
+		     struct eventfs_file *ef_parent, void *data,
+		     const struct file_operations *fops);
+
+int eventfs_add_events_file(const char *name, umode_t mode,
+			 struct dentry *parent, void *data,
+			 const struct file_operations *fops);
+
+void eventfs_remove(struct eventfs_file *ef);
+
+void eventfs_remove_events_dir(struct dentry *dentry);
+
 struct dentry *tracefs_create_file(const char *name, umode_t mode,
 				   struct dentry *parent, void *data,
 				   const struct file_operations *fops);

kernel/trace/ring_buffer.c

···
 static inline bool
 rb_time_read_cmpxchg(local_t *l, unsigned long expect, unsigned long set)
 {
-	unsigned long ret;
-
-	ret = local_cmpxchg(l, expect, set);
-	return ret == expect;
+	return local_try_cmpxchg(l, &expect, set);
 }
 
 static bool rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set)
···
 
 static bool rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set)
 {
-	u64 val;
-	val = local64_cmpxchg(&t->time, expect, set);
-	return val == expect;
+	return local64_try_cmpxchg(&t->time, &expect, set);
 }
 #endif
 
···
 {
 	unsigned long *ptr = (unsigned long *)&old->list.prev->next;
 	unsigned long val;
-	unsigned long ret;
 
 	val = *ptr & ~RB_FLAG_MASK;
 	val |= RB_PAGE_HEAD;
 
-	ret = cmpxchg(ptr, val, (unsigned long)&new->list);
-
-	return ret == val;
+	return try_cmpxchg(ptr, &val, (unsigned long)&new->list);
 }
 
 /*
···
 {
 	unsigned long new_index, old_index;
 	struct buffer_page *bpage;
-	unsigned long index;
 	unsigned long addr;
 	u64 write_stamp;
 	u64 delta;
···
 		 */
 		old_index += write_mask;
 		new_index += write_mask;
-		index = local_cmpxchg(&bpage->write, old_index, new_index);
-		if (index == old_index) {
+
+		/* caution: old_index gets updated on cmpxchg failure */
+		if (local_try_cmpxchg(&bpage->write, &old_index, new_index)) {
 			/* update counters */
 			local_sub(event_length, &cpu_buffer->entries_bytes);
 			return true;

kernel/trace/trace.c

···
 	struct ftrace_stack *fstack;
 	struct stack_entry *entry;
 	int stackidx;
-	void *ptr;
 
 	/*
 	 * Add one, for this function and the call to save_stack_trace()
···
 		nr_entries = stack_trace_save(fstack->calls, size, skip);
 	}
 
-	size = nr_entries * sizeof(unsigned long);
 	event = __trace_buffer_lock_reserve(buffer, TRACE_STACK,
-				    (sizeof(*entry) - sizeof(entry->caller)) + size,
+				    struct_size(entry, caller, nr_entries),
 				    trace_ctx);
 	if (!event)
 		goto out;
-	ptr = ring_buffer_event_data(event);
-	entry = ptr;
-
-	/*
-	 * For backward compatibility reasons, the entry->caller is an
-	 * array of 8 slots to store the stack. This is also exported
-	 * to user space. The amount allocated on the ring buffer actually
-	 * holds enough for the stack specified by nr_entries. This will
-	 * go into the location of entry->caller. Due to string fortifiers
-	 * checking the size of the destination of memcpy() it triggers
-	 * when it detects that size is greater than 8. To hide this from
-	 * the fortifiers, we use "ptr" and pointer arithmetic to assign caller.
-	 *
-	 * The below is really just:
-	 *   memcpy(&entry->caller, fstack->calls, size);
-	 */
-	ptr += offsetof(typeof(*entry), caller);
-	memcpy(ptr, fstack->calls, size);
+	entry = ring_buffer_event_data(event);
 
 	entry->size = nr_entries;
+	memcpy(&entry->caller, fstack->calls,
+	       flex_array_size(entry, caller, nr_entries));
 
 	if (!call_filter_check_discard(call, entry, buffer, event))
 		__buffer_unlock_commit(buffer, event);
···
 	loff_t l = 0;
 	int cpu;
 
-	/*
-	 * copy the tracer to avoid using a global lock all around.
-	 * iter->trace is a copy of current_trace, the pointer to the
-	 * name may be used instead of a strcmp(), as iter->trace->name
-	 * will point to the same string as current_trace->name.
-	 */
 	mutex_lock(&trace_types_lock);
-	if (unlikely(tr->current_trace && iter->trace->name != tr->current_trace->name)) {
+	if (unlikely(tr->current_trace != iter->trace)) {
 		/* Close iter->trace before switching to the new current tracer */
 		if (iter->trace->close)
 			iter->trace->close(iter);
-		*iter->trace = *tr->current_trace;
+		iter->trace = tr->current_trace;
 		/* Reopen the new current tracer */
 		if (iter->trace->open)
 			iter->trace->open(iter);
···
 	.show		= s_show,
 };
 
+/*
+ * Note, as iter itself can be allocated and freed in different
+ * ways, this function is only used to free its content, and not
+ * the iterator itself. The only requirement to all the allocations
+ * is that it must zero all fields (kzalloc), as freeing works with
+ * ethier allocated content or NULL.
+ */
+static void free_trace_iter_content(struct trace_iterator *iter)
+{
+	/* The fmt is either NULL, allocated or points to static_fmt_buf */
+	if (iter->fmt != static_fmt_buf)
+		kfree(iter->fmt);
+
+	kfree(iter->temp);
+	kfree(iter->buffer_iter);
+	mutex_destroy(&iter->mutex);
+	free_cpumask_var(iter->started);
+}
+
 static struct trace_iterator *
 __tracing_open(struct inode *inode, struct file *file, bool snapshot)
 {
···
 	iter->fmt = NULL;
 	iter->fmt_size = 0;
 
-	/*
-	 * We make a copy of the current tracer to avoid concurrent
-	 * changes on it while we are reading.
-	 */
 	mutex_lock(&trace_types_lock);
-	iter->trace = kzalloc(sizeof(*iter->trace), GFP_KERNEL);
-	if (!iter->trace)
-		goto fail;
-
-	*iter->trace = *tr->current_trace;
+	iter->trace = tr->current_trace;
 
 	if (!zalloc_cpumask_var(&iter->started, GFP_KERNEL))
 		goto fail;
···
 
  fail:
 	mutex_unlock(&trace_types_lock);
-	kfree(iter->trace);
-	kfree(iter->temp);
-	kfree(iter->buffer_iter);
+	free_trace_iter_content(iter);
 release:
 	seq_release_private(inode, file);
 	return ERR_PTR(-ENOMEM);
···
 
 	mutex_unlock(&trace_types_lock);
 
-	mutex_destroy(&iter->mutex);
-	free_cpumask_var(iter->started);
-	kfree(iter->fmt);
-	kfree(iter->temp);
-	kfree(iter->trace);
-	kfree(iter->buffer_iter);
+	free_trace_iter_content(iter);
 	seq_release_private(inode, file);
 
 	return 0;
···
 		per_cpu_ptr(buf->data, cpu)->entries = val;
 }
 
+static void update_buffer_entries(struct array_buffer *buf, int cpu)
+{
+	if (cpu == RING_BUFFER_ALL_CPUS) {
+		set_buffer_entries(buf, ring_buffer_size(buf->buffer, 0));
+	} else {
+		per_cpu_ptr(buf->data, cpu)->entries = ring_buffer_size(buf->buffer, cpu);
+	}
+}
+
 #ifdef CONFIG_TRACER_MAX_TRACE
 /* resize @tr's buffer to the size of @size_tr's entries */
 static int resize_buffer_duplicate_size(struct array_buffer *trace_buf,
···
 		return ret;
 	}
 
-	if (cpu == RING_BUFFER_ALL_CPUS)
-		set_buffer_entries(&tr->max_buffer, size);
-	else
-		per_cpu_ptr(tr->max_buffer.data, cpu)->entries = size;
+	update_buffer_entries(&tr->max_buffer, cpu);
 
  out:
 #endif /* CONFIG_TRACER_MAX_TRACE */
 
-	if (cpu == RING_BUFFER_ALL_CPUS)
-		set_buffer_entries(&tr->array_buffer, size);
-	else
-		per_cpu_ptr(tr->array_buffer.data, cpu)->entries = size;
+	update_buffer_entries(&tr->array_buffer, cpu);
 
 	return ret;
 }
···
 	close_pipe_on_cpu(tr, iter->cpu_file);
 	mutex_unlock(&trace_types_lock);
 
-	free_cpumask_var(iter->started);
-	kfree(iter->fmt);
-	kfree(iter->temp);
-	mutex_destroy(&iter->mutex);
+	free_trace_iter_content(iter);
 	kfree(iter);
 
 	trace_array_put(tr);

kernel/trace/trace.h

···
 #undef __array
 #define __array(type, item, size)	type	item[size];
 
+/*
+ * For backward compatibility, older user space expects to see the
+ * kernel_stack event with a fixed size caller field. But today the fix
+ * size is ignored by the kernel, and the real structure is dynamic.
+ * Expose to user space: "unsigned long caller[8];" but the real structure
+ * will be "unsigned long caller[] __counted_by(size)"
+ */
+#undef __stack_array
+#define __stack_array(type, item, size, field)		type item[] __counted_by(field);
+
 #undef __array_desc
 #define __array_desc(type, container, item, size)
 
···
 int tracer_init(struct tracer *t, struct trace_array *tr);
 int tracing_is_enabled(void);
 void tracing_reset_online_cpus(struct array_buffer *buf);
-void tracing_reset_current(int cpu);
 void tracing_reset_all_online_cpus(void);
 void tracing_reset_all_online_cpus_unlocked(void);
 int tracing_open_generic(struct inode *inode, struct file *filp);
···
 void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos);
 void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos);
 int trace_pid_show(struct seq_file *m, void *v);
-void trace_free_pid_list(struct trace_pid_list *pid_list);
 int trace_pid_write(struct trace_pid_list *filtered_pids,
 		    struct trace_pid_list **new_pid_list,
 		    const char __user *ubuf, size_t cnt);
···
 	struct list_head		list;
 	struct event_subsystem		*subsystem;
 	struct trace_array		*tr;
-	struct dentry			*entry;
+	struct eventfs_file             *ef;
 	int				ref_count;
 	int				nr_events;
 };

kernel/trace/trace_entries.h

···
 
 	F_STRUCT(
 		__field(	int,		size	)
-		__array(	unsigned long,	caller,	FTRACE_STACK_ENTRIES	)
+		__stack_array(	unsigned long,	caller,	FTRACE_STACK_ENTRIES, size)
 	),
 
 	F_printk("\t=> %ps\n\t=> %ps\n\t=> %ps\n"

kernel/trace/trace_events.c

···
 		return;
 
 	if (!--dir->nr_events) {
-		tracefs_remove(dir->entry);
+		eventfs_remove(dir->ef);
 		list_del(&dir->list);
 		__put_system_dir(dir);
 	}
···
 
 		tracefs_remove(dir);
 	}
-
+	eventfs_remove(file->ef);
 	list_del(&file->list);
 	remove_subsystem(file->system);
 	free_event_filter(file->filter);
···
 	return NULL;
 }
 
-static struct dentry *
+static struct eventfs_file *
 event_subsystem_dir(struct trace_array *tr, const char *name,
 		    struct trace_event_file *file, struct dentry *parent)
 {
 	struct event_subsystem *system, *iter;
 	struct trace_subsystem_dir *dir;
-	struct dentry *entry;
+	int res;
 
 	/* First see if we did not already create this dir */
 	list_for_each_entry(dir, &tr->systems, list) {
···
 		if (strcmp(system->name, name) == 0) {
 			dir->nr_events++;
 			file->system = dir;
-			return dir->entry;
+			return dir->ef;
 		}
 	}
 
···
 	} else
 		__get_system(system);
 
-	dir->entry = tracefs_create_dir(name, parent);
-	if (!dir->entry) {
+	dir->ef = eventfs_add_subsystem_dir(name, parent);
+	if (IS_ERR(dir->ef)) {
 		pr_warn("Failed to create system directory %s\n", name);
 		__put_system(system);
 		goto out_free;
···
 	/* the ftrace system is special, do not create enable or filter files */
 	if (strcmp(name, "ftrace") != 0) {
 
-		entry = tracefs_create_file("filter", TRACE_MODE_WRITE,
-					    dir->entry, dir,
+		res = eventfs_add_file("filter", TRACE_MODE_WRITE,
+					    dir->ef, dir,
 					    &ftrace_subsystem_filter_fops);
-		if (!entry) {
+		if (res) {
 			kfree(system->filter);
 			system->filter = NULL;
 			pr_warn("Could not create tracefs '%s/filter' entry\n", name);
 		}
 
-		trace_create_file("enable", TRACE_MODE_WRITE, dir->entry, dir,
+		eventfs_add_file("enable", TRACE_MODE_WRITE, dir->ef, dir,
 				  &ftrace_system_enable_fops);
 	}
 
 	list_add(&dir->list, &tr->systems);
 
-	return dir->entry;
+	return dir->ef;
 
  out_free:
 	kfree(dir);
···
 event_create_dir(struct dentry *parent, struct trace_event_file *file)
 {
 	struct trace_event_call *call = file->event_call;
+	struct eventfs_file *ef_subsystem = NULL;
 	struct trace_array *tr = file->tr;
-	struct dentry *d_events;
 	const char *name;
 	int ret;
 
 	/*
 	 * If the trace point header did not define TRACE_SYSTEM
-	 * then the system would be called "TRACE_SYSTEM".
+	 * then the system would be called "TRACE_SYSTEM". This should
+	 * never happen.
 	 */
-	if (strcmp(call->class->system, TRACE_SYSTEM) != 0) {
-		d_events = event_subsystem_dir(tr, call->class->system, file, parent);
-		if (!d_events)
-			return -ENOMEM;
-	} else
-		d_events = parent;
+	if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0))
+		return -ENODEV;
+
+	ef_subsystem = event_subsystem_dir(tr, call->class->system, file, parent);
+	if (!ef_subsystem)
+		return -ENOMEM;
 
 	name = trace_event_name(call);
-	file->dir = tracefs_create_dir(name, d_events);
-	if (!file->dir) {
+	file->ef = eventfs_add_dir(name, ef_subsystem);
+	if (IS_ERR(file->ef)) {
 		pr_warn("Could not create tracefs '%s' directory\n", name);
 		return -1;
 	}
 
 	if (call->class->reg && !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE))
-		trace_create_file("enable", TRACE_MODE_WRITE, file->dir, file,
+		eventfs_add_file("enable", TRACE_MODE_WRITE, file->ef, file,
 				  &ftrace_enable_fops);
 
 #ifdef CONFIG_PERF_EVENTS
 	if (call->event.type && call->class->reg)
-		trace_create_file("id", TRACE_MODE_READ, file->dir,
+		eventfs_add_file("id", TRACE_MODE_READ, file->ef,
 				  (void *)(long)call->event.type,
 				  &ftrace_event_id_fops);
 #endif
···
 	 * triggers or filters.
 	 */
 	if (!(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)) {
-		trace_create_file("filter", TRACE_MODE_WRITE, file->dir,
+		eventfs_add_file("filter", TRACE_MODE_WRITE, file->ef,
 				  file, &ftrace_event_filter_fops);
 
-		trace_create_file("trigger", TRACE_MODE_WRITE, file->dir,
+		eventfs_add_file("trigger", TRACE_MODE_WRITE, file->ef,
 				  file, &event_trigger_fops);
 	}
 
 #ifdef CONFIG_HIST_TRIGGERS
-	trace_create_file("hist", TRACE_MODE_READ, file->dir, file,
+	eventfs_add_file("hist", TRACE_MODE_READ, file->ef, file,
 			  &event_hist_fops);
 #endif
 #ifdef CONFIG_HIST_TRIGGERS_DEBUG
-	trace_create_file("hist_debug", TRACE_MODE_READ, file->dir, file,
+	eventfs_add_file("hist_debug", TRACE_MODE_READ, file->ef, file,
 			  &event_hist_debug_fops);
 #endif
-	trace_create_file("format", TRACE_MODE_READ, file->dir, call,
+	eventfs_add_file("format", TRACE_MODE_READ, file->ef, call,
 			  &ftrace_event_format_fops);
 
 #ifdef CONFIG_TRACE_EVENT_INJECT
 	if (call->event.type && call->class->reg)
-		trace_create_file("inject", 0200, file->dir, file,
+		eventfs_add_file("inject", 0200, file->ef, file,
 				  &event_inject_fops);
 #endif
 
···
 {
 	struct dentry *d_events;
 	struct dentry *entry;
+	int error = 0;
 
 	entry = trace_create_file("set_event", TRACE_MODE_WRITE, parent,
 				  tr, &ftrace_set_event_fops);
 	if (!entry)
 		return -ENOMEM;
 
-	d_events = tracefs_create_dir("events", parent);
-	if (!d_events) {
+	d_events = eventfs_create_events_dir("events", parent);
+	if (IS_ERR(d_events)) {
 		pr_warn("Could not create tracefs 'events' directory\n");
 		return -ENOMEM;
 	}
 
-	entry = trace_create_file("enable", TRACE_MODE_WRITE, d_events,
+	error = eventfs_add_events_file("enable", TRACE_MODE_WRITE, d_events,
 				  tr, &ftrace_tr_enable_fops);
-	if (!entry)
+	if (error)
 		return -ENOMEM;
 
 	/* There are not as crucial, just warn if they are not created */
···
 			  &ftrace_set_event_notrace_pid_fops);
 
 	/* ring buffer internal formats */
-	trace_create_file("header_page", TRACE_MODE_READ, d_events,
+	eventfs_add_events_file("header_page", TRACE_MODE_READ, d_events,
 				  ring_buffer_print_page_header,
 				  &ftrace_show_header_fops);
 
-	trace_create_file("header_event", TRACE_MODE_READ, d_events,
+	eventfs_add_events_file("header_event", TRACE_MODE_READ, d_events,
 				  ring_buffer_print_entry_header,
 				  &ftrace_show_header_fops);
 
···
 
 	down_write(&trace_event_sem);
 	__trace_remove_event_dirs(tr);
-	tracefs_remove(tr->event_dir);
+	eventfs_remove_events_dir(tr->event_dir);
 	up_write(&trace_event_sem);
 
 	tr->event_dir = NULL;

kernel/trace/trace_events_filter.c

···
 enum filter_pred_fn {
 	FILTER_PRED_FN_NOP,
 	FILTER_PRED_FN_64,
+	FILTER_PRED_FN_64_CPUMASK,
 	FILTER_PRED_FN_S64,
 	FILTER_PRED_FN_U64,
 	FILTER_PRED_FN_32,
+	FILTER_PRED_FN_32_CPUMASK,
 	FILTER_PRED_FN_S32,
 	FILTER_PRED_FN_U32,
 	FILTER_PRED_FN_16,
+	FILTER_PRED_FN_16_CPUMASK,
 	FILTER_PRED_FN_S16,
 	FILTER_PRED_FN_U16,
 	FILTER_PRED_FN_8,
+	FILTER_PRED_FN_8_CPUMASK,
 	FILTER_PRED_FN_S8,
 	FILTER_PRED_FN_U8,
 	FILTER_PRED_FN_COMM,
···
 	FILTER_PRED_FN_PCHAR_USER,
 	FILTER_PRED_FN_PCHAR,
 	FILTER_PRED_FN_CPU,
+	FILTER_PRED_FN_CPU_CPUMASK,
+	FILTER_PRED_FN_CPUMASK,
+	FILTER_PRED_FN_CPUMASK_CPU,
 	FILTER_PRED_FN_FUNCTION,
 	FILTER_PRED_FN_,
 	FILTER_PRED_TEST_VISITED,
 };
 
 struct filter_pred {
-	enum filter_pred_fn 	fn_num;
-	u64 			val;
-	u64 			val2;
-	struct regex		regex;
+	struct regex		*regex;
+	struct cpumask          *mask;
 	unsigned short		*ops;
 	struct ftrace_event_field *field;
-	int 			offset;
+	u64			val;
+	u64			val2;
+	enum filter_pred_fn	fn_num;
+	int			offset;
 	int			not;
-	int 			op;
+	int			op;
 };
 
 /*
···
 	C(TOO_MANY_OPEN,	"Too many '('"),			\
 	C(TOO_MANY_CLOSE,	"Too few '('"),				\
 	C(MISSING_QUOTE,	"Missing matching quote"),		\
+	C(MISSING_BRACE_OPEN,   "Missing '{'"),				\
+	C(MISSING_BRACE_CLOSE,  "Missing '}'"),				\
 	C(OPERAND_TOO_LONG,	"Operand too long"),			\
 	C(EXPECT_STRING,	"Expecting string field"),		\
 	C(EXPECT_DIGIT,		"Expecting numeric field"),		\
···
 	C(BAD_SUBSYS_FILTER,	"Couldn't find or set field in one of a subsystem's events"), \
 	C(TOO_MANY_PREDS,	"Too many terms in predicate expression"), \
 	C(INVALID_FILTER,	"Meaningless filter expression"),	\
+	C(INVALID_CPULIST,	"Invalid cpulist"),	\
 	C(IP_FIELD_ONLY,	"Only 'ip' field is supported for function trace"), \
 	C(INVALID_VALUE,	"Invalid value (did you forget quotes)?"), \
 	C(NO_FUNCTION,		"Function not found"),			\
···
 	PROCESS_AND	= 2,
 	PROCESS_OR	= 4,
 };
+
+static void free_predicate(struct filter_pred *pred)
+{
+	if (pred) {
+		kfree(pred->regex);
+		kfree(pred->mask);
+		kfree(pred);
+	}
+}
 
 /*
  * Without going into a formal proof, this explains the method that is used in
···
 	kfree(inverts);
 	if (prog_stack) {
 		for (i = 0; prog_stack[i].pred; i++)
-			kfree(prog_stack[i].pred);
+			free_predicate(prog_stack[i].pred);
 		kfree(prog_stack);
 	}
 	return ERR_PTR(ret);
+}
+
+static inline int
+do_filter_cpumask(int op, const struct cpumask *mask, const struct cpumask *cmp)
+{
+	switch (op) {
+	case OP_EQ:
+		return cpumask_equal(mask, cmp);
+	case OP_NE:
+		return !cpumask_equal(mask, cmp);
+	case OP_BAND:
+		return cpumask_intersects(mask, cmp);
+	default:
+		return 0;
+	}
+}
+
+/* Optimisation of do_filter_cpumask() for scalar fields */
+static inline int
+do_filter_scalar_cpumask(int op, unsigned int cpu, const struct cpumask *mask)
+{
+	/*
+	 * Per the weight-of-one cpumask optimisations, the mask passed in this
+	 * function has a weight >= 2, so it is never equal to a single scalar.
+	 */
+	switch (op) {
+	case OP_EQ:
+		return false;
+	case OP_NE:
+		return true;
+	case OP_BAND:
+		return cpumask_test_cpu(cpu, mask);
+	default:
+		return 0;
+	}
+}
+
+static inline int
+do_filter_cpumask_scalar(int op, const struct cpumask *mask, unsigned int cpu)
+{
+	switch (op) {
+	case OP_EQ:
+		return cpumask_test_cpu(cpu, mask) &&
+			cpumask_nth(1, mask) >= nr_cpu_ids;
+	case OP_NE:
+		return !cpumask_test_cpu(cpu, mask) ||
+			cpumask_nth(1, mask) < nr_cpu_ids;
+	case OP_BAND:
+		return cpumask_test_cpu(cpu, mask);
+	default:
+		return 0;
+	}
 }
 
 enum pred_cmp_types {
···
 	}								\
 }
 
+#define DEFINE_CPUMASK_COMPARISON_PRED(size)					\
+static int filter_pred_##size##_cpumask(struct filter_pred *pred, void *event)	\
+{										\
+	u##size *addr = (u##size *)(event + pred->offset);			\
+	unsigned int cpu = *addr;						\
+										\
+	if (cpu >= nr_cpu_ids)							\
+		return 0;							\
+										\
+	return do_filter_scalar_cpumask(pred->op, cpu, pred->mask);		\
+}
+
 #define DEFINE_EQUALITY_PRED(size)					\
 static int filter_pred_##size(struct filter_pred *pred, void *event)	\
 {									\
···
 DEFINE_COMPARISON_PRED(u16);
 DEFINE_COMPARISON_PRED(s8);
 DEFINE_COMPARISON_PRED(u8);
+
+DEFINE_CPUMASK_COMPARISON_PRED(64);
+DEFINE_CPUMASK_COMPARISON_PRED(32);
+DEFINE_CPUMASK_COMPARISON_PRED(16);
+DEFINE_CPUMASK_COMPARISON_PRED(8);
 
 DEFINE_EQUALITY_PRED(64);
 DEFINE_EQUALITY_PRED(32);
···
 	char *addr = (char *)(event + pred->offset);
 	int cmp, match;
 
-	cmp = pred->regex.match(addr, &pred->regex, pred->regex.field_len);
+	cmp = pred->regex->match(addr, pred->regex, pred->regex->field_len);
 
 	match = cmp ^ pred->not;
 
···
 	int len;
 
 	len = strlen(str) + 1;	/* including tailing '\0' */
-	cmp = pred->regex.match(str, &pred->regex, len);
+	cmp = pred->regex->match(str, pred->regex, len);
 
 	match = cmp ^ pred->not;
 
···
 	char *addr = (char *)(event + str_loc);
 	int cmp, match;
 
-	cmp = pred->regex.match(addr, &pred->regex, str_len);
+	cmp = pred->regex->match(addr, pred->regex, str_len);
 
 	match = cmp ^ pred->not;
 
···
 	char *addr = (char *)(&item[1]) + str_loc;
 	int cmp, match;
 
-	cmp = pred->regex.match(addr, &pred->regex, str_len);
+	cmp = pred->regex->match(addr, pred->regex, str_len);
 
 	match = cmp ^ pred->not;
 
···
 	}
 }
 
+/* Filter predicate for current CPU vs user-provided cpumask */
+static int filter_pred_cpu_cpumask(struct filter_pred *pred, void *event)
+{
+	int cpu = raw_smp_processor_id();
+
+	return do_filter_scalar_cpumask(pred->op, cpu, pred->mask);
+}
+
+/* Filter predicate for cpumask field vs user-provided cpumask */
+static int filter_pred_cpumask(struct filter_pred *pred, void *event)
+{
+	u32 item = *(u32 *)(event + pred->offset);
+	int loc = item & 0xffff;
+	const struct cpumask *mask = (event + loc);
+	const struct cpumask *cmp = pred->mask;
+
+	return do_filter_cpumask(pred->op, mask, cmp);
+}
+
+/* Filter predicate for cpumask field vs user-provided scalar  */
+static int filter_pred_cpumask_cpu(struct filter_pred *pred, void *event)
+{
+	u32 item = *(u32 *)(event + pred->offset);
+	int loc = item & 0xffff;
+	const struct cpumask *mask = (event + loc);
+	unsigned int cpu = pred->val;
+
+	return do_filter_cpumask_scalar(pred->op, mask, cpu);
+}
+
 /* Filter predicate for COMM. */
 static int filter_pred_comm(struct filter_pred *pred, void *event)
 {
 	int cmp;
 
-	cmp = pred->regex.match(current->comm, &pred->regex,
+	cmp = pred->regex->match(current->comm, pred->regex,
 				TASK_COMM_LEN);
 	return cmp ^ pred->not;
 }
···
 
 static void filter_build_regex(struct filter_pred *pred)
 {
-	struct regex *r = &pred->regex;
+	struct regex *r = pred->regex;
 	char *search;
 	enum regex_type type = MATCH_FULL;
 
···
 		return;
 
 	for (i = 0; prog[i].pred; i++)
-		kfree(prog[i].pred);
+		free_predicate(prog[i].pred);
 	kfree(prog);
 }
 
···
 
 int filter_assign_type(const char *type)
 {
-	if (strstr(type, "__data_loc") && strstr(type, "char"))
-		return FILTER_DYN_STRING;
+	if (strstr(type, "__data_loc")) {
+		if (strstr(type, "char"))
+			return FILTER_DYN_STRING;
+		if (strstr(type, "cpumask_t"))
+			return FILTER_CPUMASK;
+		}
 
 	if (strstr(type, "__rel_loc") && strstr(type, "char"))
 		return FILTER_RDYN_STRING;
···
 	switch (pred->fn_num) {
 	case FILTER_PRED_FN_64:
 		return filter_pred_64(pred, event);
+	case FILTER_PRED_FN_64_CPUMASK:
+		return filter_pred_64_cpumask(pred, event);
 	case FILTER_PRED_FN_S64:
 		return filter_pred_s64(pred, event);
 	case FILTER_PRED_FN_U64:
 		return filter_pred_u64(pred, event);
 	case FILTER_PRED_FN_32:
 		return filter_pred_32(pred, event);
+	case FILTER_PRED_FN_32_CPUMASK:
+		return filter_pred_32_cpumask(pred, event);
 	case FILTER_PRED_FN_S32:
 		return filter_pred_s32(pred, event);
 	case FILTER_PRED_FN_U32:
 		return filter_pred_u32(pred, event);
 	case FILTER_PRED_FN_16:
 		return filter_pred_16(pred, event);
+	case FILTER_PRED_FN_16_CPUMASK:
+		return filter_pred_16_cpumask(pred, event);
 	case FILTER_PRED_FN_S16:
 		return filter_pred_s16(pred, event);
 	case FILTER_PRED_FN_U16:
 		return filter_pred_u16(pred, event);
 	case FILTER_PRED_FN_8:
 		return filter_pred_8(pred, event);
+	case FILTER_PRED_FN_8_CPUMASK:
+		return filter_pred_8_cpumask(pred, event);
 	case FILTER_PRED_FN_S8:
 		return filter_pred_s8(pred, event);
 	case FILTER_PRED_FN_U8:
···
 		return filter_pred_pchar(pred, event);
 	case FILTER_PRED_FN_CPU:
 		return filter_pred_cpu(pred, event);
+	case FILTER_PRED_FN_CPU_CPUMASK:
+		return filter_pred_cpu_cpumask(pred, event);
+	case FILTER_PRED_FN_CPUMASK:
+		return filter_pred_cpumask(pred, event);
+	case FILTER_PRED_FN_CPUMASK_CPU:
+		return filter_pred_cpumask_cpu(pred, event);
 	case FILTER_PRED_FN_FUNCTION:
 		return filter_pred_function(pred, event);
 	case FILTER_PRED_TEST_VISITED:
···
 			goto err_free;
 		}
 
-		pred->regex.len = len;
-		strncpy(pred->regex.pattern, str + s, len);
-		pred->regex.pattern[len] = 0;
+		pred->regex = kzalloc(sizeof(*pred->regex), GFP_KERNEL);
+		if (!pred->regex)
+			goto err_mem;
+		pred->regex->len = len;
+		strncpy(pred->regex->pattern, str + s, len);
+		pred->regex->pattern[len] = 0;
+
+	} else if (!strncmp(str + i, "CPUS", 4)) {
+		unsigned int maskstart;
+		bool single;
+		char *tmp;
+
+		switch (field->filter_type) {
+		case FILTER_CPUMASK:
+		case FILTER_CPU:
+		case FILTER_OTHER:
+			break;
+		default:
+			parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i);
+			goto err_free;
+		}
+
+		switch (op) {
+		case OP_EQ:
+		case OP_NE:
+		case OP_BAND:
+			break;
+		default:
+			parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i);
+			goto err_free;
+		}
+
+		/* Skip CPUS */
+		i += 4;
+		if (str[i++] != '{') {
+			parse_error(pe, FILT_ERR_MISSING_BRACE_OPEN, pos + i);
+			goto err_free;
+		}
+		maskstart = i;
+
+		/* Walk the cpulist until closing } */
+		for (; str[i] && str[i] != '}'; i++);
+		if (str[i] != '}') {
+			parse_error(pe, FILT_ERR_MISSING_BRACE_CLOSE, pos + i);
+			goto err_free;
+		}
+
+		if (maskstart == i) {
+			parse_error(pe, FILT_ERR_INVALID_CPULIST, pos + i);
+			goto err_free;
+		}
+
+		/* Copy the cpulist between { and } */
+		tmp = kmalloc((i - maskstart) + 1, GFP_KERNEL);
+		strscpy(tmp, str + maskstart, (i - maskstart) + 1);
+
+		pred->mask = kzalloc(cpumask_size(), GFP_KERNEL);
+		if (!pred->mask)
+			goto err_mem;
+
+		/* Now parse it */
+		if (cpulist_parse(tmp, pred->mask)) {
+			parse_error(pe, FILT_ERR_INVALID_CPULIST, pos + i);
+			goto err_free;
+		}
+
+		/* Move along */
+		i++;
+
+		/*
+		 * Optimisation: if the user-provided mask has a weight of one
+		 * then we can treat it as a scalar input.
+		 */
+		single = cpumask_weight(pred->mask) == 1;
+		if (single) {
+			pred->val = cpumask_first(pred->mask);
+			kfree(pred->mask);
+		}
+
+		if (field->filter_type == FILTER_CPUMASK) {
+			pred->fn_num = single ?
+				FILTER_PRED_FN_CPUMASK_CPU :
+				FILTER_PRED_FN_CPUMASK;
+		} else if (field->filter_type == FILTER_CPU) {
+			if (single) {
+				pred->op = pred->op == OP_BAND ? OP_EQ : pred->op;
+				pred->fn_num = FILTER_PRED_FN_CPU;
+			} else {
+				pred->fn_num = FILTER_PRED_FN_CPU_CPUMASK;
+			}
+		} else if (single) {
+			pred->op = pred->op == OP_BAND ? OP_EQ : pred->op;
+			pred->fn_num = select_comparison_fn(pred->op, field->size, false);
+			if (pred->op == OP_NE)
+				pred->not = 1;
+		} else {
+			switch (field->size) {
+			case 8:
+				pred->fn_num = FILTER_PRED_FN_64_CPUMASK;
+				break;
+			case 4:
+				pred->fn_num = FILTER_PRED_FN_32_CPUMASK;
+				break;
+			case 2:
+				pred->fn_num = FILTER_PRED_FN_16_CPUMASK;
+				break;
+			case 1:
+				pred->fn_num = FILTER_PRED_FN_8_CPUMASK;
+				break;
+			}
+		}
 
 	/* This is either a string, or an integer */
 	} else if (str[i] == '\'' || str[i] == '"') {
···
 			goto err_free;
 		}
 
-		pred->regex.len = len;
-		strncpy(pred->regex.pattern, str + s, len);
-		pred->regex.pattern[len] = 0;
+		pred->regex = kzalloc(sizeof(*pred->regex), GFP_KERNEL);
+		if (!pred->regex)
+			goto err_mem;
+		pred->regex->len = len;
+		strncpy(pred->regex->pattern, str + s, len);
+		pred->regex->pattern[len] = 0;
 
 		filter_build_regex(pred);
 
···
 
 		} else if (field->filter_type == FILTER_STATIC_STRING) {
 			pred->fn_num = FILTER_PRED_FN_STRING;
-			pred->regex.field_len = field->size;
+			pred->regex->field_len = field->size;
 
 		} else if (field->filter_type == FILTER_DYN_STRING) {
 			pred->fn_num = FILTER_PRED_FN_STRLOC;
···
 	return i;
 
 err_free:
-	kfree(pred);
+	free_predicate(pred);
 	return -EINVAL;
 err_mem:
-	kfree(pred);
+	free_predicate(pred);
 	return -ENOMEM;
 }
 
···
 		return ret;
 
 	return __ftrace_function_set_filter(pred->op == OP_EQ,
-					    pred->regex.pattern,
-					    pred->regex.len,
+					    pred->regex->pattern,
+					    pred->regex->len,
 					    data);
 }
 

kernel/trace/trace_events_user.c

···
 
 static int user_event_set_print_fmt(struct user_event *user, char *buf, int len)
 {
-	struct ftrace_event_field *field, *next;
+	struct ftrace_event_field *field;
 	struct list_head *head = &user->fields;
 	int pos = 0, depth = 0;
 	const char *str_func;
 
 	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 
-	list_for_each_entry_safe_reverse(field, next, head, link) {
+	list_for_each_entry_reverse(field, head, link) {
 		if (depth != 0)
 			pos += snprintf(buf + pos, LEN_OR_ZERO, " ");
 
···
 
 	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 
-	list_for_each_entry_safe_reverse(field, next, head, link) {
+	list_for_each_entry_reverse(field, head, link) {
 		if (user_field_is_dyn_string(field->type, &str_func))
 			pos += snprintf(buf + pos, LEN_OR_ZERO,
 					", %s(%s)", str_func, field->name);
···
 static int user_event_show(struct seq_file *m, struct dyn_event *ev)
 {
 	struct user_event *user = container_of(ev, struct user_event, devent);
-	struct ftrace_event_field *field, *next;
+	struct ftrace_event_field *field;
 	struct list_head *head;
 	int depth = 0;
 
···
 
 	head = trace_get_fields(&user->call);
 
-	list_for_each_entry_safe_reverse(field, next, head, link) {
+	list_for_each_entry_reverse(field, head, link) {
 		if (depth == 0)
 			seq_puts(m, " ");
 		else
···
 static bool user_fields_match(struct user_event *user, int argc,
 			      const char **argv)
 {
-	struct ftrace_event_field *field, *next;
+	struct ftrace_event_field *field;
 	struct list_head *head = &user->fields;
 	int i = 0;
 
-	list_for_each_entry_safe_reverse(field, next, head, link)
+	list_for_each_entry_reverse(field, head, link) {
 		if (!user_field_match(field, argc, argv, &i))
 			return false;
+	}
 
 	if (i != argc)
 		return false;

kernel/trace/trace_export.c

···
 #undef __array
 #define __array(type, item, size)			type item[size];
 
+#undef __stack_array
+#define __stack_array(type, item, size, field)		__array(type, item, size)
+
 #undef __array_desc
 #define __array_desc(type, container, item, size)	type item[size];
 
···
 	is_signed_type(_type), .filter_type = FILTER_OTHER,			\
 	.len = _len },
 
+#undef __stack_array
+#define __stack_array(_type, _item, _len, _field) __array(_type, _item, _len)
+
 #undef __array_desc
 #define __array_desc(_type, _container, _item, _len) __array(_type, _item, _len)
 
···
 
 #undef __array
 #define __array(type, item, len)
+
+#undef __stack_array
+#define __stack_array(type, item, len, field)
 
 #undef __array_desc
 #define __array_desc(type, container, item, len)

tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_char.tc

···
 esac
 
 : "Test get argument (1)"
-echo "p:testprobe tracefs_create_dir arg1=+0(${ARG1}):char" > kprobe_events
+if grep -q eventfs_add_dir available_filter_functions; then
+  DIR_NAME="eventfs_add_dir"
+else
+  DIR_NAME="tracefs_create_dir"
+fi
+echo "p:testprobe ${DIR_NAME} arg1=+0(${ARG1}):char" > kprobe_events
 echo 1 > events/kprobes/testprobe/enable
 echo "p:test $FUNCTION_FORK" >> kprobe_events
 grep -qe "testprobe.* arg1='t'" trace
 
 echo 0 > events/kprobes/testprobe/enable
 : "Test get argument (2)"
-echo "p:testprobe tracefs_create_dir arg1=+0(${ARG1}):char arg2=+0(${ARG1}):char[4]" > kprobe_events
+echo "p:testprobe ${DIR_NAME} arg1=+0(${ARG1}):char arg2=+0(${ARG1}):char[4]" > kprobe_events
 echo 1 > events/kprobes/testprobe/enable
 echo "p:test $FUNCTION_FORK" >> kprobe_events
 grep -qe "testprobe.* arg1='t' arg2={'t','e','s','t'}" trace

tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_string.tc

···
 esac
 
 : "Test get argument (1)"
-echo "p:testprobe tracefs_create_dir arg1=+0(${ARG1}):string" > kprobe_events
+if grep -q eventfs_add_dir available_filter_functions; then
+  DIR_NAME="eventfs_add_dir"
+else
+  DIR_NAME="tracefs_create_dir"
+fi
+echo "p:testprobe ${DIR_NAME} arg1=+0(${ARG1}):string" > kprobe_events
 echo 1 > events/kprobes/testprobe/enable
 echo "p:test $FUNCTION_FORK" >> kprobe_events
 grep -qe "testprobe.* arg1=\"test\"" trace
 
 echo 0 > events/kprobes/testprobe/enable
 : "Test get argument (2)"
-echo "p:testprobe tracefs_create_dir arg1=+0(${ARG1}):string arg2=+0(${ARG1}):string" > kprobe_events
+echo "p:testprobe ${DIR_NAME} arg1=+0(${ARG1}):string arg2=+0(${ARG1}):string" > kprobe_events
 echo 1 > events/kprobes/testprobe/enable
 echo "p:test $FUNCTION_FORK" >> kprobe_events
 grep -qe "testprobe.* arg1=\"test\" arg2=\"test\"" trace