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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* tracefs.h - a pseudo file system for activating tracing
*
* Based on debugfs by: 2004 Greg Kroah-Hartman <greg@kroah.com>
*
* Copyright (C) 2014 Red Hat Inc, author: Steven Rostedt <srostedt@redhat.com>
*
* tracefs is the file system that is used by the tracing infrastructure.
*/
#ifndef _TRACEFS_H_
#define _TRACEFS_H_
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/types.h>
struct file_operations;
#ifdef CONFIG_TRACING
struct eventfs_file;
/**
* eventfs_callback - A callback function to create dynamic files in eventfs
* @name: The name of the file that is to be created
* @mode: return the file mode for the file (RW access, etc)
* @data: data to pass to the created file ops
* @fops: the file operations of the created file
*
* The evetnfs files are dynamically created. The struct eventfs_entry array
* is passed to eventfs_create_dir() or eventfs_create_events_dir() that will
* be used to create the files within those directories. When a lookup
* or access to a file within the directory is made, the struct eventfs_entry
* array is used to find a callback() with the matching name that is being
* referenced (for lookups, the entire array is iterated and each callback
* will be called).
*
* The callback will be called with @name for the name of the file to create.
* The callback can return less than 1 to indicate that no file should be
* created.
*
* If a file is to be created, then @mode should be populated with the file
* mode (permissions) for which the file is created for. This would be
* used to set the created inode i_mode field.
*
* The @data should be set to the data passed to the other file operations
* (read, write, etc). Note, @data will also point to the data passed in
* to eventfs_create_dir() or eventfs_create_events_dir(), but the callback
* can replace the data if it chooses to. Otherwise, the original data
* will be used for the file operation functions.
*
* The @fops should be set to the file operations that will be used to create
* the inode.
*
* NB. This callback is called while holding internal locks of the eventfs
* system. The callback must not call any code that might also call into
* the tracefs or eventfs system or it will risk creating a deadlock.
*/
typedef int (*eventfs_callback)(const char *name, umode_t *mode, void **data,
const struct file_operations **fops);
/**
* struct eventfs_entry - dynamically created eventfs file call back handler
* @name: Then name of the dynamic file in an eventfs directory
* @callback: The callback to get the fops of the file when it is created
*
* See evenfs_callback() typedef for how to set up @callback.
*/
struct eventfs_entry {
const char *name;
eventfs_callback callback;
};
struct eventfs_inode;
struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry *parent,
const struct eventfs_entry *entries,
int size, void *data);
struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode *parent,
const struct eventfs_entry *entries,
int size, void *data);
void eventfs_remove_events_dir(struct eventfs_inode *ei);
void eventfs_remove_dir(struct eventfs_inode *ei);
struct dentry *tracefs_create_file(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops);
struct dentry *tracefs_create_dir(const char *name, struct dentry *parent);
void tracefs_remove(struct dentry *dentry);
struct dentry *tracefs_create_instance_dir(const char *name, struct dentry *parent,
int (*mkdir)(const char *name),
int (*rmdir)(const char *name));
bool tracefs_initialized(void);
#endif /* CONFIG_TRACING */
#endif
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