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