| 1 |
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| 2 | |
| 3 | * tracefs.h - a pseudo file system for activating tracing
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| 4 | *
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| 5 | * Based on debugfs by: 2004 Greg Kroah-Hartman <[email protected]>
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| 6 | *
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| 7 | * Copyright (C) 2014 Red Hat Inc, author: Steven Rostedt <[email protected]>
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| 8 | *
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| 9 | * tracefs is the file system that is used by the tracing infrastructure.
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| 10 |
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| 11 |
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| 12 | #ifndef _TRACEFS_H_
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| 13 | #define _TRACEFS_H_
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| 14 |
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| 15 | #include <linux/fs.h>
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| 16 | #include <linux/seq_file.h>
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| 17 |
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| 18 | #include <linux/types.h>
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| 19 |
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| 20 | struct file_operations;
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| 21 |
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| 22 | #ifdef CONFIG_TRACING
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| 23 |
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| 24 | struct eventfs_file;
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| 25 |
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| 26 | |
| 27 | * eventfs_callback - A callback function to create dynamic files in eventfs
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| 28 | * @name: The name of the file that is to be created
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| 29 | * @mode: return the file mode for the file (RW access, etc)
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| 30 | * @data: data to pass to the created file ops
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| 31 | * @fops: the file operations of the created file
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| 32 | *
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| 33 | * The evetnfs files are dynamically created. The struct eventfs_entry array
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| 34 | * is passed to eventfs_create_dir() or eventfs_create_events_dir() that will
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| 35 | * be used to create the files within those directories. When a lookup
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| 36 | * or access to a file within the directory is made, the struct eventfs_entry
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| 37 | * array is used to find a callback() with the matching name that is being
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| 38 | * referenced (for lookups, the entire array is iterated and each callback
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| 39 | * will be called).
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| 40 | *
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| 41 | * The callback will be called with @name for the name of the file to create.
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| 42 | * The callback can return less than 1 to indicate that no file should be
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| 43 | * created.
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| 44 | *
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| 45 | * If a file is to be created, then @mode should be populated with the file
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| 46 | * mode (permissions) for which the file is created for. This would be
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| 47 | * used to set the created inode i_mode field.
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| 48 | *
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| 49 | * The @data should be set to the data passed to the other file operations
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| 50 | * (read, write, etc). Note, @data will also point to the data passed in
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| 51 | * to eventfs_create_dir() or eventfs_create_events_dir(), but the callback
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| 52 | * can replace the data if it chooses to. Otherwise, the original data
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| 53 | * will be used for the file operation functions.
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| 54 | *
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| 55 | * The @fops should be set to the file operations that will be used to create
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| 56 | * the inode.
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| 57 | *
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| 58 | * NB. This callback is called while holding internal locks of the eventfs
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| 59 | * system. The callback must not call any code that might also call into
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| 60 | * the tracefs or eventfs system or it will risk creating a deadlock.
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| 61 |
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| 62 | typedef int (*eventfs_callback)(const char *name, umode_t *mode, void **data,
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| 63 | const struct file_operations **fops);
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| 64 |
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| 65 | typedef void (*eventfs_release)(const char *name, void *data);
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| 66 |
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| 67 | |
| 68 | * struct eventfs_entry - dynamically created eventfs file call back handler
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| 69 | * @name: Then name of the dynamic file in an eventfs directory
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| 70 | * @callback: The callback to get the fops of the file when it is created
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| 71 | *
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| 72 | * See evenfs_callback() typedef for how to set up @callback.
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| 73 |
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| 74 | struct eventfs_entry {
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| 75 | const char *name;
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| 76 | eventfs_callback callback;
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| 77 | eventfs_release release;
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| 78 | };
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| 79 |
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| 80 | struct eventfs_inode;
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| 81 |
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| 82 | struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry *parent,
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| 83 | const struct eventfs_entry *entries,
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| 84 | int size, void *data);
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| 85 |
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| 86 | struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode *parent,
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| 87 | const struct eventfs_entry *entries,
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| 88 | int size, void *data);
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| 89 |
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| 90 | void eventfs_remove_events_dir(struct eventfs_inode *ei);
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| 91 | void eventfs_remove_dir(struct eventfs_inode *ei);
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| 92 |
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| 93 | struct dentry *tracefs_create_file(const char *name, umode_t mode,
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| 94 | struct dentry *parent, void *data,
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| 95 | const struct file_operations *fops);
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| 96 |
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| 97 | struct dentry *tracefs_create_dir(const char *name, struct dentry *parent);
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| 98 |
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| 99 | void tracefs_remove(struct dentry *dentry);
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| 100 |
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| 101 | struct dentry *tracefs_create_instance_dir(const char *name, struct dentry *parent,
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| 102 | int (*mkdir)(const char *name),
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| 103 | int (*rmdir)(const char *name));
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| 104 |
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| 105 | bool tracefs_initialized(void);
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| 106 |
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| 107 | #endif
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| 108 |
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| 109 | #endif
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