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linux-next/include/linux/debugfs.h
Nicolai Stange c646880814 debugfs: add support for self-protecting attribute file fops 
In order to protect them against file removal issues, debugfs_create_file()
creates a lifetime managing proxy around each struct file_operations
handed in.

In cases where this struct file_operations is able to manage file lifetime
by itself already, the proxy created by debugfs is a waste of resources.

The most common class of struct file_operations given to debugfs are those
defined by means of the DEFINE_SIMPLE_ATTRIBUTE() macro.

Introduce a DEFINE_DEBUGFS_ATTRIBUTE() macro to allow any
struct file_operations of this class to be easily made file lifetime aware
and thus, to be operated unproxied.

Specifically, introduce debugfs_attr_read() and debugfs_attr_write()
which wrap simple_attr_read() and simple_attr_write() under the protection
of a debugfs_use_file_start()/debugfs_use_file_finish() pair.

Make DEFINE_DEBUGFS_ATTRIBUTE() set the defined struct file_operations'
->read() and ->write() members to these wrappers.

Export debugfs_create_file_unsafe() in order to allow debugfs users to
create their files in non-proxying operation mode.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-04-12 14:14:21 -07:00

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/*
* debugfs.h - a tiny little debug file system
*
* Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
* Copyright (C) 2004 IBM Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* debugfs is for people to use instead of /proc or /sys.
* See Documentation/DocBook/filesystems for more details.
*/
#ifndef _DEBUGFS_H_
#define _DEBUGFS_H_
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/types.h>
#include <linux/compiler.h>
struct device;
struct file_operations;
struct srcu_struct;
struct debugfs_blob_wrapper {
void *data;
unsigned long size;
};
struct debugfs_reg32 {
char *name;
unsigned long offset;
};
struct debugfs_regset32 {
const struct debugfs_reg32 *regs;
int nregs;
void __iomem *base;
};
extern struct dentry *arch_debugfs_dir;
extern struct srcu_struct debugfs_srcu;
#if defined(CONFIG_DEBUG_FS)
struct dentry *debugfs_create_file(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops);
struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops);
struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops,
loff_t file_size);
struct dentry *debugfs_create_dir(const char *name, struct dentry *parent);
struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
const char *dest);
struct dentry *debugfs_create_automount(const char *name,
struct dentry *parent,
struct vfsmount *(*f)(void *),
void *data);
void debugfs_remove(struct dentry *dentry);
void debugfs_remove_recursive(struct dentry *dentry);
int debugfs_use_file_start(const struct dentry *dentry, int *srcu_idx)
__acquires(&debugfs_srcu);
void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu);
ssize_t debugfs_attr_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos);
ssize_t debugfs_attr_write(struct file *file, const char __user *buf,
size_t len, loff_t *ppos);
#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \
static int __fops ## _open(struct inode *inode, struct file *file) \
{ \
__simple_attr_check_format(__fmt, 0ull); \
return simple_attr_open(inode, file, __get, __set, __fmt); \
} \
static const struct file_operations __fops = { \
.owner = THIS_MODULE, \
.open = __fops ## _open, \
.release = simple_attr_release, \
.read = debugfs_attr_read, \
.write = debugfs_attr_write, \
.llseek = generic_file_llseek, \
}
struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
struct dentry *new_dir, const char *new_name);
struct dentry *debugfs_create_u8(const char *name, umode_t mode,
struct dentry *parent, u8 *value);
struct dentry *debugfs_create_u16(const char *name, umode_t mode,
struct dentry *parent, u16 *value);
struct dentry *debugfs_create_u32(const char *name, umode_t mode,
struct dentry *parent, u32 *value);
struct dentry *debugfs_create_u64(const char *name, umode_t mode,
struct dentry *parent, u64 *value);
struct dentry *debugfs_create_ulong(const char *name, umode_t mode,
struct dentry *parent, unsigned long *value);
struct dentry *debugfs_create_x8(const char *name, umode_t mode,
struct dentry *parent, u8 *value);
struct dentry *debugfs_create_x16(const char *name, umode_t mode,
struct dentry *parent, u16 *value);
struct dentry *debugfs_create_x32(const char *name, umode_t mode,
struct dentry *parent, u32 *value);
struct dentry *debugfs_create_x64(const char *name, umode_t mode,
struct dentry *parent, u64 *value);
struct dentry *debugfs_create_size_t(const char *name, umode_t mode,
struct dentry *parent, size_t *value);
struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode,
struct dentry *parent, atomic_t *value);
struct dentry *debugfs_create_bool(const char *name, umode_t mode,
struct dentry *parent, bool *value);
struct dentry *debugfs_create_blob(const char *name, umode_t mode,
struct dentry *parent,
struct debugfs_blob_wrapper *blob);
struct dentry *debugfs_create_regset32(const char *name, umode_t mode,
struct dentry *parent,
struct debugfs_regset32 *regset);
void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
int nregs, void __iomem *base, char *prefix);
struct dentry *debugfs_create_u32_array(const char *name, umode_t mode,
struct dentry *parent,
u32 *array, u32 elements);
struct dentry *debugfs_create_devm_seqfile(struct device *dev, const char *name,
struct dentry *parent,
int (*read_fn)(struct seq_file *s,
void *data));
bool debugfs_initialized(void);
ssize_t debugfs_read_file_bool(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos);
ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf,
size_t count, loff_t *ppos);
#else
#include <linux/err.h>
/*
* We do not return NULL from these functions if CONFIG_DEBUG_FS is not enabled
* so users have a chance to detect if there was a real error or not. We don't
* want to duplicate the design decision mistakes of procfs and devfs again.
*/
static inline struct dentry *debugfs_create_file(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops,
loff_t file_size)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_dir(const char *name,
struct dentry *parent)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_symlink(const char *name,
struct dentry *parent,
const char *dest)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_automount(const char *name,
struct dentry *parent,
struct vfsmount *(*f)(void *),
void *data)
{
return ERR_PTR(-ENODEV);
}
static inline void debugfs_remove(struct dentry *dentry)
{ }
static inline void debugfs_remove_recursive(struct dentry *dentry)
{ }
static inline int debugfs_use_file_start(const struct dentry *dentry,
int *srcu_idx)
__acquires(&debugfs_srcu)
{
return 0;
}
static inline void debugfs_use_file_finish(int srcu_idx)
__releases(&debugfs_srcu)
{ }
#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \
static const struct file_operations __fops = { 0 }
static inline struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
struct dentry *new_dir, char *new_name)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_u8(const char *name, umode_t mode,
struct dentry *parent,
u8 *value)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_u16(const char *name, umode_t mode,
struct dentry *parent,
u16 *value)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_u32(const char *name, umode_t mode,
struct dentry *parent,
u32 *value)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_u64(const char *name, umode_t mode,
struct dentry *parent,
u64 *value)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_x8(const char *name, umode_t mode,
struct dentry *parent,
u8 *value)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_x16(const char *name, umode_t mode,
struct dentry *parent,
u16 *value)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_x32(const char *name, umode_t mode,
struct dentry *parent,
u32 *value)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_x64(const char *name, umode_t mode,
struct dentry *parent,
u64 *value)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_size_t(const char *name, umode_t mode,
struct dentry *parent,
size_t *value)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode,
struct dentry *parent, atomic_t *value)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_bool(const char *name, umode_t mode,
struct dentry *parent,
bool *value)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_blob(const char *name, umode_t mode,
struct dentry *parent,
struct debugfs_blob_wrapper *blob)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_regset32(const char *name,
umode_t mode, struct dentry *parent,
struct debugfs_regset32 *regset)
{
return ERR_PTR(-ENODEV);
}
static inline void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
int nregs, void __iomem *base, char *prefix)
{
}
static inline bool debugfs_initialized(void)
{
return false;
}
static inline struct dentry *debugfs_create_u32_array(const char *name, umode_t mode,
struct dentry *parent,
u32 *array, u32 elements)
{
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_devm_seqfile(struct device *dev,
const char *name,
struct dentry *parent,
int (*read_fn)(struct seq_file *s,
void *data))
{
return ERR_PTR(-ENODEV);
}
static inline ssize_t debugfs_read_file_bool(struct file *file,
char __user *user_buf,
size_t count, loff_t *ppos)
{
return -ENODEV;
}
static inline ssize_t debugfs_write_file_bool(struct file *file,
const char __user *user_buf,
size_t count, loff_t *ppos)
{
return -ENODEV;
}
#endif
#endif
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