mirror of
https://github.com/torvalds/linux.git
synced 2024-12-05 02:23:16 +00:00
c0f92ba99b
Impact: add new debugfs API With ftrace, some tracers are registered in early initcalls and attempt to create files on the debugfs filesystem. Depending on when they are activated, they can try to create their file at any time. Some checks can be done on the tracing area but providing a helper to know if debugfs is registered make it really more easy. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <1237759847-21025-2-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
542 lines
15 KiB
C
542 lines
15 KiB
C
/*
|
|
* file.c - part of debugfs, 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/kernel-api for more details.
|
|
*
|
|
*/
|
|
|
|
/* uncomment to get debug messages from the debug filesystem, ah the irony. */
|
|
/* #define DEBUG */
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/init.h>
|
|
#include <linux/kobject.h>
|
|
#include <linux/namei.h>
|
|
#include <linux/debugfs.h>
|
|
#include <linux/fsnotify.h>
|
|
#include <linux/string.h>
|
|
#include <linux/magic.h>
|
|
|
|
static struct vfsmount *debugfs_mount;
|
|
static int debugfs_mount_count;
|
|
static bool debugfs_registered;
|
|
|
|
static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev)
|
|
{
|
|
struct inode *inode = new_inode(sb);
|
|
|
|
if (inode) {
|
|
inode->i_mode = mode;
|
|
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
|
|
switch (mode & S_IFMT) {
|
|
default:
|
|
init_special_inode(inode, mode, dev);
|
|
break;
|
|
case S_IFREG:
|
|
inode->i_fop = &debugfs_file_operations;
|
|
break;
|
|
case S_IFLNK:
|
|
inode->i_op = &debugfs_link_operations;
|
|
break;
|
|
case S_IFDIR:
|
|
inode->i_op = &simple_dir_inode_operations;
|
|
inode->i_fop = &simple_dir_operations;
|
|
|
|
/* directory inodes start off with i_nlink == 2
|
|
* (for "." entry) */
|
|
inc_nlink(inode);
|
|
break;
|
|
}
|
|
}
|
|
return inode;
|
|
}
|
|
|
|
/* SMP-safe */
|
|
static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
|
|
int mode, dev_t dev)
|
|
{
|
|
struct inode *inode;
|
|
int error = -EPERM;
|
|
|
|
if (dentry->d_inode)
|
|
return -EEXIST;
|
|
|
|
inode = debugfs_get_inode(dir->i_sb, mode, dev);
|
|
if (inode) {
|
|
d_instantiate(dentry, inode);
|
|
dget(dentry);
|
|
error = 0;
|
|
}
|
|
return error;
|
|
}
|
|
|
|
static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
|
|
{
|
|
int res;
|
|
|
|
mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
|
|
res = debugfs_mknod(dir, dentry, mode, 0);
|
|
if (!res) {
|
|
inc_nlink(dir);
|
|
fsnotify_mkdir(dir, dentry);
|
|
}
|
|
return res;
|
|
}
|
|
|
|
static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode)
|
|
{
|
|
mode = (mode & S_IALLUGO) | S_IFLNK;
|
|
return debugfs_mknod(dir, dentry, mode, 0);
|
|
}
|
|
|
|
static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode)
|
|
{
|
|
int res;
|
|
|
|
mode = (mode & S_IALLUGO) | S_IFREG;
|
|
res = debugfs_mknod(dir, dentry, mode, 0);
|
|
if (!res)
|
|
fsnotify_create(dir, dentry);
|
|
return res;
|
|
}
|
|
|
|
static inline int debugfs_positive(struct dentry *dentry)
|
|
{
|
|
return dentry->d_inode && !d_unhashed(dentry);
|
|
}
|
|
|
|
static int debug_fill_super(struct super_block *sb, void *data, int silent)
|
|
{
|
|
static struct tree_descr debug_files[] = {{""}};
|
|
|
|
return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
|
|
}
|
|
|
|
static int debug_get_sb(struct file_system_type *fs_type,
|
|
int flags, const char *dev_name,
|
|
void *data, struct vfsmount *mnt)
|
|
{
|
|
return get_sb_single(fs_type, flags, data, debug_fill_super, mnt);
|
|
}
|
|
|
|
static struct file_system_type debug_fs_type = {
|
|
.owner = THIS_MODULE,
|
|
.name = "debugfs",
|
|
.get_sb = debug_get_sb,
|
|
.kill_sb = kill_litter_super,
|
|
};
|
|
|
|
static int debugfs_create_by_name(const char *name, mode_t mode,
|
|
struct dentry *parent,
|
|
struct dentry **dentry)
|
|
{
|
|
int error = 0;
|
|
|
|
/* 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) {
|
|
if (debugfs_mount && debugfs_mount->mnt_sb) {
|
|
parent = debugfs_mount->mnt_sb->s_root;
|
|
}
|
|
}
|
|
if (!parent) {
|
|
pr_debug("debugfs: Ah! can not find a parent!\n");
|
|
return -EFAULT;
|
|
}
|
|
|
|
*dentry = NULL;
|
|
mutex_lock(&parent->d_inode->i_mutex);
|
|
*dentry = lookup_one_len(name, parent, strlen(name));
|
|
if (!IS_ERR(*dentry)) {
|
|
switch (mode & S_IFMT) {
|
|
case S_IFDIR:
|
|
error = debugfs_mkdir(parent->d_inode, *dentry, mode);
|
|
break;
|
|
case S_IFLNK:
|
|
error = debugfs_link(parent->d_inode, *dentry, mode);
|
|
break;
|
|
default:
|
|
error = debugfs_create(parent->d_inode, *dentry, mode);
|
|
break;
|
|
}
|
|
dput(*dentry);
|
|
} else
|
|
error = PTR_ERR(*dentry);
|
|
mutex_unlock(&parent->d_inode->i_mutex);
|
|
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* debugfs_create_file - create a file in the debugfs filesystem
|
|
* @name: a pointer to a string containing the name of the file to create.
|
|
* @mode: the permission that the file should have
|
|
* @parent: a pointer to the parent dentry for this file. This should be a
|
|
* directory dentry if set. If this paramater is NULL, then the
|
|
* file will be created in the root of the debugfs filesystem.
|
|
* @data: a pointer to 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.
|
|
* @fops: a pointer to a struct file_operations that should be used for
|
|
* this file.
|
|
*
|
|
* This is the basic "create a file" function for debugfs. It allows for a
|
|
* wide range of flexibility in createing a file, or a directory (if you
|
|
* want to create a directory, the debugfs_create_dir() function is
|
|
* recommended to be used instead.)
|
|
*
|
|
* This function will return a pointer to a dentry if it succeeds. This
|
|
* pointer must be passed to the debugfs_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 debugfs is not enabled in the kernel, the value -%ENODEV will be
|
|
* returned.
|
|
*/
|
|
struct dentry *debugfs_create_file(const char *name, mode_t mode,
|
|
struct dentry *parent, void *data,
|
|
const struct file_operations *fops)
|
|
{
|
|
struct dentry *dentry = NULL;
|
|
int error;
|
|
|
|
pr_debug("debugfs: creating file '%s'\n",name);
|
|
|
|
error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
|
|
&debugfs_mount_count);
|
|
if (error)
|
|
goto exit;
|
|
|
|
error = debugfs_create_by_name(name, mode, parent, &dentry);
|
|
if (error) {
|
|
dentry = NULL;
|
|
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
|
|
goto exit;
|
|
}
|
|
|
|
if (dentry->d_inode) {
|
|
if (data)
|
|
dentry->d_inode->i_private = data;
|
|
if (fops)
|
|
dentry->d_inode->i_fop = fops;
|
|
}
|
|
exit:
|
|
return dentry;
|
|
}
|
|
EXPORT_SYMBOL_GPL(debugfs_create_file);
|
|
|
|
/**
|
|
* debugfs_create_dir - create a directory in the debugfs filesystem
|
|
* @name: a pointer to a string containing the name of the directory to
|
|
* create.
|
|
* @parent: a pointer to the parent dentry for this file. This should be a
|
|
* directory dentry if set. If this paramater is NULL, then the
|
|
* directory will be created in the root of the debugfs filesystem.
|
|
*
|
|
* This function creates a directory in debugfs with the given name.
|
|
*
|
|
* This function will return a pointer to a dentry if it succeeds. This
|
|
* pointer must be passed to the debugfs_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 debugfs is not enabled in the kernel, the value -%ENODEV will be
|
|
* returned.
|
|
*/
|
|
struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
|
|
{
|
|
return debugfs_create_file(name,
|
|
S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
|
|
parent, NULL, NULL);
|
|
}
|
|
EXPORT_SYMBOL_GPL(debugfs_create_dir);
|
|
|
|
/**
|
|
* debugfs_create_symlink- create a symbolic link in the debugfs filesystem
|
|
* @name: a pointer to a string containing the name of the symbolic link to
|
|
* create.
|
|
* @parent: a pointer to the parent dentry for this symbolic link. This
|
|
* should be a directory dentry if set. If this paramater is NULL,
|
|
* then the symbolic link will be created in the root of the debugfs
|
|
* filesystem.
|
|
* @target: a pointer to a string containing the path to the target of the
|
|
* symbolic link.
|
|
*
|
|
* This function creates a symbolic link with the given name in debugfs that
|
|
* links to the given target path.
|
|
*
|
|
* This function will return a pointer to a dentry if it succeeds. This
|
|
* pointer must be passed to the debugfs_remove() function when the symbolic
|
|
* link 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 debugfs is not enabled in the kernel, the value -%ENODEV will be
|
|
* returned.
|
|
*/
|
|
struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
|
|
const char *target)
|
|
{
|
|
struct dentry *result;
|
|
char *link;
|
|
|
|
link = kstrdup(target, GFP_KERNEL);
|
|
if (!link)
|
|
return NULL;
|
|
|
|
result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link,
|
|
NULL);
|
|
if (!result)
|
|
kfree(link);
|
|
return result;
|
|
}
|
|
EXPORT_SYMBOL_GPL(debugfs_create_symlink);
|
|
|
|
static void __debugfs_remove(struct dentry *dentry, struct dentry *parent)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (debugfs_positive(dentry)) {
|
|
if (dentry->d_inode) {
|
|
dget(dentry);
|
|
switch (dentry->d_inode->i_mode & S_IFMT) {
|
|
case S_IFDIR:
|
|
ret = simple_rmdir(parent->d_inode, dentry);
|
|
break;
|
|
case S_IFLNK:
|
|
kfree(dentry->d_inode->i_private);
|
|
/* fall through */
|
|
default:
|
|
simple_unlink(parent->d_inode, dentry);
|
|
break;
|
|
}
|
|
if (!ret)
|
|
d_delete(dentry);
|
|
dput(dentry);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* debugfs_remove - removes a file or directory from the debugfs filesystem
|
|
* @dentry: a pointer to a the dentry of the file or directory to be
|
|
* removed.
|
|
*
|
|
* This function removes a file or directory in debugfs that was previously
|
|
* created with a call to another debugfs function (like
|
|
* debugfs_create_file() or variants thereof.)
|
|
*
|
|
* This function is required to be called in order for the file to be
|
|
* removed, no automatic cleanup of files will happen when a module is
|
|
* removed, you are responsible here.
|
|
*/
|
|
void debugfs_remove(struct dentry *dentry)
|
|
{
|
|
struct dentry *parent;
|
|
|
|
if (!dentry)
|
|
return;
|
|
|
|
parent = dentry->d_parent;
|
|
if (!parent || !parent->d_inode)
|
|
return;
|
|
|
|
mutex_lock(&parent->d_inode->i_mutex);
|
|
__debugfs_remove(dentry, parent);
|
|
mutex_unlock(&parent->d_inode->i_mutex);
|
|
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
|
|
}
|
|
EXPORT_SYMBOL_GPL(debugfs_remove);
|
|
|
|
/**
|
|
* debugfs_remove_recursive - recursively removes a directory
|
|
* @dentry: a pointer to a the dentry of the directory to be removed.
|
|
*
|
|
* This function recursively removes a directory tree in debugfs that
|
|
* was previously created with a call to another debugfs function
|
|
* (like debugfs_create_file() or variants thereof.)
|
|
*
|
|
* This function is required to be called in order for the file to be
|
|
* removed, no automatic cleanup of files will happen when a module is
|
|
* removed, you are responsible here.
|
|
*/
|
|
void debugfs_remove_recursive(struct dentry *dentry)
|
|
{
|
|
struct dentry *child;
|
|
struct dentry *parent;
|
|
|
|
if (!dentry)
|
|
return;
|
|
|
|
parent = dentry->d_parent;
|
|
if (!parent || !parent->d_inode)
|
|
return;
|
|
|
|
parent = dentry;
|
|
mutex_lock(&parent->d_inode->i_mutex);
|
|
|
|
while (1) {
|
|
/*
|
|
* When all dentries under "parent" has been removed,
|
|
* walk up the tree until we reach our starting point.
|
|
*/
|
|
if (list_empty(&parent->d_subdirs)) {
|
|
mutex_unlock(&parent->d_inode->i_mutex);
|
|
if (parent == dentry)
|
|
break;
|
|
parent = parent->d_parent;
|
|
mutex_lock(&parent->d_inode->i_mutex);
|
|
}
|
|
child = list_entry(parent->d_subdirs.next, struct dentry,
|
|
d_u.d_child);
|
|
|
|
/*
|
|
* If "child" isn't empty, walk down the tree and
|
|
* remove all its descendants first.
|
|
*/
|
|
if (!list_empty(&child->d_subdirs)) {
|
|
mutex_unlock(&parent->d_inode->i_mutex);
|
|
parent = child;
|
|
mutex_lock(&parent->d_inode->i_mutex);
|
|
continue;
|
|
}
|
|
__debugfs_remove(child, parent);
|
|
if (parent->d_subdirs.next == &child->d_u.d_child) {
|
|
/*
|
|
* Avoid infinite loop if we fail to remove
|
|
* one dentry.
|
|
*/
|
|
mutex_unlock(&parent->d_inode->i_mutex);
|
|
break;
|
|
}
|
|
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
|
|
}
|
|
|
|
parent = dentry->d_parent;
|
|
mutex_lock(&parent->d_inode->i_mutex);
|
|
__debugfs_remove(dentry, parent);
|
|
mutex_unlock(&parent->d_inode->i_mutex);
|
|
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
|
|
}
|
|
EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
|
|
|
|
/**
|
|
* debugfs_rename - rename a file/directory in the debugfs filesystem
|
|
* @old_dir: a pointer to the parent dentry for the renamed object. This
|
|
* should be a directory dentry.
|
|
* @old_dentry: dentry of an object to be renamed.
|
|
* @new_dir: a pointer to the parent dentry where the object should be
|
|
* moved. This should be a directory dentry.
|
|
* @new_name: a pointer to a string containing the target name.
|
|
*
|
|
* This function renames a file/directory in debugfs. The target must not
|
|
* exist for rename to succeed.
|
|
*
|
|
* This function will return a pointer to old_dentry (which is updated to
|
|
* reflect renaming) if it succeeds. If an error occurs, %NULL will be
|
|
* returned.
|
|
*
|
|
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
|
|
* returned.
|
|
*/
|
|
struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
|
|
struct dentry *new_dir, const char *new_name)
|
|
{
|
|
int error;
|
|
struct dentry *dentry = NULL, *trap;
|
|
const char *old_name;
|
|
|
|
trap = lock_rename(new_dir, old_dir);
|
|
/* Source or destination directories don't exist? */
|
|
if (!old_dir->d_inode || !new_dir->d_inode)
|
|
goto exit;
|
|
/* Source does not exist, cyclic rename, or mountpoint? */
|
|
if (!old_dentry->d_inode || old_dentry == trap ||
|
|
d_mountpoint(old_dentry))
|
|
goto exit;
|
|
dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
|
|
/* Lookup failed, cyclic rename or target exists? */
|
|
if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
|
|
goto exit;
|
|
|
|
old_name = fsnotify_oldname_init(old_dentry->d_name.name);
|
|
|
|
error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
|
|
dentry);
|
|
if (error) {
|
|
fsnotify_oldname_free(old_name);
|
|
goto exit;
|
|
}
|
|
d_move(old_dentry, dentry);
|
|
fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
|
|
old_dentry->d_name.name, S_ISDIR(old_dentry->d_inode->i_mode),
|
|
NULL, old_dentry);
|
|
fsnotify_oldname_free(old_name);
|
|
unlock_rename(new_dir, old_dir);
|
|
dput(dentry);
|
|
return old_dentry;
|
|
exit:
|
|
if (dentry && !IS_ERR(dentry))
|
|
dput(dentry);
|
|
unlock_rename(new_dir, old_dir);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(debugfs_rename);
|
|
|
|
/**
|
|
* debugfs_initialized - Tells whether debugfs has been registered
|
|
*/
|
|
bool debugfs_initialized(void)
|
|
{
|
|
return debugfs_registered;
|
|
}
|
|
EXPORT_SYMBOL_GPL(debugfs_initialized);
|
|
|
|
|
|
static struct kobject *debug_kobj;
|
|
|
|
static int __init debugfs_init(void)
|
|
{
|
|
int retval;
|
|
|
|
debug_kobj = kobject_create_and_add("debug", kernel_kobj);
|
|
if (!debug_kobj)
|
|
return -EINVAL;
|
|
|
|
retval = register_filesystem(&debug_fs_type);
|
|
if (retval)
|
|
kobject_put(debug_kobj);
|
|
else
|
|
debugfs_registered = true;
|
|
|
|
return retval;
|
|
}
|
|
|
|
static void __exit debugfs_exit(void)
|
|
{
|
|
debugfs_registered = false;
|
|
|
|
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
|
|
unregister_filesystem(&debug_fs_type);
|
|
kobject_put(debug_kobj);
|
|
}
|
|
|
|
core_initcall(debugfs_init);
|
|
module_exit(debugfs_exit);
|
|
MODULE_LICENSE("GPL");
|
|
|