![Greg Kroah-Hartman](/assets/img/avatar_default.png)
We need to work on cleaning up the relationship between kobjects, ksets and ktypes. The removal of 'struct subsystem' is the first step of this, especially as it is not really needed at all. Thanks to Kay for fixing the bugs in this patch. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
399 lines
11 KiB
C
399 lines
11 KiB
C
/*
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* file.c - part of debugfs, a tiny little debug file system
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*
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* Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
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* Copyright (C) 2004 IBM Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version
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* 2 as published by the Free Software Foundation.
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*
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* debugfs is for people to use instead of /proc or /sys.
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* See Documentation/DocBook/kernel-api for more details.
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*
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*/
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/* uncomment to get debug messages from the debug filesystem, ah the irony. */
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/* #define DEBUG */
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/pagemap.h>
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#include <linux/init.h>
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#include <linux/kobject.h>
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#include <linux/namei.h>
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#include <linux/debugfs.h>
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#include <linux/fsnotify.h>
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#include <linux/string.h>
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#define DEBUGFS_MAGIC 0x64626720
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/* declared over in file.c */
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extern struct file_operations debugfs_file_operations;
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extern struct inode_operations debugfs_link_operations;
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static struct vfsmount *debugfs_mount;
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static int debugfs_mount_count;
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static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev)
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{
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struct inode *inode = new_inode(sb);
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if (inode) {
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inode->i_mode = mode;
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inode->i_uid = 0;
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inode->i_gid = 0;
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inode->i_blocks = 0;
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inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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switch (mode & S_IFMT) {
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default:
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init_special_inode(inode, mode, dev);
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break;
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case S_IFREG:
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inode->i_fop = &debugfs_file_operations;
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break;
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case S_IFLNK:
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inode->i_op = &debugfs_link_operations;
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break;
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case S_IFDIR:
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inode->i_op = &simple_dir_inode_operations;
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inode->i_fop = &simple_dir_operations;
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/* directory inodes start off with i_nlink == 2
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* (for "." entry) */
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inc_nlink(inode);
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break;
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}
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}
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return inode;
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}
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/* SMP-safe */
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static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
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int mode, dev_t dev)
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{
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struct inode *inode;
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int error = -EPERM;
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if (dentry->d_inode)
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return -EEXIST;
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inode = debugfs_get_inode(dir->i_sb, mode, dev);
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if (inode) {
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d_instantiate(dentry, inode);
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dget(dentry);
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error = 0;
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}
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return error;
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}
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static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
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{
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int res;
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mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
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res = debugfs_mknod(dir, dentry, mode, 0);
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if (!res) {
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inc_nlink(dir);
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fsnotify_mkdir(dir, dentry);
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}
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return res;
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}
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static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode)
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{
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mode = (mode & S_IALLUGO) | S_IFLNK;
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return debugfs_mknod(dir, dentry, mode, 0);
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}
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static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode)
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{
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int res;
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mode = (mode & S_IALLUGO) | S_IFREG;
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res = debugfs_mknod(dir, dentry, mode, 0);
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if (!res)
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fsnotify_create(dir, dentry);
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return res;
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}
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static inline int debugfs_positive(struct dentry *dentry)
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{
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return dentry->d_inode && !d_unhashed(dentry);
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}
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static int debug_fill_super(struct super_block *sb, void *data, int silent)
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{
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static struct tree_descr debug_files[] = {{""}};
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return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
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}
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static int debug_get_sb(struct file_system_type *fs_type,
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int flags, const char *dev_name,
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void *data, struct vfsmount *mnt)
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{
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return get_sb_single(fs_type, flags, data, debug_fill_super, mnt);
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}
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static struct file_system_type debug_fs_type = {
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.owner = THIS_MODULE,
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.name = "debugfs",
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.get_sb = debug_get_sb,
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.kill_sb = kill_litter_super,
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};
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static int debugfs_create_by_name(const char *name, mode_t mode,
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struct dentry *parent,
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struct dentry **dentry)
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{
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int error = 0;
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/* If the parent is not specified, we create it in the root.
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* We need the root dentry to do this, which is in the super
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* block. A pointer to that is in the struct vfsmount that we
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* have around.
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*/
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if (!parent) {
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if (debugfs_mount && debugfs_mount->mnt_sb) {
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parent = debugfs_mount->mnt_sb->s_root;
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}
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}
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if (!parent) {
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pr_debug("debugfs: Ah! can not find a parent!\n");
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return -EFAULT;
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}
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*dentry = NULL;
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mutex_lock(&parent->d_inode->i_mutex);
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*dentry = lookup_one_len(name, parent, strlen(name));
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if (!IS_ERR(*dentry)) {
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switch (mode & S_IFMT) {
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case S_IFDIR:
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error = debugfs_mkdir(parent->d_inode, *dentry, mode);
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break;
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case S_IFLNK:
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error = debugfs_link(parent->d_inode, *dentry, mode);
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break;
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default:
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error = debugfs_create(parent->d_inode, *dentry, mode);
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break;
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}
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dput(*dentry);
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} else
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error = PTR_ERR(*dentry);
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mutex_unlock(&parent->d_inode->i_mutex);
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return error;
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}
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/**
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* debugfs_create_file - create a file in the debugfs filesystem
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* @name: a pointer to a string containing the name of the file to create.
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* @mode: the permission that the file should have
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* @parent: a pointer to the parent dentry for this file. This should be a
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* directory dentry if set. If this paramater is NULL, then the
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* file will be created in the root of the debugfs filesystem.
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* @data: a pointer to something that the caller will want to get to later
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* on. The inode.i_private pointer will point to this value on
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* the open() call.
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* @fops: a pointer to a struct file_operations that should be used for
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* this file.
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*
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* This is the basic "create a file" function for debugfs. It allows for a
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* wide range of flexibility in createing a file, or a directory (if you
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* want to create a directory, the debugfs_create_dir() function is
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* recommended to be used instead.)
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*
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* This function will return a pointer to a dentry if it succeeds. This
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* pointer must be passed to the debugfs_remove() function when the file is
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* to be removed (no automatic cleanup happens if your module is unloaded,
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* you are responsible here.) If an error occurs, %NULL will be returned.
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*
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* If debugfs is not enabled in the kernel, the value -%ENODEV will be
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* returned.
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*/
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struct dentry *debugfs_create_file(const char *name, mode_t mode,
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struct dentry *parent, void *data,
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const struct file_operations *fops)
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{
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struct dentry *dentry = NULL;
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int error;
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pr_debug("debugfs: creating file '%s'\n",name);
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error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
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&debugfs_mount_count);
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if (error)
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goto exit;
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error = debugfs_create_by_name(name, mode, parent, &dentry);
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if (error) {
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dentry = NULL;
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simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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goto exit;
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}
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if (dentry->d_inode) {
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if (data)
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dentry->d_inode->i_private = data;
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if (fops)
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dentry->d_inode->i_fop = fops;
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}
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exit:
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return dentry;
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}
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EXPORT_SYMBOL_GPL(debugfs_create_file);
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/**
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* debugfs_create_dir - create a directory in the debugfs filesystem
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* @name: a pointer to a string containing the name of the directory to
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* create.
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* @parent: a pointer to the parent dentry for this file. This should be a
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* directory dentry if set. If this paramater is NULL, then the
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* directory will be created in the root of the debugfs filesystem.
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*
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* This function creates a directory in debugfs with the given name.
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*
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* This function will return a pointer to a dentry if it succeeds. This
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* pointer must be passed to the debugfs_remove() function when the file is
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* to be removed (no automatic cleanup happens if your module is unloaded,
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* you are responsible here.) If an error occurs, %NULL will be returned.
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*
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* If debugfs is not enabled in the kernel, the value -%ENODEV will be
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* returned.
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*/
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struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
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{
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return debugfs_create_file(name,
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S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
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parent, NULL, NULL);
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}
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EXPORT_SYMBOL_GPL(debugfs_create_dir);
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/**
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* debugfs_create_symlink- create a symbolic link in the debugfs filesystem
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* @name: a pointer to a string containing the name of the symbolic link to
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* create.
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* @parent: a pointer to the parent dentry for this symbolic link. This
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* should be a directory dentry if set. If this paramater is NULL,
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* then the symbolic link will be created in the root of the debugfs
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* filesystem.
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* @target: a pointer to a string containing the path to the target of the
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* symbolic link.
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*
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* This function creates a symbolic link with the given name in debugfs that
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* links to the given target path.
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*
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* This function will return a pointer to a dentry if it succeeds. This
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* pointer must be passed to the debugfs_remove() function when the symbolic
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* link is to be removed (no automatic cleanup happens if your module is
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* unloaded, you are responsible here.) If an error occurs, %NULL will be
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* returned.
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*
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* If debugfs is not enabled in the kernel, the value -%ENODEV will be
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* returned.
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*/
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struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
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const char *target)
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{
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struct dentry *result;
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char *link;
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link = kstrdup(target, GFP_KERNEL);
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if (!link)
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return NULL;
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result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link,
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NULL);
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if (!result)
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kfree(link);
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return result;
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}
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EXPORT_SYMBOL_GPL(debugfs_create_symlink);
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/**
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* debugfs_remove - removes a file or directory from the debugfs filesystem
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* @dentry: a pointer to a the dentry of the file or directory to be
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* removed.
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*
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* This function removes a file or directory in debugfs that was previously
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* created with a call to another debugfs function (like
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* debugfs_create_file() or variants thereof.)
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*
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* This function is required to be called in order for the file to be
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* removed, no automatic cleanup of files will happen when a module is
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* removed, you are responsible here.
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*/
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void debugfs_remove(struct dentry *dentry)
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{
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struct dentry *parent;
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int ret = 0;
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if (!dentry)
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return;
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parent = dentry->d_parent;
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if (!parent || !parent->d_inode)
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return;
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mutex_lock(&parent->d_inode->i_mutex);
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if (debugfs_positive(dentry)) {
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if (dentry->d_inode) {
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dget(dentry);
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switch (dentry->d_inode->i_mode & S_IFMT) {
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case S_IFDIR:
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ret = simple_rmdir(parent->d_inode, dentry);
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if (ret)
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printk(KERN_ERR
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"DebugFS rmdir on %s failed : "
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"directory not empty.\n",
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dentry->d_name.name);
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break;
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case S_IFLNK:
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kfree(dentry->d_inode->i_private);
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/* fall through */
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default:
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simple_unlink(parent->d_inode, dentry);
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break;
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}
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if (!ret)
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d_delete(dentry);
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dput(dentry);
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}
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}
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mutex_unlock(&parent->d_inode->i_mutex);
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simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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}
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EXPORT_SYMBOL_GPL(debugfs_remove);
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static decl_subsys(debug, NULL, NULL);
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static int __init debugfs_init(void)
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{
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int retval;
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kobj_set_kset_s(&debug_subsys, kernel_subsys);
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retval = subsystem_register(&debug_subsys);
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if (retval)
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return retval;
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retval = register_filesystem(&debug_fs_type);
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if (retval)
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subsystem_unregister(&debug_subsys);
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return retval;
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}
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static void __exit debugfs_exit(void)
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{
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simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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unregister_filesystem(&debug_fs_type);
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subsystem_unregister(&debug_subsys);
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}
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core_initcall(debugfs_init);
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module_exit(debugfs_exit);
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MODULE_LICENSE("GPL");
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