| 1 | |
| 2 | * file.c - part of debugfs, a tiny little debug file system
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| 3 | *
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| 4 | * Copyright (C) 2004 Greg Kroah-Hartman <[email protected]>
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| 5 | * Copyright (C) 2004 IBM Inc.
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| 6 | *
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| 7 | * This program is free software; you can redistribute it and/or
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| 8 | * modify it under the terms of the GNU General Public License version
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| 9 | * 2 as published by the Free Software Foundation.
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| 10 | *
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| 11 | * debugfs is for people to use instead of /proc or /sys.
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| 12 | * See Documentation/DocBook/kernel-api for more details.
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| 13 | *
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| 14 |
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| 15 |
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| 16 |
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| 17 |
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| 18 |
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| 19 | #include <linux/module.h>
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| 20 | #include <linux/fs.h>
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| 21 | #include <linux/mount.h>
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| 22 | #include <linux/pagemap.h>
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| 23 | #include <linux/init.h>
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| 24 | #include <linux/kobject.h>
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| 25 | #include <linux/namei.h>
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| 26 | #include <linux/debugfs.h>
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| 27 | #include <linux/fsnotify.h>
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| 28 | #include <linux/string.h>
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| 29 |
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| 30 | #define DEBUGFS_MAGIC 0x64626720
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| 31 |
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| 32 |
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| 33 | extern struct file_operations debugfs_file_operations;
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| 34 | extern struct inode_operations debugfs_link_operations;
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| 35 |
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| 36 | static struct vfsmount *debugfs_mount;
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| 37 | static int debugfs_mount_count;
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| 38 |
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| 39 | static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev)
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| 40 | {
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| 41 | struct inode *inode = new_inode(sb);
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| 42 |
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| 43 | if (inode) {
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| 44 | inode->i_mode = mode;
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| 45 | inode->i_uid = 0;
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| 46 | inode->i_gid = 0;
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| 47 | inode->i_blocks = 0;
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| 48 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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| 49 | switch (mode & S_IFMT) {
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| 50 | default:
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| 51 | init_special_inode(inode, mode, dev);
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| 52 | break;
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| 53 | case S_IFREG:
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| 54 | inode->i_fop = &debugfs_file_operations;
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| 55 | break;
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| 56 | case S_IFLNK:
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| 57 | inode->i_op = &debugfs_link_operations;
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| 58 | break;
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| 59 | case S_IFDIR:
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| 60 | inode->i_op = &simple_dir_inode_operations;
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| 61 | inode->i_fop = &simple_dir_operations;
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| 62 |
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| 63 | |
| 64 | * (for "." entry)
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| 65 | inc_nlink(inode);
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| 66 | break;
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| 67 | }
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| 68 | }
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| 69 | return inode;
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| 70 | }
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| 71 |
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| 72 |
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| 73 | static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
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| 74 | int mode, dev_t dev)
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| 75 | {
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| 76 | struct inode *inode;
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| 77 | int error = -EPERM;
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| 78 |
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| 79 | if (dentry->d_inode)
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| 80 | return -EEXIST;
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| 81 |
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| 82 | inode = debugfs_get_inode(dir->i_sb, mode, dev);
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| 83 | if (inode) {
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| 84 | d_instantiate(dentry, inode);
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| 85 | dget(dentry);
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| 86 | error = 0;
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| 87 | }
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| 88 | return error;
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| 89 | }
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| 90 |
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| 91 | static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
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| 92 | {
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| 93 | int res;
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| 94 |
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| 95 | mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
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| 96 | res = debugfs_mknod(dir, dentry, mode, 0);
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| 97 | if (!res) {
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| 98 | inc_nlink(dir);
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| 99 | fsnotify_mkdir(dir, dentry);
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| 100 | }
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| 101 | return res;
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| 102 | }
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| 103 |
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| 104 | static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode)
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| 105 | {
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| 106 | mode = (mode & S_IALLUGO) | S_IFLNK;
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| 107 | return debugfs_mknod(dir, dentry, mode, 0);
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| 108 | }
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| 109 |
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| 110 | static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode)
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| 111 | {
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| 112 | int res;
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| 113 |
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| 114 | mode = (mode & S_IALLUGO) | S_IFREG;
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| 115 | res = debugfs_mknod(dir, dentry, mode, 0);
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| 116 | if (!res)
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| 117 | fsnotify_create(dir, dentry);
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| 118 | return res;
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| 119 | }
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| 120 |
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| 121 | static inline int debugfs_positive(struct dentry *dentry)
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| 122 | {
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| 123 | return dentry->d_inode && !d_unhashed(dentry);
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| 124 | }
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| 125 |
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| 126 | static int debug_fill_super(struct super_block *sb, void *data, int silent)
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| 127 | {
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| 128 | static struct tree_descr debug_files[] = {{""}};
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| 129 |
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| 130 | return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
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| 131 | }
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| 132 |
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| 133 | static int debug_get_sb(struct file_system_type *fs_type,
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| 134 | int flags, const char *dev_name,
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| 135 | void *data, struct vfsmount *mnt)
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| 136 | {
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| 137 | return get_sb_single(fs_type, flags, data, debug_fill_super, mnt);
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| 138 | }
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| 139 |
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| 140 | static struct file_system_type debug_fs_type = {
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| 141 | .owner = THIS_MODULE,
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| 142 | .name = "debugfs",
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| 143 | .get_sb = debug_get_sb,
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| 144 | .kill_sb = kill_litter_super,
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| 145 | };
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| 146 |
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| 147 | static int debugfs_create_by_name(const char *name, mode_t mode,
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| 148 | struct dentry *parent,
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| 149 | struct dentry **dentry)
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| 150 | {
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| 151 | int error = 0;
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| 152 |
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| 153 | |
| 154 | * We need the root dentry to do this, which is in the super
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| 155 | * block. A pointer to that is in the struct vfsmount that we
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| 156 | * have around.
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| 157 |
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| 158 | if (!parent) {
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| 159 | if (debugfs_mount && debugfs_mount->mnt_sb) {
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| 160 | parent = debugfs_mount->mnt_sb->s_root;
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| 161 | }
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| 162 | }
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| 163 | if (!parent) {
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| 164 | pr_debug("debugfs: Ah! can not find a parent!\n");
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| 165 | return -EFAULT;
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| 166 | }
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| 167 |
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| 168 | *dentry = NULL;
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| 169 | mutex_lock(&parent->d_inode->i_mutex);
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| 170 | *dentry = lookup_one_len(name, parent, strlen(name));
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| 171 | if (!IS_ERR(*dentry)) {
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| 172 | switch (mode & S_IFMT) {
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| 173 | case S_IFDIR:
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| 174 | error = debugfs_mkdir(parent->d_inode, *dentry, mode);
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| 175 | break;
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| 176 | case S_IFLNK:
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| 177 | error = debugfs_link(parent->d_inode, *dentry, mode);
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| 178 | break;
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| 179 | default:
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| 180 | error = debugfs_create(parent->d_inode, *dentry, mode);
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| 181 | break;
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| 182 | }
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| 183 | dput(*dentry);
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| 184 | } else
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| 185 | error = PTR_ERR(*dentry);
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| 186 | mutex_unlock(&parent->d_inode->i_mutex);
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| 187 |
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| 188 | return error;
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| 189 | }
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| 190 |
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| 191 | |
| 192 | * debugfs_create_file - create a file in the debugfs filesystem
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| 193 | * @name: a pointer to a string containing the name of the file to create.
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| 194 | * @mode: the permission that the file should have
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| 195 | * @parent: a pointer to the parent dentry for this file. This should be a
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| 196 | * directory dentry if set. If this paramater is NULL, then the
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| 197 | * file will be created in the root of the debugfs filesystem.
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| 198 | * @data: a pointer to something that the caller will want to get to later
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| 199 | * on. The inode.i_private pointer will point to this value on
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| 200 | * the open() call.
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| 201 | * @fops: a pointer to a struct file_operations that should be used for
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| 202 | * this file.
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| 203 | *
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| 204 | * This is the basic "create a file" function for debugfs. It allows for a
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| 205 | * wide range of flexibility in createing a file, or a directory (if you
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| 206 | * want to create a directory, the debugfs_create_dir() function is
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| 207 | * recommended to be used instead.)
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| 208 | *
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| 209 | * This function will return a pointer to a dentry if it succeeds. This
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| 210 | * pointer must be passed to the debugfs_remove() function when the file is
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| 211 | * to be removed (no automatic cleanup happens if your module is unloaded,
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| 212 | * you are responsible here.) If an error occurs, %NULL will be returned.
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| 213 | *
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| 214 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be
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| 215 | * returned.
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| 216 |
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| 217 | struct dentry *debugfs_create_file(const char *name, mode_t mode,
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| 218 | struct dentry *parent, void *data,
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| 219 | const struct file_operations *fops)
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| 220 | {
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| 221 | struct dentry *dentry = NULL;
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| 222 | int error;
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| 223 |
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| 224 | pr_debug("debugfs: creating file '%s'\n",name);
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| 225 |
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| 226 | error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
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| 227 | &debugfs_mount_count);
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| 228 | if (error)
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| 229 | goto exit;
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| 230 |
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| 231 | error = debugfs_create_by_name(name, mode, parent, &dentry);
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| 232 | if (error) {
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| 233 | dentry = NULL;
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| 234 | simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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| 235 | goto exit;
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| 236 | }
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| 237 |
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| 238 | if (dentry->d_inode) {
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| 239 | if (data)
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| 240 | dentry->d_inode->i_private = data;
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| 241 | if (fops)
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| 242 | dentry->d_inode->i_fop = fops;
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| 243 | }
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| 244 | exit:
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| 245 | return dentry;
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| 246 | }
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| 247 | EXPORT_SYMBOL_GPL(debugfs_create_file);
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| 248 |
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| 249 | |
| 250 | * debugfs_create_dir - create a directory in the debugfs filesystem
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| 251 | * @name: a pointer to a string containing the name of the directory to
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| 252 | * create.
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| 253 | * @parent: a pointer to the parent dentry for this file. This should be a
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| 254 | * directory dentry if set. If this paramater is NULL, then the
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| 255 | * directory will be created in the root of the debugfs filesystem.
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| 256 | *
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| 257 | * This function creates a directory in debugfs with the given name.
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| 258 | *
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| 259 | * This function will return a pointer to a dentry if it succeeds. This
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| 260 | * pointer must be passed to the debugfs_remove() function when the file is
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| 261 | * to be removed (no automatic cleanup happens if your module is unloaded,
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| 262 | * you are responsible here.) If an error occurs, %NULL will be returned.
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| 263 | *
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| 264 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be
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| 265 | * returned.
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| 266 |
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| 267 | struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
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| 268 | {
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| 269 | return debugfs_create_file(name,
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| 270 | S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
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| 271 | parent, NULL, NULL);
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| 272 | }
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| 273 | EXPORT_SYMBOL_GPL(debugfs_create_dir);
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| 274 |
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| 275 | |
| 276 | * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
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| 277 | * @name: a pointer to a string containing the name of the symbolic link to
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| 278 | * create.
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| 279 | * @parent: a pointer to the parent dentry for this symbolic link. This
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| 280 | * should be a directory dentry if set. If this paramater is NULL,
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| 281 | * then the symbolic link will be created in the root of the debugfs
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| 282 | * filesystem.
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| 283 | * @target: a pointer to a string containing the path to the target of the
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| 284 | * symbolic link.
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| 285 | *
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| 286 | * This function creates a symbolic link with the given name in debugfs that
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| 287 | * links to the given target path.
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| 288 | *
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| 289 | * This function will return a pointer to a dentry if it succeeds. This
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| 290 | * pointer must be passed to the debugfs_remove() function when the symbolic
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| 291 | * link is to be removed (no automatic cleanup happens if your module is
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| 292 | * unloaded, you are responsible here.) If an error occurs, %NULL will be
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| 293 | * returned.
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| 294 | *
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| 295 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be
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| 296 | * returned.
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| 297 |
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| 298 | struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
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| 299 | const char *target)
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| 300 | {
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| 301 | struct dentry *result;
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| 302 | char *link;
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| 303 |
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| 304 | link = kstrdup(target, GFP_KERNEL);
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| 305 | if (!link)
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| 306 | return NULL;
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| 307 |
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| 308 | result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link,
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| 309 | NULL);
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| 310 | if (!result)
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| 311 | kfree(link);
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| 312 | return result;
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| 313 | }
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| 314 | EXPORT_SYMBOL_GPL(debugfs_create_symlink);
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| 315 |
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| 316 | |
| 317 | * debugfs_remove - removes a file or directory from the debugfs filesystem
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| 318 | * @dentry: a pointer to a the dentry of the file or directory to be
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| 319 | * removed.
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| 320 | *
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| 321 | * This function removes a file or directory in debugfs that was previously
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| 322 | * created with a call to another debugfs function (like
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| 323 | * debugfs_create_file() or variants thereof.)
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| 324 | *
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| 325 | * This function is required to be called in order for the file to be
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| 326 | * removed, no automatic cleanup of files will happen when a module is
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| 327 | * removed, you are responsible here.
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| 328 |
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| 329 | void debugfs_remove(struct dentry *dentry)
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| 330 | {
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| 331 | struct dentry *parent;
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| 332 | int ret = 0;
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| 333 |
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| 334 | if (!dentry)
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| 335 | return;
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| 336 |
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| 337 | parent = dentry->d_parent;
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| 338 | if (!parent || !parent->d_inode)
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| 339 | return;
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| 340 |
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| 341 | mutex_lock(&parent->d_inode->i_mutex);
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| 342 | if (debugfs_positive(dentry)) {
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| 343 | if (dentry->d_inode) {
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| 344 | dget(dentry);
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| 345 | switch (dentry->d_inode->i_mode & S_IFMT) {
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| 346 | case S_IFDIR:
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| 347 | ret = simple_rmdir(parent->d_inode, dentry);
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| 348 | if (ret)
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| 349 | printk(KERN_ERR
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| 350 | "DebugFS rmdir on %s failed : "
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| 351 | "directory not empty.\n",
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| 352 | dentry->d_name.name);
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| 353 | break;
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| 354 | case S_IFLNK:
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| 355 | kfree(dentry->d_inode->i_private);
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| 356 |
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| 357 | default:
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| 358 | simple_unlink(parent->d_inode, dentry);
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| 359 | break;
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| 360 | }
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| 361 | if (!ret)
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| 362 | d_delete(dentry);
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| 363 | dput(dentry);
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| 364 | }
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| 365 | }
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| 366 | mutex_unlock(&parent->d_inode->i_mutex);
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| 367 | simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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| 368 | }
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| 369 | EXPORT_SYMBOL_GPL(debugfs_remove);
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| 370 |
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| 371 | static decl_subsys(debug, NULL, NULL);
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| 372 |
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| 373 | static int __init debugfs_init(void)
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| 374 | {
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| 375 | int retval;
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| 376 |
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| 377 | kset_set_kset_s(&debug_subsys, kernel_subsys);
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| 378 | retval = subsystem_register(&debug_subsys);
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| 379 | if (retval)
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| 380 | return retval;
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| 381 |
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| 382 | retval = register_filesystem(&debug_fs_type);
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| 383 | if (retval)
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| 384 | subsystem_unregister(&debug_subsys);
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| 385 | return retval;
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| 386 | }
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| 387 |
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| 388 | static void __exit debugfs_exit(void)
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| 389 | {
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| 390 | simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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| 391 | unregister_filesystem(&debug_fs_type);
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| 392 | subsystem_unregister(&debug_subsys);
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| 393 | }
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| 394 |
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| 395 | core_initcall(debugfs_init);
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| 396 | module_exit(debugfs_exit);
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| 397 | MODULE_LICENSE("GPL");
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| 398 |
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