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Commit | Line | Data |
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4282d606 SRRH |
1 | /* |
2 | * inode.c - part of tracefs, a pseudo file system for activating tracing | |
3 | * | |
4 | * Based on debugfs by: Greg Kroah-Hartman <greg@kroah.com> | |
5 | * | |
6 | * Copyright (C) 2014 Red Hat Inc, author: Steven Rostedt <srostedt@redhat.com> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public License version | |
10 | * 2 as published by the Free Software Foundation. | |
11 | * | |
12 | * tracefs is the file system that is used by the tracing infrastructure. | |
13 | * | |
14 | */ | |
15 | ||
16 | #include <linux/module.h> | |
17 | #include <linux/fs.h> | |
18 | #include <linux/mount.h> | |
cc31004a | 19 | #include <linux/kobject.h> |
4282d606 SRRH |
20 | #include <linux/namei.h> |
21 | #include <linux/tracefs.h> | |
22 | #include <linux/fsnotify.h> | |
23 | #include <linux/seq_file.h> | |
24 | #include <linux/parser.h> | |
25 | #include <linux/magic.h> | |
26 | #include <linux/slab.h> | |
27 | ||
28 | #define TRACEFS_DEFAULT_MODE 0700 | |
29 | ||
30 | static struct vfsmount *tracefs_mount; | |
31 | static int tracefs_mount_count; | |
32 | static bool tracefs_registered; | |
33 | ||
34 | static ssize_t default_read_file(struct file *file, char __user *buf, | |
35 | size_t count, loff_t *ppos) | |
36 | { | |
37 | return 0; | |
38 | } | |
39 | ||
40 | static ssize_t default_write_file(struct file *file, const char __user *buf, | |
41 | size_t count, loff_t *ppos) | |
42 | { | |
43 | return count; | |
44 | } | |
45 | ||
46 | static const struct file_operations tracefs_file_operations = { | |
47 | .read = default_read_file, | |
48 | .write = default_write_file, | |
49 | .open = simple_open, | |
50 | .llseek = noop_llseek, | |
51 | }; | |
52 | ||
eae47358 SRRH |
53 | static struct tracefs_dir_ops { |
54 | int (*mkdir)(const char *name); | |
55 | int (*rmdir)(const char *name); | |
56 | } tracefs_ops; | |
57 | ||
58 | static char *get_dname(struct dentry *dentry) | |
59 | { | |
60 | const char *dname; | |
61 | char *name; | |
62 | int len = dentry->d_name.len; | |
63 | ||
64 | dname = dentry->d_name.name; | |
65 | name = kmalloc(len + 1, GFP_KERNEL); | |
66 | if (!name) | |
67 | return NULL; | |
68 | memcpy(name, dname, len); | |
69 | name[len] = 0; | |
70 | return name; | |
71 | } | |
72 | ||
73 | static int tracefs_syscall_mkdir(struct inode *inode, struct dentry *dentry, umode_t mode) | |
74 | { | |
75 | char *name; | |
76 | int ret; | |
77 | ||
78 | name = get_dname(dentry); | |
79 | if (!name) | |
80 | return -ENOMEM; | |
81 | ||
82 | /* | |
83 | * The mkdir call can call the generic functions that create | |
84 | * the files within the tracefs system. It is up to the individual | |
85 | * mkdir routine to handle races. | |
86 | */ | |
87 | mutex_unlock(&inode->i_mutex); | |
88 | ret = tracefs_ops.mkdir(name); | |
89 | mutex_lock(&inode->i_mutex); | |
90 | ||
91 | kfree(name); | |
92 | ||
93 | return ret; | |
94 | } | |
95 | ||
96 | static int tracefs_syscall_rmdir(struct inode *inode, struct dentry *dentry) | |
97 | { | |
98 | char *name; | |
99 | int ret; | |
100 | ||
101 | name = get_dname(dentry); | |
102 | if (!name) | |
103 | return -ENOMEM; | |
104 | ||
105 | /* | |
106 | * The rmdir call can call the generic functions that create | |
107 | * the files within the tracefs system. It is up to the individual | |
108 | * rmdir routine to handle races. | |
109 | * This time we need to unlock not only the parent (inode) but | |
110 | * also the directory that is being deleted. | |
111 | */ | |
112 | mutex_unlock(&inode->i_mutex); | |
113 | mutex_unlock(&dentry->d_inode->i_mutex); | |
114 | ||
115 | ret = tracefs_ops.rmdir(name); | |
116 | ||
117 | mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT); | |
118 | mutex_lock(&dentry->d_inode->i_mutex); | |
119 | ||
120 | kfree(name); | |
121 | ||
122 | return ret; | |
123 | } | |
124 | ||
125 | static const struct inode_operations tracefs_dir_inode_operations = { | |
126 | .lookup = simple_lookup, | |
127 | .mkdir = tracefs_syscall_mkdir, | |
128 | .rmdir = tracefs_syscall_rmdir, | |
129 | }; | |
130 | ||
4282d606 SRRH |
131 | static struct inode *tracefs_get_inode(struct super_block *sb) |
132 | { | |
133 | struct inode *inode = new_inode(sb); | |
134 | if (inode) { | |
135 | inode->i_ino = get_next_ino(); | |
136 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
137 | } | |
138 | return inode; | |
139 | } | |
140 | ||
141 | struct tracefs_mount_opts { | |
142 | kuid_t uid; | |
143 | kgid_t gid; | |
144 | umode_t mode; | |
145 | }; | |
146 | ||
147 | enum { | |
148 | Opt_uid, | |
149 | Opt_gid, | |
150 | Opt_mode, | |
151 | Opt_err | |
152 | }; | |
153 | ||
154 | static const match_table_t tokens = { | |
155 | {Opt_uid, "uid=%u"}, | |
156 | {Opt_gid, "gid=%u"}, | |
157 | {Opt_mode, "mode=%o"}, | |
158 | {Opt_err, NULL} | |
159 | }; | |
160 | ||
161 | struct tracefs_fs_info { | |
162 | struct tracefs_mount_opts mount_opts; | |
163 | }; | |
164 | ||
165 | static int tracefs_parse_options(char *data, struct tracefs_mount_opts *opts) | |
166 | { | |
167 | substring_t args[MAX_OPT_ARGS]; | |
168 | int option; | |
169 | int token; | |
170 | kuid_t uid; | |
171 | kgid_t gid; | |
172 | char *p; | |
173 | ||
174 | opts->mode = TRACEFS_DEFAULT_MODE; | |
175 | ||
176 | while ((p = strsep(&data, ",")) != NULL) { | |
177 | if (!*p) | |
178 | continue; | |
179 | ||
180 | token = match_token(p, tokens, args); | |
181 | switch (token) { | |
182 | case Opt_uid: | |
183 | if (match_int(&args[0], &option)) | |
184 | return -EINVAL; | |
185 | uid = make_kuid(current_user_ns(), option); | |
186 | if (!uid_valid(uid)) | |
187 | return -EINVAL; | |
188 | opts->uid = uid; | |
189 | break; | |
190 | case Opt_gid: | |
191 | if (match_int(&args[0], &option)) | |
192 | return -EINVAL; | |
193 | gid = make_kgid(current_user_ns(), option); | |
194 | if (!gid_valid(gid)) | |
195 | return -EINVAL; | |
196 | opts->gid = gid; | |
197 | break; | |
198 | case Opt_mode: | |
199 | if (match_octal(&args[0], &option)) | |
200 | return -EINVAL; | |
201 | opts->mode = option & S_IALLUGO; | |
202 | break; | |
203 | /* | |
204 | * We might like to report bad mount options here; | |
205 | * but traditionally tracefs has ignored all mount options | |
206 | */ | |
207 | } | |
208 | } | |
209 | ||
210 | return 0; | |
211 | } | |
212 | ||
213 | static int tracefs_apply_options(struct super_block *sb) | |
214 | { | |
215 | struct tracefs_fs_info *fsi = sb->s_fs_info; | |
216 | struct inode *inode = sb->s_root->d_inode; | |
217 | struct tracefs_mount_opts *opts = &fsi->mount_opts; | |
218 | ||
219 | inode->i_mode &= ~S_IALLUGO; | |
220 | inode->i_mode |= opts->mode; | |
221 | ||
222 | inode->i_uid = opts->uid; | |
223 | inode->i_gid = opts->gid; | |
224 | ||
225 | return 0; | |
226 | } | |
227 | ||
228 | static int tracefs_remount(struct super_block *sb, int *flags, char *data) | |
229 | { | |
230 | int err; | |
231 | struct tracefs_fs_info *fsi = sb->s_fs_info; | |
232 | ||
233 | sync_filesystem(sb); | |
234 | err = tracefs_parse_options(data, &fsi->mount_opts); | |
235 | if (err) | |
236 | goto fail; | |
237 | ||
238 | tracefs_apply_options(sb); | |
239 | ||
240 | fail: | |
241 | return err; | |
242 | } | |
243 | ||
244 | static int tracefs_show_options(struct seq_file *m, struct dentry *root) | |
245 | { | |
246 | struct tracefs_fs_info *fsi = root->d_sb->s_fs_info; | |
247 | struct tracefs_mount_opts *opts = &fsi->mount_opts; | |
248 | ||
249 | if (!uid_eq(opts->uid, GLOBAL_ROOT_UID)) | |
250 | seq_printf(m, ",uid=%u", | |
251 | from_kuid_munged(&init_user_ns, opts->uid)); | |
252 | if (!gid_eq(opts->gid, GLOBAL_ROOT_GID)) | |
253 | seq_printf(m, ",gid=%u", | |
254 | from_kgid_munged(&init_user_ns, opts->gid)); | |
255 | if (opts->mode != TRACEFS_DEFAULT_MODE) | |
256 | seq_printf(m, ",mode=%o", opts->mode); | |
257 | ||
258 | return 0; | |
259 | } | |
260 | ||
261 | static const struct super_operations tracefs_super_operations = { | |
262 | .statfs = simple_statfs, | |
263 | .remount_fs = tracefs_remount, | |
264 | .show_options = tracefs_show_options, | |
265 | }; | |
266 | ||
267 | static int trace_fill_super(struct super_block *sb, void *data, int silent) | |
268 | { | |
269 | static struct tree_descr trace_files[] = {{""}}; | |
270 | struct tracefs_fs_info *fsi; | |
271 | int err; | |
272 | ||
273 | save_mount_options(sb, data); | |
274 | ||
275 | fsi = kzalloc(sizeof(struct tracefs_fs_info), GFP_KERNEL); | |
276 | sb->s_fs_info = fsi; | |
277 | if (!fsi) { | |
278 | err = -ENOMEM; | |
279 | goto fail; | |
280 | } | |
281 | ||
282 | err = tracefs_parse_options(data, &fsi->mount_opts); | |
283 | if (err) | |
284 | goto fail; | |
285 | ||
286 | err = simple_fill_super(sb, TRACEFS_MAGIC, trace_files); | |
287 | if (err) | |
288 | goto fail; | |
289 | ||
290 | sb->s_op = &tracefs_super_operations; | |
291 | ||
292 | tracefs_apply_options(sb); | |
293 | ||
294 | return 0; | |
295 | ||
296 | fail: | |
297 | kfree(fsi); | |
298 | sb->s_fs_info = NULL; | |
299 | return err; | |
300 | } | |
301 | ||
302 | static struct dentry *trace_mount(struct file_system_type *fs_type, | |
303 | int flags, const char *dev_name, | |
304 | void *data) | |
305 | { | |
306 | return mount_single(fs_type, flags, data, trace_fill_super); | |
307 | } | |
308 | ||
309 | static struct file_system_type trace_fs_type = { | |
310 | .owner = THIS_MODULE, | |
311 | .name = "tracefs", | |
312 | .mount = trace_mount, | |
313 | .kill_sb = kill_litter_super, | |
314 | }; | |
315 | MODULE_ALIAS_FS("tracefs"); | |
316 | ||
317 | static struct dentry *start_creating(const char *name, struct dentry *parent) | |
318 | { | |
319 | struct dentry *dentry; | |
320 | int error; | |
321 | ||
322 | pr_debug("tracefs: creating file '%s'\n",name); | |
323 | ||
324 | error = simple_pin_fs(&trace_fs_type, &tracefs_mount, | |
325 | &tracefs_mount_count); | |
326 | if (error) | |
327 | return ERR_PTR(error); | |
328 | ||
329 | /* If the parent is not specified, we create it in the root. | |
330 | * We need the root dentry to do this, which is in the super | |
331 | * block. A pointer to that is in the struct vfsmount that we | |
332 | * have around. | |
333 | */ | |
334 | if (!parent) | |
335 | parent = tracefs_mount->mnt_root; | |
336 | ||
337 | mutex_lock(&parent->d_inode->i_mutex); | |
338 | dentry = lookup_one_len(name, parent, strlen(name)); | |
339 | if (!IS_ERR(dentry) && dentry->d_inode) { | |
340 | dput(dentry); | |
341 | dentry = ERR_PTR(-EEXIST); | |
342 | } | |
d227c3ae DB |
343 | |
344 | if (IS_ERR(dentry)) { | |
4282d606 | 345 | mutex_unlock(&parent->d_inode->i_mutex); |
d227c3ae DB |
346 | simple_release_fs(&tracefs_mount, &tracefs_mount_count); |
347 | } | |
348 | ||
4282d606 SRRH |
349 | return dentry; |
350 | } | |
351 | ||
352 | static struct dentry *failed_creating(struct dentry *dentry) | |
353 | { | |
354 | mutex_unlock(&dentry->d_parent->d_inode->i_mutex); | |
355 | dput(dentry); | |
356 | simple_release_fs(&tracefs_mount, &tracefs_mount_count); | |
357 | return NULL; | |
358 | } | |
359 | ||
360 | static struct dentry *end_creating(struct dentry *dentry) | |
361 | { | |
362 | mutex_unlock(&dentry->d_parent->d_inode->i_mutex); | |
363 | return dentry; | |
364 | } | |
365 | ||
366 | /** | |
367 | * tracefs_create_file - create a file in the tracefs filesystem | |
368 | * @name: a pointer to a string containing the name of the file to create. | |
369 | * @mode: the permission that the file should have. | |
370 | * @parent: a pointer to the parent dentry for this file. This should be a | |
371 | * directory dentry if set. If this parameter is NULL, then the | |
372 | * file will be created in the root of the tracefs filesystem. | |
373 | * @data: a pointer to something that the caller will want to get to later | |
374 | * on. The inode.i_private pointer will point to this value on | |
375 | * the open() call. | |
376 | * @fops: a pointer to a struct file_operations that should be used for | |
377 | * this file. | |
378 | * | |
379 | * This is the basic "create a file" function for tracefs. It allows for a | |
380 | * wide range of flexibility in creating a file, or a directory (if you want | |
381 | * to create a directory, the tracefs_create_dir() function is | |
382 | * recommended to be used instead.) | |
383 | * | |
384 | * This function will return a pointer to a dentry if it succeeds. This | |
385 | * pointer must be passed to the tracefs_remove() function when the file is | |
386 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
387 | * you are responsible here.) If an error occurs, %NULL will be returned. | |
388 | * | |
389 | * If tracefs is not enabled in the kernel, the value -%ENODEV will be | |
390 | * returned. | |
391 | */ | |
392 | struct dentry *tracefs_create_file(const char *name, umode_t mode, | |
393 | struct dentry *parent, void *data, | |
394 | const struct file_operations *fops) | |
395 | { | |
396 | struct dentry *dentry; | |
397 | struct inode *inode; | |
398 | ||
399 | if (!(mode & S_IFMT)) | |
400 | mode |= S_IFREG; | |
401 | BUG_ON(!S_ISREG(mode)); | |
402 | dentry = start_creating(name, parent); | |
403 | ||
404 | if (IS_ERR(dentry)) | |
405 | return NULL; | |
406 | ||
407 | inode = tracefs_get_inode(dentry->d_sb); | |
408 | if (unlikely(!inode)) | |
409 | return failed_creating(dentry); | |
410 | ||
411 | inode->i_mode = mode; | |
412 | inode->i_fop = fops ? fops : &tracefs_file_operations; | |
413 | inode->i_private = data; | |
414 | d_instantiate(dentry, inode); | |
415 | fsnotify_create(dentry->d_parent->d_inode, dentry); | |
416 | return end_creating(dentry); | |
417 | } | |
418 | ||
eae47358 SRRH |
419 | static struct dentry *__create_dir(const char *name, struct dentry *parent, |
420 | const struct inode_operations *ops) | |
421 | { | |
422 | struct dentry *dentry = start_creating(name, parent); | |
423 | struct inode *inode; | |
424 | ||
425 | if (IS_ERR(dentry)) | |
426 | return NULL; | |
427 | ||
428 | inode = tracefs_get_inode(dentry->d_sb); | |
429 | if (unlikely(!inode)) | |
430 | return failed_creating(dentry); | |
431 | ||
432 | inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; | |
433 | inode->i_op = ops; | |
434 | inode->i_fop = &simple_dir_operations; | |
435 | ||
436 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ | |
437 | inc_nlink(inode); | |
438 | d_instantiate(dentry, inode); | |
439 | inc_nlink(dentry->d_parent->d_inode); | |
440 | fsnotify_mkdir(dentry->d_parent->d_inode, dentry); | |
441 | return end_creating(dentry); | |
442 | } | |
443 | ||
4282d606 SRRH |
444 | /** |
445 | * tracefs_create_dir - create a directory in the tracefs filesystem | |
446 | * @name: a pointer to a string containing the name of the directory to | |
447 | * create. | |
448 | * @parent: a pointer to the parent dentry for this file. This should be a | |
449 | * directory dentry if set. If this parameter is NULL, then the | |
450 | * directory will be created in the root of the tracefs filesystem. | |
451 | * | |
452 | * This function creates a directory in tracefs with the given name. | |
453 | * | |
454 | * This function will return a pointer to a dentry if it succeeds. This | |
455 | * pointer must be passed to the tracefs_remove() function when the file is | |
456 | * to be removed. If an error occurs, %NULL will be returned. | |
457 | * | |
458 | * If tracing is not enabled in the kernel, the value -%ENODEV will be | |
459 | * returned. | |
460 | */ | |
461 | struct dentry *tracefs_create_dir(const char *name, struct dentry *parent) | |
462 | { | |
eae47358 SRRH |
463 | return __create_dir(name, parent, &simple_dir_inode_operations); |
464 | } | |
4282d606 | 465 | |
eae47358 SRRH |
466 | /** |
467 | * tracefs_create_instance_dir - create the tracing instances directory | |
468 | * @name: The name of the instances directory to create | |
469 | * @parent: The parent directory that the instances directory will exist | |
470 | * @mkdir: The function to call when a mkdir is performed. | |
471 | * @rmdir: The function to call when a rmdir is performed. | |
472 | * | |
473 | * Only one instances directory is allowed. | |
474 | * | |
475 | * The instances directory is special as it allows for mkdir and rmdir to | |
476 | * to be done by userspace. When a mkdir or rmdir is performed, the inode | |
477 | * locks are released and the methhods passed in (@mkdir and @rmdir) are | |
478 | * called without locks and with the name of the directory being created | |
479 | * within the instances directory. | |
480 | * | |
481 | * Returns the dentry of the instances directory. | |
482 | */ | |
483 | struct dentry *tracefs_create_instance_dir(const char *name, struct dentry *parent, | |
484 | int (*mkdir)(const char *name), | |
485 | int (*rmdir)(const char *name)) | |
486 | { | |
487 | struct dentry *dentry; | |
488 | ||
489 | /* Only allow one instance of the instances directory. */ | |
490 | if (WARN_ON(tracefs_ops.mkdir || tracefs_ops.rmdir)) | |
4282d606 SRRH |
491 | return NULL; |
492 | ||
eae47358 SRRH |
493 | dentry = __create_dir(name, parent, &tracefs_dir_inode_operations); |
494 | if (!dentry) | |
495 | return NULL; | |
4282d606 | 496 | |
eae47358 SRRH |
497 | tracefs_ops.mkdir = mkdir; |
498 | tracefs_ops.rmdir = rmdir; | |
4282d606 | 499 | |
eae47358 | 500 | return dentry; |
4282d606 SRRH |
501 | } |
502 | ||
4282d606 SRRH |
503 | static int __tracefs_remove(struct dentry *dentry, struct dentry *parent) |
504 | { | |
505 | int ret = 0; | |
506 | ||
dc3f4198 | 507 | if (simple_positive(dentry)) { |
4282d606 SRRH |
508 | if (dentry->d_inode) { |
509 | dget(dentry); | |
510 | switch (dentry->d_inode->i_mode & S_IFMT) { | |
511 | case S_IFDIR: | |
512 | ret = simple_rmdir(parent->d_inode, dentry); | |
513 | break; | |
514 | default: | |
515 | simple_unlink(parent->d_inode, dentry); | |
516 | break; | |
517 | } | |
518 | if (!ret) | |
519 | d_delete(dentry); | |
520 | dput(dentry); | |
521 | } | |
522 | } | |
523 | return ret; | |
524 | } | |
525 | ||
526 | /** | |
527 | * tracefs_remove - removes a file or directory from the tracefs filesystem | |
528 | * @dentry: a pointer to a the dentry of the file or directory to be | |
529 | * removed. | |
530 | * | |
531 | * This function removes a file or directory in tracefs that was previously | |
532 | * created with a call to another tracefs function (like | |
533 | * tracefs_create_file() or variants thereof.) | |
534 | */ | |
535 | void tracefs_remove(struct dentry *dentry) | |
536 | { | |
537 | struct dentry *parent; | |
538 | int ret; | |
539 | ||
540 | if (IS_ERR_OR_NULL(dentry)) | |
541 | return; | |
542 | ||
543 | parent = dentry->d_parent; | |
544 | if (!parent || !parent->d_inode) | |
545 | return; | |
546 | ||
547 | mutex_lock(&parent->d_inode->i_mutex); | |
548 | ret = __tracefs_remove(dentry, parent); | |
549 | mutex_unlock(&parent->d_inode->i_mutex); | |
550 | if (!ret) | |
551 | simple_release_fs(&tracefs_mount, &tracefs_mount_count); | |
552 | } | |
553 | ||
554 | /** | |
555 | * tracefs_remove_recursive - recursively removes a directory | |
556 | * @dentry: a pointer to a the dentry of the directory to be removed. | |
557 | * | |
558 | * This function recursively removes a directory tree in tracefs that | |
559 | * was previously created with a call to another tracefs function | |
560 | * (like tracefs_create_file() or variants thereof.) | |
561 | */ | |
562 | void tracefs_remove_recursive(struct dentry *dentry) | |
563 | { | |
564 | struct dentry *child, *parent; | |
565 | ||
566 | if (IS_ERR_OR_NULL(dentry)) | |
567 | return; | |
568 | ||
569 | parent = dentry->d_parent; | |
570 | if (!parent || !parent->d_inode) | |
571 | return; | |
572 | ||
573 | parent = dentry; | |
574 | down: | |
575 | mutex_lock(&parent->d_inode->i_mutex); | |
576 | loop: | |
577 | /* | |
578 | * The parent->d_subdirs is protected by the d_lock. Outside that | |
579 | * lock, the child can be unlinked and set to be freed which can | |
580 | * use the d_u.d_child as the rcu head and corrupt this list. | |
581 | */ | |
582 | spin_lock(&parent->d_lock); | |
583 | list_for_each_entry(child, &parent->d_subdirs, d_child) { | |
dc3f4198 | 584 | if (!simple_positive(child)) |
4282d606 SRRH |
585 | continue; |
586 | ||
587 | /* perhaps simple_empty(child) makes more sense */ | |
588 | if (!list_empty(&child->d_subdirs)) { | |
589 | spin_unlock(&parent->d_lock); | |
590 | mutex_unlock(&parent->d_inode->i_mutex); | |
591 | parent = child; | |
592 | goto down; | |
593 | } | |
594 | ||
595 | spin_unlock(&parent->d_lock); | |
596 | ||
597 | if (!__tracefs_remove(child, parent)) | |
598 | simple_release_fs(&tracefs_mount, &tracefs_mount_count); | |
599 | ||
600 | /* | |
601 | * The parent->d_lock protects agaist child from unlinking | |
602 | * from d_subdirs. When releasing the parent->d_lock we can | |
603 | * no longer trust that the next pointer is valid. | |
604 | * Restart the loop. We'll skip this one with the | |
dc3f4198 | 605 | * simple_positive() check. |
4282d606 SRRH |
606 | */ |
607 | goto loop; | |
608 | } | |
609 | spin_unlock(&parent->d_lock); | |
610 | ||
611 | mutex_unlock(&parent->d_inode->i_mutex); | |
612 | child = parent; | |
613 | parent = parent->d_parent; | |
614 | mutex_lock(&parent->d_inode->i_mutex); | |
615 | ||
616 | if (child != dentry) | |
617 | /* go up */ | |
618 | goto loop; | |
619 | ||
620 | if (!__tracefs_remove(child, parent)) | |
621 | simple_release_fs(&tracefs_mount, &tracefs_mount_count); | |
622 | mutex_unlock(&parent->d_inode->i_mutex); | |
623 | } | |
624 | ||
625 | /** | |
626 | * tracefs_initialized - Tells whether tracefs has been registered | |
627 | */ | |
628 | bool tracefs_initialized(void) | |
629 | { | |
630 | return tracefs_registered; | |
631 | } | |
632 | ||
633 | static int __init tracefs_init(void) | |
634 | { | |
635 | int retval; | |
636 | ||
f9bb4882 EB |
637 | retval = sysfs_create_mount_point(kernel_kobj, "tracing"); |
638 | if (retval) | |
cc31004a SRRH |
639 | return -EINVAL; |
640 | ||
4282d606 SRRH |
641 | retval = register_filesystem(&trace_fs_type); |
642 | if (!retval) | |
643 | tracefs_registered = true; | |
644 | ||
645 | return retval; | |
646 | } | |
647 | core_initcall(tracefs_init); |