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1/*
2 * devtmpfs - kernel-maintained tmpfs-based /dev
3 *
4 * Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
5 *
6 * During bootup, before any driver core device is registered,
7 * devtmpfs, a tmpfs-based filesystem is created. Every driver-core
8 * device which requests a device node, will add a node in this
9 * filesystem.
10 * By default, all devices are named after the the name of the
11 * device, owned by root and have a default mode of 0600. Subsystems
12 * can overwrite the default setting if needed.
13 */
14
15#include <linux/kernel.h>
16#include <linux/syscalls.h>
17#include <linux/mount.h>
18#include <linux/device.h>
19#include <linux/genhd.h>
20#include <linux/namei.h>
21#include <linux/fs.h>
22#include <linux/shmem_fs.h>
23#include <linux/ramfs.h>
24#include <linux/sched.h>
25#include <linux/slab.h>
26#include <linux/kthread.h>
27
28static struct task_struct *thread;
29
30#if defined CONFIG_DEVTMPFS_MOUNT
31static int mount_dev = 1;
32#else
33static int mount_dev;
34#endif
35
36static DEFINE_SPINLOCK(req_lock);
37
38static struct req {
39 struct req *next;
40 struct completion done;
41 int err;
42 const char *name;
43 mode_t mode; /* 0 => delete */
44 struct device *dev;
45} *requests;
46
47static int __init mount_param(char *str)
48{
49 mount_dev = simple_strtoul(str, NULL, 0);
50 return 1;
51}
52__setup("devtmpfs.mount=", mount_param);
53
54static struct dentry *dev_mount(struct file_system_type *fs_type, int flags,
55 const char *dev_name, void *data)
56{
57#ifdef CONFIG_TMPFS
58 return mount_single(fs_type, flags, data, shmem_fill_super);
59#else
60 return mount_single(fs_type, flags, data, ramfs_fill_super);
61#endif
62}
63
64static struct file_system_type dev_fs_type = {
65 .name = "devtmpfs",
66 .mount = dev_mount,
67 .kill_sb = kill_litter_super,
68};
69
70#ifdef CONFIG_BLOCK
71static inline int is_blockdev(struct device *dev)
72{
73 return dev->class == &block_class;
74}
75#else
76static inline int is_blockdev(struct device *dev) { return 0; }
77#endif
78
79int devtmpfs_create_node(struct device *dev)
80{
81 const char *tmp = NULL;
82 struct req req;
83
84 if (!thread)
85 return 0;
86
87 req.mode = 0;
88 req.name = device_get_devnode(dev, &req.mode, &tmp);
89 if (!req.name)
90 return -ENOMEM;
91
92 if (req.mode == 0)
93 req.mode = 0600;
94 if (is_blockdev(dev))
95 req.mode |= S_IFBLK;
96 else
97 req.mode |= S_IFCHR;
98
99 req.dev = dev;
100
101 init_completion(&req.done);
102
103 spin_lock(&req_lock);
104 req.next = requests;
105 requests = &req;
106 spin_unlock(&req_lock);
107
108 wake_up_process(thread);
109 wait_for_completion(&req.done);
110
111 kfree(tmp);
112
113 return req.err;
114}
115
116int devtmpfs_delete_node(struct device *dev)
117{
118 const char *tmp = NULL;
119 struct req req;
120
121 if (!thread)
122 return 0;
123
124 req.name = device_get_devnode(dev, NULL, &tmp);
125 if (!req.name)
126 return -ENOMEM;
127
128 req.mode = 0;
129 req.dev = dev;
130
131 init_completion(&req.done);
132
133 spin_lock(&req_lock);
134 req.next = requests;
135 requests = &req;
136 spin_unlock(&req_lock);
137
138 wake_up_process(thread);
139 wait_for_completion(&req.done);
140
141 kfree(tmp);
142 return req.err;
143}
144
145static int dev_mkdir(const char *name, mode_t mode)
146{
147 struct dentry *dentry;
148 struct path path;
149 int err;
150
151 dentry = kern_path_create(AT_FDCWD, name, &path, 1);
152 if (IS_ERR(dentry))
153 return PTR_ERR(dentry);
154
155 err = vfs_mkdir(path.dentry->d_inode, dentry, mode);
156 if (!err)
157 /* mark as kernel-created inode */
158 dentry->d_inode->i_private = &thread;
159 dput(dentry);
160 mutex_unlock(&path.dentry->d_inode->i_mutex);
161 path_put(&path);
162 return err;
163}
164
165static int create_path(const char *nodepath)
166{
167 char *path;
168 char *s;
169 int err = 0;
170
171 /* parent directories do not exist, create them */
172 path = kstrdup(nodepath, GFP_KERNEL);
173 if (!path)
174 return -ENOMEM;
175
176 s = path;
177 for (;;) {
178 s = strchr(s, '/');
179 if (!s)
180 break;
181 s[0] = '\0';
182 err = dev_mkdir(path, 0755);
183 if (err && err != -EEXIST)
184 break;
185 s[0] = '/';
186 s++;
187 }
188 kfree(path);
189 return err;
190}
191
192static int handle_create(const char *nodename, mode_t mode, struct device *dev)
193{
194 struct dentry *dentry;
195 struct path path;
196 int err;
197
198 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
199 if (dentry == ERR_PTR(-ENOENT)) {
200 create_path(nodename);
201 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
202 }
203 if (IS_ERR(dentry))
204 return PTR_ERR(dentry);
205
206 err = vfs_mknod(path.dentry->d_inode,
207 dentry, mode, dev->devt);
208 if (!err) {
209 struct iattr newattrs;
210
211 /* fixup possibly umasked mode */
212 newattrs.ia_mode = mode;
213 newattrs.ia_valid = ATTR_MODE;
214 mutex_lock(&dentry->d_inode->i_mutex);
215 notify_change(dentry, &newattrs);
216 mutex_unlock(&dentry->d_inode->i_mutex);
217
218 /* mark as kernel-created inode */
219 dentry->d_inode->i_private = &thread;
220 }
221 dput(dentry);
222
223 mutex_unlock(&path.dentry->d_inode->i_mutex);
224 path_put(&path);
225 return err;
226}
227
228static int dev_rmdir(const char *name)
229{
230 struct nameidata nd;
231 struct dentry *dentry;
232 int err;
233
234 err = kern_path_parent(name, &nd);
235 if (err)
236 return err;
237
238 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
239 dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
240 if (!IS_ERR(dentry)) {
241 if (dentry->d_inode) {
242 if (dentry->d_inode->i_private == &thread)
243 err = vfs_rmdir(nd.path.dentry->d_inode,
244 dentry);
245 else
246 err = -EPERM;
247 } else {
248 err = -ENOENT;
249 }
250 dput(dentry);
251 } else {
252 err = PTR_ERR(dentry);
253 }
254
255 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
256 path_put(&nd.path);
257 return err;
258}
259
260static int delete_path(const char *nodepath)
261{
262 const char *path;
263 int err = 0;
264
265 path = kstrdup(nodepath, GFP_KERNEL);
266 if (!path)
267 return -ENOMEM;
268
269 for (;;) {
270 char *base;
271
272 base = strrchr(path, '/');
273 if (!base)
274 break;
275 base[0] = '\0';
276 err = dev_rmdir(path);
277 if (err)
278 break;
279 }
280
281 kfree(path);
282 return err;
283}
284
285static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
286{
287 /* did we create it */
288 if (inode->i_private != &thread)
289 return 0;
290
291 /* does the dev_t match */
292 if (is_blockdev(dev)) {
293 if (!S_ISBLK(stat->mode))
294 return 0;
295 } else {
296 if (!S_ISCHR(stat->mode))
297 return 0;
298 }
299 if (stat->rdev != dev->devt)
300 return 0;
301
302 /* ours */
303 return 1;
304}
305
306static int handle_remove(const char *nodename, struct device *dev)
307{
308 struct nameidata nd;
309 struct dentry *dentry;
310 struct kstat stat;
311 int deleted = 1;
312 int err;
313
314 err = kern_path_parent(nodename, &nd);
315 if (err)
316 return err;
317
318 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
319 dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
320 if (!IS_ERR(dentry)) {
321 if (dentry->d_inode) {
322 err = vfs_getattr(nd.path.mnt, dentry, &stat);
323 if (!err && dev_mynode(dev, dentry->d_inode, &stat)) {
324 struct iattr newattrs;
325 /*
326 * before unlinking this node, reset permissions
327 * of possible references like hardlinks
328 */
329 newattrs.ia_uid = 0;
330 newattrs.ia_gid = 0;
331 newattrs.ia_mode = stat.mode & ~0777;
332 newattrs.ia_valid =
333 ATTR_UID|ATTR_GID|ATTR_MODE;
334 mutex_lock(&dentry->d_inode->i_mutex);
335 notify_change(dentry, &newattrs);
336 mutex_unlock(&dentry->d_inode->i_mutex);
337 err = vfs_unlink(nd.path.dentry->d_inode,
338 dentry);
339 if (!err || err == -ENOENT)
340 deleted = 1;
341 }
342 } else {
343 err = -ENOENT;
344 }
345 dput(dentry);
346 } else {
347 err = PTR_ERR(dentry);
348 }
349 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
350
351 path_put(&nd.path);
352 if (deleted && strchr(nodename, '/'))
353 delete_path(nodename);
354 return err;
355}
356
357/*
358 * If configured, or requested by the commandline, devtmpfs will be
359 * auto-mounted after the kernel mounted the root filesystem.
360 */
361int devtmpfs_mount(const char *mntdir)
362{
363 int err;
364
365 if (!mount_dev)
366 return 0;
367
368 if (!thread)
369 return 0;
370
371 err = sys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT, NULL);
372 if (err)
373 printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
374 else
375 printk(KERN_INFO "devtmpfs: mounted\n");
376 return err;
377}
378
379static DECLARE_COMPLETION(setup_done);
380
381static int handle(const char *name, mode_t mode, struct device *dev)
382{
383 if (mode)
384 return handle_create(name, mode, dev);
385 else
386 return handle_remove(name, dev);
387}
388
389static int devtmpfsd(void *p)
390{
391 char options[] = "mode=0755";
392 int *err = p;
393 *err = sys_unshare(CLONE_NEWNS);
394 if (*err)
395 goto out;
396 *err = sys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, options);
397 if (*err)
398 goto out;
399 sys_chdir("/.."); /* will traverse into overmounted root */
400 sys_chroot(".");
401 complete(&setup_done);
402 while (1) {
403 spin_lock(&req_lock);
404 while (requests) {
405 struct req *req = requests;
406 requests = NULL;
407 spin_unlock(&req_lock);
408 while (req) {
409 struct req *next = req->next;
410 req->err = handle(req->name, req->mode, req->dev);
411 complete(&req->done);
412 req = next;
413 }
414 spin_lock(&req_lock);
415 }
416 set_current_state(TASK_INTERRUPTIBLE);
417 spin_unlock(&req_lock);
418 schedule();
419 __set_current_state(TASK_RUNNING);
420 }
421 return 0;
422out:
423 complete(&setup_done);
424 return *err;
425}
426
427/*
428 * Create devtmpfs instance, driver-core devices will add their device
429 * nodes here.
430 */
431int __init devtmpfs_init(void)
432{
433 int err = register_filesystem(&dev_fs_type);
434 if (err) {
435 printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
436 "type %i\n", err);
437 return err;
438 }
439
440 thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
441 if (!IS_ERR(thread)) {
442 wait_for_completion(&setup_done);
443 } else {
444 err = PTR_ERR(thread);
445 thread = NULL;
446 }
447
448 if (err) {
449 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
450 unregister_filesystem(&dev_fs_type);
451 return err;
452 }
453
454 printk(KERN_INFO "devtmpfs: initialized\n");
455 return 0;
456}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * devtmpfs - kernel-maintained tmpfs-based /dev
4 *
5 * Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
6 *
7 * During bootup, before any driver core device is registered,
8 * devtmpfs, a tmpfs-based filesystem is created. Every driver-core
9 * device which requests a device node, will add a node in this
10 * filesystem.
11 * By default, all devices are named after the name of the device,
12 * owned by root and have a default mode of 0600. Subsystems can
13 * overwrite the default setting if needed.
14 */
15
16#include <linux/kernel.h>
17#include <linux/syscalls.h>
18#include <linux/mount.h>
19#include <linux/device.h>
20#include <linux/genhd.h>
21#include <linux/namei.h>
22#include <linux/fs.h>
23#include <linux/shmem_fs.h>
24#include <linux/ramfs.h>
25#include <linux/sched.h>
26#include <linux/slab.h>
27#include <linux/kthread.h>
28#include <linux/init_syscalls.h>
29#include <uapi/linux/mount.h>
30#include "base.h"
31
32static struct task_struct *thread;
33
34static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);
35
36static DEFINE_SPINLOCK(req_lock);
37
38static struct req {
39 struct req *next;
40 struct completion done;
41 int err;
42 const char *name;
43 umode_t mode; /* 0 => delete */
44 kuid_t uid;
45 kgid_t gid;
46 struct device *dev;
47} *requests;
48
49static int __init mount_param(char *str)
50{
51 mount_dev = simple_strtoul(str, NULL, 0);
52 return 1;
53}
54__setup("devtmpfs.mount=", mount_param);
55
56static struct vfsmount *mnt;
57
58static struct dentry *public_dev_mount(struct file_system_type *fs_type, int flags,
59 const char *dev_name, void *data)
60{
61 struct super_block *s = mnt->mnt_sb;
62 atomic_inc(&s->s_active);
63 down_write(&s->s_umount);
64 return dget(s->s_root);
65}
66
67static struct file_system_type internal_fs_type = {
68 .name = "devtmpfs",
69#ifdef CONFIG_TMPFS
70 .init_fs_context = shmem_init_fs_context,
71 .parameters = shmem_fs_parameters,
72#else
73 .init_fs_context = ramfs_init_fs_context,
74 .parameters = ramfs_fs_parameters,
75#endif
76 .kill_sb = kill_litter_super,
77};
78
79static struct file_system_type dev_fs_type = {
80 .name = "devtmpfs",
81 .mount = public_dev_mount,
82};
83
84#ifdef CONFIG_BLOCK
85static inline int is_blockdev(struct device *dev)
86{
87 return dev->class == &block_class;
88}
89#else
90static inline int is_blockdev(struct device *dev) { return 0; }
91#endif
92
93static int devtmpfs_submit_req(struct req *req, const char *tmp)
94{
95 init_completion(&req->done);
96
97 spin_lock(&req_lock);
98 req->next = requests;
99 requests = req;
100 spin_unlock(&req_lock);
101
102 wake_up_process(thread);
103 wait_for_completion(&req->done);
104
105 kfree(tmp);
106
107 return req->err;
108}
109
110int devtmpfs_create_node(struct device *dev)
111{
112 const char *tmp = NULL;
113 struct req req;
114
115 if (!thread)
116 return 0;
117
118 req.mode = 0;
119 req.uid = GLOBAL_ROOT_UID;
120 req.gid = GLOBAL_ROOT_GID;
121 req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
122 if (!req.name)
123 return -ENOMEM;
124
125 if (req.mode == 0)
126 req.mode = 0600;
127 if (is_blockdev(dev))
128 req.mode |= S_IFBLK;
129 else
130 req.mode |= S_IFCHR;
131
132 req.dev = dev;
133
134 return devtmpfs_submit_req(&req, tmp);
135}
136
137int devtmpfs_delete_node(struct device *dev)
138{
139 const char *tmp = NULL;
140 struct req req;
141
142 if (!thread)
143 return 0;
144
145 req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
146 if (!req.name)
147 return -ENOMEM;
148
149 req.mode = 0;
150 req.dev = dev;
151
152 return devtmpfs_submit_req(&req, tmp);
153}
154
155static int dev_mkdir(const char *name, umode_t mode)
156{
157 struct dentry *dentry;
158 struct path path;
159 int err;
160
161 dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
162 if (IS_ERR(dentry))
163 return PTR_ERR(dentry);
164
165 err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
166 if (!err)
167 /* mark as kernel-created inode */
168 d_inode(dentry)->i_private = &thread;
169 done_path_create(&path, dentry);
170 return err;
171}
172
173static int create_path(const char *nodepath)
174{
175 char *path;
176 char *s;
177 int err = 0;
178
179 /* parent directories do not exist, create them */
180 path = kstrdup(nodepath, GFP_KERNEL);
181 if (!path)
182 return -ENOMEM;
183
184 s = path;
185 for (;;) {
186 s = strchr(s, '/');
187 if (!s)
188 break;
189 s[0] = '\0';
190 err = dev_mkdir(path, 0755);
191 if (err && err != -EEXIST)
192 break;
193 s[0] = '/';
194 s++;
195 }
196 kfree(path);
197 return err;
198}
199
200static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
201 kgid_t gid, struct device *dev)
202{
203 struct dentry *dentry;
204 struct path path;
205 int err;
206
207 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
208 if (dentry == ERR_PTR(-ENOENT)) {
209 create_path(nodename);
210 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
211 }
212 if (IS_ERR(dentry))
213 return PTR_ERR(dentry);
214
215 err = vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
216 if (!err) {
217 struct iattr newattrs;
218
219 newattrs.ia_mode = mode;
220 newattrs.ia_uid = uid;
221 newattrs.ia_gid = gid;
222 newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
223 inode_lock(d_inode(dentry));
224 notify_change(dentry, &newattrs, NULL);
225 inode_unlock(d_inode(dentry));
226
227 /* mark as kernel-created inode */
228 d_inode(dentry)->i_private = &thread;
229 }
230 done_path_create(&path, dentry);
231 return err;
232}
233
234static int dev_rmdir(const char *name)
235{
236 struct path parent;
237 struct dentry *dentry;
238 int err;
239
240 dentry = kern_path_locked(name, &parent);
241 if (IS_ERR(dentry))
242 return PTR_ERR(dentry);
243 if (d_really_is_positive(dentry)) {
244 if (d_inode(dentry)->i_private == &thread)
245 err = vfs_rmdir(d_inode(parent.dentry), dentry);
246 else
247 err = -EPERM;
248 } else {
249 err = -ENOENT;
250 }
251 dput(dentry);
252 inode_unlock(d_inode(parent.dentry));
253 path_put(&parent);
254 return err;
255}
256
257static int delete_path(const char *nodepath)
258{
259 char *path;
260 int err = 0;
261
262 path = kstrdup(nodepath, GFP_KERNEL);
263 if (!path)
264 return -ENOMEM;
265
266 for (;;) {
267 char *base;
268
269 base = strrchr(path, '/');
270 if (!base)
271 break;
272 base[0] = '\0';
273 err = dev_rmdir(path);
274 if (err)
275 break;
276 }
277
278 kfree(path);
279 return err;
280}
281
282static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
283{
284 /* did we create it */
285 if (inode->i_private != &thread)
286 return 0;
287
288 /* does the dev_t match */
289 if (is_blockdev(dev)) {
290 if (!S_ISBLK(stat->mode))
291 return 0;
292 } else {
293 if (!S_ISCHR(stat->mode))
294 return 0;
295 }
296 if (stat->rdev != dev->devt)
297 return 0;
298
299 /* ours */
300 return 1;
301}
302
303static int handle_remove(const char *nodename, struct device *dev)
304{
305 struct path parent;
306 struct dentry *dentry;
307 int deleted = 0;
308 int err;
309
310 dentry = kern_path_locked(nodename, &parent);
311 if (IS_ERR(dentry))
312 return PTR_ERR(dentry);
313
314 if (d_really_is_positive(dentry)) {
315 struct kstat stat;
316 struct path p = {.mnt = parent.mnt, .dentry = dentry};
317 err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
318 AT_STATX_SYNC_AS_STAT);
319 if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
320 struct iattr newattrs;
321 /*
322 * before unlinking this node, reset permissions
323 * of possible references like hardlinks
324 */
325 newattrs.ia_uid = GLOBAL_ROOT_UID;
326 newattrs.ia_gid = GLOBAL_ROOT_GID;
327 newattrs.ia_mode = stat.mode & ~0777;
328 newattrs.ia_valid =
329 ATTR_UID|ATTR_GID|ATTR_MODE;
330 inode_lock(d_inode(dentry));
331 notify_change(dentry, &newattrs, NULL);
332 inode_unlock(d_inode(dentry));
333 err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
334 if (!err || err == -ENOENT)
335 deleted = 1;
336 }
337 } else {
338 err = -ENOENT;
339 }
340 dput(dentry);
341 inode_unlock(d_inode(parent.dentry));
342
343 path_put(&parent);
344 if (deleted && strchr(nodename, '/'))
345 delete_path(nodename);
346 return err;
347}
348
349/*
350 * If configured, or requested by the commandline, devtmpfs will be
351 * auto-mounted after the kernel mounted the root filesystem.
352 */
353int __init devtmpfs_mount(void)
354{
355 int err;
356
357 if (!mount_dev)
358 return 0;
359
360 if (!thread)
361 return 0;
362
363 err = init_mount("devtmpfs", "dev", "devtmpfs", MS_SILENT, NULL);
364 if (err)
365 printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
366 else
367 printk(KERN_INFO "devtmpfs: mounted\n");
368 return err;
369}
370
371static DECLARE_COMPLETION(setup_done);
372
373static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
374 struct device *dev)
375{
376 if (mode)
377 return handle_create(name, mode, uid, gid, dev);
378 else
379 return handle_remove(name, dev);
380}
381
382static void __noreturn devtmpfs_work_loop(void)
383{
384 while (1) {
385 spin_lock(&req_lock);
386 while (requests) {
387 struct req *req = requests;
388 requests = NULL;
389 spin_unlock(&req_lock);
390 while (req) {
391 struct req *next = req->next;
392 req->err = handle(req->name, req->mode,
393 req->uid, req->gid, req->dev);
394 complete(&req->done);
395 req = next;
396 }
397 spin_lock(&req_lock);
398 }
399 __set_current_state(TASK_INTERRUPTIBLE);
400 spin_unlock(&req_lock);
401 schedule();
402 }
403}
404
405static int __init devtmpfs_setup(void *p)
406{
407 int err;
408
409 err = ksys_unshare(CLONE_NEWNS);
410 if (err)
411 goto out;
412 err = init_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
413 if (err)
414 goto out;
415 init_chdir("/.."); /* will traverse into overmounted root */
416 init_chroot(".");
417out:
418 *(int *)p = err;
419 complete(&setup_done);
420 return err;
421}
422
423/*
424 * The __ref is because devtmpfs_setup needs to be __init for the routines it
425 * calls. That call is done while devtmpfs_init, which is marked __init,
426 * synchronously waits for it to complete.
427 */
428static int __ref devtmpfsd(void *p)
429{
430 int err = devtmpfs_setup(p);
431
432 if (err)
433 return err;
434 devtmpfs_work_loop();
435 return 0;
436}
437
438/*
439 * Create devtmpfs instance, driver-core devices will add their device
440 * nodes here.
441 */
442int __init devtmpfs_init(void)
443{
444 char opts[] = "mode=0755";
445 int err;
446
447 mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
448 if (IS_ERR(mnt)) {
449 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
450 PTR_ERR(mnt));
451 return PTR_ERR(mnt);
452 }
453 err = register_filesystem(&dev_fs_type);
454 if (err) {
455 printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
456 "type %i\n", err);
457 return err;
458 }
459
460 thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
461 if (!IS_ERR(thread)) {
462 wait_for_completion(&setup_done);
463 } else {
464 err = PTR_ERR(thread);
465 thread = NULL;
466 }
467
468 if (err) {
469 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
470 unregister_filesystem(&dev_fs_type);
471 return err;
472 }
473
474 printk(KERN_INFO "devtmpfs: initialized\n");
475 return 0;
476}