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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/blkdev.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
32#ifdef CONFIG_DEVTMPFS_SAFE
33#define DEVTMPFS_MFLAGS (MS_SILENT | MS_NOEXEC | MS_NOSUID)
34#else
35#define DEVTMPFS_MFLAGS (MS_SILENT)
36#endif
37
38static struct task_struct *thread;
39
40static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);
41
42static DEFINE_SPINLOCK(req_lock);
43
44static struct req {
45 struct req *next;
46 struct completion done;
47 int err;
48 const char *name;
49 umode_t mode; /* 0 => delete */
50 kuid_t uid;
51 kgid_t gid;
52 struct device *dev;
53} *requests;
54
55static int __init mount_param(char *str)
56{
57 mount_dev = simple_strtoul(str, NULL, 0);
58 return 1;
59}
60__setup("devtmpfs.mount=", mount_param);
61
62static struct vfsmount *mnt;
63
64static struct dentry *public_dev_mount(struct file_system_type *fs_type, int flags,
65 const char *dev_name, void *data)
66{
67 struct super_block *s = mnt->mnt_sb;
68 int err;
69
70 atomic_inc(&s->s_active);
71 down_write(&s->s_umount);
72 err = reconfigure_single(s, flags, data);
73 if (err < 0) {
74 deactivate_locked_super(s);
75 return ERR_PTR(err);
76 }
77 return dget(s->s_root);
78}
79
80static struct file_system_type internal_fs_type = {
81 .name = "devtmpfs",
82#ifdef CONFIG_TMPFS
83 .init_fs_context = shmem_init_fs_context,
84#else
85 .init_fs_context = ramfs_init_fs_context,
86#endif
87 .kill_sb = kill_litter_super,
88};
89
90static struct file_system_type dev_fs_type = {
91 .name = "devtmpfs",
92 .mount = public_dev_mount,
93};
94
95#ifdef CONFIG_BLOCK
96static inline int is_blockdev(struct device *dev)
97{
98 return dev->class == &block_class;
99}
100#else
101static inline int is_blockdev(struct device *dev) { return 0; }
102#endif
103
104static int devtmpfs_submit_req(struct req *req, const char *tmp)
105{
106 init_completion(&req->done);
107
108 spin_lock(&req_lock);
109 req->next = requests;
110 requests = req;
111 spin_unlock(&req_lock);
112
113 wake_up_process(thread);
114 wait_for_completion(&req->done);
115
116 kfree(tmp);
117
118 return req->err;
119}
120
121int devtmpfs_create_node(struct device *dev)
122{
123 const char *tmp = NULL;
124 struct req req;
125
126 if (!thread)
127 return 0;
128
129 req.mode = 0;
130 req.uid = GLOBAL_ROOT_UID;
131 req.gid = GLOBAL_ROOT_GID;
132 req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
133 if (!req.name)
134 return -ENOMEM;
135
136 if (req.mode == 0)
137 req.mode = 0600;
138 if (is_blockdev(dev))
139 req.mode |= S_IFBLK;
140 else
141 req.mode |= S_IFCHR;
142
143 req.dev = dev;
144
145 return devtmpfs_submit_req(&req, tmp);
146}
147
148int devtmpfs_delete_node(struct device *dev)
149{
150 const char *tmp = NULL;
151 struct req req;
152
153 if (!thread)
154 return 0;
155
156 req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
157 if (!req.name)
158 return -ENOMEM;
159
160 req.mode = 0;
161 req.dev = dev;
162
163 return devtmpfs_submit_req(&req, tmp);
164}
165
166static int dev_mkdir(const char *name, umode_t mode)
167{
168 struct dentry *dentry;
169 struct path path;
170 int err;
171
172 dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
173 if (IS_ERR(dentry))
174 return PTR_ERR(dentry);
175
176 err = vfs_mkdir(&init_user_ns, d_inode(path.dentry), dentry, mode);
177 if (!err)
178 /* mark as kernel-created inode */
179 d_inode(dentry)->i_private = &thread;
180 done_path_create(&path, dentry);
181 return err;
182}
183
184static int create_path(const char *nodepath)
185{
186 char *path;
187 char *s;
188 int err = 0;
189
190 /* parent directories do not exist, create them */
191 path = kstrdup(nodepath, GFP_KERNEL);
192 if (!path)
193 return -ENOMEM;
194
195 s = path;
196 for (;;) {
197 s = strchr(s, '/');
198 if (!s)
199 break;
200 s[0] = '\0';
201 err = dev_mkdir(path, 0755);
202 if (err && err != -EEXIST)
203 break;
204 s[0] = '/';
205 s++;
206 }
207 kfree(path);
208 return err;
209}
210
211static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
212 kgid_t gid, struct device *dev)
213{
214 struct dentry *dentry;
215 struct path path;
216 int err;
217
218 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
219 if (dentry == ERR_PTR(-ENOENT)) {
220 create_path(nodename);
221 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
222 }
223 if (IS_ERR(dentry))
224 return PTR_ERR(dentry);
225
226 err = vfs_mknod(&init_user_ns, d_inode(path.dentry), dentry, mode,
227 dev->devt);
228 if (!err) {
229 struct iattr newattrs;
230
231 newattrs.ia_mode = mode;
232 newattrs.ia_uid = uid;
233 newattrs.ia_gid = gid;
234 newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
235 inode_lock(d_inode(dentry));
236 notify_change(&init_user_ns, dentry, &newattrs, NULL);
237 inode_unlock(d_inode(dentry));
238
239 /* mark as kernel-created inode */
240 d_inode(dentry)->i_private = &thread;
241 }
242 done_path_create(&path, dentry);
243 return err;
244}
245
246static int dev_rmdir(const char *name)
247{
248 struct path parent;
249 struct dentry *dentry;
250 int err;
251
252 dentry = kern_path_locked(name, &parent);
253 if (IS_ERR(dentry))
254 return PTR_ERR(dentry);
255 if (d_really_is_positive(dentry)) {
256 if (d_inode(dentry)->i_private == &thread)
257 err = vfs_rmdir(&init_user_ns, d_inode(parent.dentry),
258 dentry);
259 else
260 err = -EPERM;
261 } else {
262 err = -ENOENT;
263 }
264 dput(dentry);
265 inode_unlock(d_inode(parent.dentry));
266 path_put(&parent);
267 return err;
268}
269
270static int delete_path(const char *nodepath)
271{
272 char *path;
273 int err = 0;
274
275 path = kstrdup(nodepath, GFP_KERNEL);
276 if (!path)
277 return -ENOMEM;
278
279 for (;;) {
280 char *base;
281
282 base = strrchr(path, '/');
283 if (!base)
284 break;
285 base[0] = '\0';
286 err = dev_rmdir(path);
287 if (err)
288 break;
289 }
290
291 kfree(path);
292 return err;
293}
294
295static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
296{
297 /* did we create it */
298 if (inode->i_private != &thread)
299 return 0;
300
301 /* does the dev_t match */
302 if (is_blockdev(dev)) {
303 if (!S_ISBLK(stat->mode))
304 return 0;
305 } else {
306 if (!S_ISCHR(stat->mode))
307 return 0;
308 }
309 if (stat->rdev != dev->devt)
310 return 0;
311
312 /* ours */
313 return 1;
314}
315
316static int handle_remove(const char *nodename, struct device *dev)
317{
318 struct path parent;
319 struct dentry *dentry;
320 int deleted = 0;
321 int err;
322
323 dentry = kern_path_locked(nodename, &parent);
324 if (IS_ERR(dentry))
325 return PTR_ERR(dentry);
326
327 if (d_really_is_positive(dentry)) {
328 struct kstat stat;
329 struct path p = {.mnt = parent.mnt, .dentry = dentry};
330 err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
331 AT_STATX_SYNC_AS_STAT);
332 if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
333 struct iattr newattrs;
334 /*
335 * before unlinking this node, reset permissions
336 * of possible references like hardlinks
337 */
338 newattrs.ia_uid = GLOBAL_ROOT_UID;
339 newattrs.ia_gid = GLOBAL_ROOT_GID;
340 newattrs.ia_mode = stat.mode & ~0777;
341 newattrs.ia_valid =
342 ATTR_UID|ATTR_GID|ATTR_MODE;
343 inode_lock(d_inode(dentry));
344 notify_change(&init_user_ns, dentry, &newattrs, NULL);
345 inode_unlock(d_inode(dentry));
346 err = vfs_unlink(&init_user_ns, d_inode(parent.dentry),
347 dentry, NULL);
348 if (!err || err == -ENOENT)
349 deleted = 1;
350 }
351 } else {
352 err = -ENOENT;
353 }
354 dput(dentry);
355 inode_unlock(d_inode(parent.dentry));
356
357 path_put(&parent);
358 if (deleted && strchr(nodename, '/'))
359 delete_path(nodename);
360 return err;
361}
362
363/*
364 * If configured, or requested by the commandline, devtmpfs will be
365 * auto-mounted after the kernel mounted the root filesystem.
366 */
367int __init devtmpfs_mount(void)
368{
369 int err;
370
371 if (!mount_dev)
372 return 0;
373
374 if (!thread)
375 return 0;
376
377 err = init_mount("devtmpfs", "dev", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
378 if (err)
379 printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
380 else
381 printk(KERN_INFO "devtmpfs: mounted\n");
382 return err;
383}
384
385static __initdata DECLARE_COMPLETION(setup_done);
386
387static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
388 struct device *dev)
389{
390 if (mode)
391 return handle_create(name, mode, uid, gid, dev);
392 else
393 return handle_remove(name, dev);
394}
395
396static void __noreturn devtmpfs_work_loop(void)
397{
398 while (1) {
399 spin_lock(&req_lock);
400 while (requests) {
401 struct req *req = requests;
402 requests = NULL;
403 spin_unlock(&req_lock);
404 while (req) {
405 struct req *next = req->next;
406 req->err = handle(req->name, req->mode,
407 req->uid, req->gid, req->dev);
408 complete(&req->done);
409 req = next;
410 }
411 spin_lock(&req_lock);
412 }
413 __set_current_state(TASK_INTERRUPTIBLE);
414 spin_unlock(&req_lock);
415 schedule();
416 }
417}
418
419static noinline int __init devtmpfs_setup(void *p)
420{
421 int err;
422
423 err = ksys_unshare(CLONE_NEWNS);
424 if (err)
425 goto out;
426 err = init_mount("devtmpfs", "/", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
427 if (err)
428 goto out;
429 init_chdir("/.."); /* will traverse into overmounted root */
430 init_chroot(".");
431out:
432 *(int *)p = err;
433 return err;
434}
435
436/*
437 * The __ref is because devtmpfs_setup needs to be __init for the routines it
438 * calls. That call is done while devtmpfs_init, which is marked __init,
439 * synchronously waits for it to complete.
440 */
441static int __ref devtmpfsd(void *p)
442{
443 int err = devtmpfs_setup(p);
444
445 complete(&setup_done);
446 if (err)
447 return err;
448 devtmpfs_work_loop();
449 return 0;
450}
451
452/*
453 * Create devtmpfs instance, driver-core devices will add their device
454 * nodes here.
455 */
456int __init devtmpfs_init(void)
457{
458 char opts[] = "mode=0755";
459 int err;
460
461 mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
462 if (IS_ERR(mnt)) {
463 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
464 PTR_ERR(mnt));
465 return PTR_ERR(mnt);
466 }
467 err = register_filesystem(&dev_fs_type);
468 if (err) {
469 printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
470 "type %i\n", err);
471 return err;
472 }
473
474 thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
475 if (!IS_ERR(thread)) {
476 wait_for_completion(&setup_done);
477 } else {
478 err = PTR_ERR(thread);
479 thread = NULL;
480 }
481
482 if (err) {
483 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
484 unregister_filesystem(&dev_fs_type);
485 thread = NULL;
486 return err;
487 }
488
489 printk(KERN_INFO "devtmpfs: initialized\n");
490 return 0;
491}
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 "base.h"
29
30static struct task_struct *thread;
31
32#if defined CONFIG_DEVTMPFS_MOUNT
33static int mount_dev = 1;
34#else
35static int mount_dev;
36#endif
37
38static DEFINE_SPINLOCK(req_lock);
39
40static struct req {
41 struct req *next;
42 struct completion done;
43 int err;
44 const char *name;
45 umode_t mode; /* 0 => delete */
46 kuid_t uid;
47 kgid_t gid;
48 struct device *dev;
49} *requests;
50
51static int __init mount_param(char *str)
52{
53 mount_dev = simple_strtoul(str, NULL, 0);
54 return 1;
55}
56__setup("devtmpfs.mount=", mount_param);
57
58static struct dentry *dev_mount(struct file_system_type *fs_type, int flags,
59 const char *dev_name, void *data)
60{
61#ifdef CONFIG_TMPFS
62 return mount_single(fs_type, flags, data, shmem_fill_super);
63#else
64 return mount_single(fs_type, flags, data, ramfs_fill_super);
65#endif
66}
67
68static struct file_system_type dev_fs_type = {
69 .name = "devtmpfs",
70 .mount = dev_mount,
71 .kill_sb = kill_litter_super,
72};
73
74#ifdef CONFIG_BLOCK
75static inline int is_blockdev(struct device *dev)
76{
77 return dev->class == &block_class;
78}
79#else
80static inline int is_blockdev(struct device *dev) { return 0; }
81#endif
82
83int devtmpfs_create_node(struct device *dev)
84{
85 const char *tmp = NULL;
86 struct req req;
87
88 if (!thread)
89 return 0;
90
91 req.mode = 0;
92 req.uid = GLOBAL_ROOT_UID;
93 req.gid = GLOBAL_ROOT_GID;
94 req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
95 if (!req.name)
96 return -ENOMEM;
97
98 if (req.mode == 0)
99 req.mode = 0600;
100 if (is_blockdev(dev))
101 req.mode |= S_IFBLK;
102 else
103 req.mode |= S_IFCHR;
104
105 req.dev = dev;
106
107 init_completion(&req.done);
108
109 spin_lock(&req_lock);
110 req.next = requests;
111 requests = &req;
112 spin_unlock(&req_lock);
113
114 wake_up_process(thread);
115 wait_for_completion(&req.done);
116
117 kfree(tmp);
118
119 return req.err;
120}
121
122int devtmpfs_delete_node(struct device *dev)
123{
124 const char *tmp = NULL;
125 struct req req;
126
127 if (!thread)
128 return 0;
129
130 req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
131 if (!req.name)
132 return -ENOMEM;
133
134 req.mode = 0;
135 req.dev = dev;
136
137 init_completion(&req.done);
138
139 spin_lock(&req_lock);
140 req.next = requests;
141 requests = &req;
142 spin_unlock(&req_lock);
143
144 wake_up_process(thread);
145 wait_for_completion(&req.done);
146
147 kfree(tmp);
148 return req.err;
149}
150
151static int dev_mkdir(const char *name, umode_t mode)
152{
153 struct dentry *dentry;
154 struct path path;
155 int err;
156
157 dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
158 if (IS_ERR(dentry))
159 return PTR_ERR(dentry);
160
161 err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
162 if (!err)
163 /* mark as kernel-created inode */
164 d_inode(dentry)->i_private = &thread;
165 done_path_create(&path, dentry);
166 return err;
167}
168
169static int create_path(const char *nodepath)
170{
171 char *path;
172 char *s;
173 int err = 0;
174
175 /* parent directories do not exist, create them */
176 path = kstrdup(nodepath, GFP_KERNEL);
177 if (!path)
178 return -ENOMEM;
179
180 s = path;
181 for (;;) {
182 s = strchr(s, '/');
183 if (!s)
184 break;
185 s[0] = '\0';
186 err = dev_mkdir(path, 0755);
187 if (err && err != -EEXIST)
188 break;
189 s[0] = '/';
190 s++;
191 }
192 kfree(path);
193 return err;
194}
195
196static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
197 kgid_t gid, struct device *dev)
198{
199 struct dentry *dentry;
200 struct path path;
201 int err;
202
203 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
204 if (dentry == ERR_PTR(-ENOENT)) {
205 create_path(nodename);
206 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
207 }
208 if (IS_ERR(dentry))
209 return PTR_ERR(dentry);
210
211 err = vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
212 if (!err) {
213 struct iattr newattrs;
214
215 newattrs.ia_mode = mode;
216 newattrs.ia_uid = uid;
217 newattrs.ia_gid = gid;
218 newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
219 inode_lock(d_inode(dentry));
220 notify_change(dentry, &newattrs, NULL);
221 inode_unlock(d_inode(dentry));
222
223 /* mark as kernel-created inode */
224 d_inode(dentry)->i_private = &thread;
225 }
226 done_path_create(&path, dentry);
227 return err;
228}
229
230static int dev_rmdir(const char *name)
231{
232 struct path parent;
233 struct dentry *dentry;
234 int err;
235
236 dentry = kern_path_locked(name, &parent);
237 if (IS_ERR(dentry))
238 return PTR_ERR(dentry);
239 if (d_really_is_positive(dentry)) {
240 if (d_inode(dentry)->i_private == &thread)
241 err = vfs_rmdir(d_inode(parent.dentry), dentry);
242 else
243 err = -EPERM;
244 } else {
245 err = -ENOENT;
246 }
247 dput(dentry);
248 inode_unlock(d_inode(parent.dentry));
249 path_put(&parent);
250 return err;
251}
252
253static int delete_path(const char *nodepath)
254{
255 const char *path;
256 int err = 0;
257
258 path = kstrdup(nodepath, GFP_KERNEL);
259 if (!path)
260 return -ENOMEM;
261
262 for (;;) {
263 char *base;
264
265 base = strrchr(path, '/');
266 if (!base)
267 break;
268 base[0] = '\0';
269 err = dev_rmdir(path);
270 if (err)
271 break;
272 }
273
274 kfree(path);
275 return err;
276}
277
278static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
279{
280 /* did we create it */
281 if (inode->i_private != &thread)
282 return 0;
283
284 /* does the dev_t match */
285 if (is_blockdev(dev)) {
286 if (!S_ISBLK(stat->mode))
287 return 0;
288 } else {
289 if (!S_ISCHR(stat->mode))
290 return 0;
291 }
292 if (stat->rdev != dev->devt)
293 return 0;
294
295 /* ours */
296 return 1;
297}
298
299static int handle_remove(const char *nodename, struct device *dev)
300{
301 struct path parent;
302 struct dentry *dentry;
303 int deleted = 0;
304 int err;
305
306 dentry = kern_path_locked(nodename, &parent);
307 if (IS_ERR(dentry))
308 return PTR_ERR(dentry);
309
310 if (d_really_is_positive(dentry)) {
311 struct kstat stat;
312 struct path p = {.mnt = parent.mnt, .dentry = dentry};
313 err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
314 AT_STATX_SYNC_AS_STAT);
315 if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
316 struct iattr newattrs;
317 /*
318 * before unlinking this node, reset permissions
319 * of possible references like hardlinks
320 */
321 newattrs.ia_uid = GLOBAL_ROOT_UID;
322 newattrs.ia_gid = GLOBAL_ROOT_GID;
323 newattrs.ia_mode = stat.mode & ~0777;
324 newattrs.ia_valid =
325 ATTR_UID|ATTR_GID|ATTR_MODE;
326 inode_lock(d_inode(dentry));
327 notify_change(dentry, &newattrs, NULL);
328 inode_unlock(d_inode(dentry));
329 err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
330 if (!err || err == -ENOENT)
331 deleted = 1;
332 }
333 } else {
334 err = -ENOENT;
335 }
336 dput(dentry);
337 inode_unlock(d_inode(parent.dentry));
338
339 path_put(&parent);
340 if (deleted && strchr(nodename, '/'))
341 delete_path(nodename);
342 return err;
343}
344
345/*
346 * If configured, or requested by the commandline, devtmpfs will be
347 * auto-mounted after the kernel mounted the root filesystem.
348 */
349int devtmpfs_mount(const char *mntdir)
350{
351 int err;
352
353 if (!mount_dev)
354 return 0;
355
356 if (!thread)
357 return 0;
358
359 err = ksys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT,
360 NULL);
361 if (err)
362 printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
363 else
364 printk(KERN_INFO "devtmpfs: mounted\n");
365 return err;
366}
367
368static DECLARE_COMPLETION(setup_done);
369
370static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
371 struct device *dev)
372{
373 if (mode)
374 return handle_create(name, mode, uid, gid, dev);
375 else
376 return handle_remove(name, dev);
377}
378
379static int devtmpfsd(void *p)
380{
381 char options[] = "mode=0755";
382 int *err = p;
383 *err = ksys_unshare(CLONE_NEWNS);
384 if (*err)
385 goto out;
386 *err = ksys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, options);
387 if (*err)
388 goto out;
389 ksys_chdir("/.."); /* will traverse into overmounted root */
390 ksys_chroot(".");
391 complete(&setup_done);
392 while (1) {
393 spin_lock(&req_lock);
394 while (requests) {
395 struct req *req = requests;
396 requests = NULL;
397 spin_unlock(&req_lock);
398 while (req) {
399 struct req *next = req->next;
400 req->err = handle(req->name, req->mode,
401 req->uid, req->gid, req->dev);
402 complete(&req->done);
403 req = next;
404 }
405 spin_lock(&req_lock);
406 }
407 __set_current_state(TASK_INTERRUPTIBLE);
408 spin_unlock(&req_lock);
409 schedule();
410 }
411 return 0;
412out:
413 complete(&setup_done);
414 return *err;
415}
416
417/*
418 * Create devtmpfs instance, driver-core devices will add their device
419 * nodes here.
420 */
421int __init devtmpfs_init(void)
422{
423 int err = register_filesystem(&dev_fs_type);
424 if (err) {
425 printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
426 "type %i\n", err);
427 return err;
428 }
429
430 thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
431 if (!IS_ERR(thread)) {
432 wait_for_completion(&setup_done);
433 } else {
434 err = PTR_ERR(thread);
435 thread = NULL;
436 }
437
438 if (err) {
439 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
440 unregister_filesystem(&dev_fs_type);
441 return err;
442 }
443
444 printk(KERN_INFO "devtmpfs: initialized\n");
445 return 0;
446}