xref: /freebsd/sys/fs/devfs/devfs_devs.c (revision 0d972b25f64dc1f52aff3fe09bc62cbaf332df83)
1 /*-
2  * Copyright (c) 2000,2004
3  *	Poul-Henning Kamp.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Neither the name of the University nor the names of its contributors
11  *    may be used to endorse or promote products derived from this software
12  *    without specific prior written permission.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  * From: FreeBSD: src/sys/miscfs/kernfs/kernfs_vfsops.c 1.36
27  *
28  * $FreeBSD$
29  */
30 
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/conf.h>
34 #include <sys/dirent.h>
35 #include <sys/kernel.h>
36 #include <sys/limits.h>
37 #include <sys/lock.h>
38 #include <sys/malloc.h>
39 #include <sys/proc.h>
40 #include <sys/sx.h>
41 #include <sys/sysctl.h>
42 #include <sys/vnode.h>
43 
44 #include <sys/kdb.h>
45 
46 #include <fs/devfs/devfs.h>
47 #include <fs/devfs/devfs_int.h>
48 
49 #include <security/mac/mac_framework.h>
50 
51 /*
52  * The one true (but secret) list of active devices in the system.
53  * Locked by dev_lock()/devmtx
54  */
55 struct cdev_priv_list cdevp_list = TAILQ_HEAD_INITIALIZER(cdevp_list);
56 
57 struct unrhdr *devfs_inos;
58 
59 
60 static MALLOC_DEFINE(M_DEVFS2, "DEVFS2", "DEVFS data 2");
61 static MALLOC_DEFINE(M_DEVFS3, "DEVFS3", "DEVFS data 3");
62 static MALLOC_DEFINE(M_CDEVP, "DEVFS1", "DEVFS cdev_priv storage");
63 
64 static SYSCTL_NODE(_vfs, OID_AUTO, devfs, CTLFLAG_RW, 0, "DEVFS filesystem");
65 
66 static unsigned devfs_generation;
67 SYSCTL_UINT(_vfs_devfs, OID_AUTO, generation, CTLFLAG_RD,
68 	&devfs_generation, 0, "DEVFS generation number");
69 
70 unsigned devfs_rule_depth = 1;
71 SYSCTL_UINT(_vfs_devfs, OID_AUTO, rule_depth, CTLFLAG_RW,
72 	&devfs_rule_depth, 0, "Max depth of ruleset include");
73 
74 /*
75  * Helper sysctl for devname(3).  We're given a dev_t and return the
76  * name, if any, registered by the device driver.
77  */
78 static int
79 sysctl_devname(SYSCTL_HANDLER_ARGS)
80 {
81 	int error;
82 	dev_t ud;
83 	struct cdev_priv *cdp;
84 	struct cdev *dev;
85 
86 	error = SYSCTL_IN(req, &ud, sizeof (ud));
87 	if (error)
88 		return (error);
89 	if (ud == NODEV)
90 		return (EINVAL);
91 	dev = NULL;
92 	dev_lock();
93 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list)
94 		if (cdp->cdp_inode == ud) {
95 			dev = &cdp->cdp_c;
96 			dev_refl(dev);
97 			break;
98 		}
99 	dev_unlock();
100 	if (dev == NULL)
101 		return (ENOENT);
102 	error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
103 	dev_rel(dev);
104 	return (error);
105 }
106 
107 SYSCTL_PROC(_kern, OID_AUTO, devname,
108     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY|CTLFLAG_MPSAFE,
109     NULL, 0, sysctl_devname, "", "devname(3) handler");
110 
111 SYSCTL_INT(_debug_sizeof, OID_AUTO, cdev, CTLFLAG_RD,
112     SYSCTL_NULL_INT_PTR, sizeof(struct cdev), "sizeof(struct cdev)");
113 
114 SYSCTL_INT(_debug_sizeof, OID_AUTO, cdev_priv, CTLFLAG_RD,
115     SYSCTL_NULL_INT_PTR, sizeof(struct cdev_priv), "sizeof(struct cdev_priv)");
116 
117 struct cdev *
118 devfs_alloc(int flags)
119 {
120 	struct cdev_priv *cdp;
121 	struct cdev *cdev;
122 	struct timespec ts;
123 
124 	cdp = malloc(sizeof *cdp, M_CDEVP, M_ZERO |
125 	    ((flags & MAKEDEV_NOWAIT) ? M_NOWAIT : M_WAITOK));
126 	if (cdp == NULL)
127 		return (NULL);
128 
129 	cdp->cdp_dirents = &cdp->cdp_dirent0;
130 	cdp->cdp_dirent0 = NULL;
131 	cdp->cdp_maxdirent = 0;
132 	cdp->cdp_inode = 0;
133 
134 	cdev = &cdp->cdp_c;
135 
136 	LIST_INIT(&cdev->si_children);
137 	vfs_timestamp(&ts);
138 	cdev->si_atime = cdev->si_mtime = cdev->si_ctime = ts;
139 	cdev->si_cred = NULL;
140 
141 	return (cdev);
142 }
143 
144 int
145 devfs_dev_exists(const char *name)
146 {
147 	struct cdev_priv *cdp;
148 
149 	mtx_assert(&devmtx, MA_OWNED);
150 
151 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list) {
152 		if ((cdp->cdp_flags & CDP_ACTIVE) == 0)
153 			continue;
154 		if (devfs_pathpath(cdp->cdp_c.si_name, name) != 0)
155 			return (1);
156 		if (devfs_pathpath(name, cdp->cdp_c.si_name) != 0)
157 			return (1);
158 	}
159 	if (devfs_dir_find(name) != 0)
160 		return (1);
161 
162 	return (0);
163 }
164 
165 void
166 devfs_free(struct cdev *cdev)
167 {
168 	struct cdev_priv *cdp;
169 
170 	cdp = cdev2priv(cdev);
171 	if (cdev->si_cred != NULL)
172 		crfree(cdev->si_cred);
173 	devfs_free_cdp_inode(cdp->cdp_inode);
174 	if (cdp->cdp_maxdirent > 0)
175 		free(cdp->cdp_dirents, M_DEVFS2);
176 	free(cdp, M_CDEVP);
177 }
178 
179 struct devfs_dirent *
180 devfs_find(struct devfs_dirent *dd, const char *name, int namelen, int type)
181 {
182 	struct devfs_dirent *de;
183 
184 	TAILQ_FOREACH(de, &dd->de_dlist, de_list) {
185 		if (namelen != de->de_dirent->d_namlen)
186 			continue;
187 		if (type != 0 && type != de->de_dirent->d_type)
188 			continue;
189 
190 		/*
191 		 * The race with finding non-active name is not
192 		 * completely closed by the check, but it is similar
193 		 * to the devfs_allocv() in making it unlikely enough.
194 		 */
195 		if (de->de_dirent->d_type == DT_CHR &&
196 		    (de->de_cdp->cdp_flags & CDP_ACTIVE) == 0)
197 			continue;
198 
199 		if (bcmp(name, de->de_dirent->d_name, namelen) != 0)
200 			continue;
201 		break;
202 	}
203 	KASSERT(de == NULL || (de->de_flags & DE_DOOMED) == 0,
204 	    ("devfs_find: returning a doomed entry"));
205 	return (de);
206 }
207 
208 struct devfs_dirent *
209 devfs_newdirent(char *name, int namelen)
210 {
211 	int i;
212 	struct devfs_dirent *de;
213 	struct dirent d;
214 
215 	d.d_namlen = namelen;
216 	i = sizeof (*de) + GENERIC_DIRSIZ(&d);
217 	de = malloc(i, M_DEVFS3, M_WAITOK | M_ZERO);
218 	de->de_dirent = (struct dirent *)(de + 1);
219 	de->de_dirent->d_namlen = namelen;
220 	de->de_dirent->d_reclen = GENERIC_DIRSIZ(&d);
221 	bcopy(name, de->de_dirent->d_name, namelen);
222 	de->de_dirent->d_name[namelen] = '\0';
223 	vfs_timestamp(&de->de_ctime);
224 	de->de_mtime = de->de_atime = de->de_ctime;
225 	de->de_links = 1;
226 	de->de_holdcnt = 1;
227 #ifdef MAC
228 	mac_devfs_init(de);
229 #endif
230 	return (de);
231 }
232 
233 struct devfs_dirent *
234 devfs_parent_dirent(struct devfs_dirent *de)
235 {
236 
237 	if (de->de_dirent->d_type != DT_DIR)
238 		return (de->de_dir);
239 
240 	if (de->de_flags & (DE_DOT | DE_DOTDOT))
241 		return (NULL);
242 
243 	de = TAILQ_FIRST(&de->de_dlist);	/* "." */
244 	if (de == NULL)
245 		return (NULL);
246 	de = TAILQ_NEXT(de, de_list);		/* ".." */
247 	if (de == NULL)
248 		return (NULL);
249 
250 	return (de->de_dir);
251 }
252 
253 struct devfs_dirent *
254 devfs_vmkdir(struct devfs_mount *dmp, char *name, int namelen, struct devfs_dirent *dotdot, u_int inode)
255 {
256 	struct devfs_dirent *dd;
257 	struct devfs_dirent *de;
258 
259 	/* Create the new directory */
260 	dd = devfs_newdirent(name, namelen);
261 	TAILQ_INIT(&dd->de_dlist);
262 	dd->de_dirent->d_type = DT_DIR;
263 	dd->de_mode = 0555;
264 	dd->de_links = 2;
265 	dd->de_dir = dd;
266 	if (inode != 0)
267 		dd->de_inode = inode;
268 	else
269 		dd->de_inode = alloc_unr(devfs_inos);
270 
271 	/*
272 	 * "." and ".." are always the two first entries in the
273 	 * de_dlist list.
274 	 *
275 	 * Create the "." entry in the new directory.
276 	 */
277 	de = devfs_newdirent(".", 1);
278 	de->de_dirent->d_type = DT_DIR;
279 	de->de_flags |= DE_DOT;
280 	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
281 	de->de_dir = dd;
282 
283 	/* Create the ".." entry in the new directory. */
284 	de = devfs_newdirent("..", 2);
285 	de->de_dirent->d_type = DT_DIR;
286 	de->de_flags |= DE_DOTDOT;
287 	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
288 	if (dotdot == NULL) {
289 		de->de_dir = dd;
290 	} else {
291 		de->de_dir = dotdot;
292 		sx_assert(&dmp->dm_lock, SX_XLOCKED);
293 		TAILQ_INSERT_TAIL(&dotdot->de_dlist, dd, de_list);
294 		dotdot->de_links++;
295 		devfs_rules_apply(dmp, dd);
296 	}
297 
298 #ifdef MAC
299 	mac_devfs_create_directory(dmp->dm_mount, name, namelen, dd);
300 #endif
301 	return (dd);
302 }
303 
304 void
305 devfs_dirent_free(struct devfs_dirent *de)
306 {
307 	free(de, M_DEVFS3);
308 }
309 
310 /*
311  * Removes a directory if it is empty. Also empty parent directories are
312  * removed recursively.
313  */
314 static void
315 devfs_rmdir_empty(struct devfs_mount *dm, struct devfs_dirent *de)
316 {
317 	struct devfs_dirent *dd, *de_dot, *de_dotdot;
318 
319 	sx_assert(&dm->dm_lock, SX_XLOCKED);
320 
321 	for (;;) {
322 		KASSERT(de->de_dirent->d_type == DT_DIR,
323 		    ("devfs_rmdir_empty: de is not a directory"));
324 
325 		if ((de->de_flags & DE_DOOMED) != 0 || de == dm->dm_rootdir)
326 			return;
327 
328 		de_dot = TAILQ_FIRST(&de->de_dlist);
329 		KASSERT(de_dot != NULL, ("devfs_rmdir_empty: . missing"));
330 		de_dotdot = TAILQ_NEXT(de_dot, de_list);
331 		KASSERT(de_dotdot != NULL, ("devfs_rmdir_empty: .. missing"));
332 		/* Return if the directory is not empty. */
333 		if (TAILQ_NEXT(de_dotdot, de_list) != NULL)
334 			return;
335 
336 		dd = devfs_parent_dirent(de);
337 		KASSERT(dd != NULL, ("devfs_rmdir_empty: NULL dd"));
338 		TAILQ_REMOVE(&de->de_dlist, de_dot, de_list);
339 		TAILQ_REMOVE(&de->de_dlist, de_dotdot, de_list);
340 		TAILQ_REMOVE(&dd->de_dlist, de, de_list);
341 		DEVFS_DE_HOLD(dd);
342 		devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
343 		devfs_delete(dm, de_dot, DEVFS_DEL_NORECURSE);
344 		devfs_delete(dm, de_dotdot, DEVFS_DEL_NORECURSE);
345 		if (DEVFS_DE_DROP(dd)) {
346 			devfs_dirent_free(dd);
347 			return;
348 		}
349 
350 		de = dd;
351 	}
352 }
353 
354 /*
355  * The caller needs to hold the dm for the duration of the call since
356  * dm->dm_lock may be temporary dropped.
357  */
358 void
359 devfs_delete(struct devfs_mount *dm, struct devfs_dirent *de, int flags)
360 {
361 	struct devfs_dirent *dd;
362 	struct vnode *vp;
363 
364 	KASSERT((de->de_flags & DE_DOOMED) == 0,
365 		("devfs_delete doomed dirent"));
366 	de->de_flags |= DE_DOOMED;
367 
368 	if ((flags & DEVFS_DEL_NORECURSE) == 0) {
369 		dd = devfs_parent_dirent(de);
370 		if (dd != NULL)
371 			DEVFS_DE_HOLD(dd);
372 		if (de->de_flags & DE_USER) {
373 			KASSERT(dd != NULL, ("devfs_delete: NULL dd"));
374 			devfs_dir_unref_de(dm, dd);
375 		}
376 	} else
377 		dd = NULL;
378 
379 	mtx_lock(&devfs_de_interlock);
380 	vp = de->de_vnode;
381 	if (vp != NULL) {
382 		VI_LOCK(vp);
383 		mtx_unlock(&devfs_de_interlock);
384 		vholdl(vp);
385 		sx_unlock(&dm->dm_lock);
386 		if ((flags & DEVFS_DEL_VNLOCKED) == 0)
387 			vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK | LK_RETRY);
388 		else
389 			VI_UNLOCK(vp);
390 		vgone(vp);
391 		if ((flags & DEVFS_DEL_VNLOCKED) == 0)
392 			VOP_UNLOCK(vp, 0);
393 		vdrop(vp);
394 		sx_xlock(&dm->dm_lock);
395 	} else
396 		mtx_unlock(&devfs_de_interlock);
397 	if (de->de_symlink) {
398 		free(de->de_symlink, M_DEVFS);
399 		de->de_symlink = NULL;
400 	}
401 #ifdef MAC
402 	mac_devfs_destroy(de);
403 #endif
404 	if (de->de_inode > DEVFS_ROOTINO) {
405 		devfs_free_cdp_inode(de->de_inode);
406 		de->de_inode = 0;
407 	}
408 	if (DEVFS_DE_DROP(de))
409 		devfs_dirent_free(de);
410 
411 	if (dd != NULL) {
412 		if (DEVFS_DE_DROP(dd))
413 			devfs_dirent_free(dd);
414 		else
415 			devfs_rmdir_empty(dm, dd);
416 	}
417 }
418 
419 /*
420  * Called on unmount.
421  * Recursively removes the entire tree.
422  * The caller needs to hold the dm for the duration of the call.
423  */
424 
425 static void
426 devfs_purge(struct devfs_mount *dm, struct devfs_dirent *dd)
427 {
428 	struct devfs_dirent *de;
429 
430 	sx_assert(&dm->dm_lock, SX_XLOCKED);
431 
432 	DEVFS_DE_HOLD(dd);
433 	for (;;) {
434 		/*
435 		 * Use TAILQ_LAST() to remove "." and ".." last.
436 		 * We might need ".." to resolve a path in
437 		 * devfs_dir_unref_de().
438 		 */
439 		de = TAILQ_LAST(&dd->de_dlist, devfs_dlist_head);
440 		if (de == NULL)
441 			break;
442 		TAILQ_REMOVE(&dd->de_dlist, de, de_list);
443 		if (de->de_flags & DE_USER)
444 			devfs_dir_unref_de(dm, dd);
445 		if (de->de_flags & (DE_DOT | DE_DOTDOT))
446 			devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
447 		else if (de->de_dirent->d_type == DT_DIR)
448 			devfs_purge(dm, de);
449 		else
450 			devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
451 	}
452 	if (DEVFS_DE_DROP(dd))
453 		devfs_dirent_free(dd);
454 	else if ((dd->de_flags & DE_DOOMED) == 0)
455 		devfs_delete(dm, dd, DEVFS_DEL_NORECURSE);
456 }
457 
458 /*
459  * Each cdev_priv has an array of pointers to devfs_dirent which is indexed
460  * by the mount points dm_idx.
461  * This function extends the array when necessary, taking into account that
462  * the default array is 1 element and not malloc'ed.
463  */
464 static void
465 devfs_metoo(struct cdev_priv *cdp, struct devfs_mount *dm)
466 {
467 	struct devfs_dirent **dep;
468 	int siz;
469 
470 	siz = (dm->dm_idx + 1) * sizeof *dep;
471 	dep = malloc(siz, M_DEVFS2, M_WAITOK | M_ZERO);
472 	dev_lock();
473 	if (dm->dm_idx <= cdp->cdp_maxdirent) {
474 		/* We got raced */
475 		dev_unlock();
476 		free(dep, M_DEVFS2);
477 		return;
478 	}
479 	memcpy(dep, cdp->cdp_dirents, (cdp->cdp_maxdirent + 1) * sizeof *dep);
480 	if (cdp->cdp_maxdirent > 0)
481 		free(cdp->cdp_dirents, M_DEVFS2);
482 	cdp->cdp_dirents = dep;
483 	/*
484 	 * XXX: if malloc told us how much we actually got this could
485 	 * XXX: be optimized.
486 	 */
487 	cdp->cdp_maxdirent = dm->dm_idx;
488 	dev_unlock();
489 }
490 
491 /*
492  * The caller needs to hold the dm for the duration of the call.
493  */
494 static int
495 devfs_populate_loop(struct devfs_mount *dm, int cleanup)
496 {
497 	struct cdev_priv *cdp;
498 	struct devfs_dirent *de;
499 	struct devfs_dirent *dd, *dt;
500 	struct cdev *pdev;
501 	int de_flags, depth, j;
502 	char *q, *s;
503 
504 	sx_assert(&dm->dm_lock, SX_XLOCKED);
505 	dev_lock();
506 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list) {
507 
508 		KASSERT(cdp->cdp_dirents != NULL, ("NULL cdp_dirents"));
509 
510 		/*
511 		 * If we are unmounting, or the device has been destroyed,
512 		 * clean up our dirent.
513 		 */
514 		if ((cleanup || !(cdp->cdp_flags & CDP_ACTIVE)) &&
515 		    dm->dm_idx <= cdp->cdp_maxdirent &&
516 		    cdp->cdp_dirents[dm->dm_idx] != NULL) {
517 			de = cdp->cdp_dirents[dm->dm_idx];
518 			cdp->cdp_dirents[dm->dm_idx] = NULL;
519 			KASSERT(cdp == de->de_cdp,
520 			    ("%s %d %s %p %p", __func__, __LINE__,
521 			    cdp->cdp_c.si_name, cdp, de->de_cdp));
522 			KASSERT(de->de_dir != NULL, ("Null de->de_dir"));
523 			dev_unlock();
524 
525 			TAILQ_REMOVE(&de->de_dir->de_dlist, de, de_list);
526 			de->de_cdp = NULL;
527 			de->de_inode = 0;
528 			devfs_delete(dm, de, 0);
529 			dev_lock();
530 			cdp->cdp_inuse--;
531 			dev_unlock();
532 			return (1);
533 		}
534 		/*
535 	 	 * GC any lingering devices
536 		 */
537 		if (!(cdp->cdp_flags & CDP_ACTIVE)) {
538 			if (cdp->cdp_inuse > 0)
539 				continue;
540 			TAILQ_REMOVE(&cdevp_list, cdp, cdp_list);
541 			dev_unlock();
542 			dev_rel(&cdp->cdp_c);
543 			return (1);
544 		}
545 		/*
546 		 * Don't create any new dirents if we are unmounting
547 		 */
548 		if (cleanup)
549 			continue;
550 		KASSERT((cdp->cdp_flags & CDP_ACTIVE), ("Bogons, I tell ya'!"));
551 
552 		if (dm->dm_idx <= cdp->cdp_maxdirent &&
553 		    cdp->cdp_dirents[dm->dm_idx] != NULL) {
554 			de = cdp->cdp_dirents[dm->dm_idx];
555 			KASSERT(cdp == de->de_cdp, ("inconsistent cdp"));
556 			continue;
557 		}
558 
559 
560 		cdp->cdp_inuse++;
561 		dev_unlock();
562 
563 		if (dm->dm_idx > cdp->cdp_maxdirent)
564 		        devfs_metoo(cdp, dm);
565 
566 		dd = dm->dm_rootdir;
567 		s = cdp->cdp_c.si_name;
568 		for (;;) {
569 			for (q = s; *q != '/' && *q != '\0'; q++)
570 				continue;
571 			if (*q != '/')
572 				break;
573 			de = devfs_find(dd, s, q - s, 0);
574 			if (de == NULL)
575 				de = devfs_vmkdir(dm, s, q - s, dd, 0);
576 			else if (de->de_dirent->d_type == DT_LNK) {
577 				de = devfs_find(dd, s, q - s, DT_DIR);
578 				if (de == NULL)
579 					de = devfs_vmkdir(dm, s, q - s, dd, 0);
580 				de->de_flags |= DE_COVERED;
581 			}
582 			s = q + 1;
583 			dd = de;
584 			KASSERT(dd->de_dirent->d_type == DT_DIR &&
585 			    (dd->de_flags & (DE_DOT | DE_DOTDOT)) == 0,
586 			    ("%s: invalid directory (si_name=%s)",
587 			    __func__, cdp->cdp_c.si_name));
588 
589 		}
590 		de_flags = 0;
591 		de = devfs_find(dd, s, q - s, DT_LNK);
592 		if (de != NULL)
593 			de_flags |= DE_COVERED;
594 
595 		de = devfs_newdirent(s, q - s);
596 		if (cdp->cdp_c.si_flags & SI_ALIAS) {
597 			de->de_uid = 0;
598 			de->de_gid = 0;
599 			de->de_mode = 0755;
600 			de->de_dirent->d_type = DT_LNK;
601 			pdev = cdp->cdp_c.si_parent;
602 			dt = dd;
603 			depth = 0;
604 			while (dt != dm->dm_rootdir &&
605 			    (dt = devfs_parent_dirent(dt)) != NULL)
606 				depth++;
607 			j = depth * 3 + strlen(pdev->si_name) + 1;
608 			de->de_symlink = malloc(j, M_DEVFS, M_WAITOK);
609 			de->de_symlink[0] = 0;
610 			while (depth-- > 0)
611 				strcat(de->de_symlink, "../");
612 			strcat(de->de_symlink, pdev->si_name);
613 		} else {
614 			de->de_uid = cdp->cdp_c.si_uid;
615 			de->de_gid = cdp->cdp_c.si_gid;
616 			de->de_mode = cdp->cdp_c.si_mode;
617 			de->de_dirent->d_type = DT_CHR;
618 		}
619 		de->de_flags |= de_flags;
620 		de->de_inode = cdp->cdp_inode;
621 		de->de_cdp = cdp;
622 #ifdef MAC
623 		mac_devfs_create_device(cdp->cdp_c.si_cred, dm->dm_mount,
624 		    &cdp->cdp_c, de);
625 #endif
626 		de->de_dir = dd;
627 		TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
628 		devfs_rules_apply(dm, de);
629 		dev_lock();
630 		/* XXX: could check that cdp is still active here */
631 		KASSERT(cdp->cdp_dirents[dm->dm_idx] == NULL,
632 		    ("%s %d\n", __func__, __LINE__));
633 		cdp->cdp_dirents[dm->dm_idx] = de;
634 		KASSERT(de->de_cdp != (void *)0xdeadc0de,
635 		    ("%s %d\n", __func__, __LINE__));
636 		dev_unlock();
637 		return (1);
638 	}
639 	dev_unlock();
640 	return (0);
641 }
642 
643 /*
644  * The caller needs to hold the dm for the duration of the call.
645  */
646 void
647 devfs_populate(struct devfs_mount *dm)
648 {
649 	unsigned gen;
650 
651 	sx_assert(&dm->dm_lock, SX_XLOCKED);
652 	gen = devfs_generation;
653 	if (dm->dm_generation == gen)
654 		return;
655 	while (devfs_populate_loop(dm, 0))
656 		continue;
657 	dm->dm_generation = gen;
658 }
659 
660 /*
661  * The caller needs to hold the dm for the duration of the call.
662  */
663 void
664 devfs_cleanup(struct devfs_mount *dm)
665 {
666 
667 	sx_assert(&dm->dm_lock, SX_XLOCKED);
668 	while (devfs_populate_loop(dm, 1))
669 		continue;
670 	devfs_purge(dm, dm->dm_rootdir);
671 }
672 
673 /*
674  * devfs_create() and devfs_destroy() are called from kern_conf.c and
675  * in both cases the devlock() mutex is held, so no further locking
676  * is necessary and no sleeping allowed.
677  */
678 
679 void
680 devfs_create(struct cdev *dev)
681 {
682 	struct cdev_priv *cdp;
683 
684 	mtx_assert(&devmtx, MA_OWNED);
685 	cdp = cdev2priv(dev);
686 	cdp->cdp_flags |= CDP_ACTIVE;
687 	cdp->cdp_inode = alloc_unrl(devfs_inos);
688 	dev_refl(dev);
689 	TAILQ_INSERT_TAIL(&cdevp_list, cdp, cdp_list);
690 	devfs_generation++;
691 }
692 
693 void
694 devfs_destroy(struct cdev *dev)
695 {
696 	struct cdev_priv *cdp;
697 
698 	mtx_assert(&devmtx, MA_OWNED);
699 	cdp = cdev2priv(dev);
700 	cdp->cdp_flags &= ~CDP_ACTIVE;
701 	devfs_generation++;
702 }
703 
704 ino_t
705 devfs_alloc_cdp_inode(void)
706 {
707 
708 	return (alloc_unr(devfs_inos));
709 }
710 
711 void
712 devfs_free_cdp_inode(ino_t ino)
713 {
714 
715 	if (ino > 0)
716 		free_unr(devfs_inos, ino);
717 }
718 
719 static void
720 devfs_devs_init(void *junk __unused)
721 {
722 
723 	devfs_inos = new_unrhdr(DEVFS_ROOTINO + 1, INT_MAX, &devmtx);
724 }
725 
726 SYSINIT(devfs_devs, SI_SUB_DEVFS, SI_ORDER_FIRST, devfs_devs_init, NULL);
727