xref: /freebsd/sys/fs/devfs/devfs_devs.c (revision 545ddfbe7d4fe8adfb862903b24eac1d5896c1ef)
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 	 * Avoid race with dev_rel() by setting the initial
142 	 * reference count to 1. This last reference is taken
143 	 * by the destroy_dev() function.
144 	 */
145 	cdev->si_refcount = 1;
146 
147 	return (cdev);
148 }
149 
150 int
151 devfs_dev_exists(const char *name)
152 {
153 	struct cdev_priv *cdp;
154 
155 	mtx_assert(&devmtx, MA_OWNED);
156 
157 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list) {
158 		if ((cdp->cdp_flags & CDP_ACTIVE) == 0)
159 			continue;
160 		if (devfs_pathpath(cdp->cdp_c.si_name, name) != 0)
161 			return (1);
162 		if (devfs_pathpath(name, cdp->cdp_c.si_name) != 0)
163 			return (1);
164 	}
165 	if (devfs_dir_find(name) != 0)
166 		return (1);
167 
168 	return (0);
169 }
170 
171 void
172 devfs_free(struct cdev *cdev)
173 {
174 	struct cdev_priv *cdp;
175 
176 	cdp = cdev2priv(cdev);
177 	if (cdev->si_cred != NULL)
178 		crfree(cdev->si_cred);
179 	devfs_free_cdp_inode(cdp->cdp_inode);
180 	if (cdp->cdp_maxdirent > 0)
181 		free(cdp->cdp_dirents, M_DEVFS2);
182 	free(cdp, M_CDEVP);
183 }
184 
185 struct devfs_dirent *
186 devfs_find(struct devfs_dirent *dd, const char *name, int namelen, int type)
187 {
188 	struct devfs_dirent *de;
189 
190 	TAILQ_FOREACH(de, &dd->de_dlist, de_list) {
191 		if (namelen != de->de_dirent->d_namlen)
192 			continue;
193 		if (type != 0 && type != de->de_dirent->d_type)
194 			continue;
195 		if (bcmp(name, de->de_dirent->d_name, namelen) != 0)
196 			continue;
197 		break;
198 	}
199 	KASSERT(de == NULL || (de->de_flags & DE_DOOMED) == 0,
200 	    ("devfs_find: returning a doomed entry"));
201 	return (de);
202 }
203 
204 struct devfs_dirent *
205 devfs_newdirent(char *name, int namelen)
206 {
207 	int i;
208 	struct devfs_dirent *de;
209 	struct dirent d;
210 
211 	d.d_namlen = namelen;
212 	i = sizeof (*de) + GENERIC_DIRSIZ(&d);
213 	de = malloc(i, M_DEVFS3, M_WAITOK | M_ZERO);
214 	de->de_dirent = (struct dirent *)(de + 1);
215 	de->de_dirent->d_namlen = namelen;
216 	de->de_dirent->d_reclen = GENERIC_DIRSIZ(&d);
217 	bcopy(name, de->de_dirent->d_name, namelen);
218 	de->de_dirent->d_name[namelen] = '\0';
219 	vfs_timestamp(&de->de_ctime);
220 	de->de_mtime = de->de_atime = de->de_ctime;
221 	de->de_links = 1;
222 	de->de_holdcnt = 1;
223 #ifdef MAC
224 	mac_devfs_init(de);
225 #endif
226 	return (de);
227 }
228 
229 struct devfs_dirent *
230 devfs_parent_dirent(struct devfs_dirent *de)
231 {
232 
233 	if (de->de_dirent->d_type != DT_DIR)
234 		return (de->de_dir);
235 
236 	if (de->de_flags & (DE_DOT | DE_DOTDOT))
237 		return (NULL);
238 
239 	de = TAILQ_FIRST(&de->de_dlist);	/* "." */
240 	if (de == NULL)
241 		return (NULL);
242 	de = TAILQ_NEXT(de, de_list);		/* ".." */
243 	if (de == NULL)
244 		return (NULL);
245 
246 	return (de->de_dir);
247 }
248 
249 struct devfs_dirent *
250 devfs_vmkdir(struct devfs_mount *dmp, char *name, int namelen, struct devfs_dirent *dotdot, u_int inode)
251 {
252 	struct devfs_dirent *dd;
253 	struct devfs_dirent *de;
254 
255 	/* Create the new directory */
256 	dd = devfs_newdirent(name, namelen);
257 	TAILQ_INIT(&dd->de_dlist);
258 	dd->de_dirent->d_type = DT_DIR;
259 	dd->de_mode = 0555;
260 	dd->de_links = 2;
261 	dd->de_dir = dd;
262 	if (inode != 0)
263 		dd->de_inode = inode;
264 	else
265 		dd->de_inode = alloc_unr(devfs_inos);
266 
267 	/*
268 	 * "." and ".." are always the two first entries in the
269 	 * de_dlist list.
270 	 *
271 	 * Create the "." entry in the new directory.
272 	 */
273 	de = devfs_newdirent(".", 1);
274 	de->de_dirent->d_type = DT_DIR;
275 	de->de_flags |= DE_DOT;
276 	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
277 	de->de_dir = dd;
278 
279 	/* Create the ".." entry in the new directory. */
280 	de = devfs_newdirent("..", 2);
281 	de->de_dirent->d_type = DT_DIR;
282 	de->de_flags |= DE_DOTDOT;
283 	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
284 	if (dotdot == NULL) {
285 		de->de_dir = dd;
286 	} else {
287 		de->de_dir = dotdot;
288 		sx_assert(&dmp->dm_lock, SX_XLOCKED);
289 		TAILQ_INSERT_TAIL(&dotdot->de_dlist, dd, de_list);
290 		dotdot->de_links++;
291 		devfs_rules_apply(dmp, dd);
292 	}
293 
294 #ifdef MAC
295 	mac_devfs_create_directory(dmp->dm_mount, name, namelen, dd);
296 #endif
297 	return (dd);
298 }
299 
300 void
301 devfs_dirent_free(struct devfs_dirent *de)
302 {
303 	free(de, M_DEVFS3);
304 }
305 
306 /*
307  * Removes a directory if it is empty. Also empty parent directories are
308  * removed recursively.
309  */
310 static void
311 devfs_rmdir_empty(struct devfs_mount *dm, struct devfs_dirent *de)
312 {
313 	struct devfs_dirent *dd, *de_dot, *de_dotdot;
314 
315 	sx_assert(&dm->dm_lock, SX_XLOCKED);
316 
317 	for (;;) {
318 		KASSERT(de->de_dirent->d_type == DT_DIR,
319 		    ("devfs_rmdir_empty: de is not a directory"));
320 
321 		if ((de->de_flags & DE_DOOMED) != 0 || de == dm->dm_rootdir)
322 			return;
323 
324 		de_dot = TAILQ_FIRST(&de->de_dlist);
325 		KASSERT(de_dot != NULL, ("devfs_rmdir_empty: . missing"));
326 		de_dotdot = TAILQ_NEXT(de_dot, de_list);
327 		KASSERT(de_dotdot != NULL, ("devfs_rmdir_empty: .. missing"));
328 		/* Return if the directory is not empty. */
329 		if (TAILQ_NEXT(de_dotdot, de_list) != NULL)
330 			return;
331 
332 		dd = devfs_parent_dirent(de);
333 		KASSERT(dd != NULL, ("devfs_rmdir_empty: NULL dd"));
334 		TAILQ_REMOVE(&de->de_dlist, de_dot, de_list);
335 		TAILQ_REMOVE(&de->de_dlist, de_dotdot, de_list);
336 		TAILQ_REMOVE(&dd->de_dlist, de, de_list);
337 		DEVFS_DE_HOLD(dd);
338 		devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
339 		devfs_delete(dm, de_dot, DEVFS_DEL_NORECURSE);
340 		devfs_delete(dm, de_dotdot, DEVFS_DEL_NORECURSE);
341 		if (DEVFS_DE_DROP(dd)) {
342 			devfs_dirent_free(dd);
343 			return;
344 		}
345 
346 		de = dd;
347 	}
348 }
349 
350 /*
351  * The caller needs to hold the dm for the duration of the call since
352  * dm->dm_lock may be temporary dropped.
353  */
354 void
355 devfs_delete(struct devfs_mount *dm, struct devfs_dirent *de, int flags)
356 {
357 	struct devfs_dirent *dd;
358 	struct vnode *vp;
359 
360 	KASSERT((de->de_flags & DE_DOOMED) == 0,
361 		("devfs_delete doomed dirent"));
362 	de->de_flags |= DE_DOOMED;
363 
364 	if ((flags & DEVFS_DEL_NORECURSE) == 0) {
365 		dd = devfs_parent_dirent(de);
366 		if (dd != NULL)
367 			DEVFS_DE_HOLD(dd);
368 		if (de->de_flags & DE_USER) {
369 			KASSERT(dd != NULL, ("devfs_delete: NULL dd"));
370 			devfs_dir_unref_de(dm, dd);
371 		}
372 	} else
373 		dd = NULL;
374 
375 	mtx_lock(&devfs_de_interlock);
376 	vp = de->de_vnode;
377 	if (vp != NULL) {
378 		VI_LOCK(vp);
379 		mtx_unlock(&devfs_de_interlock);
380 		vholdl(vp);
381 		sx_unlock(&dm->dm_lock);
382 		if ((flags & DEVFS_DEL_VNLOCKED) == 0)
383 			vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK | LK_RETRY);
384 		else
385 			VI_UNLOCK(vp);
386 		vgone(vp);
387 		if ((flags & DEVFS_DEL_VNLOCKED) == 0)
388 			VOP_UNLOCK(vp, 0);
389 		vdrop(vp);
390 		sx_xlock(&dm->dm_lock);
391 	} else
392 		mtx_unlock(&devfs_de_interlock);
393 	if (de->de_symlink) {
394 		free(de->de_symlink, M_DEVFS);
395 		de->de_symlink = NULL;
396 	}
397 #ifdef MAC
398 	mac_devfs_destroy(de);
399 #endif
400 	if (de->de_inode > DEVFS_ROOTINO) {
401 		devfs_free_cdp_inode(de->de_inode);
402 		de->de_inode = 0;
403 	}
404 	if (DEVFS_DE_DROP(de))
405 		devfs_dirent_free(de);
406 
407 	if (dd != NULL) {
408 		if (DEVFS_DE_DROP(dd))
409 			devfs_dirent_free(dd);
410 		else
411 			devfs_rmdir_empty(dm, dd);
412 	}
413 }
414 
415 /*
416  * Called on unmount.
417  * Recursively removes the entire tree.
418  * The caller needs to hold the dm for the duration of the call.
419  */
420 
421 static void
422 devfs_purge(struct devfs_mount *dm, struct devfs_dirent *dd)
423 {
424 	struct devfs_dirent *de;
425 
426 	sx_assert(&dm->dm_lock, SX_XLOCKED);
427 
428 	DEVFS_DE_HOLD(dd);
429 	for (;;) {
430 		/*
431 		 * Use TAILQ_LAST() to remove "." and ".." last.
432 		 * We might need ".." to resolve a path in
433 		 * devfs_dir_unref_de().
434 		 */
435 		de = TAILQ_LAST(&dd->de_dlist, devfs_dlist_head);
436 		if (de == NULL)
437 			break;
438 		TAILQ_REMOVE(&dd->de_dlist, de, de_list);
439 		if (de->de_flags & DE_USER)
440 			devfs_dir_unref_de(dm, dd);
441 		if (de->de_flags & (DE_DOT | DE_DOTDOT))
442 			devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
443 		else if (de->de_dirent->d_type == DT_DIR)
444 			devfs_purge(dm, de);
445 		else
446 			devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
447 	}
448 	if (DEVFS_DE_DROP(dd))
449 		devfs_dirent_free(dd);
450 	else if ((dd->de_flags & DE_DOOMED) == 0)
451 		devfs_delete(dm, dd, DEVFS_DEL_NORECURSE);
452 }
453 
454 /*
455  * Each cdev_priv has an array of pointers to devfs_dirent which is indexed
456  * by the mount points dm_idx.
457  * This function extends the array when necessary, taking into account that
458  * the default array is 1 element and not malloc'ed.
459  */
460 static void
461 devfs_metoo(struct cdev_priv *cdp, struct devfs_mount *dm)
462 {
463 	struct devfs_dirent **dep;
464 	int siz;
465 
466 	siz = (dm->dm_idx + 1) * sizeof *dep;
467 	dep = malloc(siz, M_DEVFS2, M_WAITOK | M_ZERO);
468 	dev_lock();
469 	if (dm->dm_idx <= cdp->cdp_maxdirent) {
470 		/* We got raced */
471 		dev_unlock();
472 		free(dep, M_DEVFS2);
473 		return;
474 	}
475 	memcpy(dep, cdp->cdp_dirents, (cdp->cdp_maxdirent + 1) * sizeof *dep);
476 	if (cdp->cdp_maxdirent > 0)
477 		free(cdp->cdp_dirents, M_DEVFS2);
478 	cdp->cdp_dirents = dep;
479 	/*
480 	 * XXX: if malloc told us how much we actually got this could
481 	 * XXX: be optimized.
482 	 */
483 	cdp->cdp_maxdirent = dm->dm_idx;
484 	dev_unlock();
485 }
486 
487 /*
488  * The caller needs to hold the dm for the duration of the call.
489  */
490 static int
491 devfs_populate_loop(struct devfs_mount *dm, int cleanup)
492 {
493 	struct cdev_priv *cdp;
494 	struct devfs_dirent *de;
495 	struct devfs_dirent *dd, *dt;
496 	struct cdev *pdev;
497 	int de_flags, depth, j;
498 	char *q, *s;
499 
500 	sx_assert(&dm->dm_lock, SX_XLOCKED);
501 	dev_lock();
502 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list) {
503 
504 		KASSERT(cdp->cdp_dirents != NULL, ("NULL cdp_dirents"));
505 
506 		/*
507 		 * If we are unmounting, or the device has been destroyed,
508 		 * clean up our dirent.
509 		 */
510 		if ((cleanup || !(cdp->cdp_flags & CDP_ACTIVE)) &&
511 		    dm->dm_idx <= cdp->cdp_maxdirent &&
512 		    cdp->cdp_dirents[dm->dm_idx] != NULL) {
513 			de = cdp->cdp_dirents[dm->dm_idx];
514 			cdp->cdp_dirents[dm->dm_idx] = NULL;
515 			KASSERT(cdp == de->de_cdp,
516 			    ("%s %d %s %p %p", __func__, __LINE__,
517 			    cdp->cdp_c.si_name, cdp, de->de_cdp));
518 			KASSERT(de->de_dir != NULL, ("Null de->de_dir"));
519 			dev_unlock();
520 
521 			TAILQ_REMOVE(&de->de_dir->de_dlist, de, de_list);
522 			de->de_cdp = NULL;
523 			de->de_inode = 0;
524 			devfs_delete(dm, de, 0);
525 			dev_lock();
526 			cdp->cdp_inuse--;
527 			dev_unlock();
528 			return (1);
529 		}
530 		/*
531 	 	 * GC any lingering devices
532 		 */
533 		if (!(cdp->cdp_flags & CDP_ACTIVE)) {
534 			if (cdp->cdp_inuse > 0)
535 				continue;
536 			TAILQ_REMOVE(&cdevp_list, cdp, cdp_list);
537 			dev_unlock();
538 			dev_rel(&cdp->cdp_c);
539 			return (1);
540 		}
541 		/*
542 		 * Don't create any new dirents if we are unmounting
543 		 */
544 		if (cleanup)
545 			continue;
546 		KASSERT((cdp->cdp_flags & CDP_ACTIVE), ("Bogons, I tell ya'!"));
547 
548 		if (dm->dm_idx <= cdp->cdp_maxdirent &&
549 		    cdp->cdp_dirents[dm->dm_idx] != NULL) {
550 			de = cdp->cdp_dirents[dm->dm_idx];
551 			KASSERT(cdp == de->de_cdp, ("inconsistent cdp"));
552 			continue;
553 		}
554 
555 
556 		cdp->cdp_inuse++;
557 		dev_unlock();
558 
559 		if (dm->dm_idx > cdp->cdp_maxdirent)
560 		        devfs_metoo(cdp, dm);
561 
562 		dd = dm->dm_rootdir;
563 		s = cdp->cdp_c.si_name;
564 		for (;;) {
565 			for (q = s; *q != '/' && *q != '\0'; q++)
566 				continue;
567 			if (*q != '/')
568 				break;
569 			de = devfs_find(dd, s, q - s, 0);
570 			if (de == NULL)
571 				de = devfs_vmkdir(dm, s, q - s, dd, 0);
572 			else if (de->de_dirent->d_type == DT_LNK) {
573 				de = devfs_find(dd, s, q - s, DT_DIR);
574 				if (de == NULL)
575 					de = devfs_vmkdir(dm, s, q - s, dd, 0);
576 				de->de_flags |= DE_COVERED;
577 			}
578 			s = q + 1;
579 			dd = de;
580 			KASSERT(dd->de_dirent->d_type == DT_DIR &&
581 			    (dd->de_flags & (DE_DOT | DE_DOTDOT)) == 0,
582 			    ("%s: invalid directory (si_name=%s)",
583 			    __func__, cdp->cdp_c.si_name));
584 
585 		}
586 		de_flags = 0;
587 		de = devfs_find(dd, s, q - s, DT_LNK);
588 		if (de != NULL)
589 			de_flags |= DE_COVERED;
590 
591 		de = devfs_newdirent(s, q - s);
592 		if (cdp->cdp_c.si_flags & SI_ALIAS) {
593 			de->de_uid = 0;
594 			de->de_gid = 0;
595 			de->de_mode = 0755;
596 			de->de_dirent->d_type = DT_LNK;
597 			pdev = cdp->cdp_c.si_parent;
598 			dt = dd;
599 			depth = 0;
600 			while (dt != dm->dm_rootdir &&
601 			    (dt = devfs_parent_dirent(dt)) != NULL)
602 				depth++;
603 			j = depth * 3 + strlen(pdev->si_name) + 1;
604 			de->de_symlink = malloc(j, M_DEVFS, M_WAITOK);
605 			de->de_symlink[0] = 0;
606 			while (depth-- > 0)
607 				strcat(de->de_symlink, "../");
608 			strcat(de->de_symlink, pdev->si_name);
609 		} else {
610 			de->de_uid = cdp->cdp_c.si_uid;
611 			de->de_gid = cdp->cdp_c.si_gid;
612 			de->de_mode = cdp->cdp_c.si_mode;
613 			de->de_dirent->d_type = DT_CHR;
614 		}
615 		de->de_flags |= de_flags;
616 		de->de_inode = cdp->cdp_inode;
617 		de->de_cdp = cdp;
618 #ifdef MAC
619 		mac_devfs_create_device(cdp->cdp_c.si_cred, dm->dm_mount,
620 		    &cdp->cdp_c, de);
621 #endif
622 		de->de_dir = dd;
623 		TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
624 		devfs_rules_apply(dm, de);
625 		dev_lock();
626 		/* XXX: could check that cdp is still active here */
627 		KASSERT(cdp->cdp_dirents[dm->dm_idx] == NULL,
628 		    ("%s %d\n", __func__, __LINE__));
629 		cdp->cdp_dirents[dm->dm_idx] = de;
630 		KASSERT(de->de_cdp != (void *)0xdeadc0de,
631 		    ("%s %d\n", __func__, __LINE__));
632 		dev_unlock();
633 		return (1);
634 	}
635 	dev_unlock();
636 	return (0);
637 }
638 
639 /*
640  * The caller needs to hold the dm for the duration of the call.
641  */
642 void
643 devfs_populate(struct devfs_mount *dm)
644 {
645 	unsigned gen;
646 
647 	sx_assert(&dm->dm_lock, SX_XLOCKED);
648 	gen = devfs_generation;
649 	if (dm->dm_generation == gen)
650 		return;
651 	while (devfs_populate_loop(dm, 0))
652 		continue;
653 	dm->dm_generation = gen;
654 }
655 
656 /*
657  * The caller needs to hold the dm for the duration of the call.
658  */
659 void
660 devfs_cleanup(struct devfs_mount *dm)
661 {
662 
663 	sx_assert(&dm->dm_lock, SX_XLOCKED);
664 	while (devfs_populate_loop(dm, 1))
665 		continue;
666 	devfs_purge(dm, dm->dm_rootdir);
667 }
668 
669 /*
670  * devfs_create() and devfs_destroy() are called from kern_conf.c and
671  * in both cases the devlock() mutex is held, so no further locking
672  * is necessary and no sleeping allowed.
673  */
674 
675 void
676 devfs_create(struct cdev *dev)
677 {
678 	struct cdev_priv *cdp;
679 
680 	mtx_assert(&devmtx, MA_OWNED);
681 	cdp = cdev2priv(dev);
682 	cdp->cdp_flags |= CDP_ACTIVE;
683 	cdp->cdp_inode = alloc_unrl(devfs_inos);
684 	dev_refl(dev);
685 	TAILQ_INSERT_TAIL(&cdevp_list, cdp, cdp_list);
686 	devfs_generation++;
687 }
688 
689 void
690 devfs_destroy(struct cdev *dev)
691 {
692 	struct cdev_priv *cdp;
693 
694 	mtx_assert(&devmtx, MA_OWNED);
695 	cdp = cdev2priv(dev);
696 	cdp->cdp_flags &= ~CDP_ACTIVE;
697 	devfs_generation++;
698 }
699 
700 ino_t
701 devfs_alloc_cdp_inode(void)
702 {
703 
704 	return (alloc_unr(devfs_inos));
705 }
706 
707 void
708 devfs_free_cdp_inode(ino_t ino)
709 {
710 
711 	if (ino > 0)
712 		free_unr(devfs_inos, ino);
713 }
714 
715 static void
716 devfs_devs_init(void *junk __unused)
717 {
718 
719 	devfs_inos = new_unrhdr(DEVFS_ROOTINO + 1, INT_MAX, &devmtx);
720 }
721 
722 SYSINIT(devfs_devs, SI_SUB_DEVFS, SI_ORDER_FIRST, devfs_devs_init, NULL);
723