xref: /freebsd/sys/fs/devfs/devfs_devs.c (revision f1951fd745b894fe6586c298874af98544a5e272)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2000,2004
5  *	Poul-Henning Kamp.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Neither the name of the University nor the names of its contributors
13  *    may be used to endorse or promote products derived from this software
14  *    without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  *
28  * From: FreeBSD: src/sys/miscfs/kernfs/kernfs_vfsops.c 1.36
29  *
30  * $FreeBSD$
31  */
32 
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/conf.h>
36 #include <sys/dirent.h>
37 #include <sys/kernel.h>
38 #include <sys/limits.h>
39 #include <sys/lock.h>
40 #include <sys/malloc.h>
41 #include <sys/proc.h>
42 #include <sys/sx.h>
43 #include <sys/sysctl.h>
44 #include <sys/vnode.h>
45 
46 #include <sys/kdb.h>
47 
48 #include <fs/devfs/devfs.h>
49 #include <fs/devfs/devfs_int.h>
50 
51 #include <security/mac/mac_framework.h>
52 
53 /*
54  * The one true (but secret) list of active devices in the system.
55  * Locked by dev_lock()/devmtx
56  */
57 struct cdev_priv_list cdevp_list = TAILQ_HEAD_INITIALIZER(cdevp_list);
58 
59 struct unrhdr *devfs_inos;
60 
61 
62 static MALLOC_DEFINE(M_DEVFS2, "DEVFS2", "DEVFS data 2");
63 static MALLOC_DEFINE(M_DEVFS3, "DEVFS3", "DEVFS data 3");
64 static MALLOC_DEFINE(M_CDEVP, "DEVFS1", "DEVFS cdev_priv storage");
65 
66 SYSCTL_NODE(_vfs, OID_AUTO, devfs, CTLFLAG_RW, 0, "DEVFS filesystem");
67 
68 static unsigned devfs_generation;
69 SYSCTL_UINT(_vfs_devfs, OID_AUTO, generation, CTLFLAG_RD,
70 	&devfs_generation, 0, "DEVFS generation number");
71 
72 unsigned devfs_rule_depth = 1;
73 SYSCTL_UINT(_vfs_devfs, OID_AUTO, rule_depth, CTLFLAG_RW,
74 	&devfs_rule_depth, 0, "Max depth of ruleset include");
75 
76 /*
77  * Helper sysctl for devname(3).  We're given a dev_t and return the
78  * name, if any, registered by the device driver.
79  */
80 static int
81 sysctl_devname(SYSCTL_HANDLER_ARGS)
82 {
83 	int error;
84 	dev_t ud;
85 #ifdef COMPAT_FREEBSD11
86 	uint32_t ud_compat;
87 #endif
88 	struct cdev_priv *cdp;
89 	struct cdev *dev;
90 
91 #ifdef COMPAT_FREEBSD11
92 	if (req->newlen == sizeof(ud_compat)) {
93 		error = SYSCTL_IN(req, &ud_compat, sizeof(ud_compat));
94 		if (error == 0)
95 			ud = ud_compat == (uint32_t)NODEV ? NODEV : ud_compat;
96 	} else
97 #endif
98 		error = SYSCTL_IN(req, &ud, sizeof (ud));
99 	if (error)
100 		return (error);
101 	if (ud == NODEV)
102 		return (EINVAL);
103 	dev = NULL;
104 	dev_lock();
105 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list)
106 		if (cdp->cdp_inode == ud) {
107 			dev = &cdp->cdp_c;
108 			dev_refl(dev);
109 			break;
110 		}
111 	dev_unlock();
112 	if (dev == NULL)
113 		return (ENOENT);
114 	error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
115 	dev_rel(dev);
116 	return (error);
117 }
118 
119 SYSCTL_PROC(_kern, OID_AUTO, devname,
120     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY|CTLFLAG_MPSAFE,
121     NULL, 0, sysctl_devname, "", "devname(3) handler");
122 
123 SYSCTL_INT(_debug_sizeof, OID_AUTO, cdev, CTLFLAG_RD,
124     SYSCTL_NULL_INT_PTR, sizeof(struct cdev), "sizeof(struct cdev)");
125 
126 SYSCTL_INT(_debug_sizeof, OID_AUTO, cdev_priv, CTLFLAG_RD,
127     SYSCTL_NULL_INT_PTR, sizeof(struct cdev_priv), "sizeof(struct cdev_priv)");
128 
129 struct cdev *
130 devfs_alloc(int flags)
131 {
132 	struct cdev_priv *cdp;
133 	struct cdev *cdev;
134 	struct timespec ts;
135 
136 	cdp = malloc(sizeof *cdp, M_CDEVP, M_ZERO |
137 	    ((flags & MAKEDEV_NOWAIT) ? M_NOWAIT : M_WAITOK));
138 	if (cdp == NULL)
139 		return (NULL);
140 
141 	cdp->cdp_dirents = &cdp->cdp_dirent0;
142 
143 	cdev = &cdp->cdp_c;
144 	LIST_INIT(&cdev->si_children);
145 	vfs_timestamp(&ts);
146 	cdev->si_atime = cdev->si_mtime = cdev->si_ctime = ts;
147 
148 	return (cdev);
149 }
150 
151 int
152 devfs_dev_exists(const char *name)
153 {
154 	struct cdev_priv *cdp;
155 
156 	mtx_assert(&devmtx, MA_OWNED);
157 
158 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list) {
159 		if ((cdp->cdp_flags & CDP_ACTIVE) == 0)
160 			continue;
161 		if (devfs_pathpath(cdp->cdp_c.si_name, name) != 0)
162 			return (1);
163 		if (devfs_pathpath(name, cdp->cdp_c.si_name) != 0)
164 			return (1);
165 	}
166 	if (devfs_dir_find(name) != 0)
167 		return (1);
168 
169 	return (0);
170 }
171 
172 void
173 devfs_free(struct cdev *cdev)
174 {
175 	struct cdev_priv *cdp;
176 
177 	cdp = cdev2priv(cdev);
178 	if (cdev->si_cred != NULL)
179 		crfree(cdev->si_cred);
180 	devfs_free_cdp_inode(cdp->cdp_inode);
181 	if (cdp->cdp_maxdirent > 0)
182 		free(cdp->cdp_dirents, M_DEVFS2);
183 	free(cdp, M_CDEVP);
184 }
185 
186 struct devfs_dirent *
187 devfs_find(struct devfs_dirent *dd, const char *name, int namelen, int type)
188 {
189 	struct devfs_dirent *de;
190 
191 	TAILQ_FOREACH(de, &dd->de_dlist, de_list) {
192 		if (namelen != de->de_dirent->d_namlen)
193 			continue;
194 		if (type != 0 && type != de->de_dirent->d_type)
195 			continue;
196 
197 		/*
198 		 * The race with finding non-active name is not
199 		 * completely closed by the check, but it is similar
200 		 * to the devfs_allocv() in making it unlikely enough.
201 		 */
202 		if (de->de_dirent->d_type == DT_CHR &&
203 		    (de->de_cdp->cdp_flags & CDP_ACTIVE) == 0)
204 			continue;
205 
206 		if (bcmp(name, de->de_dirent->d_name, namelen) != 0)
207 			continue;
208 		break;
209 	}
210 	KASSERT(de == NULL || (de->de_flags & DE_DOOMED) == 0,
211 	    ("devfs_find: returning a doomed entry"));
212 	return (de);
213 }
214 
215 struct devfs_dirent *
216 devfs_newdirent(char *name, int namelen)
217 {
218 	int i;
219 	struct devfs_dirent *de;
220 	struct dirent d;
221 
222 	d.d_namlen = namelen;
223 	i = sizeof(*de) + GENERIC_DIRSIZ(&d);
224 	de = malloc(i, M_DEVFS3, M_WAITOK | M_ZERO);
225 	de->de_dirent = (struct dirent *)(de + 1);
226 	de->de_dirent->d_namlen = namelen;
227 	de->de_dirent->d_reclen = GENERIC_DIRSIZ(&d);
228 	bcopy(name, de->de_dirent->d_name, namelen);
229 	de->de_dirent->d_name[namelen] = '\0';
230 	vfs_timestamp(&de->de_ctime);
231 	de->de_mtime = de->de_atime = de->de_ctime;
232 	de->de_links = 1;
233 	de->de_holdcnt = 1;
234 #ifdef MAC
235 	mac_devfs_init(de);
236 #endif
237 	return (de);
238 }
239 
240 struct devfs_dirent *
241 devfs_parent_dirent(struct devfs_dirent *de)
242 {
243 
244 	if (de->de_dirent->d_type != DT_DIR)
245 		return (de->de_dir);
246 
247 	if (de->de_flags & (DE_DOT | DE_DOTDOT))
248 		return (NULL);
249 
250 	de = TAILQ_FIRST(&de->de_dlist);	/* "." */
251 	if (de == NULL)
252 		return (NULL);
253 	de = TAILQ_NEXT(de, de_list);		/* ".." */
254 	if (de == NULL)
255 		return (NULL);
256 
257 	return (de->de_dir);
258 }
259 
260 struct devfs_dirent *
261 devfs_vmkdir(struct devfs_mount *dmp, char *name, int namelen,
262     struct devfs_dirent *dotdot, u_int inode)
263 {
264 	struct devfs_dirent *dd;
265 	struct devfs_dirent *de;
266 
267 	/* Create the new directory */
268 	dd = devfs_newdirent(name, namelen);
269 	TAILQ_INIT(&dd->de_dlist);
270 	dd->de_dirent->d_type = DT_DIR;
271 	dd->de_mode = 0555;
272 	dd->de_links = 2;
273 	dd->de_dir = dd;
274 	if (inode != 0)
275 		dd->de_inode = inode;
276 	else
277 		dd->de_inode = alloc_unr(devfs_inos);
278 
279 	/*
280 	 * "." and ".." are always the two first entries in the
281 	 * de_dlist list.
282 	 *
283 	 * Create the "." entry in the new directory.
284 	 */
285 	de = devfs_newdirent(".", 1);
286 	de->de_dirent->d_type = DT_DIR;
287 	de->de_flags |= DE_DOT;
288 	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
289 	de->de_dir = dd;
290 
291 	/* Create the ".." entry in the new directory. */
292 	de = devfs_newdirent("..", 2);
293 	de->de_dirent->d_type = DT_DIR;
294 	de->de_flags |= DE_DOTDOT;
295 	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
296 	if (dotdot == NULL) {
297 		de->de_dir = dd;
298 	} else {
299 		de->de_dir = dotdot;
300 		sx_assert(&dmp->dm_lock, SX_XLOCKED);
301 		TAILQ_INSERT_TAIL(&dotdot->de_dlist, dd, de_list);
302 		dotdot->de_links++;
303 		devfs_rules_apply(dmp, dd);
304 	}
305 
306 #ifdef MAC
307 	mac_devfs_create_directory(dmp->dm_mount, name, namelen, dd);
308 #endif
309 	return (dd);
310 }
311 
312 void
313 devfs_dirent_free(struct devfs_dirent *de)
314 {
315 	struct vnode *vp;
316 
317 	vp = de->de_vnode;
318 	mtx_lock(&devfs_de_interlock);
319 	if (vp != NULL && vp->v_data == de)
320 		vp->v_data = NULL;
321 	mtx_unlock(&devfs_de_interlock);
322 	free(de, M_DEVFS3);
323 }
324 
325 /*
326  * Removes a directory if it is empty. Also empty parent directories are
327  * removed recursively.
328  */
329 static void
330 devfs_rmdir_empty(struct devfs_mount *dm, struct devfs_dirent *de)
331 {
332 	struct devfs_dirent *dd, *de_dot, *de_dotdot;
333 
334 	sx_assert(&dm->dm_lock, SX_XLOCKED);
335 
336 	for (;;) {
337 		KASSERT(de->de_dirent->d_type == DT_DIR,
338 		    ("devfs_rmdir_empty: de is not a directory"));
339 
340 		if ((de->de_flags & DE_DOOMED) != 0 || de == dm->dm_rootdir)
341 			return;
342 
343 		de_dot = TAILQ_FIRST(&de->de_dlist);
344 		KASSERT(de_dot != NULL, ("devfs_rmdir_empty: . missing"));
345 		de_dotdot = TAILQ_NEXT(de_dot, de_list);
346 		KASSERT(de_dotdot != NULL, ("devfs_rmdir_empty: .. missing"));
347 		/* Return if the directory is not empty. */
348 		if (TAILQ_NEXT(de_dotdot, de_list) != NULL)
349 			return;
350 
351 		dd = devfs_parent_dirent(de);
352 		KASSERT(dd != NULL, ("devfs_rmdir_empty: NULL dd"));
353 		TAILQ_REMOVE(&de->de_dlist, de_dot, de_list);
354 		TAILQ_REMOVE(&de->de_dlist, de_dotdot, de_list);
355 		TAILQ_REMOVE(&dd->de_dlist, de, de_list);
356 		DEVFS_DE_HOLD(dd);
357 		devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
358 		devfs_delete(dm, de_dot, DEVFS_DEL_NORECURSE);
359 		devfs_delete(dm, de_dotdot, DEVFS_DEL_NORECURSE);
360 		if (DEVFS_DE_DROP(dd)) {
361 			devfs_dirent_free(dd);
362 			return;
363 		}
364 
365 		de = dd;
366 	}
367 }
368 
369 /*
370  * The caller needs to hold the dm for the duration of the call since
371  * dm->dm_lock may be temporary dropped.
372  */
373 void
374 devfs_delete(struct devfs_mount *dm, struct devfs_dirent *de, int flags)
375 {
376 	struct devfs_dirent *dd;
377 	struct vnode *vp;
378 
379 	KASSERT((de->de_flags & DE_DOOMED) == 0,
380 		("devfs_delete doomed dirent"));
381 	de->de_flags |= DE_DOOMED;
382 
383 	if ((flags & DEVFS_DEL_NORECURSE) == 0) {
384 		dd = devfs_parent_dirent(de);
385 		if (dd != NULL)
386 			DEVFS_DE_HOLD(dd);
387 		if (de->de_flags & DE_USER) {
388 			KASSERT(dd != NULL, ("devfs_delete: NULL dd"));
389 			devfs_dir_unref_de(dm, dd);
390 		}
391 	} else
392 		dd = NULL;
393 
394 	mtx_lock(&devfs_de_interlock);
395 	vp = de->de_vnode;
396 	if (vp != NULL) {
397 		VI_LOCK(vp);
398 		mtx_unlock(&devfs_de_interlock);
399 		vholdl(vp);
400 		sx_unlock(&dm->dm_lock);
401 		if ((flags & DEVFS_DEL_VNLOCKED) == 0)
402 			vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK | LK_RETRY);
403 		else
404 			VI_UNLOCK(vp);
405 		vgone(vp);
406 		if ((flags & DEVFS_DEL_VNLOCKED) == 0)
407 			VOP_UNLOCK(vp, 0);
408 		vdrop(vp);
409 		sx_xlock(&dm->dm_lock);
410 	} else
411 		mtx_unlock(&devfs_de_interlock);
412 	if (de->de_symlink) {
413 		free(de->de_symlink, M_DEVFS);
414 		de->de_symlink = NULL;
415 	}
416 #ifdef MAC
417 	mac_devfs_destroy(de);
418 #endif
419 	if (de->de_inode > DEVFS_ROOTINO) {
420 		devfs_free_cdp_inode(de->de_inode);
421 		de->de_inode = 0;
422 	}
423 	if (DEVFS_DE_DROP(de))
424 		devfs_dirent_free(de);
425 
426 	if (dd != NULL) {
427 		if (DEVFS_DE_DROP(dd))
428 			devfs_dirent_free(dd);
429 		else
430 			devfs_rmdir_empty(dm, dd);
431 	}
432 }
433 
434 /*
435  * Called on unmount.
436  * Recursively removes the entire tree.
437  * The caller needs to hold the dm for the duration of the call.
438  */
439 
440 static void
441 devfs_purge(struct devfs_mount *dm, struct devfs_dirent *dd)
442 {
443 	struct devfs_dirent *de;
444 
445 	sx_assert(&dm->dm_lock, SX_XLOCKED);
446 
447 	DEVFS_DE_HOLD(dd);
448 	for (;;) {
449 		/*
450 		 * Use TAILQ_LAST() to remove "." and ".." last.
451 		 * We might need ".." to resolve a path in
452 		 * devfs_dir_unref_de().
453 		 */
454 		de = TAILQ_LAST(&dd->de_dlist, devfs_dlist_head);
455 		if (de == NULL)
456 			break;
457 		TAILQ_REMOVE(&dd->de_dlist, de, de_list);
458 		if (de->de_flags & DE_USER)
459 			devfs_dir_unref_de(dm, dd);
460 		if (de->de_flags & (DE_DOT | DE_DOTDOT))
461 			devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
462 		else if (de->de_dirent->d_type == DT_DIR)
463 			devfs_purge(dm, de);
464 		else
465 			devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
466 	}
467 	if (DEVFS_DE_DROP(dd))
468 		devfs_dirent_free(dd);
469 	else if ((dd->de_flags & DE_DOOMED) == 0)
470 		devfs_delete(dm, dd, DEVFS_DEL_NORECURSE);
471 }
472 
473 /*
474  * Each cdev_priv has an array of pointers to devfs_dirent which is indexed
475  * by the mount points dm_idx.
476  * This function extends the array when necessary, taking into account that
477  * the default array is 1 element and not malloc'ed.
478  */
479 static void
480 devfs_metoo(struct cdev_priv *cdp, struct devfs_mount *dm)
481 {
482 	struct devfs_dirent **dep;
483 	int siz;
484 
485 	siz = (dm->dm_idx + 1) * sizeof *dep;
486 	dep = malloc(siz, M_DEVFS2, M_WAITOK | M_ZERO);
487 	dev_lock();
488 	if (dm->dm_idx <= cdp->cdp_maxdirent) {
489 		/* We got raced */
490 		dev_unlock();
491 		free(dep, M_DEVFS2);
492 		return;
493 	}
494 	memcpy(dep, cdp->cdp_dirents, (cdp->cdp_maxdirent + 1) * sizeof *dep);
495 	if (cdp->cdp_maxdirent > 0)
496 		free(cdp->cdp_dirents, M_DEVFS2);
497 	cdp->cdp_dirents = dep;
498 	/*
499 	 * XXX: if malloc told us how much we actually got this could
500 	 * XXX: be optimized.
501 	 */
502 	cdp->cdp_maxdirent = dm->dm_idx;
503 	dev_unlock();
504 }
505 
506 /*
507  * The caller needs to hold the dm for the duration of the call.
508  */
509 static int
510 devfs_populate_loop(struct devfs_mount *dm, int cleanup)
511 {
512 	struct cdev_priv *cdp;
513 	struct devfs_dirent *de;
514 	struct devfs_dirent *dd, *dt;
515 	struct cdev *pdev;
516 	int de_flags, depth, j;
517 	char *q, *s;
518 
519 	sx_assert(&dm->dm_lock, SX_XLOCKED);
520 	dev_lock();
521 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list) {
522 
523 		KASSERT(cdp->cdp_dirents != NULL, ("NULL cdp_dirents"));
524 
525 		/*
526 		 * If we are unmounting, or the device has been destroyed,
527 		 * clean up our dirent.
528 		 */
529 		if ((cleanup || !(cdp->cdp_flags & CDP_ACTIVE)) &&
530 		    dm->dm_idx <= cdp->cdp_maxdirent &&
531 		    cdp->cdp_dirents[dm->dm_idx] != NULL) {
532 			de = cdp->cdp_dirents[dm->dm_idx];
533 			cdp->cdp_dirents[dm->dm_idx] = NULL;
534 			KASSERT(cdp == de->de_cdp,
535 			    ("%s %d %s %p %p", __func__, __LINE__,
536 			    cdp->cdp_c.si_name, cdp, de->de_cdp));
537 			KASSERT(de->de_dir != NULL, ("Null de->de_dir"));
538 			dev_unlock();
539 
540 			TAILQ_REMOVE(&de->de_dir->de_dlist, de, de_list);
541 			de->de_cdp = NULL;
542 			de->de_inode = 0;
543 			devfs_delete(dm, de, 0);
544 			dev_lock();
545 			cdp->cdp_inuse--;
546 			dev_unlock();
547 			return (1);
548 		}
549 		/*
550 	 	 * GC any lingering devices
551 		 */
552 		if (!(cdp->cdp_flags & CDP_ACTIVE)) {
553 			if (cdp->cdp_inuse > 0)
554 				continue;
555 			TAILQ_REMOVE(&cdevp_list, cdp, cdp_list);
556 			dev_unlock();
557 			dev_rel(&cdp->cdp_c);
558 			return (1);
559 		}
560 		/*
561 		 * Don't create any new dirents if we are unmounting
562 		 */
563 		if (cleanup)
564 			continue;
565 		KASSERT((cdp->cdp_flags & CDP_ACTIVE), ("Bogons, I tell ya'!"));
566 
567 		if (dm->dm_idx <= cdp->cdp_maxdirent &&
568 		    cdp->cdp_dirents[dm->dm_idx] != NULL) {
569 			de = cdp->cdp_dirents[dm->dm_idx];
570 			KASSERT(cdp == de->de_cdp, ("inconsistent cdp"));
571 			continue;
572 		}
573 
574 
575 		cdp->cdp_inuse++;
576 		dev_unlock();
577 
578 		if (dm->dm_idx > cdp->cdp_maxdirent)
579 		        devfs_metoo(cdp, dm);
580 
581 		dd = dm->dm_rootdir;
582 		s = cdp->cdp_c.si_name;
583 		for (;;) {
584 			for (q = s; *q != '/' && *q != '\0'; q++)
585 				continue;
586 			if (*q != '/')
587 				break;
588 			de = devfs_find(dd, s, q - s, 0);
589 			if (de == NULL)
590 				de = devfs_vmkdir(dm, s, q - s, dd, 0);
591 			else if (de->de_dirent->d_type == DT_LNK) {
592 				de = devfs_find(dd, s, q - s, DT_DIR);
593 				if (de == NULL)
594 					de = devfs_vmkdir(dm, s, q - s, dd, 0);
595 				de->de_flags |= DE_COVERED;
596 			}
597 			s = q + 1;
598 			dd = de;
599 			KASSERT(dd->de_dirent->d_type == DT_DIR &&
600 			    (dd->de_flags & (DE_DOT | DE_DOTDOT)) == 0,
601 			    ("%s: invalid directory (si_name=%s)",
602 			    __func__, cdp->cdp_c.si_name));
603 
604 		}
605 		de_flags = 0;
606 		de = devfs_find(dd, s, q - s, DT_LNK);
607 		if (de != NULL)
608 			de_flags |= DE_COVERED;
609 
610 		de = devfs_newdirent(s, q - s);
611 		if (cdp->cdp_c.si_flags & SI_ALIAS) {
612 			de->de_uid = 0;
613 			de->de_gid = 0;
614 			de->de_mode = 0755;
615 			de->de_dirent->d_type = DT_LNK;
616 			pdev = cdp->cdp_c.si_parent;
617 			dt = dd;
618 			depth = 0;
619 			while (dt != dm->dm_rootdir &&
620 			    (dt = devfs_parent_dirent(dt)) != NULL)
621 				depth++;
622 			j = depth * 3 + strlen(pdev->si_name) + 1;
623 			de->de_symlink = malloc(j, M_DEVFS, M_WAITOK);
624 			de->de_symlink[0] = 0;
625 			while (depth-- > 0)
626 				strcat(de->de_symlink, "../");
627 			strcat(de->de_symlink, pdev->si_name);
628 		} else {
629 			de->de_uid = cdp->cdp_c.si_uid;
630 			de->de_gid = cdp->cdp_c.si_gid;
631 			de->de_mode = cdp->cdp_c.si_mode;
632 			de->de_dirent->d_type = DT_CHR;
633 		}
634 		de->de_flags |= de_flags;
635 		de->de_inode = cdp->cdp_inode;
636 		de->de_cdp = cdp;
637 #ifdef MAC
638 		mac_devfs_create_device(cdp->cdp_c.si_cred, dm->dm_mount,
639 		    &cdp->cdp_c, de);
640 #endif
641 		de->de_dir = dd;
642 		TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
643 		devfs_rules_apply(dm, de);
644 		dev_lock();
645 		/* XXX: could check that cdp is still active here */
646 		KASSERT(cdp->cdp_dirents[dm->dm_idx] == NULL,
647 		    ("%s %d\n", __func__, __LINE__));
648 		cdp->cdp_dirents[dm->dm_idx] = de;
649 		KASSERT(de->de_cdp != (void *)0xdeadc0de,
650 		    ("%s %d\n", __func__, __LINE__));
651 		dev_unlock();
652 		return (1);
653 	}
654 	dev_unlock();
655 	return (0);
656 }
657 
658 /*
659  * The caller needs to hold the dm for the duration of the call.
660  */
661 void
662 devfs_populate(struct devfs_mount *dm)
663 {
664 	unsigned gen;
665 
666 	sx_assert(&dm->dm_lock, SX_XLOCKED);
667 	gen = devfs_generation;
668 	if (dm->dm_generation == gen)
669 		return;
670 	while (devfs_populate_loop(dm, 0))
671 		continue;
672 	dm->dm_generation = gen;
673 }
674 
675 /*
676  * The caller needs to hold the dm for the duration of the call.
677  */
678 void
679 devfs_cleanup(struct devfs_mount *dm)
680 {
681 
682 	sx_assert(&dm->dm_lock, SX_XLOCKED);
683 	while (devfs_populate_loop(dm, 1))
684 		continue;
685 	devfs_purge(dm, dm->dm_rootdir);
686 }
687 
688 /*
689  * devfs_create() and devfs_destroy() are called from kern_conf.c and
690  * in both cases the devlock() mutex is held, so no further locking
691  * is necessary and no sleeping allowed.
692  */
693 
694 void
695 devfs_create(struct cdev *dev)
696 {
697 	struct cdev_priv *cdp;
698 
699 	mtx_assert(&devmtx, MA_OWNED);
700 	cdp = cdev2priv(dev);
701 	cdp->cdp_flags |= CDP_ACTIVE;
702 	cdp->cdp_inode = alloc_unrl(devfs_inos);
703 	dev_refl(dev);
704 	TAILQ_INSERT_TAIL(&cdevp_list, cdp, cdp_list);
705 	devfs_generation++;
706 }
707 
708 void
709 devfs_destroy(struct cdev *dev)
710 {
711 	struct cdev_priv *cdp;
712 
713 	mtx_assert(&devmtx, MA_OWNED);
714 	cdp = cdev2priv(dev);
715 	cdp->cdp_flags &= ~CDP_ACTIVE;
716 	devfs_generation++;
717 }
718 
719 ino_t
720 devfs_alloc_cdp_inode(void)
721 {
722 
723 	return (alloc_unr(devfs_inos));
724 }
725 
726 void
727 devfs_free_cdp_inode(ino_t ino)
728 {
729 
730 	if (ino > 0)
731 		free_unr(devfs_inos, ino);
732 }
733 
734 static void
735 devfs_devs_init(void *junk __unused)
736 {
737 
738 	devfs_inos = new_unrhdr(DEVFS_ROOTINO + 1, INT_MAX, &devmtx);
739 }
740 
741 SYSINIT(devfs_devs, SI_SUB_DEVFS, SI_ORDER_FIRST, devfs_devs_init, NULL);
742