xref: /freebsd/sys/fs/devfs/devfs_devs.c (revision 525fe93dc7487a1e63a90f6a2b956abc601963c1)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
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 
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 static MALLOC_DEFINE(M_DEVFS2, "DEVFS2", "DEVFS data 2");
60 static MALLOC_DEFINE(M_DEVFS3, "DEVFS3", "DEVFS data 3");
61 static MALLOC_DEFINE(M_CDEVP, "DEVFS1", "DEVFS cdev_priv storage");
62 
63 SYSCTL_NODE(_vfs, OID_AUTO, devfs, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
64     "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 #ifdef COMPAT_FREEBSD11
84 	uint32_t ud_compat;
85 #endif
86 	struct cdev_priv *cdp;
87 	struct cdev *dev;
88 
89 #ifdef COMPAT_FREEBSD11
90 	if (req->newlen == sizeof(ud_compat)) {
91 		error = SYSCTL_IN(req, &ud_compat, sizeof(ud_compat));
92 		if (error == 0)
93 			ud = ud_compat == (uint32_t)NODEV ? NODEV : ud_compat;
94 	} else
95 #endif
96 		error = SYSCTL_IN(req, &ud, sizeof (ud));
97 	if (error)
98 		return (error);
99 	if (ud == NODEV)
100 		return (EINVAL);
101 	dev = NULL;
102 	dev_lock();
103 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list)
104 		if (cdp->cdp_inode == ud) {
105 			dev = &cdp->cdp_c;
106 			dev_refl(dev);
107 			break;
108 		}
109 	dev_unlock();
110 	if (dev == NULL)
111 		return (ENOENT);
112 	error = SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1);
113 	dev_rel(dev);
114 	return (error);
115 }
116 
117 SYSCTL_PROC(_kern, OID_AUTO, devname,
118     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY|CTLFLAG_MPSAFE,
119     NULL, 0, sysctl_devname, "", "devname(3) handler");
120 
121 SYSCTL_INT(_debug_sizeof, OID_AUTO, cdev, CTLFLAG_RD,
122     SYSCTL_NULL_INT_PTR, sizeof(struct cdev), "sizeof(struct cdev)");
123 
124 SYSCTL_INT(_debug_sizeof, OID_AUTO, cdev_priv, CTLFLAG_RD,
125     SYSCTL_NULL_INT_PTR, sizeof(struct cdev_priv), "sizeof(struct cdev_priv)");
126 
127 struct cdev *
128 devfs_alloc(int flags)
129 {
130 	struct cdev_priv *cdp;
131 	struct cdev *cdev;
132 	struct timespec ts;
133 
134 	cdp = malloc(sizeof *cdp, M_CDEVP, M_ZERO |
135 	    ((flags & MAKEDEV_NOWAIT) ? M_NOWAIT : M_WAITOK));
136 	if (cdp == NULL)
137 		return (NULL);
138 
139 	mtx_init(&cdp->cdp_threadlock, "devthrd", NULL, MTX_DEF);
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 	dev_lock_assert_locked();
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 	KASSERT((cdp->cdp_flags & (CDP_ACTIVE | CDP_ON_ACTIVE_LIST)) == 0,
179 	    ("%s: cdp %p (%s) still on active list",
180 	    __func__, cdp, cdev->si_name));
181 	if (cdev->si_cred != NULL)
182 		crfree(cdev->si_cred);
183 	devfs_free_cdp_inode(cdp->cdp_inode);
184 	if (cdp->cdp_maxdirent > 0)
185 		free(cdp->cdp_dirents, M_DEVFS2);
186 	mtx_destroy(&cdp->cdp_threadlock);
187 	free(cdp, M_CDEVP);
188 }
189 
190 struct devfs_dirent *
191 devfs_find(struct devfs_dirent *dd, const char *name, int namelen, int type)
192 {
193 	struct devfs_dirent *de;
194 
195 	TAILQ_FOREACH(de, &dd->de_dlist, de_list) {
196 		if (namelen != de->de_dirent->d_namlen)
197 			continue;
198 		if (type != 0 && type != de->de_dirent->d_type)
199 			continue;
200 
201 		/*
202 		 * The race with finding non-active name is not
203 		 * completely closed by the check, but it is similar
204 		 * to the devfs_allocv() in making it unlikely enough.
205 		 */
206 		if (de->de_dirent->d_type == DT_CHR &&
207 		    (de->de_cdp->cdp_flags & CDP_ACTIVE) == 0)
208 			continue;
209 
210 		if (bcmp(name, de->de_dirent->d_name, namelen) != 0)
211 			continue;
212 		break;
213 	}
214 	KASSERT(de == NULL || (de->de_flags & DE_DOOMED) == 0,
215 	    ("devfs_find: returning a doomed entry"));
216 	return (de);
217 }
218 
219 struct devfs_dirent *
220 devfs_newdirent(char *name, int namelen)
221 {
222 	int i;
223 	struct devfs_dirent *de;
224 	struct dirent d;
225 
226 	d.d_namlen = namelen;
227 	i = sizeof(*de) + GENERIC_DIRSIZ(&d);
228 	de = malloc(i, M_DEVFS3, M_WAITOK | M_ZERO);
229 	de->de_dirent = (struct dirent *)(de + 1);
230 	de->de_dirent->d_namlen = namelen;
231 	de->de_dirent->d_reclen = GENERIC_DIRSIZ(&d);
232 	bcopy(name, de->de_dirent->d_name, namelen);
233 	dirent_terminate(de->de_dirent);
234 	vfs_timestamp(&de->de_ctime);
235 	de->de_mtime = de->de_atime = de->de_ctime;
236 	de->de_links = 1;
237 	de->de_holdcnt = 1;
238 #ifdef MAC
239 	mac_devfs_init(de);
240 #endif
241 	return (de);
242 }
243 
244 struct devfs_dirent *
245 devfs_parent_dirent(struct devfs_dirent *de)
246 {
247 
248 	if (de->de_dirent->d_type != DT_DIR)
249 		return (de->de_dir);
250 
251 	if (de->de_flags & (DE_DOT | DE_DOTDOT))
252 		return (NULL);
253 
254 	de = TAILQ_FIRST(&de->de_dlist);	/* "." */
255 	if (de == NULL)
256 		return (NULL);
257 	de = TAILQ_NEXT(de, de_list);		/* ".." */
258 	if (de == NULL)
259 		return (NULL);
260 
261 	return (de->de_dir);
262 }
263 
264 struct devfs_dirent *
265 devfs_vmkdir(struct devfs_mount *dmp, char *name, int namelen,
266     struct devfs_dirent *dotdot, u_int inode)
267 {
268 	struct devfs_dirent *dd;
269 	struct devfs_dirent *de;
270 
271 	/* Create the new directory */
272 	dd = devfs_newdirent(name, namelen);
273 	TAILQ_INIT(&dd->de_dlist);
274 	dd->de_dirent->d_type = DT_DIR;
275 	dd->de_mode = 0555;
276 	dd->de_links = 2;
277 	dd->de_dir = dd;
278 	if (inode != 0)
279 		dd->de_inode = inode;
280 	else
281 		dd->de_inode = alloc_unr(devfs_inos);
282 
283 	/*
284 	 * "." and ".." are always the two first entries in the
285 	 * de_dlist list.
286 	 *
287 	 * Create the "." entry in the new directory.
288 	 */
289 	de = devfs_newdirent(".", 1);
290 	de->de_dirent->d_type = DT_DIR;
291 	de->de_flags |= DE_DOT;
292 	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
293 	de->de_dir = dd;
294 
295 	/* Create the ".." entry in the new directory. */
296 	de = devfs_newdirent("..", 2);
297 	de->de_dirent->d_type = DT_DIR;
298 	de->de_flags |= DE_DOTDOT;
299 	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
300 	if (dotdot == NULL) {
301 		de->de_dir = dd;
302 	} else {
303 		de->de_dir = dotdot;
304 		sx_assert(&dmp->dm_lock, SX_XLOCKED);
305 		TAILQ_INSERT_TAIL(&dotdot->de_dlist, dd, de_list);
306 		dotdot->de_links++;
307 		devfs_rules_apply(dmp, dd);
308 	}
309 
310 #ifdef MAC
311 	mac_devfs_create_directory(dmp->dm_mount, name, namelen, dd);
312 #endif
313 	return (dd);
314 }
315 
316 void
317 devfs_dirent_free(struct devfs_dirent *de)
318 {
319 	struct vnode *vp;
320 
321 	vp = de->de_vnode;
322 	mtx_lock(&devfs_de_interlock);
323 	if (vp != NULL && vp->v_data == de)
324 		vp->v_data = NULL;
325 	mtx_unlock(&devfs_de_interlock);
326 	free(de, M_DEVFS3);
327 }
328 
329 /*
330  * Removes a directory if it is empty. Also empty parent directories are
331  * removed recursively.
332  */
333 static void
334 devfs_rmdir_empty(struct devfs_mount *dm, struct devfs_dirent *de)
335 {
336 	struct devfs_dirent *dd, *de_dot, *de_dotdot;
337 
338 	sx_assert(&dm->dm_lock, SX_XLOCKED);
339 
340 	for (;;) {
341 		KASSERT(de->de_dirent->d_type == DT_DIR,
342 		    ("devfs_rmdir_empty: de is not a directory"));
343 
344 		if ((de->de_flags & DE_DOOMED) != 0 || de == dm->dm_rootdir)
345 			return;
346 
347 		de_dot = TAILQ_FIRST(&de->de_dlist);
348 		KASSERT(de_dot != NULL, ("devfs_rmdir_empty: . missing"));
349 		de_dotdot = TAILQ_NEXT(de_dot, de_list);
350 		KASSERT(de_dotdot != NULL, ("devfs_rmdir_empty: .. missing"));
351 		/* Return if the directory is not empty. */
352 		if (TAILQ_NEXT(de_dotdot, de_list) != NULL)
353 			return;
354 
355 		dd = devfs_parent_dirent(de);
356 		KASSERT(dd != NULL, ("devfs_rmdir_empty: NULL dd"));
357 		TAILQ_REMOVE(&de->de_dlist, de_dot, de_list);
358 		TAILQ_REMOVE(&de->de_dlist, de_dotdot, de_list);
359 		TAILQ_REMOVE(&dd->de_dlist, de, de_list);
360 		DEVFS_DE_HOLD(dd);
361 		devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
362 		devfs_delete(dm, de_dot, DEVFS_DEL_NORECURSE);
363 		devfs_delete(dm, de_dotdot, DEVFS_DEL_NORECURSE);
364 		if (DEVFS_DE_DROP(dd)) {
365 			devfs_dirent_free(dd);
366 			return;
367 		}
368 
369 		de = dd;
370 	}
371 }
372 
373 /*
374  * The caller needs to hold the dm for the duration of the call since
375  * dm->dm_lock may be temporary dropped.
376  */
377 void
378 devfs_delete(struct devfs_mount *dm, struct devfs_dirent *de, int flags)
379 {
380 	struct devfs_dirent *dd;
381 	struct vnode *vp;
382 
383 	KASSERT((de->de_flags & DE_DOOMED) == 0,
384 		("devfs_delete doomed dirent"));
385 	de->de_flags |= DE_DOOMED;
386 
387 	if ((flags & DEVFS_DEL_NORECURSE) == 0) {
388 		dd = devfs_parent_dirent(de);
389 		if (dd != NULL)
390 			DEVFS_DE_HOLD(dd);
391 		if (de->de_flags & DE_USER) {
392 			KASSERT(dd != NULL, ("devfs_delete: NULL dd"));
393 			devfs_dir_unref_de(dm, dd);
394 		}
395 	} else
396 		dd = NULL;
397 
398 	mtx_lock(&devfs_de_interlock);
399 	vp = de->de_vnode;
400 	if (vp != NULL) {
401 		vhold(vp);
402 		mtx_unlock(&devfs_de_interlock);
403 		sx_unlock(&dm->dm_lock);
404 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
405 		vgone(vp);
406 		VOP_UNLOCK(vp);
407 		vdrop(vp);
408 		sx_xlock(&dm->dm_lock);
409 	} else
410 		mtx_unlock(&devfs_de_interlock);
411 	if (de->de_symlink) {
412 		free(de->de_symlink, M_DEVFS);
413 		de->de_symlink = NULL;
414 	}
415 #ifdef MAC
416 	mac_devfs_destroy(de);
417 #endif
418 	if (de->de_inode > DEVFS_ROOTINO) {
419 		devfs_free_cdp_inode(de->de_inode);
420 		de->de_inode = 0;
421 	}
422 	if (DEVFS_DE_DROP(de))
423 		devfs_dirent_free(de);
424 
425 	if (dd != NULL) {
426 		if (DEVFS_DE_DROP(dd))
427 			devfs_dirent_free(dd);
428 		else
429 			devfs_rmdir_empty(dm, dd);
430 	}
431 }
432 
433 /*
434  * Called on unmount.
435  * Recursively removes the entire tree.
436  * The caller needs to hold the dm for the duration of the call.
437  */
438 
439 static void
440 devfs_purge(struct devfs_mount *dm, struct devfs_dirent *dd)
441 {
442 	struct devfs_dirent *de;
443 
444 	sx_assert(&dm->dm_lock, SX_XLOCKED);
445 
446 	DEVFS_DE_HOLD(dd);
447 	for (;;) {
448 		/*
449 		 * Use TAILQ_LAST() to remove "." and ".." last.
450 		 * We might need ".." to resolve a path in
451 		 * devfs_dir_unref_de().
452 		 */
453 		de = TAILQ_LAST(&dd->de_dlist, devfs_dlist_head);
454 		if (de == NULL)
455 			break;
456 		TAILQ_REMOVE(&dd->de_dlist, de, de_list);
457 		if (de->de_flags & DE_USER)
458 			devfs_dir_unref_de(dm, dd);
459 		if (de->de_flags & (DE_DOT | DE_DOTDOT))
460 			devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
461 		else if (de->de_dirent->d_type == DT_DIR)
462 			devfs_purge(dm, de);
463 		else
464 			devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
465 	}
466 	if (DEVFS_DE_DROP(dd))
467 		devfs_dirent_free(dd);
468 	else if ((dd->de_flags & DE_DOOMED) == 0)
469 		devfs_delete(dm, dd, DEVFS_DEL_NORECURSE);
470 }
471 
472 /*
473  * Each cdev_priv has an array of pointers to devfs_dirent which is indexed
474  * by the mount points dm_idx.
475  * This function extends the array when necessary, taking into account that
476  * the default array is 1 element and not malloc'ed.
477  */
478 static void
479 devfs_metoo(struct cdev_priv *cdp, struct devfs_mount *dm)
480 {
481 	struct devfs_dirent **dep, **olddep;
482 	int siz;
483 
484 	siz = (dm->dm_idx + 1) * sizeof *dep;
485 	dep = malloc(siz, M_DEVFS2, M_WAITOK | M_ZERO);
486 	dev_lock();
487 	if (dm->dm_idx <= cdp->cdp_maxdirent) {
488 		/* We got raced */
489 		dev_unlock();
490 		free(dep, M_DEVFS2);
491 		return;
492 	}
493 	memcpy(dep, cdp->cdp_dirents, (cdp->cdp_maxdirent + 1) * sizeof *dep);
494 	olddep = cdp->cdp_maxdirent > 0 ? cdp->cdp_dirents : NULL;
495 	cdp->cdp_dirents = dep;
496 	/*
497 	 * XXX: if malloc told us how much we actually got this could
498 	 * XXX: be optimized.
499 	 */
500 	cdp->cdp_maxdirent = dm->dm_idx;
501 	dev_unlock();
502 	free(olddep, M_DEVFS2);
503 }
504 
505 /*
506  * The caller needs to hold the dm for the duration of the call.
507  */
508 static int
509 devfs_populate_loop(struct devfs_mount *dm, int cleanup)
510 {
511 	struct cdev_priv *cdp;
512 	struct devfs_dirent *de;
513 	struct devfs_dirent *dd, *dt;
514 	struct cdev *pdev;
515 	int de_flags, depth, j;
516 	char *q, *s;
517 
518 	sx_assert(&dm->dm_lock, SX_XLOCKED);
519 	dev_lock();
520 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list) {
521 		KASSERT(cdp->cdp_dirents != NULL, ("NULL cdp_dirents"));
522 		KASSERT((cdp->cdp_flags & CDP_ON_ACTIVE_LIST) != 0,
523 		    ("%s: cdp %p (%s) should not be on active list",
524 		    __func__, cdp, cdp->cdp_c.si_name));
525 
526 		/*
527 		 * If we are unmounting, or the device has been destroyed,
528 		 * clean up our dirent.
529 		 */
530 		if ((cleanup || !(cdp->cdp_flags & CDP_ACTIVE)) &&
531 		    dm->dm_idx <= cdp->cdp_maxdirent &&
532 		    cdp->cdp_dirents[dm->dm_idx] != NULL) {
533 			de = cdp->cdp_dirents[dm->dm_idx];
534 			cdp->cdp_dirents[dm->dm_idx] = NULL;
535 			KASSERT(cdp == de->de_cdp,
536 			    ("%s %d %s %p %p", __func__, __LINE__,
537 			    cdp->cdp_c.si_name, cdp, de->de_cdp));
538 			KASSERT(de->de_dir != NULL, ("Null de->de_dir"));
539 			dev_unlock();
540 
541 			TAILQ_REMOVE(&de->de_dir->de_dlist, de, de_list);
542 			de->de_cdp = NULL;
543 			de->de_inode = 0;
544 			devfs_delete(dm, de, 0);
545 			dev_lock();
546 			cdp->cdp_inuse--;
547 			dev_unlock();
548 			return (1);
549 		}
550 		/*
551 	 	 * GC any lingering devices
552 		 */
553 		if (!(cdp->cdp_flags & CDP_ACTIVE)) {
554 			if (cdp->cdp_inuse > 0)
555 				continue;
556 			cdp->cdp_flags &= ~CDP_ON_ACTIVE_LIST;
557 			TAILQ_REMOVE(&cdevp_list, cdp, cdp_list);
558 			dev_unlock();
559 			dev_rel(&cdp->cdp_c);
560 			return (1);
561 		}
562 		/*
563 		 * Don't create any new dirents if we are unmounting
564 		 */
565 		if (cleanup)
566 			continue;
567 		KASSERT((cdp->cdp_flags & CDP_ACTIVE), ("Bogons, I tell ya'!"));
568 
569 		if (dm->dm_idx <= cdp->cdp_maxdirent &&
570 		    cdp->cdp_dirents[dm->dm_idx] != NULL) {
571 			de = cdp->cdp_dirents[dm->dm_idx];
572 			KASSERT(cdp == de->de_cdp, ("inconsistent cdp"));
573 			continue;
574 		}
575 
576 		cdp->cdp_inuse++;
577 		dev_unlock();
578 
579 		if (dm->dm_idx > cdp->cdp_maxdirent)
580 		        devfs_metoo(cdp, dm);
581 
582 		dd = dm->dm_rootdir;
583 		s = cdp->cdp_c.si_name;
584 		for (;;) {
585 			for (q = s; *q != '/' && *q != '\0'; q++)
586 				continue;
587 			if (*q != '/')
588 				break;
589 			de = devfs_find(dd, s, q - s, 0);
590 			if (de == NULL)
591 				de = devfs_vmkdir(dm, s, q - s, dd, 0);
592 			else if (de->de_dirent->d_type == DT_LNK) {
593 				de = devfs_find(dd, s, q - s, DT_DIR);
594 				if (de == NULL)
595 					de = devfs_vmkdir(dm, s, q - s, dd, 0);
596 				de->de_flags |= DE_COVERED;
597 			}
598 			s = q + 1;
599 			dd = de;
600 			KASSERT(dd->de_dirent->d_type == DT_DIR &&
601 			    (dd->de_flags & (DE_DOT | DE_DOTDOT)) == 0,
602 			    ("%s: invalid directory (si_name=%s)",
603 			    __func__, cdp->cdp_c.si_name));
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 int
659 devfs_populate_needed(struct devfs_mount *dm)
660 {
661 
662 	return (dm->dm_generation != devfs_generation);
663 }
664 
665 /*
666  * The caller needs to hold the dm for the duration of the call.
667  */
668 void
669 devfs_populate(struct devfs_mount *dm)
670 {
671 	unsigned gen;
672 
673 	sx_assert(&dm->dm_lock, SX_XLOCKED);
674 	if (!devfs_populate_needed(dm))
675 		return;
676 	gen = devfs_generation;
677 	while (devfs_populate_loop(dm, 0))
678 		continue;
679 	dm->dm_generation = gen;
680 }
681 
682 /*
683  * The caller needs to hold the dm for the duration of the call.
684  */
685 void
686 devfs_cleanup(struct devfs_mount *dm)
687 {
688 
689 	sx_assert(&dm->dm_lock, SX_XLOCKED);
690 	while (devfs_populate_loop(dm, 1))
691 		continue;
692 	devfs_purge(dm, dm->dm_rootdir);
693 }
694 
695 /*
696  * devfs_create() and devfs_destroy() are called from kern_conf.c and
697  * in both cases the devlock() mutex is held, so no further locking
698  * is necessary and no sleeping allowed.
699  */
700 
701 void
702 devfs_create(struct cdev *dev)
703 {
704 	struct cdev_priv *cdp;
705 
706 	dev_lock_assert_locked();
707 	cdp = cdev2priv(dev);
708 	KASSERT((cdp->cdp_flags & CDP_ON_ACTIVE_LIST) == 0,
709 	    ("%s: cdp %p (%s) already on active list",
710 	    __func__, cdp, dev->si_name));
711 	cdp->cdp_flags |= (CDP_ACTIVE | CDP_ON_ACTIVE_LIST);
712 	cdp->cdp_inode = alloc_unrl(devfs_inos);
713 	dev_refl(dev);
714 	TAILQ_INSERT_TAIL(&cdevp_list, cdp, cdp_list);
715 	devfs_generation++;
716 }
717 
718 void
719 devfs_destroy(struct cdev *dev)
720 {
721 	struct cdev_priv *cdp;
722 
723 	dev_lock_assert_locked();
724 	cdp = cdev2priv(dev);
725 	cdp->cdp_flags &= ~CDP_ACTIVE;
726 	devfs_generation++;
727 }
728 
729 ino_t
730 devfs_alloc_cdp_inode(void)
731 {
732 
733 	return (alloc_unr(devfs_inos));
734 }
735 
736 void
737 devfs_free_cdp_inode(ino_t ino)
738 {
739 
740 	if (ino > 0)
741 		free_unr(devfs_inos, ino);
742 }
743 
744 static void
745 devfs_devs_init(void *junk __unused)
746 {
747 
748 	devfs_inos = new_unrhdr(DEVFS_ROOTINO + 1, INT_MAX, &devmtx);
749 }
750 
751 SYSINIT(devfs_devs, SI_SUB_DEVFS, SI_ORDER_FIRST, devfs_devs_init, NULL);
752