xref: /freebsd/sys/fs/devfs/devfs_devs.c (revision 911f0260390e18cf85f3dbf2c719b593efdc1e3c)
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  * $FreeBSD$
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 static MALLOC_DEFINE(M_DEVFS2, "DEVFS2", "DEVFS data 2");
62 static MALLOC_DEFINE(M_DEVFS3, "DEVFS3", "DEVFS data 3");
63 static MALLOC_DEFINE(M_CDEVP, "DEVFS1", "DEVFS cdev_priv storage");
64 
65 SYSCTL_NODE(_vfs, OID_AUTO, devfs, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
66     "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 	mtx_init(&cdp->cdp_threadlock, "devthrd", NULL, MTX_DEF);
142 
143 	cdp->cdp_dirents = &cdp->cdp_dirent0;
144 
145 	cdev = &cdp->cdp_c;
146 	LIST_INIT(&cdev->si_children);
147 	vfs_timestamp(&ts);
148 	cdev->si_atime = cdev->si_mtime = cdev->si_ctime = ts;
149 
150 	return (cdev);
151 }
152 
153 int
154 devfs_dev_exists(const char *name)
155 {
156 	struct cdev_priv *cdp;
157 
158 	dev_lock_assert_locked();
159 
160 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list) {
161 		if ((cdp->cdp_flags & CDP_ACTIVE) == 0)
162 			continue;
163 		if (devfs_pathpath(cdp->cdp_c.si_name, name) != 0)
164 			return (1);
165 		if (devfs_pathpath(name, cdp->cdp_c.si_name) != 0)
166 			return (1);
167 	}
168 	if (devfs_dir_find(name) != 0)
169 		return (1);
170 
171 	return (0);
172 }
173 
174 void
175 devfs_free(struct cdev *cdev)
176 {
177 	struct cdev_priv *cdp;
178 
179 	cdp = cdev2priv(cdev);
180 	if (cdev->si_cred != NULL)
181 		crfree(cdev->si_cred);
182 	devfs_free_cdp_inode(cdp->cdp_inode);
183 	if (cdp->cdp_maxdirent > 0)
184 		free(cdp->cdp_dirents, M_DEVFS2);
185 	mtx_destroy(&cdp->cdp_threadlock);
186 	free(cdp, M_CDEVP);
187 }
188 
189 struct devfs_dirent *
190 devfs_find(struct devfs_dirent *dd, const char *name, int namelen, int type)
191 {
192 	struct devfs_dirent *de;
193 
194 	TAILQ_FOREACH(de, &dd->de_dlist, de_list) {
195 		if (namelen != de->de_dirent->d_namlen)
196 			continue;
197 		if (type != 0 && type != de->de_dirent->d_type)
198 			continue;
199 
200 		/*
201 		 * The race with finding non-active name is not
202 		 * completely closed by the check, but it is similar
203 		 * to the devfs_allocv() in making it unlikely enough.
204 		 */
205 		if (de->de_dirent->d_type == DT_CHR &&
206 		    (de->de_cdp->cdp_flags & CDP_ACTIVE) == 0)
207 			continue;
208 
209 		if (bcmp(name, de->de_dirent->d_name, namelen) != 0)
210 			continue;
211 		break;
212 	}
213 	KASSERT(de == NULL || (de->de_flags & DE_DOOMED) == 0,
214 	    ("devfs_find: returning a doomed entry"));
215 	return (de);
216 }
217 
218 struct devfs_dirent *
219 devfs_newdirent(char *name, int namelen)
220 {
221 	int i;
222 	struct devfs_dirent *de;
223 	struct dirent d;
224 
225 	d.d_namlen = namelen;
226 	i = sizeof(*de) + GENERIC_DIRSIZ(&d);
227 	de = malloc(i, M_DEVFS3, M_WAITOK | M_ZERO);
228 	de->de_dirent = (struct dirent *)(de + 1);
229 	de->de_dirent->d_namlen = namelen;
230 	de->de_dirent->d_reclen = GENERIC_DIRSIZ(&d);
231 	bcopy(name, de->de_dirent->d_name, namelen);
232 	dirent_terminate(de->de_dirent);
233 	vfs_timestamp(&de->de_ctime);
234 	de->de_mtime = de->de_atime = de->de_ctime;
235 	de->de_links = 1;
236 	de->de_holdcnt = 1;
237 #ifdef MAC
238 	mac_devfs_init(de);
239 #endif
240 	return (de);
241 }
242 
243 struct devfs_dirent *
244 devfs_parent_dirent(struct devfs_dirent *de)
245 {
246 
247 	if (de->de_dirent->d_type != DT_DIR)
248 		return (de->de_dir);
249 
250 	if (de->de_flags & (DE_DOT | DE_DOTDOT))
251 		return (NULL);
252 
253 	de = TAILQ_FIRST(&de->de_dlist);	/* "." */
254 	if (de == NULL)
255 		return (NULL);
256 	de = TAILQ_NEXT(de, de_list);		/* ".." */
257 	if (de == NULL)
258 		return (NULL);
259 
260 	return (de->de_dir);
261 }
262 
263 struct devfs_dirent *
264 devfs_vmkdir(struct devfs_mount *dmp, char *name, int namelen,
265     struct devfs_dirent *dotdot, u_int inode)
266 {
267 	struct devfs_dirent *dd;
268 	struct devfs_dirent *de;
269 
270 	/* Create the new directory */
271 	dd = devfs_newdirent(name, namelen);
272 	TAILQ_INIT(&dd->de_dlist);
273 	dd->de_dirent->d_type = DT_DIR;
274 	dd->de_mode = 0555;
275 	dd->de_links = 2;
276 	dd->de_dir = dd;
277 	if (inode != 0)
278 		dd->de_inode = inode;
279 	else
280 		dd->de_inode = alloc_unr(devfs_inos);
281 
282 	/*
283 	 * "." and ".." are always the two first entries in the
284 	 * de_dlist list.
285 	 *
286 	 * Create the "." entry in the new directory.
287 	 */
288 	de = devfs_newdirent(".", 1);
289 	de->de_dirent->d_type = DT_DIR;
290 	de->de_flags |= DE_DOT;
291 	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
292 	de->de_dir = dd;
293 
294 	/* Create the ".." entry in the new directory. */
295 	de = devfs_newdirent("..", 2);
296 	de->de_dirent->d_type = DT_DIR;
297 	de->de_flags |= DE_DOTDOT;
298 	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
299 	if (dotdot == NULL) {
300 		de->de_dir = dd;
301 	} else {
302 		de->de_dir = dotdot;
303 		sx_assert(&dmp->dm_lock, SX_XLOCKED);
304 		TAILQ_INSERT_TAIL(&dotdot->de_dlist, dd, de_list);
305 		dotdot->de_links++;
306 		devfs_rules_apply(dmp, dd);
307 	}
308 
309 #ifdef MAC
310 	mac_devfs_create_directory(dmp->dm_mount, name, namelen, dd);
311 #endif
312 	return (dd);
313 }
314 
315 void
316 devfs_dirent_free(struct devfs_dirent *de)
317 {
318 	struct vnode *vp;
319 
320 	vp = de->de_vnode;
321 	mtx_lock(&devfs_de_interlock);
322 	if (vp != NULL && vp->v_data == de)
323 		vp->v_data = NULL;
324 	mtx_unlock(&devfs_de_interlock);
325 	free(de, M_DEVFS3);
326 }
327 
328 /*
329  * Removes a directory if it is empty. Also empty parent directories are
330  * removed recursively.
331  */
332 static void
333 devfs_rmdir_empty(struct devfs_mount *dm, struct devfs_dirent *de)
334 {
335 	struct devfs_dirent *dd, *de_dot, *de_dotdot;
336 
337 	sx_assert(&dm->dm_lock, SX_XLOCKED);
338 
339 	for (;;) {
340 		KASSERT(de->de_dirent->d_type == DT_DIR,
341 		    ("devfs_rmdir_empty: de is not a directory"));
342 
343 		if ((de->de_flags & DE_DOOMED) != 0 || de == dm->dm_rootdir)
344 			return;
345 
346 		de_dot = TAILQ_FIRST(&de->de_dlist);
347 		KASSERT(de_dot != NULL, ("devfs_rmdir_empty: . missing"));
348 		de_dotdot = TAILQ_NEXT(de_dot, de_list);
349 		KASSERT(de_dotdot != NULL, ("devfs_rmdir_empty: .. missing"));
350 		/* Return if the directory is not empty. */
351 		if (TAILQ_NEXT(de_dotdot, de_list) != NULL)
352 			return;
353 
354 		dd = devfs_parent_dirent(de);
355 		KASSERT(dd != NULL, ("devfs_rmdir_empty: NULL dd"));
356 		TAILQ_REMOVE(&de->de_dlist, de_dot, de_list);
357 		TAILQ_REMOVE(&de->de_dlist, de_dotdot, de_list);
358 		TAILQ_REMOVE(&dd->de_dlist, de, de_list);
359 		DEVFS_DE_HOLD(dd);
360 		devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
361 		devfs_delete(dm, de_dot, DEVFS_DEL_NORECURSE);
362 		devfs_delete(dm, de_dotdot, DEVFS_DEL_NORECURSE);
363 		if (DEVFS_DE_DROP(dd)) {
364 			devfs_dirent_free(dd);
365 			return;
366 		}
367 
368 		de = dd;
369 	}
370 }
371 
372 /*
373  * The caller needs to hold the dm for the duration of the call since
374  * dm->dm_lock may be temporary dropped.
375  */
376 void
377 devfs_delete(struct devfs_mount *dm, struct devfs_dirent *de, int flags)
378 {
379 	struct devfs_dirent *dd;
380 	struct vnode *vp;
381 
382 	KASSERT((de->de_flags & DE_DOOMED) == 0,
383 		("devfs_delete doomed dirent"));
384 	de->de_flags |= DE_DOOMED;
385 
386 	if ((flags & DEVFS_DEL_NORECURSE) == 0) {
387 		dd = devfs_parent_dirent(de);
388 		if (dd != NULL)
389 			DEVFS_DE_HOLD(dd);
390 		if (de->de_flags & DE_USER) {
391 			KASSERT(dd != NULL, ("devfs_delete: NULL dd"));
392 			devfs_dir_unref_de(dm, dd);
393 		}
394 	} else
395 		dd = NULL;
396 
397 	mtx_lock(&devfs_de_interlock);
398 	vp = de->de_vnode;
399 	if (vp != NULL) {
400 		vhold(vp);
401 		mtx_unlock(&devfs_de_interlock);
402 		sx_unlock(&dm->dm_lock);
403 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
404 		vgone(vp);
405 		VOP_UNLOCK(vp);
406 		vdrop(vp);
407 		sx_xlock(&dm->dm_lock);
408 	} else
409 		mtx_unlock(&devfs_de_interlock);
410 	if (de->de_symlink) {
411 		free(de->de_symlink, M_DEVFS);
412 		de->de_symlink = NULL;
413 	}
414 #ifdef MAC
415 	mac_devfs_destroy(de);
416 #endif
417 	if (de->de_inode > DEVFS_ROOTINO) {
418 		devfs_free_cdp_inode(de->de_inode);
419 		de->de_inode = 0;
420 	}
421 	if (DEVFS_DE_DROP(de))
422 		devfs_dirent_free(de);
423 
424 	if (dd != NULL) {
425 		if (DEVFS_DE_DROP(dd))
426 			devfs_dirent_free(dd);
427 		else
428 			devfs_rmdir_empty(dm, dd);
429 	}
430 }
431 
432 /*
433  * Called on unmount.
434  * Recursively removes the entire tree.
435  * The caller needs to hold the dm for the duration of the call.
436  */
437 
438 static void
439 devfs_purge(struct devfs_mount *dm, struct devfs_dirent *dd)
440 {
441 	struct devfs_dirent *de;
442 
443 	sx_assert(&dm->dm_lock, SX_XLOCKED);
444 
445 	DEVFS_DE_HOLD(dd);
446 	for (;;) {
447 		/*
448 		 * Use TAILQ_LAST() to remove "." and ".." last.
449 		 * We might need ".." to resolve a path in
450 		 * devfs_dir_unref_de().
451 		 */
452 		de = TAILQ_LAST(&dd->de_dlist, devfs_dlist_head);
453 		if (de == NULL)
454 			break;
455 		TAILQ_REMOVE(&dd->de_dlist, de, de_list);
456 		if (de->de_flags & DE_USER)
457 			devfs_dir_unref_de(dm, dd);
458 		if (de->de_flags & (DE_DOT | DE_DOTDOT))
459 			devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
460 		else if (de->de_dirent->d_type == DT_DIR)
461 			devfs_purge(dm, de);
462 		else
463 			devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
464 	}
465 	if (DEVFS_DE_DROP(dd))
466 		devfs_dirent_free(dd);
467 	else if ((dd->de_flags & DE_DOOMED) == 0)
468 		devfs_delete(dm, dd, DEVFS_DEL_NORECURSE);
469 }
470 
471 /*
472  * Each cdev_priv has an array of pointers to devfs_dirent which is indexed
473  * by the mount points dm_idx.
474  * This function extends the array when necessary, taking into account that
475  * the default array is 1 element and not malloc'ed.
476  */
477 static void
478 devfs_metoo(struct cdev_priv *cdp, struct devfs_mount *dm)
479 {
480 	struct devfs_dirent **dep, **olddep;
481 	int siz;
482 
483 	siz = (dm->dm_idx + 1) * sizeof *dep;
484 	dep = malloc(siz, M_DEVFS2, M_WAITOK | M_ZERO);
485 	dev_lock();
486 	if (dm->dm_idx <= cdp->cdp_maxdirent) {
487 		/* We got raced */
488 		dev_unlock();
489 		free(dep, M_DEVFS2);
490 		return;
491 	}
492 	memcpy(dep, cdp->cdp_dirents, (cdp->cdp_maxdirent + 1) * sizeof *dep);
493 	olddep = cdp->cdp_maxdirent > 0 ? cdp->cdp_dirents : NULL;
494 	cdp->cdp_dirents = dep;
495 	/*
496 	 * XXX: if malloc told us how much we actually got this could
497 	 * XXX: be optimized.
498 	 */
499 	cdp->cdp_maxdirent = dm->dm_idx;
500 	dev_unlock();
501 	free(olddep, M_DEVFS2);
502 }
503 
504 /*
505  * The caller needs to hold the dm for the duration of the call.
506  */
507 static int
508 devfs_populate_loop(struct devfs_mount *dm, int cleanup)
509 {
510 	struct cdev_priv *cdp;
511 	struct devfs_dirent *de;
512 	struct devfs_dirent *dd, *dt;
513 	struct cdev *pdev;
514 	int de_flags, depth, j;
515 	char *q, *s;
516 
517 	sx_assert(&dm->dm_lock, SX_XLOCKED);
518 	dev_lock();
519 	TAILQ_FOREACH(cdp, &cdevp_list, cdp_list) {
520 		KASSERT(cdp->cdp_dirents != NULL, ("NULL cdp_dirents"));
521 
522 		/*
523 		 * If we are unmounting, or the device has been destroyed,
524 		 * clean up our dirent.
525 		 */
526 		if ((cleanup || !(cdp->cdp_flags & CDP_ACTIVE)) &&
527 		    dm->dm_idx <= cdp->cdp_maxdirent &&
528 		    cdp->cdp_dirents[dm->dm_idx] != NULL) {
529 			de = cdp->cdp_dirents[dm->dm_idx];
530 			cdp->cdp_dirents[dm->dm_idx] = NULL;
531 			KASSERT(cdp == de->de_cdp,
532 			    ("%s %d %s %p %p", __func__, __LINE__,
533 			    cdp->cdp_c.si_name, cdp, de->de_cdp));
534 			KASSERT(de->de_dir != NULL, ("Null de->de_dir"));
535 			dev_unlock();
536 
537 			TAILQ_REMOVE(&de->de_dir->de_dlist, de, de_list);
538 			de->de_cdp = NULL;
539 			de->de_inode = 0;
540 			devfs_delete(dm, de, 0);
541 			dev_lock();
542 			cdp->cdp_inuse--;
543 			dev_unlock();
544 			return (1);
545 		}
546 		/*
547 	 	 * GC any lingering devices
548 		 */
549 		if (!(cdp->cdp_flags & CDP_ACTIVE)) {
550 			if (cdp->cdp_inuse > 0)
551 				continue;
552 			TAILQ_REMOVE(&cdevp_list, cdp, cdp_list);
553 			dev_unlock();
554 			dev_rel(&cdp->cdp_c);
555 			return (1);
556 		}
557 		/*
558 		 * Don't create any new dirents if we are unmounting
559 		 */
560 		if (cleanup)
561 			continue;
562 		KASSERT((cdp->cdp_flags & CDP_ACTIVE), ("Bogons, I tell ya'!"));
563 
564 		if (dm->dm_idx <= cdp->cdp_maxdirent &&
565 		    cdp->cdp_dirents[dm->dm_idx] != NULL) {
566 			de = cdp->cdp_dirents[dm->dm_idx];
567 			KASSERT(cdp == de->de_cdp, ("inconsistent cdp"));
568 			continue;
569 		}
570 
571 		cdp->cdp_inuse++;
572 		dev_unlock();
573 
574 		if (dm->dm_idx > cdp->cdp_maxdirent)
575 		        devfs_metoo(cdp, dm);
576 
577 		dd = dm->dm_rootdir;
578 		s = cdp->cdp_c.si_name;
579 		for (;;) {
580 			for (q = s; *q != '/' && *q != '\0'; q++)
581 				continue;
582 			if (*q != '/')
583 				break;
584 			de = devfs_find(dd, s, q - s, 0);
585 			if (de == NULL)
586 				de = devfs_vmkdir(dm, s, q - s, dd, 0);
587 			else if (de->de_dirent->d_type == DT_LNK) {
588 				de = devfs_find(dd, s, q - s, DT_DIR);
589 				if (de == NULL)
590 					de = devfs_vmkdir(dm, s, q - s, dd, 0);
591 				de->de_flags |= DE_COVERED;
592 			}
593 			s = q + 1;
594 			dd = de;
595 			KASSERT(dd->de_dirent->d_type == DT_DIR &&
596 			    (dd->de_flags & (DE_DOT | DE_DOTDOT)) == 0,
597 			    ("%s: invalid directory (si_name=%s)",
598 			    __func__, cdp->cdp_c.si_name));
599 		}
600 		de_flags = 0;
601 		de = devfs_find(dd, s, q - s, DT_LNK);
602 		if (de != NULL)
603 			de_flags |= DE_COVERED;
604 
605 		de = devfs_newdirent(s, q - s);
606 		if (cdp->cdp_c.si_flags & SI_ALIAS) {
607 			de->de_uid = 0;
608 			de->de_gid = 0;
609 			de->de_mode = 0755;
610 			de->de_dirent->d_type = DT_LNK;
611 			pdev = cdp->cdp_c.si_parent;
612 			dt = dd;
613 			depth = 0;
614 			while (dt != dm->dm_rootdir &&
615 			    (dt = devfs_parent_dirent(dt)) != NULL)
616 				depth++;
617 			j = depth * 3 + strlen(pdev->si_name) + 1;
618 			de->de_symlink = malloc(j, M_DEVFS, M_WAITOK);
619 			de->de_symlink[0] = 0;
620 			while (depth-- > 0)
621 				strcat(de->de_symlink, "../");
622 			strcat(de->de_symlink, pdev->si_name);
623 		} else {
624 			de->de_uid = cdp->cdp_c.si_uid;
625 			de->de_gid = cdp->cdp_c.si_gid;
626 			de->de_mode = cdp->cdp_c.si_mode;
627 			de->de_dirent->d_type = DT_CHR;
628 		}
629 		de->de_flags |= de_flags;
630 		de->de_inode = cdp->cdp_inode;
631 		de->de_cdp = cdp;
632 #ifdef MAC
633 		mac_devfs_create_device(cdp->cdp_c.si_cred, dm->dm_mount,
634 		    &cdp->cdp_c, de);
635 #endif
636 		de->de_dir = dd;
637 		TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
638 		devfs_rules_apply(dm, de);
639 		dev_lock();
640 		/* XXX: could check that cdp is still active here */
641 		KASSERT(cdp->cdp_dirents[dm->dm_idx] == NULL,
642 		    ("%s %d\n", __func__, __LINE__));
643 		cdp->cdp_dirents[dm->dm_idx] = de;
644 		KASSERT(de->de_cdp != (void *)0xdeadc0de,
645 		    ("%s %d\n", __func__, __LINE__));
646 		dev_unlock();
647 		return (1);
648 	}
649 	dev_unlock();
650 	return (0);
651 }
652 
653 int
654 devfs_populate_needed(struct devfs_mount *dm)
655 {
656 
657 	return (dm->dm_generation != devfs_generation);
658 }
659 
660 /*
661  * The caller needs to hold the dm for the duration of the call.
662  */
663 void
664 devfs_populate(struct devfs_mount *dm)
665 {
666 	unsigned gen;
667 
668 	sx_assert(&dm->dm_lock, SX_XLOCKED);
669 	if (!devfs_populate_needed(dm))
670 		return;
671 	gen = devfs_generation;
672 	while (devfs_populate_loop(dm, 0))
673 		continue;
674 	dm->dm_generation = gen;
675 }
676 
677 /*
678  * The caller needs to hold the dm for the duration of the call.
679  */
680 void
681 devfs_cleanup(struct devfs_mount *dm)
682 {
683 
684 	sx_assert(&dm->dm_lock, SX_XLOCKED);
685 	while (devfs_populate_loop(dm, 1))
686 		continue;
687 	devfs_purge(dm, dm->dm_rootdir);
688 }
689 
690 /*
691  * devfs_create() and devfs_destroy() are called from kern_conf.c and
692  * in both cases the devlock() mutex is held, so no further locking
693  * is necessary and no sleeping allowed.
694  */
695 
696 void
697 devfs_create(struct cdev *dev)
698 {
699 	struct cdev_priv *cdp;
700 
701 	dev_lock_assert_locked();
702 	cdp = cdev2priv(dev);
703 	cdp->cdp_flags |= CDP_ACTIVE;
704 	cdp->cdp_inode = alloc_unrl(devfs_inos);
705 	dev_refl(dev);
706 	TAILQ_INSERT_TAIL(&cdevp_list, cdp, cdp_list);
707 	devfs_generation++;
708 }
709 
710 void
711 devfs_destroy(struct cdev *dev)
712 {
713 	struct cdev_priv *cdp;
714 
715 	dev_lock_assert_locked();
716 	cdp = cdev2priv(dev);
717 	cdp->cdp_flags &= ~CDP_ACTIVE;
718 	devfs_generation++;
719 }
720 
721 ino_t
722 devfs_alloc_cdp_inode(void)
723 {
724 
725 	return (alloc_unr(devfs_inos));
726 }
727 
728 void
729 devfs_free_cdp_inode(ino_t ino)
730 {
731 
732 	if (ino > 0)
733 		free_unr(devfs_inos, ino);
734 }
735 
736 static void
737 devfs_devs_init(void *junk __unused)
738 {
739 
740 	devfs_inos = new_unrhdr(DEVFS_ROOTINO + 1, INT_MAX, &devmtx);
741 }
742 
743 SYSINIT(devfs_devs, SI_SUB_DEVFS, SI_ORDER_FIRST, devfs_devs_init, NULL);
744