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kern_drvctl.c revision 1.49 
      1 /* $NetBSD: kern_drvctl.c,v 1.49 2021/06/16 00:19:46 riastradh Exp $ */
      2 
      3 /*
      4  * Copyright (c) 2004
      5  * 	Matthias Drochner.  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. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 
     29 #include <sys/cdefs.h>
     30 __KERNEL_RCSID(0, "$NetBSD: kern_drvctl.c,v 1.49 2021/06/16 00:19:46 riastradh Exp $");
     31 
     32 #include <sys/param.h>
     33 #include <sys/systm.h>
     34 #include <sys/kernel.h>
     35 #include <sys/conf.h>
     36 #include <sys/device.h>
     37 #include <sys/event.h>
     38 #include <sys/kmem.h>
     39 #include <sys/ioctl.h>
     40 #include <sys/fcntl.h>
     41 #include <sys/file.h>
     42 #include <sys/filedesc.h>
     43 #include <sys/select.h>
     44 #include <sys/poll.h>
     45 #include <sys/drvctlio.h>
     46 #include <sys/devmon.h>
     47 #include <sys/stat.h>
     48 #include <sys/kauth.h>
     49 #include <sys/lwp.h>
     50 #include <sys/module.h>
     51 
     52 #include "ioconf.h"
     53 
     54 struct drvctl_event {
     55 	TAILQ_ENTRY(drvctl_event) dce_link;
     56 	prop_dictionary_t	dce_event;
     57 };
     58 
     59 TAILQ_HEAD(drvctl_queue, drvctl_event);
     60 
     61 static struct drvctl_queue	drvctl_eventq;		/* FIFO */
     62 static kcondvar_t		drvctl_cond;
     63 static kmutex_t			drvctl_lock;
     64 static int			drvctl_nopen = 0, drvctl_eventcnt = 0;
     65 static struct selinfo		drvctl_rdsel;
     66 
     67 #define DRVCTL_EVENTQ_DEPTH	64	/* arbitrary queue limit */
     68 
     69 dev_type_open(drvctlopen);
     70 
     71 const struct cdevsw drvctl_cdevsw = {
     72 	.d_open = drvctlopen,
     73 	.d_close = nullclose,
     74 	.d_read = nullread,
     75 	.d_write = nullwrite,
     76 	.d_ioctl = noioctl,
     77 	.d_stop = nostop,
     78 	.d_tty = notty,
     79 	.d_poll = nopoll,
     80 	.d_mmap = nommap,
     81 	.d_kqfilter = nokqfilter,
     82 	.d_discard = nodiscard,
     83 	.d_flag = D_OTHER
     84 };
     85 
     86 static int	drvctl_read(struct file *, off_t *, struct uio *,
     87 			    kauth_cred_t, int);
     88 static int	drvctl_write(struct file *, off_t *, struct uio *,
     89 			     kauth_cred_t, int);
     90 static int	drvctl_ioctl(struct file *, u_long, void *);
     91 static int	drvctl_poll(struct file *, int);
     92 static int	drvctl_stat(struct file *, struct stat *);
     93 static int	drvctl_close(struct file *);
     94 
     95 static const struct fileops drvctl_fileops = {
     96 	.fo_name = "drvctl",
     97 	.fo_read = drvctl_read,
     98 	.fo_write = drvctl_write,
     99 	.fo_ioctl = drvctl_ioctl,
    100 	.fo_fcntl = fnullop_fcntl,
    101 	.fo_poll = drvctl_poll,
    102 	.fo_stat = drvctl_stat,
    103 	.fo_close = drvctl_close,
    104 	.fo_kqfilter = fnullop_kqfilter,
    105 	.fo_restart = fnullop_restart,
    106 };
    107 
    108 #define MAXLOCATORS 100
    109 
    110 static int (*saved_insert_vec)(const char *, prop_dictionary_t) = NULL;
    111 
    112 static int drvctl_command(struct lwp *, struct plistref *, u_long, int);
    113 static int drvctl_getevent(struct lwp *, struct plistref *, u_long, int);
    114 
    115 void
    116 drvctl_init(void)
    117 {
    118 	TAILQ_INIT(&drvctl_eventq);
    119 	mutex_init(&drvctl_lock, MUTEX_DEFAULT, IPL_NONE);
    120 	cv_init(&drvctl_cond, "devmon");
    121 	selinit(&drvctl_rdsel);
    122 }
    123 
    124 void
    125 drvctl_fini(void)
    126 {
    127 
    128 	seldestroy(&drvctl_rdsel);
    129 	cv_destroy(&drvctl_cond);
    130 	mutex_destroy(&drvctl_lock);
    131 }
    132 
    133 int
    134 devmon_insert(const char *event, prop_dictionary_t ev)
    135 {
    136 	struct drvctl_event *dce, *odce;
    137 
    138 	mutex_enter(&drvctl_lock);
    139 
    140 	if (drvctl_nopen == 0) {
    141 		prop_object_release(ev);
    142 		mutex_exit(&drvctl_lock);
    143 		return 0;
    144 	}
    145 
    146 	/* Fill in mandatory member */
    147 	if (!prop_dictionary_set_string_nocopy(ev, "event", event)) {
    148 		prop_object_release(ev);
    149 		mutex_exit(&drvctl_lock);
    150 		return 0;
    151 	}
    152 
    153 	dce = kmem_alloc(sizeof(*dce), KM_SLEEP);
    154 	dce->dce_event = ev;
    155 
    156 	if (drvctl_eventcnt == DRVCTL_EVENTQ_DEPTH) {
    157 		odce = TAILQ_FIRST(&drvctl_eventq);
    158 		TAILQ_REMOVE(&drvctl_eventq, odce, dce_link);
    159 		prop_object_release(odce->dce_event);
    160 		kmem_free(odce, sizeof(*odce));
    161 		--drvctl_eventcnt;
    162 	}
    163 
    164 	TAILQ_INSERT_TAIL(&drvctl_eventq, dce, dce_link);
    165 	++drvctl_eventcnt;
    166 	cv_broadcast(&drvctl_cond);
    167 	selnotify(&drvctl_rdsel, 0, 0);
    168 
    169 	mutex_exit(&drvctl_lock);
    170 	return 0;
    171 }
    172 
    173 int
    174 drvctlopen(dev_t dev, int flags, int mode, struct lwp *l)
    175 {
    176 	struct file *fp;
    177 	int fd;
    178 	int ret;
    179 
    180 	ret = fd_allocfile(&fp, &fd);
    181 	if (ret)
    182 		return ret;
    183 
    184 	/* XXX setup context */
    185 	mutex_enter(&drvctl_lock);
    186 	ret = fd_clone(fp, fd, flags, &drvctl_fileops, /* context */NULL);
    187 	++drvctl_nopen;
    188 	mutex_exit(&drvctl_lock);
    189 
    190 	return ret;
    191 }
    192 
    193 static int
    194 pmdevbyname(u_long cmd, struct devpmargs *a)
    195 {
    196 	device_t d;
    197 
    198 	KASSERT(KERNEL_LOCKED_P());
    199 
    200 	if ((d = device_find_by_xname(a->devname)) == NULL)
    201 		return ENXIO;
    202 
    203 	switch (cmd) {
    204 	case DRVSUSPENDDEV:
    205 		return pmf_device_recursive_suspend(d, PMF_Q_DRVCTL) ? 0 : EBUSY;
    206 	case DRVRESUMEDEV:
    207 		if (a->flags & DEVPM_F_SUBTREE) {
    208 			return pmf_device_subtree_resume(d, PMF_Q_DRVCTL)
    209 			    ? 0 : EBUSY;
    210 		} else {
    211 			return pmf_device_recursive_resume(d, PMF_Q_DRVCTL)
    212 			    ? 0 : EBUSY;
    213 		}
    214 	default:
    215 		return EPASSTHROUGH;
    216 	}
    217 }
    218 
    219 static int
    220 listdevbyname(struct devlistargs *l)
    221 {
    222 	device_t d, child;
    223 	deviter_t di;
    224 	int cnt = 0, idx, error = 0;
    225 
    226 	KASSERT(KERNEL_LOCKED_P());
    227 
    228 	if (*l->l_devname == '\0')
    229 		d = NULL;
    230 	else if (memchr(l->l_devname, 0, sizeof(l->l_devname)) == NULL)
    231 		return EINVAL;
    232 	else if ((d = device_find_by_xname(l->l_devname)) == NULL)
    233 		return ENXIO;
    234 
    235 	for (child = deviter_first(&di, 0); child != NULL;
    236 	     child = deviter_next(&di)) {
    237 		if (device_parent(child) != d)
    238 			continue;
    239 		idx = cnt++;
    240 		if (l->l_childname == NULL || idx >= l->l_children)
    241 			continue;
    242 		error = copyoutstr(device_xname(child), l->l_childname[idx],
    243 				sizeof(l->l_childname[idx]), NULL);
    244 		if (error != 0)
    245 			break;
    246 	}
    247 	deviter_release(&di);
    248 
    249 	l->l_children = cnt;
    250 	return error;
    251 }
    252 
    253 static int
    254 detachdevbyname(const char *devname)
    255 {
    256 	device_t d;
    257 	deviter_t di;
    258 	int error;
    259 
    260 	KASSERT(KERNEL_LOCKED_P());
    261 
    262 	for (d = deviter_first(&di, DEVITER_F_RW);
    263 	     d != NULL;
    264 	     d = deviter_next(&di)) {
    265 		if (strcmp(device_xname(d), devname) == 0)
    266 			break;
    267 	}
    268 	if (d == NULL) {
    269 		error = ENXIO;
    270 		goto out;
    271 	}
    272 
    273 #ifndef XXXFULLRISK
    274 	/*
    275 	 * If the parent cannot be notified, it might keep
    276 	 * pointers to the detached device.
    277 	 * There might be a private notification mechanism,
    278 	 * but better play it safe here.
    279 	 */
    280 	if (d->dv_parent && !d->dv_parent->dv_cfattach->ca_childdetached) {
    281 		error = ENOTSUP;
    282 		goto out;
    283 	}
    284 #endif
    285 
    286 	error = config_detach(d, 0);
    287 out:	deviter_release(&di);
    288 	return error;
    289 }
    290 
    291 static int
    292 rescanbus(const char *busname, const char *ifattr,
    293 	  int numlocators, const int *locators)
    294 {
    295 	int i, rc;
    296 	device_t d;
    297 	const struct cfiattrdata * const *ap;
    298 
    299 	KASSERT(KERNEL_LOCKED_P());
    300 
    301 	/* XXX there should be a way to get limits and defaults (per device)
    302 	   from config generated data */
    303 	int locs[MAXLOCATORS];
    304 	for (i = 0; i < MAXLOCATORS; i++)
    305 		locs[i] = -1;
    306 
    307 	for (i = 0; i < numlocators;i++)
    308 		locs[i] = locators[i];
    309 
    310 	if ((d = device_find_by_xname(busname)) == NULL)
    311 		return ENXIO;
    312 
    313 	/*
    314 	 * must support rescan, and must have something
    315 	 * to attach to
    316 	 */
    317 	if (!d->dv_cfattach->ca_rescan ||
    318 	    !d->dv_cfdriver->cd_attrs)
    319 		return ENODEV;
    320 
    321 	/* rescan all ifattrs if none is specified */
    322 	if (!ifattr) {
    323 		rc = 0;
    324 		for (ap = d->dv_cfdriver->cd_attrs; *ap; ap++) {
    325 			rc = (*d->dv_cfattach->ca_rescan)(d, (*ap)->ci_name,
    326 			    locs);
    327 			if (rc)
    328 				break;
    329 		}
    330 	} else {
    331 		/* check for valid attribute passed */
    332 		for (ap = d->dv_cfdriver->cd_attrs; *ap; ap++)
    333 			if (!strcmp((*ap)->ci_name, ifattr))
    334 				break;
    335 		if (!*ap)
    336 			return EINVAL;
    337 		rc = (*d->dv_cfattach->ca_rescan)(d, ifattr, locs);
    338 	}
    339 
    340 	config_deferred(NULL);
    341 	return rc;
    342 }
    343 
    344 static int
    345 drvctl_read(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred,
    346     int flags)
    347 {
    348 	return ENODEV;
    349 }
    350 
    351 static int
    352 drvctl_write(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred,
    353     int flags)
    354 {
    355 	return ENODEV;
    356 }
    357 
    358 static int
    359 drvctl_ioctl(struct file *fp, u_long cmd, void *data)
    360 {
    361 	int res;
    362 	char *ifattr;
    363 	int *locs;
    364 	size_t locs_sz = 0; /* XXXgcc */
    365 
    366 	KERNEL_LOCK(1, NULL);
    367 	switch (cmd) {
    368 	case DRVSUSPENDDEV:
    369 	case DRVRESUMEDEV:
    370 #define d ((struct devpmargs *)data)
    371 		res = pmdevbyname(cmd, d);
    372 #undef d
    373 		break;
    374 	case DRVLISTDEV:
    375 		res = listdevbyname((struct devlistargs *)data);
    376 		break;
    377 	case DRVDETACHDEV:
    378 #define d ((struct devdetachargs *)data)
    379 		res = detachdevbyname(d->devname);
    380 #undef d
    381 		break;
    382 	case DRVRESCANBUS:
    383 #define d ((struct devrescanargs *)data)
    384 		d->busname[sizeof(d->busname) - 1] = '\0';
    385 
    386 		/* XXX better copyin? */
    387 		if (d->ifattr[0]) {
    388 			d->ifattr[sizeof(d->ifattr) - 1] = '\0';
    389 			ifattr = d->ifattr;
    390 		} else
    391 			ifattr = 0;
    392 
    393 		if (d->numlocators) {
    394 			if (d->numlocators > MAXLOCATORS) {
    395 				res = EINVAL;
    396 				goto out;
    397 			}
    398 			locs_sz = d->numlocators * sizeof(int);
    399 			locs = kmem_alloc(locs_sz, KM_SLEEP);
    400 			res = copyin(d->locators, locs, locs_sz);
    401 			if (res) {
    402 				kmem_free(locs, locs_sz);
    403 				goto out;
    404 			}
    405 		} else
    406 			locs = NULL;
    407 		res = rescanbus(d->busname, ifattr, d->numlocators, locs);
    408 		if (locs)
    409 			kmem_free(locs, locs_sz);
    410 #undef d
    411 		break;
    412 	case DRVCTLCOMMAND:
    413 	    	res = drvctl_command(curlwp, (struct plistref *)data, cmd,
    414 		    fp->f_flag);
    415 	    	break;
    416 	case DRVGETEVENT:
    417 		res = drvctl_getevent(curlwp, (struct plistref *)data, cmd,
    418 		    fp->f_flag);
    419 		break;
    420 	default:
    421 		res = EPASSTHROUGH;
    422 		break;
    423 	}
    424 out:	KERNEL_UNLOCK_ONE(NULL);
    425 	return res;
    426 }
    427 
    428 static int
    429 drvctl_stat(struct file *fp, struct stat *st)
    430 {
    431 	(void)memset(st, 0, sizeof(*st));
    432 	st->st_uid = kauth_cred_geteuid(fp->f_cred);
    433 	st->st_gid = kauth_cred_getegid(fp->f_cred);
    434 	return 0;
    435 }
    436 
    437 static int
    438 drvctl_poll(struct file *fp, int events)
    439 {
    440 	int revents = 0;
    441 
    442 	if (!TAILQ_EMPTY(&drvctl_eventq))
    443 		revents |= events & (POLLIN | POLLRDNORM);
    444 	else
    445 		selrecord(curlwp, &drvctl_rdsel);
    446 
    447 	return revents;
    448 }
    449 
    450 static int
    451 drvctl_close(struct file *fp)
    452 {
    453 	struct drvctl_event *dce;
    454 
    455 	/* XXX free context */
    456 	mutex_enter(&drvctl_lock);
    457 	KASSERT(drvctl_nopen > 0);
    458 	--drvctl_nopen;
    459 	if (drvctl_nopen == 0) {
    460 		/* flush queue */
    461 		while ((dce = TAILQ_FIRST(&drvctl_eventq)) != NULL) {
    462 			TAILQ_REMOVE(&drvctl_eventq, dce, dce_link);
    463 			KASSERT(drvctl_eventcnt > 0);
    464 			--drvctl_eventcnt;
    465 			prop_object_release(dce->dce_event);
    466 			kmem_free(dce, sizeof(*dce));
    467 		}
    468 	}
    469 	mutex_exit(&drvctl_lock);
    470 
    471 	return 0;
    472 }
    473 
    474 void
    475 drvctlattach(int arg __unused)
    476 {
    477 }
    478 
    479 /*****************************************************************************
    480  * Driver control command processing engine
    481  *****************************************************************************/
    482 
    483 static int
    484 drvctl_command_get_properties(struct lwp *l,
    485 			      prop_dictionary_t command_dict,
    486 			      prop_dictionary_t results_dict)
    487 {
    488 	prop_dictionary_t args_dict;
    489 	prop_string_t devname_string;
    490 	device_t dev;
    491 	deviter_t di;
    492 
    493 	args_dict = prop_dictionary_get(command_dict, "drvctl-arguments");
    494 	if (args_dict == NULL)
    495 		return EINVAL;
    496 
    497 	devname_string = prop_dictionary_get(args_dict, "device-name");
    498 	if (devname_string == NULL)
    499 		return EINVAL;
    500 
    501 	for (dev = deviter_first(&di, 0); dev != NULL;
    502 	     dev = deviter_next(&di)) {
    503 		if (prop_string_equals_string(devname_string,
    504 					       device_xname(dev))) {
    505 			prop_dictionary_set(results_dict, "drvctl-result-data",
    506 			    device_properties(dev));
    507 			break;
    508 		}
    509 	}
    510 
    511 	deviter_release(&di);
    512 
    513 	if (dev == NULL)
    514 		return ESRCH;
    515 
    516 	return 0;
    517 }
    518 
    519 struct drvctl_command_desc {
    520 	const char *dcd_name;		/* command name */
    521 	int (*dcd_func)(struct lwp *,	/* handler function */
    522 			prop_dictionary_t,
    523 			prop_dictionary_t);
    524 	int dcd_rw;			/* read or write required */
    525 };
    526 
    527 static const struct drvctl_command_desc drvctl_command_table[] = {
    528 	{ .dcd_name = "get-properties",
    529 	  .dcd_func = drvctl_command_get_properties,
    530 	  .dcd_rw   = FREAD,
    531 	},
    532 
    533 	{ .dcd_name = NULL }
    534 };
    535 
    536 static int
    537 drvctl_command(struct lwp *l, struct plistref *pref, u_long ioctl_cmd,
    538 	       int fflag)
    539 {
    540 	prop_dictionary_t command_dict, results_dict;
    541 	prop_string_t command_string;
    542 	const struct drvctl_command_desc *dcd;
    543 	int error;
    544 
    545 	error = prop_dictionary_copyin_ioctl(pref, ioctl_cmd, &command_dict);
    546 	if (error)
    547 		return error;
    548 
    549 	results_dict = prop_dictionary_create();
    550 	if (results_dict == NULL) {
    551 		prop_object_release(command_dict);
    552 		return ENOMEM;
    553 	}
    554 
    555 	command_string = prop_dictionary_get(command_dict, "drvctl-command");
    556 	if (command_string == NULL) {
    557 		error = EINVAL;
    558 		goto out;
    559 	}
    560 
    561 	for (dcd = drvctl_command_table; dcd->dcd_name != NULL; dcd++) {
    562 		if (prop_string_equals_string(command_string,
    563 					      dcd->dcd_name))
    564 			break;
    565 	}
    566 
    567 	if (dcd->dcd_name == NULL) {
    568 		error = EINVAL;
    569 		goto out;
    570 	}
    571 
    572 	if ((fflag & dcd->dcd_rw) == 0) {
    573 		error = EPERM;
    574 		goto out;
    575 	}
    576 
    577 	error = (*dcd->dcd_func)(l, command_dict, results_dict);
    578 
    579 	prop_dictionary_set_int32(results_dict, "drvctl-error", error);
    580 
    581 	error = prop_dictionary_copyout_ioctl(pref, ioctl_cmd, results_dict);
    582  out:
    583 	prop_object_release(command_dict);
    584 	prop_object_release(results_dict);
    585 	return error;
    586 }
    587 
    588 static int
    589 drvctl_getevent(struct lwp *l, struct plistref *pref, u_long ioctl_cmd,
    590 	        int fflag)
    591 {
    592 	struct drvctl_event *dce;
    593 	int ret;
    594 
    595 	if ((fflag & (FREAD|FWRITE)) != (FREAD|FWRITE))
    596 		return EPERM;
    597 
    598 	mutex_enter(&drvctl_lock);
    599 	while ((dce = TAILQ_FIRST(&drvctl_eventq)) == NULL) {
    600 		if (fflag & O_NONBLOCK) {
    601 			mutex_exit(&drvctl_lock);
    602 			return EWOULDBLOCK;
    603 		}
    604 
    605 		ret = cv_wait_sig(&drvctl_cond, &drvctl_lock);
    606 		if (ret) {
    607 			mutex_exit(&drvctl_lock);
    608 			return ret;
    609 		}
    610 	}
    611 	TAILQ_REMOVE(&drvctl_eventq, dce, dce_link);
    612 	KASSERT(drvctl_eventcnt > 0);
    613 	--drvctl_eventcnt;
    614 	mutex_exit(&drvctl_lock);
    615 
    616 	ret = prop_dictionary_copyout_ioctl(pref, ioctl_cmd, dce->dce_event);
    617 
    618 	prop_object_release(dce->dce_event);
    619 	kmem_free(dce, sizeof(*dce));
    620 
    621 	return ret;
    622 }
    623 
    624 /*
    625  * Module glue
    626  */
    627 
    628 MODULE(MODULE_CLASS_DRIVER, drvctl, NULL);
    629 
    630 int
    631 drvctl_modcmd(modcmd_t cmd, void *arg)
    632 {
    633 	int error;
    634 #ifdef _MODULE
    635 	int bmajor, cmajor;
    636 #endif
    637 
    638 	error = 0;
    639 	switch (cmd) {
    640 	case MODULE_CMD_INIT:
    641 		drvctl_init();
    642 
    643 		mutex_enter(&drvctl_lock);
    644 #ifdef _MODULE
    645 		bmajor = cmajor = -1;
    646 		error = devsw_attach("drvctl", NULL, &bmajor,
    647 		    &drvctl_cdevsw, &cmajor);
    648 #endif
    649 		if (error == 0) {
    650 			KASSERT(saved_insert_vec == NULL);
    651 			saved_insert_vec = devmon_insert_vec;
    652 			devmon_insert_vec = devmon_insert;
    653 		}
    654 
    655 		mutex_exit(&drvctl_lock);
    656 		break;
    657 
    658 	case MODULE_CMD_FINI:
    659 		mutex_enter(&drvctl_lock);
    660 		if (drvctl_nopen != 0 || drvctl_eventcnt != 0 ) {
    661 			mutex_exit(&drvctl_lock);
    662 			return EBUSY;
    663 		}
    664 		KASSERT(saved_insert_vec != NULL);
    665 		devmon_insert_vec = saved_insert_vec;
    666 		saved_insert_vec = NULL;
    667 #ifdef _MODULE
    668 		error = devsw_detach(NULL, &drvctl_cdevsw);
    669 		if (error != 0) {
    670 			saved_insert_vec = devmon_insert_vec;
    671 			devmon_insert_vec = devmon_insert;
    672 		}
    673 #endif
    674 		mutex_exit(&drvctl_lock);
    675 		if (error == 0)
    676 			drvctl_fini();
    677 
    678 		break;
    679 	default:
    680 		error = ENOTTY;
    681 		break;
    682 	}
    683 
    684 	return error;
    685 }
    686