1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (C) 2012-2013 Intel Corporation
5 * 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/param.h>
30 #include <sys/bio.h>
31 #include <sys/bus.h>
32 #include <sys/conf.h>
33 #include <sys/disk.h>
34 #include <sys/fcntl.h>
35 #include <sys/ioccom.h>
36 #include <sys/malloc.h>
37 #include <sys/module.h>
38 #include <sys/proc.h>
39 #include <sys/systm.h>
40
41 #include <dev/pci/pcivar.h>
42
43 #include <geom/geom.h>
44
45 #include "nvme_private.h"
46 #include "nvme_linux.h"
47
48 static void nvme_bio_child_inbed(struct bio *parent, int bio_error);
49 static void nvme_bio_child_done(void *arg,
50 const struct nvme_completion *cpl);
51 static uint32_t nvme_get_num_segments(uint64_t addr, uint64_t size,
52 uint32_t alignment);
53 static void nvme_free_child_bios(int num_bios,
54 struct bio **child_bios);
55 static struct bio ** nvme_allocate_child_bios(int num_bios);
56 static struct bio ** nvme_construct_child_bios(struct bio *bp,
57 uint32_t alignment,
58 int *num_bios);
59 static int nvme_ns_split_bio(struct nvme_namespace *ns,
60 struct bio *bp,
61 uint32_t alignment);
62
63 static int
nvme_ns_ioctl(struct cdev * cdev,u_long cmd,caddr_t arg,int flag,struct thread * td)64 nvme_ns_ioctl(struct cdev *cdev, u_long cmd, caddr_t arg, int flag,
65 struct thread *td)
66 {
67 struct nvme_namespace *ns;
68 struct nvme_controller *ctrlr;
69 struct nvme_pt_command *pt;
70
71 ns = cdev->si_drv1;
72 ctrlr = ns->ctrlr;
73
74 switch (cmd) {
75 case NVME_IO_TEST:
76 case NVME_BIO_TEST:
77 nvme_ns_test(ns, cmd, arg);
78 break;
79 case NVME_PASSTHROUGH_CMD:
80 pt = (struct nvme_pt_command *)arg;
81 return (nvme_ctrlr_passthrough_cmd(ctrlr, pt, ns->id,
82 1 /* is_user_buffer */, 0 /* is_admin_cmd */));
83 case NVME_GET_NSID:
84 {
85 struct nvme_get_nsid *gnsid = (struct nvme_get_nsid *)arg;
86 strlcpy(gnsid->cdev, device_get_nameunit(ctrlr->dev),
87 sizeof(gnsid->cdev));
88 gnsid->nsid = ns->id;
89 break;
90 }
91 case DIOCGMEDIASIZE:
92 *(off_t *)arg = (off_t)nvme_ns_get_size(ns);
93 break;
94 case DIOCGSECTORSIZE:
95 *(u_int *)arg = nvme_ns_get_sector_size(ns);
96 break;
97 /* Linux Compatible (see nvme_linux.h) */
98 case NVME_IOCTL_ID:
99 td->td_retval[0] = ns->id;
100 return (0);
101
102 case NVME_IOCTL_ADMIN_CMD:
103 case NVME_IOCTL_IO_CMD: {
104 struct nvme_passthru_cmd *npc = (struct nvme_passthru_cmd *)arg;
105
106 return (nvme_ctrlr_linux_passthru_cmd(ctrlr, npc, ns->id, true,
107 cmd == NVME_IOCTL_ADMIN_CMD));
108 }
109 default:
110 return (ENOTTY);
111 }
112
113 return (0);
114 }
115
116 static int
nvme_ns_open(struct cdev * dev __unused,int flags,int fmt __unused,struct thread * td)117 nvme_ns_open(struct cdev *dev __unused, int flags, int fmt __unused,
118 struct thread *td)
119 {
120 int error = 0;
121
122 if (flags & FWRITE)
123 error = securelevel_gt(td->td_ucred, 0);
124
125 return (error);
126 }
127
128 static int
nvme_ns_close(struct cdev * dev __unused,int flags,int fmt __unused,struct thread * td)129 nvme_ns_close(struct cdev *dev __unused, int flags, int fmt __unused,
130 struct thread *td)
131 {
132 return (0);
133 }
134
135 static void
nvme_ns_strategy_done(void * arg,const struct nvme_completion * cpl)136 nvme_ns_strategy_done(void *arg, const struct nvme_completion *cpl)
137 {
138 struct bio *bp = arg;
139
140 /*
141 * TODO: add more extensive translation of NVMe status codes
142 * to different bio error codes (i.e. EIO, EINVAL, etc.)
143 */
144 if (nvme_completion_is_error(cpl)) {
145 bp->bio_error = EIO;
146 bp->bio_flags |= BIO_ERROR;
147 bp->bio_resid = bp->bio_bcount;
148 } else
149 bp->bio_resid = 0;
150
151 biodone(bp);
152 }
153
154 static void
nvme_ns_strategy(struct bio * bp)155 nvme_ns_strategy(struct bio *bp)
156 {
157 struct nvme_namespace *ns;
158 int err;
159
160 ns = bp->bio_dev->si_drv1;
161 err = nvme_ns_bio_process(ns, bp, nvme_ns_strategy_done);
162
163 if (err) {
164 bp->bio_error = err;
165 bp->bio_flags |= BIO_ERROR;
166 bp->bio_resid = bp->bio_bcount;
167 biodone(bp);
168 }
169
170 }
171
172 static struct cdevsw nvme_ns_cdevsw = {
173 .d_version = D_VERSION,
174 .d_flags = D_DISK,
175 .d_read = physread,
176 .d_write = physwrite,
177 .d_open = nvme_ns_open,
178 .d_close = nvme_ns_close,
179 .d_strategy = nvme_ns_strategy,
180 .d_ioctl = nvme_ns_ioctl
181 };
182
183 uint32_t
nvme_ns_get_max_io_xfer_size(struct nvme_namespace * ns)184 nvme_ns_get_max_io_xfer_size(struct nvme_namespace *ns)
185 {
186 return ns->ctrlr->max_xfer_size;
187 }
188
189 uint32_t
nvme_ns_get_sector_size(struct nvme_namespace * ns)190 nvme_ns_get_sector_size(struct nvme_namespace *ns)
191 {
192 uint8_t flbas_fmt, lbads;
193
194 flbas_fmt = NVMEV(NVME_NS_DATA_FLBAS_FORMAT, ns->data.flbas);
195 lbads = NVMEV(NVME_NS_DATA_LBAF_LBADS, ns->data.lbaf[flbas_fmt]);
196
197 return (1 << lbads);
198 }
199
200 uint64_t
nvme_ns_get_num_sectors(struct nvme_namespace * ns)201 nvme_ns_get_num_sectors(struct nvme_namespace *ns)
202 {
203 return (ns->data.nsze);
204 }
205
206 uint64_t
nvme_ns_get_size(struct nvme_namespace * ns)207 nvme_ns_get_size(struct nvme_namespace *ns)
208 {
209 return (nvme_ns_get_num_sectors(ns) * nvme_ns_get_sector_size(ns));
210 }
211
212 uint32_t
nvme_ns_get_flags(struct nvme_namespace * ns)213 nvme_ns_get_flags(struct nvme_namespace *ns)
214 {
215 return (ns->flags);
216 }
217
218 const char *
nvme_ns_get_serial_number(struct nvme_namespace * ns)219 nvme_ns_get_serial_number(struct nvme_namespace *ns)
220 {
221 return ((const char *)ns->ctrlr->cdata.sn);
222 }
223
224 const char *
nvme_ns_get_model_number(struct nvme_namespace * ns)225 nvme_ns_get_model_number(struct nvme_namespace *ns)
226 {
227 return ((const char *)ns->ctrlr->cdata.mn);
228 }
229
230 const struct nvme_namespace_data *
nvme_ns_get_data(struct nvme_namespace * ns)231 nvme_ns_get_data(struct nvme_namespace *ns)
232 {
233 return (&ns->data);
234 }
235
236 uint32_t
nvme_ns_get_stripesize(struct nvme_namespace * ns)237 nvme_ns_get_stripesize(struct nvme_namespace *ns)
238 {
239 uint32_t ss;
240
241 if (NVMEV(NVME_NS_DATA_NSFEAT_NPVALID, ns->data.nsfeat) != 0) {
242 ss = nvme_ns_get_sector_size(ns);
243 if (ns->data.npwa != 0)
244 return ((ns->data.npwa + 1) * ss);
245 else if (ns->data.npwg != 0)
246 return ((ns->data.npwg + 1) * ss);
247 }
248 return (ns->boundary);
249 }
250
251 static void
nvme_ns_bio_done(void * arg,const struct nvme_completion * status)252 nvme_ns_bio_done(void *arg, const struct nvme_completion *status)
253 {
254 struct bio *bp = arg;
255 nvme_cb_fn_t bp_cb_fn;
256
257 bp_cb_fn = bp->bio_driver1;
258
259 if (bp->bio_driver2)
260 free(bp->bio_driver2, M_NVME);
261
262 if (nvme_completion_is_error(status)) {
263 bp->bio_flags |= BIO_ERROR;
264 if (bp->bio_error == 0)
265 bp->bio_error = EIO;
266 }
267
268 if ((bp->bio_flags & BIO_ERROR) == 0)
269 bp->bio_resid = 0;
270 else
271 bp->bio_resid = bp->bio_bcount;
272
273 bp_cb_fn(bp, status);
274 }
275
276 static void
nvme_bio_child_inbed(struct bio * parent,int bio_error)277 nvme_bio_child_inbed(struct bio *parent, int bio_error)
278 {
279 struct nvme_completion parent_cpl;
280 int children, inbed;
281
282 if (bio_error != 0) {
283 parent->bio_flags |= BIO_ERROR;
284 parent->bio_error = bio_error;
285 }
286
287 /*
288 * atomic_fetchadd will return value before adding 1, so we still
289 * must add 1 to get the updated inbed number. Save bio_children
290 * before incrementing to guard against race conditions when
291 * two children bios complete on different queues.
292 */
293 children = atomic_load_acq_int(&parent->bio_children);
294 inbed = atomic_fetchadd_int(&parent->bio_inbed, 1) + 1;
295 if (inbed == children) {
296 bzero(&parent_cpl, sizeof(parent_cpl));
297 if (parent->bio_flags & BIO_ERROR) {
298 parent_cpl.status &= ~NVMEM(NVME_STATUS_SC);
299 parent_cpl.status |= NVMEF(NVME_STATUS_SC,
300 NVME_SC_DATA_TRANSFER_ERROR);
301 }
302 nvme_ns_bio_done(parent, &parent_cpl);
303 }
304 }
305
306 static void
nvme_bio_child_done(void * arg,const struct nvme_completion * cpl)307 nvme_bio_child_done(void *arg, const struct nvme_completion *cpl)
308 {
309 struct bio *child = arg;
310 struct bio *parent;
311 int bio_error;
312
313 parent = child->bio_parent;
314 g_destroy_bio(child);
315 bio_error = nvme_completion_is_error(cpl) ? EIO : 0;
316 nvme_bio_child_inbed(parent, bio_error);
317 }
318
319 static uint32_t
nvme_get_num_segments(uint64_t addr,uint64_t size,uint32_t align)320 nvme_get_num_segments(uint64_t addr, uint64_t size, uint32_t align)
321 {
322 uint32_t num_segs, offset, remainder;
323
324 if (align == 0)
325 return (1);
326
327 KASSERT((align & (align - 1)) == 0, ("alignment not power of 2\n"));
328
329 num_segs = size / align;
330 remainder = size & (align - 1);
331 offset = addr & (align - 1);
332 if (remainder > 0 || offset > 0)
333 num_segs += 1 + (remainder + offset - 1) / align;
334 return (num_segs);
335 }
336
337 static void
nvme_free_child_bios(int num_bios,struct bio ** child_bios)338 nvme_free_child_bios(int num_bios, struct bio **child_bios)
339 {
340 int i;
341
342 for (i = 0; i < num_bios; i++) {
343 if (child_bios[i] != NULL)
344 g_destroy_bio(child_bios[i]);
345 }
346
347 free(child_bios, M_NVME);
348 }
349
350 static struct bio **
nvme_allocate_child_bios(int num_bios)351 nvme_allocate_child_bios(int num_bios)
352 {
353 struct bio **child_bios;
354 int err = 0, i;
355
356 child_bios = malloc(num_bios * sizeof(struct bio *), M_NVME, M_NOWAIT);
357 if (child_bios == NULL)
358 return (NULL);
359
360 for (i = 0; i < num_bios; i++) {
361 child_bios[i] = g_new_bio();
362 if (child_bios[i] == NULL)
363 err = ENOMEM;
364 }
365
366 if (err == ENOMEM) {
367 nvme_free_child_bios(num_bios, child_bios);
368 return (NULL);
369 }
370
371 return (child_bios);
372 }
373
374 static struct bio **
nvme_construct_child_bios(struct bio * bp,uint32_t alignment,int * num_bios)375 nvme_construct_child_bios(struct bio *bp, uint32_t alignment, int *num_bios)
376 {
377 struct bio **child_bios;
378 struct bio *child;
379 uint64_t cur_offset;
380 caddr_t data;
381 uint32_t rem_bcount;
382 int i;
383 struct vm_page **ma;
384 uint32_t ma_offset;
385
386 *num_bios = nvme_get_num_segments(bp->bio_offset, bp->bio_bcount,
387 alignment);
388 child_bios = nvme_allocate_child_bios(*num_bios);
389 if (child_bios == NULL)
390 return (NULL);
391
392 bp->bio_children = *num_bios;
393 bp->bio_inbed = 0;
394 cur_offset = bp->bio_offset;
395 rem_bcount = bp->bio_bcount;
396 data = bp->bio_data;
397 ma_offset = bp->bio_ma_offset;
398 ma = bp->bio_ma;
399
400 for (i = 0; i < *num_bios; i++) {
401 child = child_bios[i];
402 child->bio_parent = bp;
403 child->bio_cmd = bp->bio_cmd;
404 child->bio_offset = cur_offset;
405 child->bio_bcount = min(rem_bcount,
406 alignment - (cur_offset & (alignment - 1)));
407 child->bio_flags = bp->bio_flags;
408 if (bp->bio_flags & BIO_UNMAPPED) {
409 child->bio_ma_offset = ma_offset;
410 child->bio_ma = ma;
411 child->bio_ma_n =
412 nvme_get_num_segments(child->bio_ma_offset,
413 child->bio_bcount, PAGE_SIZE);
414 ma_offset = (ma_offset + child->bio_bcount) &
415 PAGE_MASK;
416 ma += child->bio_ma_n;
417 if (ma_offset != 0)
418 ma -= 1;
419 } else {
420 child->bio_data = data;
421 data += child->bio_bcount;
422 }
423 cur_offset += child->bio_bcount;
424 rem_bcount -= child->bio_bcount;
425 }
426
427 return (child_bios);
428 }
429
430 static int
nvme_ns_split_bio(struct nvme_namespace * ns,struct bio * bp,uint32_t alignment)431 nvme_ns_split_bio(struct nvme_namespace *ns, struct bio *bp,
432 uint32_t alignment)
433 {
434 struct bio *child;
435 struct bio **child_bios;
436 int err, i, num_bios;
437
438 child_bios = nvme_construct_child_bios(bp, alignment, &num_bios);
439 if (child_bios == NULL)
440 return (ENOMEM);
441
442 counter_u64_add(ns->ctrlr->alignment_splits, 1);
443 for (i = 0; i < num_bios; i++) {
444 child = child_bios[i];
445 err = nvme_ns_bio_process(ns, child, nvme_bio_child_done);
446 if (err != 0) {
447 nvme_bio_child_inbed(bp, err);
448 g_destroy_bio(child);
449 }
450 }
451
452 free(child_bios, M_NVME);
453 return (0);
454 }
455
456 int
nvme_ns_bio_process(struct nvme_namespace * ns,struct bio * bp,nvme_cb_fn_t cb_fn)457 nvme_ns_bio_process(struct nvme_namespace *ns, struct bio *bp,
458 nvme_cb_fn_t cb_fn)
459 {
460 struct nvme_dsm_range *dsm_range;
461 uint32_t num_bios;
462 int err;
463
464 bp->bio_driver1 = cb_fn;
465
466 if (ns->boundary > 0 &&
467 (bp->bio_cmd == BIO_READ || bp->bio_cmd == BIO_WRITE)) {
468 num_bios = nvme_get_num_segments(bp->bio_offset,
469 bp->bio_bcount, ns->boundary);
470 if (num_bios > 1)
471 return (nvme_ns_split_bio(ns, bp, ns->boundary));
472 }
473
474 switch (bp->bio_cmd) {
475 case BIO_READ:
476 err = nvme_ns_cmd_read_bio(ns, bp, nvme_ns_bio_done, bp);
477 break;
478 case BIO_WRITE:
479 err = nvme_ns_cmd_write_bio(ns, bp, nvme_ns_bio_done, bp);
480 break;
481 case BIO_FLUSH:
482 err = nvme_ns_cmd_flush(ns, nvme_ns_bio_done, bp);
483 break;
484 case BIO_DELETE:
485 dsm_range =
486 malloc(sizeof(struct nvme_dsm_range), M_NVME,
487 M_ZERO | M_NOWAIT);
488 if (!dsm_range) {
489 err = ENOMEM;
490 break;
491 }
492 dsm_range->length =
493 htole32(bp->bio_bcount/nvme_ns_get_sector_size(ns));
494 dsm_range->starting_lba =
495 htole64(bp->bio_offset/nvme_ns_get_sector_size(ns));
496 bp->bio_driver2 = dsm_range;
497 err = nvme_ns_cmd_deallocate(ns, dsm_range, 1,
498 nvme_ns_bio_done, bp);
499 if (err != 0)
500 free(dsm_range, M_NVME);
501 break;
502 default:
503 err = EOPNOTSUPP;
504 break;
505 }
506
507 return (err);
508 }
509
510 int
nvme_ns_ioctl_process(struct nvme_namespace * ns,u_long cmd,caddr_t arg,int flag,struct thread * td)511 nvme_ns_ioctl_process(struct nvme_namespace *ns, u_long cmd, caddr_t arg,
512 int flag, struct thread *td)
513 {
514 return (nvme_ns_ioctl(ns->cdev, cmd, arg, flag, td));
515 }
516
517 int
nvme_ns_construct(struct nvme_namespace * ns,uint32_t id,struct nvme_controller * ctrlr)518 nvme_ns_construct(struct nvme_namespace *ns, uint32_t id,
519 struct nvme_controller *ctrlr)
520 {
521 struct make_dev_args md_args;
522 struct nvme_completion_poll_status status;
523 int res;
524 int unit;
525 uint8_t flbas_fmt;
526 uint8_t vwc_present;
527
528 ns->ctrlr = ctrlr;
529 ns->id = id;
530
531 /*
532 * Namespaces are reconstructed after a controller reset, so check
533 * to make sure we only call mtx_init once on each mtx.
534 *
535 * TODO: Move this somewhere where it gets called at controller
536 * construction time, which is not invoked as part of each
537 * controller reset.
538 */
539 if (!mtx_initialized(&ns->lock))
540 mtx_init(&ns->lock, "nvme ns lock", NULL, MTX_DEF);
541
542 status.done = 0;
543 nvme_ctrlr_cmd_identify_namespace(ctrlr, id, &ns->data,
544 nvme_completion_poll_cb, &status);
545 nvme_completion_poll(&status);
546 if (nvme_completion_is_error(&status.cpl)) {
547 nvme_printf(ctrlr, "nvme_identify_namespace failed\n");
548 return (ENXIO);
549 }
550
551 /* Convert data to host endian */
552 nvme_namespace_data_swapbytes(&ns->data);
553
554 /*
555 * If the size of is zero, chances are this isn't a valid
556 * namespace (eg one that's not been configured yet). The
557 * standard says the entire id will be zeros, so this is a
558 * cheap way to test for that.
559 */
560 if (ns->data.nsze == 0)
561 return (ENXIO);
562
563 flbas_fmt = NVMEV(NVME_NS_DATA_FLBAS_FORMAT, ns->data.flbas);
564
565 /*
566 * Note: format is a 0-based value, so > is appropriate here,
567 * not >=.
568 */
569 if (flbas_fmt > ns->data.nlbaf) {
570 nvme_printf(ctrlr,
571 "lba format %d exceeds number supported (%d)\n",
572 flbas_fmt, ns->data.nlbaf + 1);
573 return (ENXIO);
574 }
575
576 /*
577 * Older Intel devices (like the PC35xxx and P45xx series) advertise in
578 * vendor specific space an alignment that improves performance. If
579 * present use for the stripe size. NVMe 1.3 standardized this as
580 * NOIOB, and newer Intel drives use that.
581 */
582 if ((ctrlr->quirks & QUIRK_INTEL_ALIGNMENT) != 0) {
583 if (ctrlr->cdata.vs[3] != 0)
584 ns->boundary =
585 1 << (ctrlr->cdata.vs[3] + NVME_MPS_SHIFT +
586 NVME_CAP_HI_MPSMIN(ctrlr->cap_hi));
587 else
588 ns->boundary = 0;
589 } else {
590 ns->boundary = ns->data.noiob * nvme_ns_get_sector_size(ns);
591 }
592
593 if (nvme_ctrlr_has_dataset_mgmt(&ctrlr->cdata))
594 ns->flags |= NVME_NS_DEALLOCATE_SUPPORTED;
595
596 vwc_present = NVMEV(NVME_CTRLR_DATA_VWC_PRESENT, ctrlr->cdata.vwc);
597 if (vwc_present)
598 ns->flags |= NVME_NS_FLUSH_SUPPORTED;
599
600 /*
601 * cdev may have already been created, if we are reconstructing the
602 * namespace after a controller-level reset.
603 */
604 if (ns->cdev != NULL)
605 return (0);
606
607 /*
608 * Namespace IDs start at 1, so we need to subtract 1 to create a
609 * correct unit number.
610 */
611 unit = device_get_unit(ctrlr->dev) * NVME_MAX_NAMESPACES + ns->id - 1;
612
613 make_dev_args_init(&md_args);
614 md_args.mda_devsw = &nvme_ns_cdevsw;
615 md_args.mda_unit = unit;
616 md_args.mda_mode = 0600;
617 md_args.mda_si_drv1 = ns;
618 res = make_dev_s(&md_args, &ns->cdev, "%sn%d",
619 device_get_nameunit(ctrlr->dev), ns->id);
620 if (res != 0)
621 return (ENXIO);
622 ns->cdev->si_drv2 = make_dev_alias(ns->cdev, "%sns%d",
623 device_get_nameunit(ctrlr->dev), ns->id);
624 ns->cdev->si_flags |= SI_UNMAPPED;
625
626 return (0);
627 }
628
629 void
nvme_ns_destruct(struct nvme_namespace * ns)630 nvme_ns_destruct(struct nvme_namespace *ns)
631 {
632 if (ns->cdev != NULL) {
633 if (ns->cdev->si_drv2 != NULL)
634 destroy_dev(ns->cdev->si_drv2);
635 destroy_dev(ns->cdev);
636 }
637 }
638