1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * RDMA Network Block Driver
4  *
5  * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
6  * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
7  * Copyright (c) 2019 - 2020 1&1 IONOS SE. All rights reserved.
8  */
9 
10 #undef pr_fmt
11 #define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt
12 
13 #include <linux/types.h>
14 #include <linux/ctype.h>
15 #include <linux/parser.h>
16 #include <linux/module.h>
17 #include <linux/in6.h>
18 #include <linux/fs.h>
19 #include <linux/uaccess.h>
20 #include <linux/device.h>
21 #include <rdma/ib.h>
22 #include <rdma/rdma_cm.h>
23 
24 #include "rnbd-clt.h"
25 
26 static struct device *rnbd_dev;
27 static const struct class rnbd_dev_class = {
28 	.name = "rnbd-client",
29 };
30 static struct kobject *rnbd_devs_kobj;
31 
32 enum {
33 	RNBD_OPT_ERR		= 0,
34 	RNBD_OPT_DEST_PORT	= 1 << 0,
35 	RNBD_OPT_PATH		= 1 << 1,
36 	RNBD_OPT_DEV_PATH	= 1 << 2,
37 	RNBD_OPT_ACCESS_MODE	= 1 << 3,
38 	RNBD_OPT_SESSNAME	= 1 << 6,
39 	RNBD_OPT_NR_POLL_QUEUES	= 1 << 7,
40 };
41 
42 static const unsigned int rnbd_opt_mandatory[] = {
43 	RNBD_OPT_DEV_PATH,
44 	RNBD_OPT_SESSNAME,
45 };
46 
47 static const match_table_t rnbd_opt_tokens = {
48 	{RNBD_OPT_PATH,			"path=%s"		},
49 	{RNBD_OPT_DEV_PATH,		"device_path=%s"	},
50 	{RNBD_OPT_DEST_PORT,		"dest_port=%d"		},
51 	{RNBD_OPT_ACCESS_MODE,		"access_mode=%s"	},
52 	{RNBD_OPT_SESSNAME,		"sessname=%s"		},
53 	{RNBD_OPT_NR_POLL_QUEUES,	"nr_poll_queues=%d"	},
54 	{RNBD_OPT_ERR,			NULL			},
55 };
56 
57 struct rnbd_map_options {
58 	char *sessname;
59 	struct rtrs_addr *paths;
60 	size_t *path_cnt;
61 	char *pathname;
62 	u16 *dest_port;
63 	enum rnbd_access_mode *access_mode;
64 	u32 *nr_poll_queues;
65 };
66 
67 static int rnbd_clt_parse_map_options(const char *buf, size_t max_path_cnt,
68 				       struct rnbd_map_options *opt)
69 {
70 	char *options, *sep_opt;
71 	char *p;
72 	substring_t args[MAX_OPT_ARGS];
73 	int opt_mask = 0;
74 	int token;
75 	int ret = -EINVAL;
76 	int nr_poll_queues = 0;
77 	int dest_port = 0;
78 	int p_cnt = 0;
79 	int i;
80 
81 	options = kstrdup(buf, GFP_KERNEL);
82 	if (!options)
83 		return -ENOMEM;
84 
85 	sep_opt = strstrip(options);
86 	while ((p = strsep(&sep_opt, " ")) != NULL) {
87 		if (!*p)
88 			continue;
89 
90 		token = match_token(p, rnbd_opt_tokens, args);
91 		opt_mask |= token;
92 
93 		switch (token) {
94 		case RNBD_OPT_SESSNAME:
95 			p = match_strdup(args);
96 			if (!p) {
97 				ret = -ENOMEM;
98 				goto out;
99 			}
100 			if (strlen(p) > NAME_MAX) {
101 				pr_err("map_device: sessname too long\n");
102 				ret = -EINVAL;
103 				kfree(p);
104 				goto out;
105 			}
106 			strscpy(opt->sessname, p, NAME_MAX);
107 			kfree(p);
108 			break;
109 
110 		case RNBD_OPT_PATH:
111 			if (p_cnt >= max_path_cnt) {
112 				pr_err("map_device: too many (> %zu) paths provided\n",
113 				       max_path_cnt);
114 				ret = -ENOMEM;
115 				goto out;
116 			}
117 			p = match_strdup(args);
118 			if (!p) {
119 				ret = -ENOMEM;
120 				goto out;
121 			}
122 
123 			ret = rtrs_addr_to_sockaddr(p, strlen(p),
124 						    *opt->dest_port,
125 						    &opt->paths[p_cnt]);
126 			if (ret) {
127 				pr_err("Can't parse path %s: %d\n", p, ret);
128 				kfree(p);
129 				goto out;
130 			}
131 
132 			p_cnt++;
133 
134 			kfree(p);
135 			break;
136 
137 		case RNBD_OPT_DEV_PATH:
138 			p = match_strdup(args);
139 			if (!p) {
140 				ret = -ENOMEM;
141 				goto out;
142 			}
143 			if (strlen(p) > NAME_MAX) {
144 				pr_err("map_device: Device path too long\n");
145 				ret = -EINVAL;
146 				kfree(p);
147 				goto out;
148 			}
149 			strscpy(opt->pathname, p, NAME_MAX);
150 			kfree(p);
151 			break;
152 
153 		case RNBD_OPT_DEST_PORT:
154 			if (match_int(args, &dest_port) || dest_port < 0 ||
155 			    dest_port > 65535) {
156 				pr_err("bad destination port number parameter '%d'\n",
157 				       dest_port);
158 				ret = -EINVAL;
159 				goto out;
160 			}
161 			*opt->dest_port = dest_port;
162 			break;
163 
164 		case RNBD_OPT_ACCESS_MODE:
165 			p = match_strdup(args);
166 			if (!p) {
167 				ret = -ENOMEM;
168 				goto out;
169 			}
170 
171 			if (!strcmp(p, "ro")) {
172 				*opt->access_mode = RNBD_ACCESS_RO;
173 			} else if (!strcmp(p, "rw")) {
174 				*opt->access_mode = RNBD_ACCESS_RW;
175 			} else if (!strcmp(p, "migration")) {
176 				*opt->access_mode = RNBD_ACCESS_MIGRATION;
177 			} else {
178 				pr_err("map_device: Invalid access_mode: '%s'\n",
179 				       p);
180 				ret = -EINVAL;
181 				kfree(p);
182 				goto out;
183 			}
184 
185 			kfree(p);
186 			break;
187 
188 		case RNBD_OPT_NR_POLL_QUEUES:
189 			if (match_int(args, &nr_poll_queues) || nr_poll_queues < -1 ||
190 			    nr_poll_queues > (int)nr_cpu_ids) {
191 				pr_err("bad nr_poll_queues parameter '%d'\n",
192 				       nr_poll_queues);
193 				ret = -EINVAL;
194 				goto out;
195 			}
196 			if (nr_poll_queues == -1)
197 				nr_poll_queues = nr_cpu_ids;
198 			*opt->nr_poll_queues = nr_poll_queues;
199 			break;
200 
201 		default:
202 			pr_err("map_device: Unknown parameter or missing value '%s'\n",
203 			       p);
204 			ret = -EINVAL;
205 			goto out;
206 		}
207 	}
208 
209 	for (i = 0; i < ARRAY_SIZE(rnbd_opt_mandatory); i++) {
210 		if ((opt_mask & rnbd_opt_mandatory[i])) {
211 			ret = 0;
212 		} else {
213 			pr_err("map_device: Parameters missing\n");
214 			ret = -EINVAL;
215 			break;
216 		}
217 	}
218 
219 out:
220 	*opt->path_cnt = p_cnt;
221 	kfree(options);
222 	return ret;
223 }
224 
225 static ssize_t state_show(struct kobject *kobj,
226 			  struct kobj_attribute *attr, char *page)
227 {
228 	struct rnbd_clt_dev *dev;
229 
230 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
231 
232 	switch (dev->dev_state) {
233 	case DEV_STATE_INIT:
234 		return sysfs_emit(page, "init\n");
235 	case DEV_STATE_MAPPED:
236 		/* TODO fix cli tool before changing to proper state */
237 		return sysfs_emit(page, "open\n");
238 	case DEV_STATE_MAPPED_DISCONNECTED:
239 		/* TODO fix cli tool before changing to proper state */
240 		return sysfs_emit(page, "closed\n");
241 	case DEV_STATE_UNMAPPED:
242 		return sysfs_emit(page, "unmapped\n");
243 	default:
244 		return sysfs_emit(page, "unknown\n");
245 	}
246 }
247 
248 static struct kobj_attribute rnbd_clt_state_attr = __ATTR_RO(state);
249 
250 static ssize_t nr_poll_queues_show(struct kobject *kobj,
251 				   struct kobj_attribute *attr, char *page)
252 {
253 	struct rnbd_clt_dev *dev;
254 
255 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
256 
257 	return sysfs_emit(page, "%d\n", dev->nr_poll_queues);
258 }
259 
260 static struct kobj_attribute rnbd_clt_nr_poll_queues =
261 	__ATTR_RO(nr_poll_queues);
262 
263 static ssize_t mapping_path_show(struct kobject *kobj,
264 				 struct kobj_attribute *attr, char *page)
265 {
266 	struct rnbd_clt_dev *dev;
267 
268 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
269 
270 	return sysfs_emit(page, "%s\n", dev->pathname);
271 }
272 
273 static struct kobj_attribute rnbd_clt_mapping_path_attr =
274 	__ATTR_RO(mapping_path);
275 
276 static ssize_t access_mode_show(struct kobject *kobj,
277 				struct kobj_attribute *attr, char *page)
278 {
279 	struct rnbd_clt_dev *dev;
280 
281 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
282 
283 	return sysfs_emit(page, "%s\n", rnbd_access_modes[dev->access_mode].str);
284 }
285 
286 static struct kobj_attribute rnbd_clt_access_mode =
287 	__ATTR_RO(access_mode);
288 
289 static ssize_t rnbd_clt_unmap_dev_show(struct kobject *kobj,
290 					struct kobj_attribute *attr, char *page)
291 {
292 	return sysfs_emit(page, "Usage: echo <normal|force> > %s\n",
293 			  attr->attr.name);
294 }
295 
296 static ssize_t rnbd_clt_unmap_dev_store(struct kobject *kobj,
297 					 struct kobj_attribute *attr,
298 					 const char *buf, size_t count)
299 {
300 	struct rnbd_clt_dev *dev;
301 	char *opt, *options;
302 	bool force;
303 	int err;
304 
305 	opt = kstrdup(buf, GFP_KERNEL);
306 	if (!opt)
307 		return -ENOMEM;
308 
309 	options = strstrip(opt);
310 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
311 	if (sysfs_streq(options, "normal")) {
312 		force = false;
313 	} else if (sysfs_streq(options, "force")) {
314 		force = true;
315 	} else {
316 		rnbd_clt_err(dev,
317 			      "unmap_device: Invalid value: %s\n",
318 			      options);
319 		err = -EINVAL;
320 		goto out;
321 	}
322 
323 	rnbd_clt_info(dev, "Unmapping device, option: %s.\n",
324 		       force ? "force" : "normal");
325 
326 	/*
327 	 * We take explicit module reference only for one reason: do not
328 	 * race with lockless rnbd_destroy_sessions().
329 	 */
330 	if (!try_module_get(THIS_MODULE)) {
331 		err = -ENODEV;
332 		goto out;
333 	}
334 	err = rnbd_clt_unmap_device(dev, force, &attr->attr);
335 	if (err) {
336 		if (err != -EALREADY)
337 			rnbd_clt_err(dev, "unmap_device: %d\n",  err);
338 		goto module_put;
339 	}
340 
341 	/*
342 	 * Here device can be vanished!
343 	 */
344 
345 	err = count;
346 
347 module_put:
348 	module_put(THIS_MODULE);
349 out:
350 	kfree(opt);
351 
352 	return err;
353 }
354 
355 static struct kobj_attribute rnbd_clt_unmap_device_attr =
356 	__ATTR(unmap_device, 0644, rnbd_clt_unmap_dev_show,
357 	       rnbd_clt_unmap_dev_store);
358 
359 static ssize_t rnbd_clt_resize_dev_show(struct kobject *kobj,
360 					 struct kobj_attribute *attr,
361 					 char *page)
362 {
363 	return sysfs_emit(page, "Usage: echo <new size in sectors> > %s\n",
364 			  attr->attr.name);
365 }
366 
367 static ssize_t rnbd_clt_resize_dev_store(struct kobject *kobj,
368 					  struct kobj_attribute *attr,
369 					  const char *buf, size_t count)
370 {
371 	int ret;
372 	unsigned long sectors;
373 	struct rnbd_clt_dev *dev;
374 
375 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
376 
377 	ret = kstrtoul(buf, 0, &sectors);
378 	if (ret)
379 		return ret;
380 
381 	ret = rnbd_clt_resize_disk(dev, sectors);
382 	if (ret)
383 		return ret;
384 
385 	return count;
386 }
387 
388 static struct kobj_attribute rnbd_clt_resize_dev_attr =
389 	__ATTR(resize, 0644, rnbd_clt_resize_dev_show,
390 	       rnbd_clt_resize_dev_store);
391 
392 static ssize_t rnbd_clt_remap_dev_show(struct kobject *kobj,
393 					struct kobj_attribute *attr, char *page)
394 {
395 	return sysfs_emit(page, "Usage: echo <1> > %s\n", attr->attr.name);
396 }
397 
398 static ssize_t rnbd_clt_remap_dev_store(struct kobject *kobj,
399 					 struct kobj_attribute *attr,
400 					 const char *buf, size_t count)
401 {
402 	struct rnbd_clt_dev *dev;
403 	char *opt, *options;
404 	int err;
405 
406 	opt = kstrdup(buf, GFP_KERNEL);
407 	if (!opt)
408 		return -ENOMEM;
409 
410 	options = strstrip(opt);
411 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
412 	if (!sysfs_streq(options, "1")) {
413 		rnbd_clt_err(dev,
414 			      "remap_device: Invalid value: %s\n",
415 			      options);
416 		err = -EINVAL;
417 		goto out;
418 	}
419 	err = rnbd_clt_remap_device(dev);
420 	if (likely(!err))
421 		err = count;
422 
423 out:
424 	kfree(opt);
425 
426 	return err;
427 }
428 
429 static struct kobj_attribute rnbd_clt_remap_device_attr =
430 	__ATTR(remap_device, 0644, rnbd_clt_remap_dev_show,
431 	       rnbd_clt_remap_dev_store);
432 
433 static ssize_t session_show(struct kobject *kobj, struct kobj_attribute *attr,
434 			    char *page)
435 {
436 	struct rnbd_clt_dev *dev;
437 
438 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
439 
440 	return sysfs_emit(page, "%s\n", dev->sess->sessname);
441 }
442 
443 static struct kobj_attribute rnbd_clt_session_attr =
444 	__ATTR_RO(session);
445 
446 static struct attribute *rnbd_dev_attrs[] = {
447 	&rnbd_clt_unmap_device_attr.attr,
448 	&rnbd_clt_resize_dev_attr.attr,
449 	&rnbd_clt_remap_device_attr.attr,
450 	&rnbd_clt_mapping_path_attr.attr,
451 	&rnbd_clt_state_attr.attr,
452 	&rnbd_clt_session_attr.attr,
453 	&rnbd_clt_access_mode.attr,
454 	&rnbd_clt_nr_poll_queues.attr,
455 	NULL,
456 };
457 ATTRIBUTE_GROUPS(rnbd_dev);
458 
459 void rnbd_clt_remove_dev_symlink(struct rnbd_clt_dev *dev)
460 {
461 	/*
462 	 * The module unload rnbd_client_exit path is racing with unmapping of
463 	 * the last single device from the sysfs manually
464 	 * i.e. rnbd_clt_unmap_dev_store() leading to a sysfs warning because
465 	 * of sysfs link already was removed already.
466 	 */
467 	if (dev->blk_symlink_name) {
468 		if (try_module_get(THIS_MODULE)) {
469 			sysfs_remove_link(rnbd_devs_kobj, dev->blk_symlink_name);
470 			module_put(THIS_MODULE);
471 		}
472 		/* It should be freed always. */
473 		kfree(dev->blk_symlink_name);
474 		dev->blk_symlink_name = NULL;
475 	}
476 }
477 
478 static struct kobj_type rnbd_dev_ktype = {
479 	.sysfs_ops      = &kobj_sysfs_ops,
480 	.default_groups = rnbd_dev_groups,
481 };
482 
483 static int rnbd_clt_add_dev_kobj(struct rnbd_clt_dev *dev)
484 {
485 	int ret;
486 	struct kobject *gd_kobj = &disk_to_dev(dev->gd)->kobj;
487 
488 	ret = kobject_init_and_add(&dev->kobj, &rnbd_dev_ktype, gd_kobj, "%s",
489 				   "rnbd");
490 	if (ret) {
491 		rnbd_clt_err(dev, "Failed to create device sysfs dir, err: %d\n",
492 			      ret);
493 		kobject_put(&dev->kobj);
494 	}
495 	kobject_uevent(gd_kobj, KOBJ_ONLINE);
496 
497 	return ret;
498 }
499 
500 static ssize_t rnbd_clt_map_device_show(struct kobject *kobj,
501 					 struct kobj_attribute *attr,
502 					 char *page)
503 {
504 	return sysfs_emit(page,
505 			  "Usage: echo \"[dest_port=server port number] sessname=<name of the rtrs session> path=<[srcaddr@]dstaddr> [path=<[srcaddr@]dstaddr>] device_path=<full path on remote side> [access_mode=<ro|rw|migration>] [nr_poll_queues=<number of queues>]\" > %s\n\naddr ::= [ ip:<ipv4> | ip:<ipv6> | gid:<gid> ]\n",
506 			 attr->attr.name);
507 }
508 
509 static int rnbd_clt_get_path_name(struct rnbd_clt_dev *dev, char *buf,
510 				   size_t len)
511 {
512 	int ret;
513 	char pathname[NAME_MAX], *s;
514 
515 	strscpy(pathname, dev->pathname, sizeof(pathname));
516 	while ((s = strchr(pathname, '/')))
517 		s[0] = '!';
518 
519 	ret = snprintf(buf, len, "%s@%s", pathname, dev->sess->sessname);
520 	if (ret >= len)
521 		return -ENAMETOOLONG;
522 
523 	return 0;
524 }
525 
526 static int rnbd_clt_add_dev_symlink(struct rnbd_clt_dev *dev)
527 {
528 	struct kobject *gd_kobj = &disk_to_dev(dev->gd)->kobj;
529 	int ret, len;
530 
531 	len = strlen(dev->pathname) + strlen(dev->sess->sessname) + 2;
532 	dev->blk_symlink_name = kzalloc(len, GFP_KERNEL);
533 	if (!dev->blk_symlink_name) {
534 		rnbd_clt_err(dev, "Failed to allocate memory for blk_symlink_name\n");
535 		return -ENOMEM;
536 	}
537 
538 	ret = rnbd_clt_get_path_name(dev, dev->blk_symlink_name,
539 				      len);
540 	if (ret) {
541 		rnbd_clt_err(dev, "Failed to get /sys/block symlink path, err: %d\n",
542 			      ret);
543 		goto out_err;
544 	}
545 
546 	ret = sysfs_create_link(rnbd_devs_kobj, gd_kobj,
547 				dev->blk_symlink_name);
548 	if (ret) {
549 		rnbd_clt_err(dev, "Creating /sys/block symlink failed, err: %d\n",
550 			      ret);
551 		goto out_err;
552 	}
553 
554 	return 0;
555 
556 out_err:
557 	kfree(dev->blk_symlink_name);
558 	dev->blk_symlink_name = NULL ;
559 	return ret;
560 }
561 
562 static ssize_t rnbd_clt_map_device_store(struct kobject *kobj,
563 					  struct kobj_attribute *attr,
564 					  const char *buf, size_t count)
565 {
566 	struct rnbd_clt_dev *dev;
567 	struct rnbd_map_options opt;
568 	int ret;
569 	char pathname[NAME_MAX];
570 	char sessname[NAME_MAX];
571 	enum rnbd_access_mode access_mode = RNBD_ACCESS_RW;
572 	u16 port_nr = RTRS_PORT;
573 	u32 nr_poll_queues = 0;
574 
575 	struct sockaddr_storage *addrs;
576 	struct rtrs_addr paths[6];
577 	size_t path_cnt;
578 
579 	opt.sessname = sessname;
580 	opt.paths = paths;
581 	opt.path_cnt = &path_cnt;
582 	opt.pathname = pathname;
583 	opt.dest_port = &port_nr;
584 	opt.access_mode = &access_mode;
585 	opt.nr_poll_queues = &nr_poll_queues;
586 	addrs = kcalloc(ARRAY_SIZE(paths) * 2, sizeof(*addrs), GFP_KERNEL);
587 	if (!addrs)
588 		return -ENOMEM;
589 
590 	for (path_cnt = 0; path_cnt < ARRAY_SIZE(paths); path_cnt++) {
591 		paths[path_cnt].src = &addrs[path_cnt * 2];
592 		paths[path_cnt].dst = &addrs[path_cnt * 2 + 1];
593 	}
594 
595 	ret = rnbd_clt_parse_map_options(buf, ARRAY_SIZE(paths), &opt);
596 	if (ret)
597 		goto out;
598 
599 	pr_info("Mapping device %s on session %s, (access_mode: %s, nr_poll_queues: %d)\n",
600 		pathname, sessname,
601 		rnbd_access_modes[access_mode].str,
602 		nr_poll_queues);
603 
604 	dev = rnbd_clt_map_device(sessname, paths, path_cnt, port_nr, pathname,
605 				  access_mode, nr_poll_queues);
606 	if (IS_ERR(dev)) {
607 		ret = PTR_ERR(dev);
608 		goto out;
609 	}
610 
611 	ret = rnbd_clt_add_dev_kobj(dev);
612 	if (ret)
613 		goto unmap_dev;
614 
615 	ret = rnbd_clt_add_dev_symlink(dev);
616 	if (ret)
617 		goto unmap_dev;
618 
619 	kfree(addrs);
620 	return count;
621 
622 unmap_dev:
623 	rnbd_clt_unmap_device(dev, true, NULL);
624 out:
625 	kfree(addrs);
626 	return ret;
627 }
628 
629 static struct kobj_attribute rnbd_clt_map_device_attr =
630 	__ATTR(map_device, 0644,
631 	       rnbd_clt_map_device_show, rnbd_clt_map_device_store);
632 
633 static struct attribute *default_attrs[] = {
634 	&rnbd_clt_map_device_attr.attr,
635 	NULL,
636 };
637 
638 static struct attribute_group default_attr_group = {
639 	.attrs = default_attrs,
640 };
641 
642 static const struct attribute_group *default_attr_groups[] = {
643 	&default_attr_group,
644 	NULL,
645 };
646 
647 int rnbd_clt_create_sysfs_files(void)
648 {
649 	int err;
650 
651 	err = class_register(&rnbd_dev_class);
652 	if (err)
653 		return err;
654 
655 	rnbd_dev = device_create_with_groups(&rnbd_dev_class, NULL,
656 					      MKDEV(0, 0), NULL,
657 					      default_attr_groups, "ctl");
658 	if (IS_ERR(rnbd_dev)) {
659 		err = PTR_ERR(rnbd_dev);
660 		goto cls_destroy;
661 	}
662 	rnbd_devs_kobj = kobject_create_and_add("devices", &rnbd_dev->kobj);
663 	if (!rnbd_devs_kobj) {
664 		err = -ENOMEM;
665 		goto dev_destroy;
666 	}
667 
668 	return 0;
669 
670 dev_destroy:
671 	device_destroy(&rnbd_dev_class, MKDEV(0, 0));
672 cls_destroy:
673 	class_unregister(&rnbd_dev_class);
674 
675 	return err;
676 }
677 
678 void rnbd_clt_destroy_sysfs_files(void)
679 {
680 	sysfs_remove_group(&rnbd_dev->kobj, &default_attr_group);
681 	kobject_del(rnbd_devs_kobj);
682 	kobject_put(rnbd_devs_kobj);
683 	device_destroy(&rnbd_dev_class, MKDEV(0, 0));
684 	class_unregister(&rnbd_dev_class);
685 }
686