Merge branch 'for-6.3/hid-bpf' into for-linus
[platform/kernel/linux-starfive.git] / net / core / flow_offload.c
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #include <linux/kernel.h>
3 #include <linux/slab.h>
4 #include <net/act_api.h>
5 #include <net/flow_offload.h>
6 #include <linux/rtnetlink.h>
7 #include <linux/mutex.h>
8 #include <linux/rhashtable.h>
9
10 struct flow_rule *flow_rule_alloc(unsigned int num_actions)
11 {
12         struct flow_rule *rule;
13         int i;
14
15         rule = kzalloc(struct_size(rule, action.entries, num_actions),
16                        GFP_KERNEL);
17         if (!rule)
18                 return NULL;
19
20         rule->action.num_entries = num_actions;
21         /* Pre-fill each action hw_stats with DONT_CARE.
22          * Caller can override this if it wants stats for a given action.
23          */
24         for (i = 0; i < num_actions; i++)
25                 rule->action.entries[i].hw_stats = FLOW_ACTION_HW_STATS_DONT_CARE;
26
27         return rule;
28 }
29 EXPORT_SYMBOL(flow_rule_alloc);
30
31 struct flow_offload_action *offload_action_alloc(unsigned int num_actions)
32 {
33         struct flow_offload_action *fl_action;
34         int i;
35
36         fl_action = kzalloc(struct_size(fl_action, action.entries, num_actions),
37                             GFP_KERNEL);
38         if (!fl_action)
39                 return NULL;
40
41         fl_action->action.num_entries = num_actions;
42         /* Pre-fill each action hw_stats with DONT_CARE.
43          * Caller can override this if it wants stats for a given action.
44          */
45         for (i = 0; i < num_actions; i++)
46                 fl_action->action.entries[i].hw_stats = FLOW_ACTION_HW_STATS_DONT_CARE;
47
48         return fl_action;
49 }
50
51 #define FLOW_DISSECTOR_MATCH(__rule, __type, __out)                             \
52         const struct flow_match *__m = &(__rule)->match;                        \
53         struct flow_dissector *__d = (__m)->dissector;                          \
54                                                                                 \
55         (__out)->key = skb_flow_dissector_target(__d, __type, (__m)->key);      \
56         (__out)->mask = skb_flow_dissector_target(__d, __type, (__m)->mask);    \
57
58 void flow_rule_match_meta(const struct flow_rule *rule,
59                           struct flow_match_meta *out)
60 {
61         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_META, out);
62 }
63 EXPORT_SYMBOL(flow_rule_match_meta);
64
65 void flow_rule_match_basic(const struct flow_rule *rule,
66                            struct flow_match_basic *out)
67 {
68         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_BASIC, out);
69 }
70 EXPORT_SYMBOL(flow_rule_match_basic);
71
72 void flow_rule_match_control(const struct flow_rule *rule,
73                              struct flow_match_control *out)
74 {
75         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_CONTROL, out);
76 }
77 EXPORT_SYMBOL(flow_rule_match_control);
78
79 void flow_rule_match_eth_addrs(const struct flow_rule *rule,
80                                struct flow_match_eth_addrs *out)
81 {
82         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_ETH_ADDRS, out);
83 }
84 EXPORT_SYMBOL(flow_rule_match_eth_addrs);
85
86 void flow_rule_match_vlan(const struct flow_rule *rule,
87                           struct flow_match_vlan *out)
88 {
89         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_VLAN, out);
90 }
91 EXPORT_SYMBOL(flow_rule_match_vlan);
92
93 void flow_rule_match_cvlan(const struct flow_rule *rule,
94                            struct flow_match_vlan *out)
95 {
96         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_CVLAN, out);
97 }
98 EXPORT_SYMBOL(flow_rule_match_cvlan);
99
100 void flow_rule_match_arp(const struct flow_rule *rule,
101                          struct flow_match_arp *out)
102 {
103         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_ARP, out);
104 }
105 EXPORT_SYMBOL(flow_rule_match_arp);
106
107 void flow_rule_match_ipv4_addrs(const struct flow_rule *rule,
108                                 struct flow_match_ipv4_addrs *out)
109 {
110         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_IPV4_ADDRS, out);
111 }
112 EXPORT_SYMBOL(flow_rule_match_ipv4_addrs);
113
114 void flow_rule_match_ipv6_addrs(const struct flow_rule *rule,
115                                 struct flow_match_ipv6_addrs *out)
116 {
117         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_IPV6_ADDRS, out);
118 }
119 EXPORT_SYMBOL(flow_rule_match_ipv6_addrs);
120
121 void flow_rule_match_ip(const struct flow_rule *rule,
122                         struct flow_match_ip *out)
123 {
124         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_IP, out);
125 }
126 EXPORT_SYMBOL(flow_rule_match_ip);
127
128 void flow_rule_match_ports(const struct flow_rule *rule,
129                            struct flow_match_ports *out)
130 {
131         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_PORTS, out);
132 }
133 EXPORT_SYMBOL(flow_rule_match_ports);
134
135 void flow_rule_match_ports_range(const struct flow_rule *rule,
136                                  struct flow_match_ports_range *out)
137 {
138         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_PORTS_RANGE, out);
139 }
140 EXPORT_SYMBOL(flow_rule_match_ports_range);
141
142 void flow_rule_match_tcp(const struct flow_rule *rule,
143                          struct flow_match_tcp *out)
144 {
145         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_TCP, out);
146 }
147 EXPORT_SYMBOL(flow_rule_match_tcp);
148
149 void flow_rule_match_icmp(const struct flow_rule *rule,
150                           struct flow_match_icmp *out)
151 {
152         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_ICMP, out);
153 }
154 EXPORT_SYMBOL(flow_rule_match_icmp);
155
156 void flow_rule_match_mpls(const struct flow_rule *rule,
157                           struct flow_match_mpls *out)
158 {
159         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_MPLS, out);
160 }
161 EXPORT_SYMBOL(flow_rule_match_mpls);
162
163 void flow_rule_match_enc_control(const struct flow_rule *rule,
164                                  struct flow_match_control *out)
165 {
166         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_ENC_CONTROL, out);
167 }
168 EXPORT_SYMBOL(flow_rule_match_enc_control);
169
170 void flow_rule_match_enc_ipv4_addrs(const struct flow_rule *rule,
171                                     struct flow_match_ipv4_addrs *out)
172 {
173         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS, out);
174 }
175 EXPORT_SYMBOL(flow_rule_match_enc_ipv4_addrs);
176
177 void flow_rule_match_enc_ipv6_addrs(const struct flow_rule *rule,
178                                     struct flow_match_ipv6_addrs *out)
179 {
180         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_ENC_IPV6_ADDRS, out);
181 }
182 EXPORT_SYMBOL(flow_rule_match_enc_ipv6_addrs);
183
184 void flow_rule_match_enc_ip(const struct flow_rule *rule,
185                             struct flow_match_ip *out)
186 {
187         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_ENC_IP, out);
188 }
189 EXPORT_SYMBOL(flow_rule_match_enc_ip);
190
191 void flow_rule_match_enc_ports(const struct flow_rule *rule,
192                                struct flow_match_ports *out)
193 {
194         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_ENC_PORTS, out);
195 }
196 EXPORT_SYMBOL(flow_rule_match_enc_ports);
197
198 void flow_rule_match_enc_keyid(const struct flow_rule *rule,
199                                struct flow_match_enc_keyid *out)
200 {
201         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_ENC_KEYID, out);
202 }
203 EXPORT_SYMBOL(flow_rule_match_enc_keyid);
204
205 void flow_rule_match_enc_opts(const struct flow_rule *rule,
206                               struct flow_match_enc_opts *out)
207 {
208         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_ENC_OPTS, out);
209 }
210 EXPORT_SYMBOL(flow_rule_match_enc_opts);
211
212 struct flow_action_cookie *flow_action_cookie_create(void *data,
213                                                      unsigned int len,
214                                                      gfp_t gfp)
215 {
216         struct flow_action_cookie *cookie;
217
218         cookie = kmalloc(sizeof(*cookie) + len, gfp);
219         if (!cookie)
220                 return NULL;
221         cookie->cookie_len = len;
222         memcpy(cookie->cookie, data, len);
223         return cookie;
224 }
225 EXPORT_SYMBOL(flow_action_cookie_create);
226
227 void flow_action_cookie_destroy(struct flow_action_cookie *cookie)
228 {
229         kfree(cookie);
230 }
231 EXPORT_SYMBOL(flow_action_cookie_destroy);
232
233 void flow_rule_match_ct(const struct flow_rule *rule,
234                         struct flow_match_ct *out)
235 {
236         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_CT, out);
237 }
238 EXPORT_SYMBOL(flow_rule_match_ct);
239
240 void flow_rule_match_pppoe(const struct flow_rule *rule,
241                            struct flow_match_pppoe *out)
242 {
243         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_PPPOE, out);
244 }
245 EXPORT_SYMBOL(flow_rule_match_pppoe);
246
247 void flow_rule_match_l2tpv3(const struct flow_rule *rule,
248                             struct flow_match_l2tpv3 *out)
249 {
250         FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_L2TPV3, out);
251 }
252 EXPORT_SYMBOL(flow_rule_match_l2tpv3);
253
254 struct flow_block_cb *flow_block_cb_alloc(flow_setup_cb_t *cb,
255                                           void *cb_ident, void *cb_priv,
256                                           void (*release)(void *cb_priv))
257 {
258         struct flow_block_cb *block_cb;
259
260         block_cb = kzalloc(sizeof(*block_cb), GFP_KERNEL);
261         if (!block_cb)
262                 return ERR_PTR(-ENOMEM);
263
264         block_cb->cb = cb;
265         block_cb->cb_ident = cb_ident;
266         block_cb->cb_priv = cb_priv;
267         block_cb->release = release;
268
269         return block_cb;
270 }
271 EXPORT_SYMBOL(flow_block_cb_alloc);
272
273 void flow_block_cb_free(struct flow_block_cb *block_cb)
274 {
275         if (block_cb->release)
276                 block_cb->release(block_cb->cb_priv);
277
278         kfree(block_cb);
279 }
280 EXPORT_SYMBOL(flow_block_cb_free);
281
282 struct flow_block_cb *flow_block_cb_lookup(struct flow_block *block,
283                                            flow_setup_cb_t *cb, void *cb_ident)
284 {
285         struct flow_block_cb *block_cb;
286
287         list_for_each_entry(block_cb, &block->cb_list, list) {
288                 if (block_cb->cb == cb &&
289                     block_cb->cb_ident == cb_ident)
290                         return block_cb;
291         }
292
293         return NULL;
294 }
295 EXPORT_SYMBOL(flow_block_cb_lookup);
296
297 void *flow_block_cb_priv(struct flow_block_cb *block_cb)
298 {
299         return block_cb->cb_priv;
300 }
301 EXPORT_SYMBOL(flow_block_cb_priv);
302
303 void flow_block_cb_incref(struct flow_block_cb *block_cb)
304 {
305         block_cb->refcnt++;
306 }
307 EXPORT_SYMBOL(flow_block_cb_incref);
308
309 unsigned int flow_block_cb_decref(struct flow_block_cb *block_cb)
310 {
311         return --block_cb->refcnt;
312 }
313 EXPORT_SYMBOL(flow_block_cb_decref);
314
315 bool flow_block_cb_is_busy(flow_setup_cb_t *cb, void *cb_ident,
316                            struct list_head *driver_block_list)
317 {
318         struct flow_block_cb *block_cb;
319
320         list_for_each_entry(block_cb, driver_block_list, driver_list) {
321                 if (block_cb->cb == cb &&
322                     block_cb->cb_ident == cb_ident)
323                         return true;
324         }
325
326         return false;
327 }
328 EXPORT_SYMBOL(flow_block_cb_is_busy);
329
330 int flow_block_cb_setup_simple(struct flow_block_offload *f,
331                                struct list_head *driver_block_list,
332                                flow_setup_cb_t *cb,
333                                void *cb_ident, void *cb_priv,
334                                bool ingress_only)
335 {
336         struct flow_block_cb *block_cb;
337
338         if (ingress_only &&
339             f->binder_type != FLOW_BLOCK_BINDER_TYPE_CLSACT_INGRESS)
340                 return -EOPNOTSUPP;
341
342         f->driver_block_list = driver_block_list;
343
344         switch (f->command) {
345         case FLOW_BLOCK_BIND:
346                 if (flow_block_cb_is_busy(cb, cb_ident, driver_block_list))
347                         return -EBUSY;
348
349                 block_cb = flow_block_cb_alloc(cb, cb_ident, cb_priv, NULL);
350                 if (IS_ERR(block_cb))
351                         return PTR_ERR(block_cb);
352
353                 flow_block_cb_add(block_cb, f);
354                 list_add_tail(&block_cb->driver_list, driver_block_list);
355                 return 0;
356         case FLOW_BLOCK_UNBIND:
357                 block_cb = flow_block_cb_lookup(f->block, cb, cb_ident);
358                 if (!block_cb)
359                         return -ENOENT;
360
361                 flow_block_cb_remove(block_cb, f);
362                 list_del(&block_cb->driver_list);
363                 return 0;
364         default:
365                 return -EOPNOTSUPP;
366         }
367 }
368 EXPORT_SYMBOL(flow_block_cb_setup_simple);
369
370 static DEFINE_MUTEX(flow_indr_block_lock);
371 static LIST_HEAD(flow_block_indr_list);
372 static LIST_HEAD(flow_block_indr_dev_list);
373 static LIST_HEAD(flow_indir_dev_list);
374
375 struct flow_indr_dev {
376         struct list_head                list;
377         flow_indr_block_bind_cb_t       *cb;
378         void                            *cb_priv;
379         refcount_t                      refcnt;
380 };
381
382 static struct flow_indr_dev *flow_indr_dev_alloc(flow_indr_block_bind_cb_t *cb,
383                                                  void *cb_priv)
384 {
385         struct flow_indr_dev *indr_dev;
386
387         indr_dev = kmalloc(sizeof(*indr_dev), GFP_KERNEL);
388         if (!indr_dev)
389                 return NULL;
390
391         indr_dev->cb            = cb;
392         indr_dev->cb_priv       = cb_priv;
393         refcount_set(&indr_dev->refcnt, 1);
394
395         return indr_dev;
396 }
397
398 struct flow_indir_dev_info {
399         void *data;
400         struct net_device *dev;
401         struct Qdisc *sch;
402         enum tc_setup_type type;
403         void (*cleanup)(struct flow_block_cb *block_cb);
404         struct list_head list;
405         enum flow_block_command command;
406         enum flow_block_binder_type binder_type;
407         struct list_head *cb_list;
408 };
409
410 static void existing_qdiscs_register(flow_indr_block_bind_cb_t *cb, void *cb_priv)
411 {
412         struct flow_block_offload bo;
413         struct flow_indir_dev_info *cur;
414
415         list_for_each_entry(cur, &flow_indir_dev_list, list) {
416                 memset(&bo, 0, sizeof(bo));
417                 bo.command = cur->command;
418                 bo.binder_type = cur->binder_type;
419                 INIT_LIST_HEAD(&bo.cb_list);
420                 cb(cur->dev, cur->sch, cb_priv, cur->type, &bo, cur->data, cur->cleanup);
421                 list_splice(&bo.cb_list, cur->cb_list);
422         }
423 }
424
425 int flow_indr_dev_register(flow_indr_block_bind_cb_t *cb, void *cb_priv)
426 {
427         struct flow_indr_dev *indr_dev;
428
429         mutex_lock(&flow_indr_block_lock);
430         list_for_each_entry(indr_dev, &flow_block_indr_dev_list, list) {
431                 if (indr_dev->cb == cb &&
432                     indr_dev->cb_priv == cb_priv) {
433                         refcount_inc(&indr_dev->refcnt);
434                         mutex_unlock(&flow_indr_block_lock);
435                         return 0;
436                 }
437         }
438
439         indr_dev = flow_indr_dev_alloc(cb, cb_priv);
440         if (!indr_dev) {
441                 mutex_unlock(&flow_indr_block_lock);
442                 return -ENOMEM;
443         }
444
445         list_add(&indr_dev->list, &flow_block_indr_dev_list);
446         existing_qdiscs_register(cb, cb_priv);
447         mutex_unlock(&flow_indr_block_lock);
448
449         tcf_action_reoffload_cb(cb, cb_priv, true);
450
451         return 0;
452 }
453 EXPORT_SYMBOL(flow_indr_dev_register);
454
455 static void __flow_block_indr_cleanup(void (*release)(void *cb_priv),
456                                       void *cb_priv,
457                                       struct list_head *cleanup_list)
458 {
459         struct flow_block_cb *this, *next;
460
461         list_for_each_entry_safe(this, next, &flow_block_indr_list, indr.list) {
462                 if (this->release == release &&
463                     this->indr.cb_priv == cb_priv)
464                         list_move(&this->indr.list, cleanup_list);
465         }
466 }
467
468 static void flow_block_indr_notify(struct list_head *cleanup_list)
469 {
470         struct flow_block_cb *this, *next;
471
472         list_for_each_entry_safe(this, next, cleanup_list, indr.list) {
473                 list_del(&this->indr.list);
474                 this->indr.cleanup(this);
475         }
476 }
477
478 void flow_indr_dev_unregister(flow_indr_block_bind_cb_t *cb, void *cb_priv,
479                               void (*release)(void *cb_priv))
480 {
481         struct flow_indr_dev *this, *next, *indr_dev = NULL;
482         LIST_HEAD(cleanup_list);
483
484         mutex_lock(&flow_indr_block_lock);
485         list_for_each_entry_safe(this, next, &flow_block_indr_dev_list, list) {
486                 if (this->cb == cb &&
487                     this->cb_priv == cb_priv &&
488                     refcount_dec_and_test(&this->refcnt)) {
489                         indr_dev = this;
490                         list_del(&indr_dev->list);
491                         break;
492                 }
493         }
494
495         if (!indr_dev) {
496                 mutex_unlock(&flow_indr_block_lock);
497                 return;
498         }
499
500         __flow_block_indr_cleanup(release, cb_priv, &cleanup_list);
501         mutex_unlock(&flow_indr_block_lock);
502
503         tcf_action_reoffload_cb(cb, cb_priv, false);
504         flow_block_indr_notify(&cleanup_list);
505         kfree(indr_dev);
506 }
507 EXPORT_SYMBOL(flow_indr_dev_unregister);
508
509 static void flow_block_indr_init(struct flow_block_cb *flow_block,
510                                  struct flow_block_offload *bo,
511                                  struct net_device *dev, struct Qdisc *sch, void *data,
512                                  void *cb_priv,
513                                  void (*cleanup)(struct flow_block_cb *block_cb))
514 {
515         flow_block->indr.binder_type = bo->binder_type;
516         flow_block->indr.data = data;
517         flow_block->indr.cb_priv = cb_priv;
518         flow_block->indr.dev = dev;
519         flow_block->indr.sch = sch;
520         flow_block->indr.cleanup = cleanup;
521 }
522
523 struct flow_block_cb *flow_indr_block_cb_alloc(flow_setup_cb_t *cb,
524                                                void *cb_ident, void *cb_priv,
525                                                void (*release)(void *cb_priv),
526                                                struct flow_block_offload *bo,
527                                                struct net_device *dev,
528                                                struct Qdisc *sch, void *data,
529                                                void *indr_cb_priv,
530                                                void (*cleanup)(struct flow_block_cb *block_cb))
531 {
532         struct flow_block_cb *block_cb;
533
534         block_cb = flow_block_cb_alloc(cb, cb_ident, cb_priv, release);
535         if (IS_ERR(block_cb))
536                 goto out;
537
538         flow_block_indr_init(block_cb, bo, dev, sch, data, indr_cb_priv, cleanup);
539         list_add(&block_cb->indr.list, &flow_block_indr_list);
540
541 out:
542         return block_cb;
543 }
544 EXPORT_SYMBOL(flow_indr_block_cb_alloc);
545
546 static struct flow_indir_dev_info *find_indir_dev(void *data)
547 {
548         struct flow_indir_dev_info *cur;
549
550         list_for_each_entry(cur, &flow_indir_dev_list, list) {
551                 if (cur->data == data)
552                         return cur;
553         }
554         return NULL;
555 }
556
557 static int indir_dev_add(void *data, struct net_device *dev, struct Qdisc *sch,
558                          enum tc_setup_type type, void (*cleanup)(struct flow_block_cb *block_cb),
559                          struct flow_block_offload *bo)
560 {
561         struct flow_indir_dev_info *info;
562
563         info = find_indir_dev(data);
564         if (info)
565                 return -EEXIST;
566
567         info = kzalloc(sizeof(*info), GFP_KERNEL);
568         if (!info)
569                 return -ENOMEM;
570
571         info->data = data;
572         info->dev = dev;
573         info->sch = sch;
574         info->type = type;
575         info->cleanup = cleanup;
576         info->command = bo->command;
577         info->binder_type = bo->binder_type;
578         info->cb_list = bo->cb_list_head;
579
580         list_add(&info->list, &flow_indir_dev_list);
581         return 0;
582 }
583
584 static int indir_dev_remove(void *data)
585 {
586         struct flow_indir_dev_info *info;
587
588         info = find_indir_dev(data);
589         if (!info)
590                 return -ENOENT;
591
592         list_del(&info->list);
593
594         kfree(info);
595         return 0;
596 }
597
598 int flow_indr_dev_setup_offload(struct net_device *dev, struct Qdisc *sch,
599                                 enum tc_setup_type type, void *data,
600                                 struct flow_block_offload *bo,
601                                 void (*cleanup)(struct flow_block_cb *block_cb))
602 {
603         struct flow_indr_dev *this;
604         u32 count = 0;
605         int err;
606
607         mutex_lock(&flow_indr_block_lock);
608         if (bo) {
609                 if (bo->command == FLOW_BLOCK_BIND)
610                         indir_dev_add(data, dev, sch, type, cleanup, bo);
611                 else if (bo->command == FLOW_BLOCK_UNBIND)
612                         indir_dev_remove(data);
613         }
614
615         list_for_each_entry(this, &flow_block_indr_dev_list, list) {
616                 err = this->cb(dev, sch, this->cb_priv, type, bo, data, cleanup);
617                 if (!err)
618                         count++;
619         }
620
621         mutex_unlock(&flow_indr_block_lock);
622
623         return (bo && list_empty(&bo->cb_list)) ? -EOPNOTSUPP : count;
624 }
625 EXPORT_SYMBOL(flow_indr_dev_setup_offload);
626
627 bool flow_indr_dev_exists(void)
628 {
629         return !list_empty(&flow_block_indr_dev_list);
630 }
631 EXPORT_SYMBOL(flow_indr_dev_exists);