1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * CAIF Interface registration.
4 * Copyright (C) ST-Ericsson AB 2010
5 * Author: Sjur Brendeland
6 *
7 * Borrowed heavily from file: pn_dev.c. Thanks to Remi Denis-Courmont
8 * and Sakari Ailus <sakari.ailus@nokia.com>
9 */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
12
13 #include <linux/kernel.h>
14 #include <linux/if_arp.h>
15 #include <linux/net.h>
16 #include <linux/netdevice.h>
17 #include <linux/mutex.h>
18 #include <linux/module.h>
19 #include <linux/spinlock.h>
20 #include <net/netns/generic.h>
21 #include <net/net_namespace.h>
22 #include <net/pkt_sched.h>
23 #include <net/caif/caif_device.h>
24 #include <net/caif/caif_layer.h>
25 #include <net/caif/caif_dev.h>
26 #include <net/caif/cfpkt.h>
27 #include <net/caif/cfcnfg.h>
28 #include <net/caif/cfserl.h>
29
30 MODULE_LICENSE("GPL");
31
32 /* Used for local tracking of the CAIF net devices */
33 struct caif_device_entry {
34 struct cflayer layer;
35 struct list_head list;
36 struct net_device *netdev;
37 int __percpu *pcpu_refcnt;
38 spinlock_t flow_lock;
39 struct sk_buff *xoff_skb;
40 void (*xoff_skb_dtor)(struct sk_buff *skb);
41 bool xoff;
42 };
43
44 struct caif_device_entry_list {
45 struct list_head list;
46 /* Protects simulanous deletes in list */
47 struct mutex lock;
48 };
49
50 struct caif_net {
51 struct cfcnfg *cfg;
52 struct caif_device_entry_list caifdevs;
53 };
54
55 static unsigned int caif_net_id;
56 static int q_high = 50; /* Percent */
57
get_cfcnfg(struct net * net)58 struct cfcnfg *get_cfcnfg(struct net *net)
59 {
60 struct caif_net *caifn;
61 caifn = net_generic(net, caif_net_id);
62 return caifn->cfg;
63 }
64 EXPORT_SYMBOL(get_cfcnfg);
65
caif_device_list(struct net * net)66 static struct caif_device_entry_list *caif_device_list(struct net *net)
67 {
68 struct caif_net *caifn;
69 caifn = net_generic(net, caif_net_id);
70 return &caifn->caifdevs;
71 }
72
caifd_put(struct caif_device_entry * e)73 static void caifd_put(struct caif_device_entry *e)
74 {
75 this_cpu_dec(*e->pcpu_refcnt);
76 }
77
caifd_hold(struct caif_device_entry * e)78 static void caifd_hold(struct caif_device_entry *e)
79 {
80 this_cpu_inc(*e->pcpu_refcnt);
81 }
82
caifd_refcnt_read(struct caif_device_entry * e)83 static int caifd_refcnt_read(struct caif_device_entry *e)
84 {
85 int i, refcnt = 0;
86 for_each_possible_cpu(i)
87 refcnt += *per_cpu_ptr(e->pcpu_refcnt, i);
88 return refcnt;
89 }
90
91 /* Allocate new CAIF device. */
caif_device_alloc(struct net_device * dev)92 static struct caif_device_entry *caif_device_alloc(struct net_device *dev)
93 {
94 struct caif_device_entry *caifd;
95
96 caifd = kzalloc(sizeof(*caifd), GFP_KERNEL);
97 if (!caifd)
98 return NULL;
99 caifd->pcpu_refcnt = alloc_percpu(int);
100 if (!caifd->pcpu_refcnt) {
101 kfree(caifd);
102 return NULL;
103 }
104 caifd->netdev = dev;
105 dev_hold(dev);
106 return caifd;
107 }
108
caif_get(struct net_device * dev)109 static struct caif_device_entry *caif_get(struct net_device *dev)
110 {
111 struct caif_device_entry_list *caifdevs =
112 caif_device_list(dev_net(dev));
113 struct caif_device_entry *caifd;
114
115 list_for_each_entry_rcu(caifd, &caifdevs->list, list) {
116 if (caifd->netdev == dev)
117 return caifd;
118 }
119 return NULL;
120 }
121
caif_flow_cb(struct sk_buff * skb)122 static void caif_flow_cb(struct sk_buff *skb)
123 {
124 struct caif_device_entry *caifd;
125 void (*dtor)(struct sk_buff *skb) = NULL;
126 bool send_xoff;
127
128 WARN_ON(skb->dev == NULL);
129
130 rcu_read_lock();
131 caifd = caif_get(skb->dev);
132
133 WARN_ON(caifd == NULL);
134 if (!caifd) {
135 rcu_read_unlock();
136 return;
137 }
138
139 caifd_hold(caifd);
140 rcu_read_unlock();
141
142 spin_lock_bh(&caifd->flow_lock);
143 send_xoff = caifd->xoff;
144 caifd->xoff = 0;
145 dtor = caifd->xoff_skb_dtor;
146
147 if (WARN_ON(caifd->xoff_skb != skb))
148 skb = NULL;
149
150 caifd->xoff_skb = NULL;
151 caifd->xoff_skb_dtor = NULL;
152
153 spin_unlock_bh(&caifd->flow_lock);
154
155 if (dtor && skb)
156 dtor(skb);
157
158 if (send_xoff)
159 caifd->layer.up->
160 ctrlcmd(caifd->layer.up,
161 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
162 caifd->layer.id);
163 caifd_put(caifd);
164 }
165
transmit(struct cflayer * layer,struct cfpkt * pkt)166 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
167 {
168 int err, high = 0, qlen = 0;
169 struct caif_device_entry *caifd =
170 container_of(layer, struct caif_device_entry, layer);
171 struct sk_buff *skb;
172 struct netdev_queue *txq;
173
174 rcu_read_lock_bh();
175
176 skb = cfpkt_tonative(pkt);
177 skb->dev = caifd->netdev;
178 skb_reset_network_header(skb);
179 skb->protocol = htons(ETH_P_CAIF);
180
181 /* Check if we need to handle xoff */
182 if (likely(caifd->netdev->priv_flags & IFF_NO_QUEUE))
183 goto noxoff;
184
185 if (unlikely(caifd->xoff))
186 goto noxoff;
187
188 if (likely(!netif_queue_stopped(caifd->netdev))) {
189 struct Qdisc *sch;
190
191 /* If we run with a TX queue, check if the queue is too long*/
192 txq = netdev_get_tx_queue(skb->dev, 0);
193 sch = rcu_dereference_bh(txq->qdisc);
194 if (likely(qdisc_is_empty(sch)))
195 goto noxoff;
196
197 /* can check for explicit qdisc len value only !NOLOCK,
198 * always set flow off otherwise
199 */
200 high = (caifd->netdev->tx_queue_len * q_high) / 100;
201 if (!(sch->flags & TCQ_F_NOLOCK) && likely(sch->q.qlen < high))
202 goto noxoff;
203 }
204
205 /* Hold lock while accessing xoff */
206 spin_lock_bh(&caifd->flow_lock);
207 if (caifd->xoff) {
208 spin_unlock_bh(&caifd->flow_lock);
209 goto noxoff;
210 }
211
212 /*
213 * Handle flow off, we do this by temporary hi-jacking this
214 * skb's destructor function, and replace it with our own
215 * flow-on callback. The callback will set flow-on and call
216 * the original destructor.
217 */
218
219 pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
220 netif_queue_stopped(caifd->netdev),
221 qlen, high);
222 caifd->xoff = 1;
223 caifd->xoff_skb = skb;
224 caifd->xoff_skb_dtor = skb->destructor;
225 skb->destructor = caif_flow_cb;
226 spin_unlock_bh(&caifd->flow_lock);
227
228 caifd->layer.up->ctrlcmd(caifd->layer.up,
229 _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
230 caifd->layer.id);
231 noxoff:
232 rcu_read_unlock_bh();
233
234 err = dev_queue_xmit(skb);
235 if (err > 0)
236 err = -EIO;
237
238 return err;
239 }
240
241 /*
242 * Stuff received packets into the CAIF stack.
243 * On error, returns non-zero and releases the skb.
244 */
receive(struct sk_buff * skb,struct net_device * dev,struct packet_type * pkttype,struct net_device * orig_dev)245 static int receive(struct sk_buff *skb, struct net_device *dev,
246 struct packet_type *pkttype, struct net_device *orig_dev)
247 {
248 struct cfpkt *pkt;
249 struct caif_device_entry *caifd;
250 int err;
251
252 pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
253
254 rcu_read_lock();
255 caifd = caif_get(dev);
256
257 if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
258 !netif_oper_up(caifd->netdev)) {
259 rcu_read_unlock();
260 kfree_skb(skb);
261 return NET_RX_DROP;
262 }
263
264 /* Hold reference to netdevice while using CAIF stack */
265 caifd_hold(caifd);
266 rcu_read_unlock();
267
268 err = caifd->layer.up->receive(caifd->layer.up, pkt);
269
270 /* For -EILSEQ the packet is not freed so so it now */
271 if (err == -EILSEQ)
272 cfpkt_destroy(pkt);
273
274 /* Release reference to stack upwards */
275 caifd_put(caifd);
276
277 if (err != 0)
278 err = NET_RX_DROP;
279 return err;
280 }
281
282 static struct packet_type caif_packet_type __read_mostly = {
283 .type = cpu_to_be16(ETH_P_CAIF),
284 .func = receive,
285 };
286
dev_flowctrl(struct net_device * dev,int on)287 static void dev_flowctrl(struct net_device *dev, int on)
288 {
289 struct caif_device_entry *caifd;
290
291 rcu_read_lock();
292
293 caifd = caif_get(dev);
294 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
295 rcu_read_unlock();
296 return;
297 }
298
299 caifd_hold(caifd);
300 rcu_read_unlock();
301
302 caifd->layer.up->ctrlcmd(caifd->layer.up,
303 on ?
304 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
305 _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
306 caifd->layer.id);
307 caifd_put(caifd);
308 }
309
caif_enroll_dev(struct net_device * dev,struct caif_dev_common * caifdev,struct cflayer * link_support,int head_room,struct cflayer ** layer,int (** rcv_func)(struct sk_buff *,struct net_device *,struct packet_type *,struct net_device *))310 int caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
311 struct cflayer *link_support, int head_room,
312 struct cflayer **layer,
313 int (**rcv_func)(struct sk_buff *, struct net_device *,
314 struct packet_type *,
315 struct net_device *))
316 {
317 struct caif_device_entry *caifd;
318 enum cfcnfg_phy_preference pref;
319 struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
320 struct caif_device_entry_list *caifdevs;
321 int res;
322
323 caifdevs = caif_device_list(dev_net(dev));
324 caifd = caif_device_alloc(dev);
325 if (!caifd)
326 return -ENOMEM;
327 *layer = &caifd->layer;
328 spin_lock_init(&caifd->flow_lock);
329
330 switch (caifdev->link_select) {
331 case CAIF_LINK_HIGH_BANDW:
332 pref = CFPHYPREF_HIGH_BW;
333 break;
334 case CAIF_LINK_LOW_LATENCY:
335 pref = CFPHYPREF_LOW_LAT;
336 break;
337 default:
338 pref = CFPHYPREF_HIGH_BW;
339 break;
340 }
341 mutex_lock(&caifdevs->lock);
342 list_add_rcu(&caifd->list, &caifdevs->list);
343
344 strlcpy(caifd->layer.name, dev->name,
345 sizeof(caifd->layer.name));
346 caifd->layer.transmit = transmit;
347 res = cfcnfg_add_phy_layer(cfg,
348 dev,
349 &caifd->layer,
350 pref,
351 link_support,
352 caifdev->use_fcs,
353 head_room);
354 mutex_unlock(&caifdevs->lock);
355 if (rcv_func)
356 *rcv_func = receive;
357 return res;
358 }
359 EXPORT_SYMBOL(caif_enroll_dev);
360
361 /* notify Caif of device events */
caif_device_notify(struct notifier_block * me,unsigned long what,void * ptr)362 static int caif_device_notify(struct notifier_block *me, unsigned long what,
363 void *ptr)
364 {
365 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
366 struct caif_device_entry *caifd = NULL;
367 struct caif_dev_common *caifdev;
368 struct cfcnfg *cfg;
369 struct cflayer *layer, *link_support;
370 int head_room = 0;
371 struct caif_device_entry_list *caifdevs;
372 int res;
373
374 cfg = get_cfcnfg(dev_net(dev));
375 caifdevs = caif_device_list(dev_net(dev));
376
377 caifd = caif_get(dev);
378 if (caifd == NULL && dev->type != ARPHRD_CAIF)
379 return 0;
380
381 switch (what) {
382 case NETDEV_REGISTER:
383 if (caifd != NULL)
384 break;
385
386 caifdev = netdev_priv(dev);
387
388 link_support = NULL;
389 if (caifdev->use_frag) {
390 head_room = 1;
391 link_support = cfserl_create(dev->ifindex,
392 caifdev->use_stx);
393 if (!link_support) {
394 pr_warn("Out of memory\n");
395 break;
396 }
397 }
398 res = caif_enroll_dev(dev, caifdev, link_support, head_room,
399 &layer, NULL);
400 if (res)
401 cfserl_release(link_support);
402 caifdev->flowctrl = dev_flowctrl;
403 break;
404
405 case NETDEV_UP:
406 rcu_read_lock();
407
408 caifd = caif_get(dev);
409 if (caifd == NULL) {
410 rcu_read_unlock();
411 break;
412 }
413
414 caifd->xoff = 0;
415 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
416 rcu_read_unlock();
417
418 break;
419
420 case NETDEV_DOWN:
421 rcu_read_lock();
422
423 caifd = caif_get(dev);
424 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
425 rcu_read_unlock();
426 return -EINVAL;
427 }
428
429 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
430 caifd_hold(caifd);
431 rcu_read_unlock();
432
433 caifd->layer.up->ctrlcmd(caifd->layer.up,
434 _CAIF_CTRLCMD_PHYIF_DOWN_IND,
435 caifd->layer.id);
436
437 spin_lock_bh(&caifd->flow_lock);
438
439 /*
440 * Replace our xoff-destructor with original destructor.
441 * We trust that skb->destructor *always* is called before
442 * the skb reference is invalid. The hijacked SKB destructor
443 * takes the flow_lock so manipulating the skb->destructor here
444 * should be safe.
445 */
446 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
447 caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
448
449 caifd->xoff = 0;
450 caifd->xoff_skb_dtor = NULL;
451 caifd->xoff_skb = NULL;
452
453 spin_unlock_bh(&caifd->flow_lock);
454 caifd_put(caifd);
455 break;
456
457 case NETDEV_UNREGISTER:
458 mutex_lock(&caifdevs->lock);
459
460 caifd = caif_get(dev);
461 if (caifd == NULL) {
462 mutex_unlock(&caifdevs->lock);
463 break;
464 }
465 list_del_rcu(&caifd->list);
466
467 /*
468 * NETDEV_UNREGISTER is called repeatedly until all reference
469 * counts for the net-device are released. If references to
470 * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
471 * the next call to NETDEV_UNREGISTER.
472 *
473 * If any packets are in flight down the CAIF Stack,
474 * cfcnfg_del_phy_layer will return nonzero.
475 * If no packets are in flight, the CAIF Stack associated
476 * with the net-device un-registering is freed.
477 */
478
479 if (caifd_refcnt_read(caifd) != 0 ||
480 cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
481
482 pr_info("Wait for device inuse\n");
483 /* Enrole device if CAIF Stack is still in use */
484 list_add_rcu(&caifd->list, &caifdevs->list);
485 mutex_unlock(&caifdevs->lock);
486 break;
487 }
488
489 synchronize_rcu();
490 dev_put(caifd->netdev);
491 free_percpu(caifd->pcpu_refcnt);
492 kfree(caifd);
493
494 mutex_unlock(&caifdevs->lock);
495 break;
496 }
497 return 0;
498 }
499
500 static struct notifier_block caif_device_notifier = {
501 .notifier_call = caif_device_notify,
502 .priority = 0,
503 };
504
505 /* Per-namespace Caif devices handling */
caif_init_net(struct net * net)506 static int caif_init_net(struct net *net)
507 {
508 struct caif_net *caifn = net_generic(net, caif_net_id);
509 INIT_LIST_HEAD(&caifn->caifdevs.list);
510 mutex_init(&caifn->caifdevs.lock);
511
512 caifn->cfg = cfcnfg_create();
513 if (!caifn->cfg)
514 return -ENOMEM;
515
516 return 0;
517 }
518
caif_exit_net(struct net * net)519 static void caif_exit_net(struct net *net)
520 {
521 struct caif_device_entry *caifd, *tmp;
522 struct caif_device_entry_list *caifdevs =
523 caif_device_list(net);
524 struct cfcnfg *cfg = get_cfcnfg(net);
525
526 rtnl_lock();
527 mutex_lock(&caifdevs->lock);
528
529 list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
530 int i = 0;
531 list_del_rcu(&caifd->list);
532 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
533
534 while (i < 10 &&
535 (caifd_refcnt_read(caifd) != 0 ||
536 cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
537
538 pr_info("Wait for device inuse\n");
539 msleep(250);
540 i++;
541 }
542 synchronize_rcu();
543 dev_put(caifd->netdev);
544 free_percpu(caifd->pcpu_refcnt);
545 kfree(caifd);
546 }
547 cfcnfg_remove(cfg);
548
549 mutex_unlock(&caifdevs->lock);
550 rtnl_unlock();
551 }
552
553 static struct pernet_operations caif_net_ops = {
554 .init = caif_init_net,
555 .exit = caif_exit_net,
556 .id = &caif_net_id,
557 .size = sizeof(struct caif_net),
558 };
559
560 /* Initialize Caif devices list */
caif_device_init(void)561 static int __init caif_device_init(void)
562 {
563 int result;
564
565 result = register_pernet_subsys(&caif_net_ops);
566
567 if (result)
568 return result;
569
570 register_netdevice_notifier(&caif_device_notifier);
571 dev_add_pack(&caif_packet_type);
572
573 return result;
574 }
575
caif_device_exit(void)576 static void __exit caif_device_exit(void)
577 {
578 unregister_netdevice_notifier(&caif_device_notifier);
579 dev_remove_pack(&caif_packet_type);
580 unregister_pernet_subsys(&caif_net_ops);
581 }
582
583 module_init(caif_device_init);
584 module_exit(caif_device_exit);
585