xref: /linux/net/caif/caif_dev.c (revision 0be3ff0c) 
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 
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 
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 
73 static void caifd_put(struct caif_device_entry *e)
74 {
75 	this_cpu_dec(*e->pcpu_refcnt);
76 }
77 
78 static void caifd_hold(struct caif_device_entry *e)
79 {
80 	this_cpu_inc(*e->pcpu_refcnt);
81 }
82 
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. */
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 
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 				lockdep_rtnl_is_held()) {
117 		if (caifd->netdev == dev)
118 			return caifd;
119 	}
120 	return NULL;
121 }
122 
123 static void caif_flow_cb(struct sk_buff *skb)
124 {
125 	struct caif_device_entry *caifd;
126 	void (*dtor)(struct sk_buff *skb) = NULL;
127 	bool send_xoff;
128 
129 	WARN_ON(skb->dev == NULL);
130 
131 	rcu_read_lock();
132 	caifd = caif_get(skb->dev);
133 
134 	WARN_ON(caifd == NULL);
135 	if (!caifd) {
136 		rcu_read_unlock();
137 		return;
138 	}
139 
140 	caifd_hold(caifd);
141 	rcu_read_unlock();
142 
143 	spin_lock_bh(&caifd->flow_lock);
144 	send_xoff = caifd->xoff;
145 	caifd->xoff = false;
146 	dtor = caifd->xoff_skb_dtor;
147 
148 	if (WARN_ON(caifd->xoff_skb != skb))
149 		skb = NULL;
150 
151 	caifd->xoff_skb = NULL;
152 	caifd->xoff_skb_dtor = NULL;
153 
154 	spin_unlock_bh(&caifd->flow_lock);
155 
156 	if (dtor && skb)
157 		dtor(skb);
158 
159 	if (send_xoff)
160 		caifd->layer.up->
161 			ctrlcmd(caifd->layer.up,
162 				_CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
163 				caifd->layer.id);
164 	caifd_put(caifd);
165 }
166 
167 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
168 {
169 	int err, high = 0, qlen = 0;
170 	struct caif_device_entry *caifd =
171 	    container_of(layer, struct caif_device_entry, layer);
172 	struct sk_buff *skb;
173 	struct netdev_queue *txq;
174 
175 	rcu_read_lock_bh();
176 
177 	skb = cfpkt_tonative(pkt);
178 	skb->dev = caifd->netdev;
179 	skb_reset_network_header(skb);
180 	skb->protocol = htons(ETH_P_CAIF);
181 
182 	/* Check if we need to handle xoff */
183 	if (likely(caifd->netdev->priv_flags & IFF_NO_QUEUE))
184 		goto noxoff;
185 
186 	if (unlikely(caifd->xoff))
187 		goto noxoff;
188 
189 	if (likely(!netif_queue_stopped(caifd->netdev))) {
190 		struct Qdisc *sch;
191 
192 		/* If we run with a TX queue, check if the queue is too long*/
193 		txq = netdev_get_tx_queue(skb->dev, 0);
194 		sch = rcu_dereference_bh(txq->qdisc);
195 		if (likely(qdisc_is_empty(sch)))
196 			goto noxoff;
197 
198 		/* can check for explicit qdisc len value only !NOLOCK,
199 		 * always set flow off otherwise
200 		 */
201 		high = (caifd->netdev->tx_queue_len * q_high) / 100;
202 		if (!(sch->flags & TCQ_F_NOLOCK) && likely(sch->q.qlen < high))
203 			goto noxoff;
204 	}
205 
206 	/* Hold lock while accessing xoff */
207 	spin_lock_bh(&caifd->flow_lock);
208 	if (caifd->xoff) {
209 		spin_unlock_bh(&caifd->flow_lock);
210 		goto noxoff;
211 	}
212 
213 	/*
214 	 * Handle flow off, we do this by temporary hi-jacking this
215 	 * skb's destructor function, and replace it with our own
216 	 * flow-on callback. The callback will set flow-on and call
217 	 * the original destructor.
218 	 */
219 
220 	pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
221 			netif_queue_stopped(caifd->netdev),
222 			qlen, high);
223 	caifd->xoff = true;
224 	caifd->xoff_skb = skb;
225 	caifd->xoff_skb_dtor = skb->destructor;
226 	skb->destructor = caif_flow_cb;
227 	spin_unlock_bh(&caifd->flow_lock);
228 
229 	caifd->layer.up->ctrlcmd(caifd->layer.up,
230 					_CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
231 					caifd->layer.id);
232 noxoff:
233 	rcu_read_unlock_bh();
234 
235 	err = dev_queue_xmit(skb);
236 	if (err > 0)
237 		err = -EIO;
238 
239 	return err;
240 }
241 
242 /*
243  * Stuff received packets into the CAIF stack.
244  * On error, returns non-zero and releases the skb.
245  */
246 static int receive(struct sk_buff *skb, struct net_device *dev,
247 		   struct packet_type *pkttype, struct net_device *orig_dev)
248 {
249 	struct cfpkt *pkt;
250 	struct caif_device_entry *caifd;
251 	int err;
252 
253 	pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
254 
255 	rcu_read_lock();
256 	caifd = caif_get(dev);
257 
258 	if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
259 			!netif_oper_up(caifd->netdev)) {
260 		rcu_read_unlock();
261 		kfree_skb(skb);
262 		return NET_RX_DROP;
263 	}
264 
265 	/* Hold reference to netdevice while using CAIF stack */
266 	caifd_hold(caifd);
267 	rcu_read_unlock();
268 
269 	err = caifd->layer.up->receive(caifd->layer.up, pkt);
270 
271 	/* For -EILSEQ the packet is not freed so free it now */
272 	if (err == -EILSEQ)
273 		cfpkt_destroy(pkt);
274 
275 	/* Release reference to stack upwards */
276 	caifd_put(caifd);
277 
278 	if (err != 0)
279 		err = NET_RX_DROP;
280 	return err;
281 }
282 
283 static struct packet_type caif_packet_type __read_mostly = {
284 	.type = cpu_to_be16(ETH_P_CAIF),
285 	.func = receive,
286 };
287 
288 static void dev_flowctrl(struct net_device *dev, int on)
289 {
290 	struct caif_device_entry *caifd;
291 
292 	rcu_read_lock();
293 
294 	caifd = caif_get(dev);
295 	if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
296 		rcu_read_unlock();
297 		return;
298 	}
299 
300 	caifd_hold(caifd);
301 	rcu_read_unlock();
302 
303 	caifd->layer.up->ctrlcmd(caifd->layer.up,
304 				 on ?
305 				 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
306 				 _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
307 				 caifd->layer.id);
308 	caifd_put(caifd);
309 }
310 
311 int caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
312 		     struct cflayer *link_support, int head_room,
313 		     struct cflayer **layer,
314 		     int (**rcv_func)(struct sk_buff *, struct net_device *,
315 				      struct packet_type *,
316 				      struct net_device *))
317 {
318 	struct caif_device_entry *caifd;
319 	enum cfcnfg_phy_preference pref;
320 	struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
321 	struct caif_device_entry_list *caifdevs;
322 	int res;
323 
324 	caifdevs = caif_device_list(dev_net(dev));
325 	caifd = caif_device_alloc(dev);
326 	if (!caifd)
327 		return -ENOMEM;
328 	*layer = &caifd->layer;
329 	spin_lock_init(&caifd->flow_lock);
330 
331 	switch (caifdev->link_select) {
332 	case CAIF_LINK_HIGH_BANDW:
333 		pref = CFPHYPREF_HIGH_BW;
334 		break;
335 	case CAIF_LINK_LOW_LATENCY:
336 		pref = CFPHYPREF_LOW_LAT;
337 		break;
338 	default:
339 		pref = CFPHYPREF_HIGH_BW;
340 		break;
341 	}
342 	mutex_lock(&caifdevs->lock);
343 	list_add_rcu(&caifd->list, &caifdevs->list);
344 
345 	strlcpy(caifd->layer.name, dev->name,
346 		sizeof(caifd->layer.name));
347 	caifd->layer.transmit = transmit;
348 	res = cfcnfg_add_phy_layer(cfg,
349 				dev,
350 				&caifd->layer,
351 				pref,
352 				link_support,
353 				caifdev->use_fcs,
354 				head_room);
355 	mutex_unlock(&caifdevs->lock);
356 	if (rcv_func)
357 		*rcv_func = receive;
358 	return res;
359 }
360 EXPORT_SYMBOL(caif_enroll_dev);
361 
362 /* notify Caif of device events */
363 static int caif_device_notify(struct notifier_block *me, unsigned long what,
364 			      void *ptr)
365 {
366 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
367 	struct caif_device_entry *caifd = NULL;
368 	struct caif_dev_common *caifdev;
369 	struct cfcnfg *cfg;
370 	struct cflayer *layer, *link_support;
371 	int head_room = 0;
372 	struct caif_device_entry_list *caifdevs;
373 	int res;
374 
375 	cfg = get_cfcnfg(dev_net(dev));
376 	caifdevs = caif_device_list(dev_net(dev));
377 
378 	caifd = caif_get(dev);
379 	if (caifd == NULL && dev->type != ARPHRD_CAIF)
380 		return 0;
381 
382 	switch (what) {
383 	case NETDEV_REGISTER:
384 		if (caifd != NULL)
385 			break;
386 
387 		caifdev = netdev_priv(dev);
388 
389 		link_support = NULL;
390 		if (caifdev->use_frag) {
391 			head_room = 1;
392 			link_support = cfserl_create(dev->ifindex,
393 							caifdev->use_stx);
394 			if (!link_support) {
395 				pr_warn("Out of memory\n");
396 				break;
397 			}
398 		}
399 		res = caif_enroll_dev(dev, caifdev, link_support, head_room,
400 				&layer, NULL);
401 		if (res)
402 			cfserl_release(link_support);
403 		caifdev->flowctrl = dev_flowctrl;
404 		break;
405 
406 	case NETDEV_UP:
407 		rcu_read_lock();
408 
409 		caifd = caif_get(dev);
410 		if (caifd == NULL) {
411 			rcu_read_unlock();
412 			break;
413 		}
414 
415 		caifd->xoff = false;
416 		cfcnfg_set_phy_state(cfg, &caifd->layer, true);
417 		rcu_read_unlock();
418 
419 		break;
420 
421 	case NETDEV_DOWN:
422 		rcu_read_lock();
423 
424 		caifd = caif_get(dev);
425 		if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
426 			rcu_read_unlock();
427 			return -EINVAL;
428 		}
429 
430 		cfcnfg_set_phy_state(cfg, &caifd->layer, false);
431 		caifd_hold(caifd);
432 		rcu_read_unlock();
433 
434 		caifd->layer.up->ctrlcmd(caifd->layer.up,
435 					 _CAIF_CTRLCMD_PHYIF_DOWN_IND,
436 					 caifd->layer.id);
437 
438 		spin_lock_bh(&caifd->flow_lock);
439 
440 		/*
441 		 * Replace our xoff-destructor with original destructor.
442 		 * We trust that skb->destructor *always* is called before
443 		 * the skb reference is invalid. The hijacked SKB destructor
444 		 * takes the flow_lock so manipulating the skb->destructor here
445 		 * should be safe.
446 		*/
447 		if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
448 			caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
449 
450 		caifd->xoff = false;
451 		caifd->xoff_skb_dtor = NULL;
452 		caifd->xoff_skb = NULL;
453 
454 		spin_unlock_bh(&caifd->flow_lock);
455 		caifd_put(caifd);
456 		break;
457 
458 	case NETDEV_UNREGISTER:
459 		mutex_lock(&caifdevs->lock);
460 
461 		caifd = caif_get(dev);
462 		if (caifd == NULL) {
463 			mutex_unlock(&caifdevs->lock);
464 			break;
465 		}
466 		list_del_rcu(&caifd->list);
467 
468 		/*
469 		 * NETDEV_UNREGISTER is called repeatedly until all reference
470 		 * counts for the net-device are released. If references to
471 		 * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
472 		 * the next call to NETDEV_UNREGISTER.
473 		 *
474 		 * If any packets are in flight down the CAIF Stack,
475 		 * cfcnfg_del_phy_layer will return nonzero.
476 		 * If no packets are in flight, the CAIF Stack associated
477 		 * with the net-device un-registering is freed.
478 		 */
479 
480 		if (caifd_refcnt_read(caifd) != 0 ||
481 			cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
482 
483 			pr_info("Wait for device inuse\n");
484 			/* Enrole device if CAIF Stack is still in use */
485 			list_add_rcu(&caifd->list, &caifdevs->list);
486 			mutex_unlock(&caifdevs->lock);
487 			break;
488 		}
489 
490 		synchronize_rcu();
491 		dev_put(caifd->netdev);
492 		free_percpu(caifd->pcpu_refcnt);
493 		kfree(caifd);
494 
495 		mutex_unlock(&caifdevs->lock);
496 		break;
497 	}
498 	return 0;
499 }
500 
501 static struct notifier_block caif_device_notifier = {
502 	.notifier_call = caif_device_notify,
503 	.priority = 0,
504 };
505 
506 /* Per-namespace Caif devices handling */
507 static int caif_init_net(struct net *net)
508 {
509 	struct caif_net *caifn = net_generic(net, caif_net_id);
510 	INIT_LIST_HEAD(&caifn->caifdevs.list);
511 	mutex_init(&caifn->caifdevs.lock);
512 
513 	caifn->cfg = cfcnfg_create();
514 	if (!caifn->cfg)
515 		return -ENOMEM;
516 
517 	return 0;
518 }
519 
520 static void caif_exit_net(struct net *net)
521 {
522 	struct caif_device_entry *caifd, *tmp;
523 	struct caif_device_entry_list *caifdevs =
524 	    caif_device_list(net);
525 	struct cfcnfg *cfg =  get_cfcnfg(net);
526 
527 	rtnl_lock();
528 	mutex_lock(&caifdevs->lock);
529 
530 	list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
531 		int i = 0;
532 		list_del_rcu(&caifd->list);
533 		cfcnfg_set_phy_state(cfg, &caifd->layer, false);
534 
535 		while (i < 10 &&
536 			(caifd_refcnt_read(caifd) != 0 ||
537 			cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
538 
539 			pr_info("Wait for device inuse\n");
540 			msleep(250);
541 			i++;
542 		}
543 		synchronize_rcu();
544 		dev_put(caifd->netdev);
545 		free_percpu(caifd->pcpu_refcnt);
546 		kfree(caifd);
547 	}
548 	cfcnfg_remove(cfg);
549 
550 	mutex_unlock(&caifdevs->lock);
551 	rtnl_unlock();
552 }
553 
554 static struct pernet_operations caif_net_ops = {
555 	.init = caif_init_net,
556 	.exit = caif_exit_net,
557 	.id   = &caif_net_id,
558 	.size = sizeof(struct caif_net),
559 };
560 
561 /* Initialize Caif devices list */
562 static int __init caif_device_init(void)
563 {
564 	int result;
565 
566 	result = register_pernet_subsys(&caif_net_ops);
567 
568 	if (result)
569 		return result;
570 
571 	register_netdevice_notifier(&caif_device_notifier);
572 	dev_add_pack(&caif_packet_type);
573 
574 	return result;
575 }
576 
577 static void __exit caif_device_exit(void)
578 {
579 	unregister_netdevice_notifier(&caif_device_notifier);
580 	dev_remove_pack(&caif_packet_type);
581 	unregister_pernet_subsys(&caif_net_ops);
582 }
583 
584 module_init(caif_device_init);
585 module_exit(caif_device_exit);
586