xref: /openbmc/linux/net/caif/caif_dev.c (revision 82df5b73)
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 so 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 void 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 
323 	caifdevs = caif_device_list(dev_net(dev));
324 	caifd = caif_device_alloc(dev);
325 	if (!caifd)
326 		return;
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 	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 }
358 EXPORT_SYMBOL(caif_enroll_dev);
359 
360 /* notify Caif of device events */
361 static int caif_device_notify(struct notifier_block *me, unsigned long what,
362 			      void *ptr)
363 {
364 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
365 	struct caif_device_entry *caifd = NULL;
366 	struct caif_dev_common *caifdev;
367 	struct cfcnfg *cfg;
368 	struct cflayer *layer, *link_support;
369 	int head_room = 0;
370 	struct caif_device_entry_list *caifdevs;
371 
372 	cfg = get_cfcnfg(dev_net(dev));
373 	caifdevs = caif_device_list(dev_net(dev));
374 
375 	caifd = caif_get(dev);
376 	if (caifd == NULL && dev->type != ARPHRD_CAIF)
377 		return 0;
378 
379 	switch (what) {
380 	case NETDEV_REGISTER:
381 		if (caifd != NULL)
382 			break;
383 
384 		caifdev = netdev_priv(dev);
385 
386 		link_support = NULL;
387 		if (caifdev->use_frag) {
388 			head_room = 1;
389 			link_support = cfserl_create(dev->ifindex,
390 							caifdev->use_stx);
391 			if (!link_support) {
392 				pr_warn("Out of memory\n");
393 				break;
394 			}
395 		}
396 		caif_enroll_dev(dev, caifdev, link_support, head_room,
397 				&layer, NULL);
398 		caifdev->flowctrl = dev_flowctrl;
399 		break;
400 
401 	case NETDEV_UP:
402 		rcu_read_lock();
403 
404 		caifd = caif_get(dev);
405 		if (caifd == NULL) {
406 			rcu_read_unlock();
407 			break;
408 		}
409 
410 		caifd->xoff = false;
411 		cfcnfg_set_phy_state(cfg, &caifd->layer, true);
412 		rcu_read_unlock();
413 
414 		break;
415 
416 	case NETDEV_DOWN:
417 		rcu_read_lock();
418 
419 		caifd = caif_get(dev);
420 		if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
421 			rcu_read_unlock();
422 			return -EINVAL;
423 		}
424 
425 		cfcnfg_set_phy_state(cfg, &caifd->layer, false);
426 		caifd_hold(caifd);
427 		rcu_read_unlock();
428 
429 		caifd->layer.up->ctrlcmd(caifd->layer.up,
430 					 _CAIF_CTRLCMD_PHYIF_DOWN_IND,
431 					 caifd->layer.id);
432 
433 		spin_lock_bh(&caifd->flow_lock);
434 
435 		/*
436 		 * Replace our xoff-destructor with original destructor.
437 		 * We trust that skb->destructor *always* is called before
438 		 * the skb reference is invalid. The hijacked SKB destructor
439 		 * takes the flow_lock so manipulating the skb->destructor here
440 		 * should be safe.
441 		*/
442 		if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
443 			caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
444 
445 		caifd->xoff = false;
446 		caifd->xoff_skb_dtor = NULL;
447 		caifd->xoff_skb = NULL;
448 
449 		spin_unlock_bh(&caifd->flow_lock);
450 		caifd_put(caifd);
451 		break;
452 
453 	case NETDEV_UNREGISTER:
454 		mutex_lock(&caifdevs->lock);
455 
456 		caifd = caif_get(dev);
457 		if (caifd == NULL) {
458 			mutex_unlock(&caifdevs->lock);
459 			break;
460 		}
461 		list_del_rcu(&caifd->list);
462 
463 		/*
464 		 * NETDEV_UNREGISTER is called repeatedly until all reference
465 		 * counts for the net-device are released. If references to
466 		 * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
467 		 * the next call to NETDEV_UNREGISTER.
468 		 *
469 		 * If any packets are in flight down the CAIF Stack,
470 		 * cfcnfg_del_phy_layer will return nonzero.
471 		 * If no packets are in flight, the CAIF Stack associated
472 		 * with the net-device un-registering is freed.
473 		 */
474 
475 		if (caifd_refcnt_read(caifd) != 0 ||
476 			cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
477 
478 			pr_info("Wait for device inuse\n");
479 			/* Enrole device if CAIF Stack is still in use */
480 			list_add_rcu(&caifd->list, &caifdevs->list);
481 			mutex_unlock(&caifdevs->lock);
482 			break;
483 		}
484 
485 		synchronize_rcu();
486 		dev_put(caifd->netdev);
487 		free_percpu(caifd->pcpu_refcnt);
488 		kfree(caifd);
489 
490 		mutex_unlock(&caifdevs->lock);
491 		break;
492 	}
493 	return 0;
494 }
495 
496 static struct notifier_block caif_device_notifier = {
497 	.notifier_call = caif_device_notify,
498 	.priority = 0,
499 };
500 
501 /* Per-namespace Caif devices handling */
502 static int caif_init_net(struct net *net)
503 {
504 	struct caif_net *caifn = net_generic(net, caif_net_id);
505 	INIT_LIST_HEAD(&caifn->caifdevs.list);
506 	mutex_init(&caifn->caifdevs.lock);
507 
508 	caifn->cfg = cfcnfg_create();
509 	if (!caifn->cfg)
510 		return -ENOMEM;
511 
512 	return 0;
513 }
514 
515 static void caif_exit_net(struct net *net)
516 {
517 	struct caif_device_entry *caifd, *tmp;
518 	struct caif_device_entry_list *caifdevs =
519 	    caif_device_list(net);
520 	struct cfcnfg *cfg =  get_cfcnfg(net);
521 
522 	rtnl_lock();
523 	mutex_lock(&caifdevs->lock);
524 
525 	list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
526 		int i = 0;
527 		list_del_rcu(&caifd->list);
528 		cfcnfg_set_phy_state(cfg, &caifd->layer, false);
529 
530 		while (i < 10 &&
531 			(caifd_refcnt_read(caifd) != 0 ||
532 			cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
533 
534 			pr_info("Wait for device inuse\n");
535 			msleep(250);
536 			i++;
537 		}
538 		synchronize_rcu();
539 		dev_put(caifd->netdev);
540 		free_percpu(caifd->pcpu_refcnt);
541 		kfree(caifd);
542 	}
543 	cfcnfg_remove(cfg);
544 
545 	mutex_unlock(&caifdevs->lock);
546 	rtnl_unlock();
547 }
548 
549 static struct pernet_operations caif_net_ops = {
550 	.init = caif_init_net,
551 	.exit = caif_exit_net,
552 	.id   = &caif_net_id,
553 	.size = sizeof(struct caif_net),
554 };
555 
556 /* Initialize Caif devices list */
557 static int __init caif_device_init(void)
558 {
559 	int result;
560 
561 	result = register_pernet_subsys(&caif_net_ops);
562 
563 	if (result)
564 		return result;
565 
566 	register_netdevice_notifier(&caif_device_notifier);
567 	dev_add_pack(&caif_packet_type);
568 
569 	return result;
570 }
571 
572 static void __exit caif_device_exit(void)
573 {
574 	unregister_netdevice_notifier(&caif_device_notifier);
575 	dev_remove_pack(&caif_packet_type);
576 	unregister_pernet_subsys(&caif_net_ops);
577 }
578 
579 module_init(caif_device_init);
580 module_exit(caif_device_exit);
581