xref: /openbmc/linux/net/caif/caif_dev.c (revision 97da55fc) 
1 /*
2  * CAIF Interface registration.
3  * Copyright (C) ST-Ericsson AB 2010
4  * Author:	Sjur Brendeland/sjur.brandeland@stericsson.com
5  * License terms: GNU General Public License (GPL) version 2
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/cfpkt.h>
26 #include <net/caif/cfcnfg.h>
27 #include <net/caif/cfserl.h>
28 
29 MODULE_LICENSE("GPL");
30 
31 /* Used for local tracking of the CAIF net devices */
32 struct caif_device_entry {
33 	struct cflayer layer;
34 	struct list_head list;
35 	struct net_device *netdev;
36 	int __percpu *pcpu_refcnt;
37 	spinlock_t flow_lock;
38 	struct sk_buff *xoff_skb;
39 	void (*xoff_skb_dtor)(struct sk_buff *skb);
40 	bool xoff;
41 };
42 
43 struct caif_device_entry_list {
44 	struct list_head list;
45 	/* Protects simulanous deletes in list */
46 	struct mutex lock;
47 };
48 
49 struct caif_net {
50 	struct cfcnfg *cfg;
51 	struct caif_device_entry_list caifdevs;
52 };
53 
54 static int caif_net_id;
55 static int q_high = 50; /* Percent */
56 
57 struct cfcnfg *get_cfcnfg(struct net *net)
58 {
59 	struct caif_net *caifn;
60 	caifn = net_generic(net, caif_net_id);
61 	return caifn->cfg;
62 }
63 EXPORT_SYMBOL(get_cfcnfg);
64 
65 static struct caif_device_entry_list *caif_device_list(struct net *net)
66 {
67 	struct caif_net *caifn;
68 	caifn = net_generic(net, caif_net_id);
69 	return &caifn->caifdevs;
70 }
71 
72 static void caifd_put(struct caif_device_entry *e)
73 {
74 	this_cpu_dec(*e->pcpu_refcnt);
75 }
76 
77 static void caifd_hold(struct caif_device_entry *e)
78 {
79 	this_cpu_inc(*e->pcpu_refcnt);
80 }
81 
82 static int caifd_refcnt_read(struct caif_device_entry *e)
83 {
84 	int i, refcnt = 0;
85 	for_each_possible_cpu(i)
86 		refcnt += *per_cpu_ptr(e->pcpu_refcnt, i);
87 	return refcnt;
88 }
89 
90 /* Allocate new CAIF device. */
91 static struct caif_device_entry *caif_device_alloc(struct net_device *dev)
92 {
93 	struct caif_device_entry *caifd;
94 
95 	caifd = kzalloc(sizeof(*caifd), GFP_KERNEL);
96 	if (!caifd)
97 		return NULL;
98 	caifd->pcpu_refcnt = alloc_percpu(int);
99 	if (!caifd->pcpu_refcnt) {
100 		kfree(caifd);
101 		return NULL;
102 	}
103 	caifd->netdev = dev;
104 	dev_hold(dev);
105 	return caifd;
106 }
107 
108 static struct caif_device_entry *caif_get(struct net_device *dev)
109 {
110 	struct caif_device_entry_list *caifdevs =
111 	    caif_device_list(dev_net(dev));
112 	struct caif_device_entry *caifd;
113 
114 	list_for_each_entry_rcu(caifd, &caifdevs->list, list) {
115 		if (caifd->netdev == dev)
116 			return caifd;
117 	}
118 	return NULL;
119 }
120 
121 static void caif_flow_cb(struct sk_buff *skb)
122 {
123 	struct caif_device_entry *caifd;
124 	void (*dtor)(struct sk_buff *skb) = NULL;
125 	bool send_xoff;
126 
127 	WARN_ON(skb->dev == NULL);
128 
129 	rcu_read_lock();
130 	caifd = caif_get(skb->dev);
131 
132 	WARN_ON(caifd == NULL);
133 	if (caifd == NULL)
134 		return;
135 
136 	caifd_hold(caifd);
137 	rcu_read_unlock();
138 
139 	spin_lock_bh(&caifd->flow_lock);
140 	send_xoff = caifd->xoff;
141 	caifd->xoff = 0;
142 	dtor = caifd->xoff_skb_dtor;
143 
144 	if (WARN_ON(caifd->xoff_skb != skb))
145 		skb = NULL;
146 
147 	caifd->xoff_skb = NULL;
148 	caifd->xoff_skb_dtor = NULL;
149 
150 	spin_unlock_bh(&caifd->flow_lock);
151 
152 	if (dtor && skb)
153 		dtor(skb);
154 
155 	if (send_xoff)
156 		caifd->layer.up->
157 			ctrlcmd(caifd->layer.up,
158 				_CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
159 				caifd->layer.id);
160 	caifd_put(caifd);
161 }
162 
163 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
164 {
165 	int err, high = 0, qlen = 0;
166 	struct caif_device_entry *caifd =
167 	    container_of(layer, struct caif_device_entry, layer);
168 	struct sk_buff *skb;
169 	struct netdev_queue *txq;
170 
171 	rcu_read_lock_bh();
172 
173 	skb = cfpkt_tonative(pkt);
174 	skb->dev = caifd->netdev;
175 	skb_reset_network_header(skb);
176 	skb->protocol = htons(ETH_P_CAIF);
177 
178 	/* Check if we need to handle xoff */
179 	if (likely(caifd->netdev->tx_queue_len == 0))
180 		goto noxoff;
181 
182 	if (unlikely(caifd->xoff))
183 		goto noxoff;
184 
185 	if (likely(!netif_queue_stopped(caifd->netdev))) {
186 		/* If we run with a TX queue, check if the queue is too long*/
187 		txq = netdev_get_tx_queue(skb->dev, 0);
188 		qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
189 
190 		if (likely(qlen == 0))
191 			goto noxoff;
192 
193 		high = (caifd->netdev->tx_queue_len * q_high) / 100;
194 		if (likely(qlen < high))
195 			goto noxoff;
196 	}
197 
198 	/* Hold lock while accessing xoff */
199 	spin_lock_bh(&caifd->flow_lock);
200 	if (caifd->xoff) {
201 		spin_unlock_bh(&caifd->flow_lock);
202 		goto noxoff;
203 	}
204 
205 	/*
206 	 * Handle flow off, we do this by temporary hi-jacking this
207 	 * skb's destructor function, and replace it with our own
208 	 * flow-on callback. The callback will set flow-on and call
209 	 * the original destructor.
210 	 */
211 
212 	pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
213 			netif_queue_stopped(caifd->netdev),
214 			qlen, high);
215 	caifd->xoff = 1;
216 	caifd->xoff_skb = skb;
217 	caifd->xoff_skb_dtor = skb->destructor;
218 	skb->destructor = caif_flow_cb;
219 	spin_unlock_bh(&caifd->flow_lock);
220 
221 	caifd->layer.up->ctrlcmd(caifd->layer.up,
222 					_CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
223 					caifd->layer.id);
224 noxoff:
225 	rcu_read_unlock_bh();
226 
227 	err = dev_queue_xmit(skb);
228 	if (err > 0)
229 		err = -EIO;
230 
231 	return err;
232 }
233 
234 /*
235  * Stuff received packets into the CAIF stack.
236  * On error, returns non-zero and releases the skb.
237  */
238 static int receive(struct sk_buff *skb, struct net_device *dev,
239 		   struct packet_type *pkttype, struct net_device *orig_dev)
240 {
241 	struct cfpkt *pkt;
242 	struct caif_device_entry *caifd;
243 	int err;
244 
245 	pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
246 
247 	rcu_read_lock();
248 	caifd = caif_get(dev);
249 
250 	if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
251 			!netif_oper_up(caifd->netdev)) {
252 		rcu_read_unlock();
253 		kfree_skb(skb);
254 		return NET_RX_DROP;
255 	}
256 
257 	/* Hold reference to netdevice while using CAIF stack */
258 	caifd_hold(caifd);
259 	rcu_read_unlock();
260 
261 	err = caifd->layer.up->receive(caifd->layer.up, pkt);
262 
263 	/* For -EILSEQ the packet is not freed so so it now */
264 	if (err == -EILSEQ)
265 		cfpkt_destroy(pkt);
266 
267 	/* Release reference to stack upwards */
268 	caifd_put(caifd);
269 
270 	if (err != 0)
271 		err = NET_RX_DROP;
272 	return err;
273 }
274 
275 static struct packet_type caif_packet_type __read_mostly = {
276 	.type = cpu_to_be16(ETH_P_CAIF),
277 	.func = receive,
278 };
279 
280 static void dev_flowctrl(struct net_device *dev, int on)
281 {
282 	struct caif_device_entry *caifd;
283 
284 	rcu_read_lock();
285 
286 	caifd = caif_get(dev);
287 	if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
288 		rcu_read_unlock();
289 		return;
290 	}
291 
292 	caifd_hold(caifd);
293 	rcu_read_unlock();
294 
295 	caifd->layer.up->ctrlcmd(caifd->layer.up,
296 				 on ?
297 				 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
298 				 _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
299 				 caifd->layer.id);
300 	caifd_put(caifd);
301 }
302 
303 void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
304 			struct cflayer *link_support, int head_room,
305 			struct cflayer **layer, int (**rcv_func)(
306 				struct sk_buff *, struct net_device *,
307 				struct packet_type *, struct net_device *))
308 {
309 	struct caif_device_entry *caifd;
310 	enum cfcnfg_phy_preference pref;
311 	struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
312 	struct caif_device_entry_list *caifdevs;
313 
314 	caifdevs = caif_device_list(dev_net(dev));
315 	caifd = caif_device_alloc(dev);
316 	if (!caifd)
317 		return;
318 	*layer = &caifd->layer;
319 	spin_lock_init(&caifd->flow_lock);
320 
321 	switch (caifdev->link_select) {
322 	case CAIF_LINK_HIGH_BANDW:
323 		pref = CFPHYPREF_HIGH_BW;
324 		break;
325 	case CAIF_LINK_LOW_LATENCY:
326 		pref = CFPHYPREF_LOW_LAT;
327 		break;
328 	default:
329 		pref = CFPHYPREF_HIGH_BW;
330 		break;
331 	}
332 	mutex_lock(&caifdevs->lock);
333 	list_add_rcu(&caifd->list, &caifdevs->list);
334 
335 	strncpy(caifd->layer.name, dev->name,
336 		sizeof(caifd->layer.name) - 1);
337 	caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
338 	caifd->layer.transmit = transmit;
339 	cfcnfg_add_phy_layer(cfg,
340 				dev,
341 				&caifd->layer,
342 				pref,
343 				link_support,
344 				caifdev->use_fcs,
345 				head_room);
346 	mutex_unlock(&caifdevs->lock);
347 	if (rcv_func)
348 		*rcv_func = receive;
349 }
350 EXPORT_SYMBOL(caif_enroll_dev);
351 
352 /* notify Caif of device events */
353 static int caif_device_notify(struct notifier_block *me, unsigned long what,
354 			      void *arg)
355 {
356 	struct net_device *dev = arg;
357 	struct caif_device_entry *caifd = NULL;
358 	struct caif_dev_common *caifdev;
359 	struct cfcnfg *cfg;
360 	struct cflayer *layer, *link_support;
361 	int head_room = 0;
362 	struct caif_device_entry_list *caifdevs;
363 
364 	cfg = get_cfcnfg(dev_net(dev));
365 	caifdevs = caif_device_list(dev_net(dev));
366 
367 	caifd = caif_get(dev);
368 	if (caifd == NULL && dev->type != ARPHRD_CAIF)
369 		return 0;
370 
371 	switch (what) {
372 	case NETDEV_REGISTER:
373 		if (caifd != NULL)
374 			break;
375 
376 		caifdev = netdev_priv(dev);
377 
378 		link_support = NULL;
379 		if (caifdev->use_frag) {
380 			head_room = 1;
381 			link_support = cfserl_create(dev->ifindex,
382 							caifdev->use_stx);
383 			if (!link_support) {
384 				pr_warn("Out of memory\n");
385 				break;
386 			}
387 		}
388 		caif_enroll_dev(dev, caifdev, link_support, head_room,
389 				&layer, NULL);
390 		caifdev->flowctrl = dev_flowctrl;
391 		break;
392 
393 	case NETDEV_UP:
394 		rcu_read_lock();
395 
396 		caifd = caif_get(dev);
397 		if (caifd == NULL) {
398 			rcu_read_unlock();
399 			break;
400 		}
401 
402 		caifd->xoff = 0;
403 		cfcnfg_set_phy_state(cfg, &caifd->layer, true);
404 		rcu_read_unlock();
405 
406 		break;
407 
408 	case NETDEV_DOWN:
409 		rcu_read_lock();
410 
411 		caifd = caif_get(dev);
412 		if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
413 			rcu_read_unlock();
414 			return -EINVAL;
415 		}
416 
417 		cfcnfg_set_phy_state(cfg, &caifd->layer, false);
418 		caifd_hold(caifd);
419 		rcu_read_unlock();
420 
421 		caifd->layer.up->ctrlcmd(caifd->layer.up,
422 					 _CAIF_CTRLCMD_PHYIF_DOWN_IND,
423 					 caifd->layer.id);
424 
425 		spin_lock_bh(&caifd->flow_lock);
426 
427 		/*
428 		 * Replace our xoff-destructor with original destructor.
429 		 * We trust that skb->destructor *always* is called before
430 		 * the skb reference is invalid. The hijacked SKB destructor
431 		 * takes the flow_lock so manipulating the skb->destructor here
432 		 * should be safe.
433 		*/
434 		if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
435 			caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
436 
437 		caifd->xoff = 0;
438 		caifd->xoff_skb_dtor = NULL;
439 		caifd->xoff_skb = NULL;
440 
441 		spin_unlock_bh(&caifd->flow_lock);
442 		caifd_put(caifd);
443 		break;
444 
445 	case NETDEV_UNREGISTER:
446 		mutex_lock(&caifdevs->lock);
447 
448 		caifd = caif_get(dev);
449 		if (caifd == NULL) {
450 			mutex_unlock(&caifdevs->lock);
451 			break;
452 		}
453 		list_del_rcu(&caifd->list);
454 
455 		/*
456 		 * NETDEV_UNREGISTER is called repeatedly until all reference
457 		 * counts for the net-device are released. If references to
458 		 * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
459 		 * the next call to NETDEV_UNREGISTER.
460 		 *
461 		 * If any packets are in flight down the CAIF Stack,
462 		 * cfcnfg_del_phy_layer will return nonzero.
463 		 * If no packets are in flight, the CAIF Stack associated
464 		 * with the net-device un-registering is freed.
465 		 */
466 
467 		if (caifd_refcnt_read(caifd) != 0 ||
468 			cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
469 
470 			pr_info("Wait for device inuse\n");
471 			/* Enrole device if CAIF Stack is still in use */
472 			list_add_rcu(&caifd->list, &caifdevs->list);
473 			mutex_unlock(&caifdevs->lock);
474 			break;
475 		}
476 
477 		synchronize_rcu();
478 		dev_put(caifd->netdev);
479 		free_percpu(caifd->pcpu_refcnt);
480 		kfree(caifd);
481 
482 		mutex_unlock(&caifdevs->lock);
483 		break;
484 	}
485 	return 0;
486 }
487 
488 static struct notifier_block caif_device_notifier = {
489 	.notifier_call = caif_device_notify,
490 	.priority = 0,
491 };
492 
493 /* Per-namespace Caif devices handling */
494 static int caif_init_net(struct net *net)
495 {
496 	struct caif_net *caifn = net_generic(net, caif_net_id);
497 	INIT_LIST_HEAD(&caifn->caifdevs.list);
498 	mutex_init(&caifn->caifdevs.lock);
499 
500 	caifn->cfg = cfcnfg_create();
501 	if (!caifn->cfg)
502 		return -ENOMEM;
503 
504 	return 0;
505 }
506 
507 static void caif_exit_net(struct net *net)
508 {
509 	struct caif_device_entry *caifd, *tmp;
510 	struct caif_device_entry_list *caifdevs =
511 	    caif_device_list(net);
512 	struct cfcnfg *cfg =  get_cfcnfg(net);
513 
514 	rtnl_lock();
515 	mutex_lock(&caifdevs->lock);
516 
517 	list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
518 		int i = 0;
519 		list_del_rcu(&caifd->list);
520 		cfcnfg_set_phy_state(cfg, &caifd->layer, false);
521 
522 		while (i < 10 &&
523 			(caifd_refcnt_read(caifd) != 0 ||
524 			cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
525 
526 			pr_info("Wait for device inuse\n");
527 			msleep(250);
528 			i++;
529 		}
530 		synchronize_rcu();
531 		dev_put(caifd->netdev);
532 		free_percpu(caifd->pcpu_refcnt);
533 		kfree(caifd);
534 	}
535 	cfcnfg_remove(cfg);
536 
537 	mutex_unlock(&caifdevs->lock);
538 	rtnl_unlock();
539 }
540 
541 static struct pernet_operations caif_net_ops = {
542 	.init = caif_init_net,
543 	.exit = caif_exit_net,
544 	.id   = &caif_net_id,
545 	.size = sizeof(struct caif_net),
546 };
547 
548 /* Initialize Caif devices list */
549 static int __init caif_device_init(void)
550 {
551 	int result;
552 
553 	result = register_pernet_subsys(&caif_net_ops);
554 
555 	if (result)
556 		return result;
557 
558 	register_netdevice_notifier(&caif_device_notifier);
559 	dev_add_pack(&caif_packet_type);
560 
561 	return result;
562 }
563 
564 static void __exit caif_device_exit(void)
565 {
566 	unregister_netdevice_notifier(&caif_device_notifier);
567 	dev_remove_pack(&caif_packet_type);
568 	unregister_pernet_subsys(&caif_net_ops);
569 }
570 
571 module_init(caif_device_init);
572 module_exit(caif_device_exit);
573