xref: /openbmc/linux/net/caif/caif_dev.c (revision 63dc02bd) 
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
8  *  Remi Denis-Courmont <remi.denis-courmont@nokia.com>
9  *  and Sakari Ailus <sakari.ailus@nokia.com>
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
13 
14 #include <linux/kernel.h>
15 #include <linux/if_arp.h>
16 #include <linux/net.h>
17 #include <linux/netdevice.h>
18 #include <linux/mutex.h>
19 #include <linux/module.h>
20 #include <linux/spinlock.h>
21 #include <net/netns/generic.h>
22 #include <net/net_namespace.h>
23 #include <net/pkt_sched.h>
24 #include <net/caif/caif_device.h>
25 #include <net/caif/caif_layer.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 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_list *caifdevs;
95 	struct caif_device_entry *caifd;
96 
97 	caifdevs = caif_device_list(dev_net(dev));
98 
99 	caifd = kzalloc(sizeof(*caifd), GFP_KERNEL);
100 	if (!caifd)
101 		return NULL;
102 	caifd->pcpu_refcnt = alloc_percpu(int);
103 	if (!caifd->pcpu_refcnt) {
104 		kfree(caifd);
105 		return NULL;
106 	}
107 	caifd->netdev = dev;
108 	dev_hold(dev);
109 	return caifd;
110 }
111 
112 static struct caif_device_entry *caif_get(struct net_device *dev)
113 {
114 	struct caif_device_entry_list *caifdevs =
115 	    caif_device_list(dev_net(dev));
116 	struct caif_device_entry *caifd;
117 
118 	list_for_each_entry_rcu(caifd, &caifdevs->list, list) {
119 		if (caifd->netdev == dev)
120 			return caifd;
121 	}
122 	return NULL;
123 }
124 
125 void caif_flow_cb(struct sk_buff *skb)
126 {
127 	struct caif_device_entry *caifd;
128 	void (*dtor)(struct sk_buff *skb) = NULL;
129 	bool send_xoff;
130 
131 	WARN_ON(skb->dev == NULL);
132 
133 	rcu_read_lock();
134 	caifd = caif_get(skb->dev);
135 	caifd_hold(caifd);
136 	rcu_read_unlock();
137 
138 	spin_lock_bh(&caifd->flow_lock);
139 	send_xoff = caifd->xoff;
140 	caifd->xoff = 0;
141 	dtor = caifd->xoff_skb_dtor;
142 
143 	if (WARN_ON(caifd->xoff_skb != skb))
144 		skb = NULL;
145 
146 	caifd->xoff_skb = NULL;
147 	caifd->xoff_skb_dtor = NULL;
148 
149 	spin_unlock_bh(&caifd->flow_lock);
150 
151 	if (dtor && skb)
152 		dtor(skb);
153 
154 	if (send_xoff)
155 		caifd->layer.up->
156 			ctrlcmd(caifd->layer.up,
157 				_CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
158 				caifd->layer.id);
159 	caifd_put(caifd);
160 }
161 
162 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
163 {
164 	int err, high = 0, qlen = 0;
165 	struct caif_device_entry *caifd =
166 	    container_of(layer, struct caif_device_entry, layer);
167 	struct sk_buff *skb;
168 	struct netdev_queue *txq;
169 
170 	rcu_read_lock_bh();
171 
172 	skb = cfpkt_tonative(pkt);
173 	skb->dev = caifd->netdev;
174 	skb_reset_network_header(skb);
175 	skb->protocol = htons(ETH_P_CAIF);
176 
177 	/* Check if we need to handle xoff */
178 	if (likely(caifd->netdev->tx_queue_len == 0))
179 		goto noxoff;
180 
181 	if (unlikely(caifd->xoff))
182 		goto noxoff;
183 
184 	if (likely(!netif_queue_stopped(caifd->netdev))) {
185 		/* If we run with a TX queue, check if the queue is too long*/
186 		txq = netdev_get_tx_queue(skb->dev, 0);
187 		qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
188 
189 		if (likely(qlen == 0))
190 			goto noxoff;
191 
192 		high = (caifd->netdev->tx_queue_len * q_high) / 100;
193 		if (likely(qlen < high))
194 			goto noxoff;
195 	}
196 
197 	/* Hold lock while accessing xoff */
198 	spin_lock_bh(&caifd->flow_lock);
199 	if (caifd->xoff) {
200 		spin_unlock_bh(&caifd->flow_lock);
201 		goto noxoff;
202 	}
203 
204 	/*
205 	 * Handle flow off, we do this by temporary hi-jacking this
206 	 * skb's destructor function, and replace it with our own
207 	 * flow-on callback. The callback will set flow-on and call
208 	 * the original destructor.
209 	 */
210 
211 	pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
212 			netif_queue_stopped(caifd->netdev),
213 			qlen, high);
214 	caifd->xoff = 1;
215 	caifd->xoff_skb = skb;
216 	caifd->xoff_skb_dtor = skb->destructor;
217 	skb->destructor = caif_flow_cb;
218 	spin_unlock_bh(&caifd->flow_lock);
219 
220 	caifd->layer.up->ctrlcmd(caifd->layer.up,
221 					_CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
222 					caifd->layer.id);
223 noxoff:
224 	rcu_read_unlock_bh();
225 
226 	err = dev_queue_xmit(skb);
227 	if (err > 0)
228 		err = -EIO;
229 
230 	return err;
231 }
232 
233 /*
234  * Stuff received packets into the CAIF stack.
235  * On error, returns non-zero and releases the skb.
236  */
237 static int receive(struct sk_buff *skb, struct net_device *dev,
238 		   struct packet_type *pkttype, struct net_device *orig_dev)
239 {
240 	struct cfpkt *pkt;
241 	struct caif_device_entry *caifd;
242 	int err;
243 
244 	pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
245 
246 	rcu_read_lock();
247 	caifd = caif_get(dev);
248 
249 	if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
250 			!netif_oper_up(caifd->netdev)) {
251 		rcu_read_unlock();
252 		kfree_skb(skb);
253 		return NET_RX_DROP;
254 	}
255 
256 	/* Hold reference to netdevice while using CAIF stack */
257 	caifd_hold(caifd);
258 	rcu_read_unlock();
259 
260 	err = caifd->layer.up->receive(caifd->layer.up, pkt);
261 
262 	/* For -EILSEQ the packet is not freed so so it now */
263 	if (err == -EILSEQ)
264 		cfpkt_destroy(pkt);
265 
266 	/* Release reference to stack upwards */
267 	caifd_put(caifd);
268 
269 	if (err != 0)
270 		err = NET_RX_DROP;
271 	return err;
272 }
273 
274 static struct packet_type caif_packet_type __read_mostly = {
275 	.type = cpu_to_be16(ETH_P_CAIF),
276 	.func = receive,
277 };
278 
279 static void dev_flowctrl(struct net_device *dev, int on)
280 {
281 	struct caif_device_entry *caifd;
282 
283 	rcu_read_lock();
284 
285 	caifd = caif_get(dev);
286 	if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
287 		rcu_read_unlock();
288 		return;
289 	}
290 
291 	caifd_hold(caifd);
292 	rcu_read_unlock();
293 
294 	caifd->layer.up->ctrlcmd(caifd->layer.up,
295 				 on ?
296 				 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
297 				 _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
298 				 caifd->layer.id);
299 	caifd_put(caifd);
300 }
301 
302 void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
303 			struct cflayer *link_support, int head_room,
304 			struct cflayer **layer, int (**rcv_func)(
305 				struct sk_buff *, struct net_device *,
306 				struct packet_type *, struct net_device *))
307 {
308 	struct caif_device_entry *caifd;
309 	enum cfcnfg_phy_preference pref;
310 	struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
311 	struct caif_device_entry_list *caifdevs;
312 
313 	caifdevs = caif_device_list(dev_net(dev));
314 	caifd = caif_device_alloc(dev);
315 	if (!caifd)
316 		return;
317 	*layer = &caifd->layer;
318 	spin_lock_init(&caifd->flow_lock);
319 
320 	switch (caifdev->link_select) {
321 	case CAIF_LINK_HIGH_BANDW:
322 		pref = CFPHYPREF_HIGH_BW;
323 		break;
324 	case CAIF_LINK_LOW_LATENCY:
325 		pref = CFPHYPREF_LOW_LAT;
326 		break;
327 	default:
328 		pref = CFPHYPREF_HIGH_BW;
329 		break;
330 	}
331 	mutex_lock(&caifdevs->lock);
332 	list_add_rcu(&caifd->list, &caifdevs->list);
333 
334 	strncpy(caifd->layer.name, dev->name,
335 		sizeof(caifd->layer.name) - 1);
336 	caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
337 	caifd->layer.transmit = transmit;
338 	cfcnfg_add_phy_layer(cfg,
339 				dev,
340 				&caifd->layer,
341 				pref,
342 				link_support,
343 				caifdev->use_fcs,
344 				head_room);
345 	mutex_unlock(&caifdevs->lock);
346 	if (rcv_func)
347 		*rcv_func = receive;
348 }
349 EXPORT_SYMBOL(caif_enroll_dev);
350 
351 /* notify Caif of device events */
352 static int caif_device_notify(struct notifier_block *me, unsigned long what,
353 			      void *arg)
354 {
355 	struct net_device *dev = arg;
356 	struct caif_device_entry *caifd = NULL;
357 	struct caif_dev_common *caifdev;
358 	struct cfcnfg *cfg;
359 	struct cflayer *layer, *link_support;
360 	int head_room = 0;
361 	struct caif_device_entry_list *caifdevs;
362 
363 	cfg = get_cfcnfg(dev_net(dev));
364 	caifdevs = caif_device_list(dev_net(dev));
365 
366 	caifd = caif_get(dev);
367 	if (caifd == NULL && dev->type != ARPHRD_CAIF)
368 		return 0;
369 
370 	switch (what) {
371 	case NETDEV_REGISTER:
372 		if (caifd != NULL)
373 			break;
374 
375 		caifdev = netdev_priv(dev);
376 
377 		link_support = NULL;
378 		if (caifdev->use_frag) {
379 			head_room = 1;
380 			link_support = cfserl_create(dev->ifindex,
381 							caifdev->use_stx);
382 			if (!link_support) {
383 				pr_warn("Out of memory\n");
384 				break;
385 			}
386 		}
387 		caif_enroll_dev(dev, caifdev, link_support, head_room,
388 				&layer, NULL);
389 		caifdev->flowctrl = dev_flowctrl;
390 		break;
391 
392 	case NETDEV_UP:
393 		rcu_read_lock();
394 
395 		caifd = caif_get(dev);
396 		if (caifd == NULL) {
397 			rcu_read_unlock();
398 			break;
399 		}
400 
401 		caifd->xoff = 0;
402 		cfcnfg_set_phy_state(cfg, &caifd->layer, true);
403 		rcu_read_unlock();
404 
405 		break;
406 
407 	case NETDEV_DOWN:
408 		rcu_read_lock();
409 
410 		caifd = caif_get(dev);
411 		if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
412 			rcu_read_unlock();
413 			return -EINVAL;
414 		}
415 
416 		cfcnfg_set_phy_state(cfg, &caifd->layer, false);
417 		caifd_hold(caifd);
418 		rcu_read_unlock();
419 
420 		caifd->layer.up->ctrlcmd(caifd->layer.up,
421 					 _CAIF_CTRLCMD_PHYIF_DOWN_IND,
422 					 caifd->layer.id);
423 
424 		spin_lock_bh(&caifd->flow_lock);
425 
426 		/*
427 		 * Replace our xoff-destructor with original destructor.
428 		 * We trust that skb->destructor *always* is called before
429 		 * the skb reference is invalid. The hijacked SKB destructor
430 		 * takes the flow_lock so manipulating the skb->destructor here
431 		 * should be safe.
432 		*/
433 		if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
434 			caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
435 
436 		caifd->xoff = 0;
437 		caifd->xoff_skb_dtor = NULL;
438 		caifd->xoff_skb = NULL;
439 
440 		spin_unlock_bh(&caifd->flow_lock);
441 		caifd_put(caifd);
442 		break;
443 
444 	case NETDEV_UNREGISTER:
445 		mutex_lock(&caifdevs->lock);
446 
447 		caifd = caif_get(dev);
448 		if (caifd == NULL) {
449 			mutex_unlock(&caifdevs->lock);
450 			break;
451 		}
452 		list_del_rcu(&caifd->list);
453 
454 		/*
455 		 * NETDEV_UNREGISTER is called repeatedly until all reference
456 		 * counts for the net-device are released. If references to
457 		 * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
458 		 * the next call to NETDEV_UNREGISTER.
459 		 *
460 		 * If any packets are in flight down the CAIF Stack,
461 		 * cfcnfg_del_phy_layer will return nonzero.
462 		 * If no packets are in flight, the CAIF Stack associated
463 		 * with the net-device un-registering is freed.
464 		 */
465 
466 		if (caifd_refcnt_read(caifd) != 0 ||
467 			cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
468 
469 			pr_info("Wait for device inuse\n");
470 			/* Enrole device if CAIF Stack is still in use */
471 			list_add_rcu(&caifd->list, &caifdevs->list);
472 			mutex_unlock(&caifdevs->lock);
473 			break;
474 		}
475 
476 		synchronize_rcu();
477 		dev_put(caifd->netdev);
478 		free_percpu(caifd->pcpu_refcnt);
479 		kfree(caifd);
480 
481 		mutex_unlock(&caifdevs->lock);
482 		break;
483 	}
484 	return 0;
485 }
486 
487 static struct notifier_block caif_device_notifier = {
488 	.notifier_call = caif_device_notify,
489 	.priority = 0,
490 };
491 
492 /* Per-namespace Caif devices handling */
493 static int caif_init_net(struct net *net)
494 {
495 	struct caif_net *caifn = net_generic(net, caif_net_id);
496 	INIT_LIST_HEAD(&caifn->caifdevs.list);
497 	mutex_init(&caifn->caifdevs.lock);
498 
499 	caifn->cfg = cfcnfg_create();
500 	if (!caifn->cfg)
501 		return -ENOMEM;
502 
503 	return 0;
504 }
505 
506 static void caif_exit_net(struct net *net)
507 {
508 	struct caif_device_entry *caifd, *tmp;
509 	struct caif_device_entry_list *caifdevs =
510 	    caif_device_list(net);
511 	struct cfcnfg *cfg =  get_cfcnfg(net);
512 
513 	rtnl_lock();
514 	mutex_lock(&caifdevs->lock);
515 
516 	list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
517 		int i = 0;
518 		list_del_rcu(&caifd->list);
519 		cfcnfg_set_phy_state(cfg, &caifd->layer, false);
520 
521 		while (i < 10 &&
522 			(caifd_refcnt_read(caifd) != 0 ||
523 			cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
524 
525 			pr_info("Wait for device inuse\n");
526 			msleep(250);
527 			i++;
528 		}
529 		synchronize_rcu();
530 		dev_put(caifd->netdev);
531 		free_percpu(caifd->pcpu_refcnt);
532 		kfree(caifd);
533 	}
534 	cfcnfg_remove(cfg);
535 
536 	mutex_unlock(&caifdevs->lock);
537 	rtnl_unlock();
538 }
539 
540 static struct pernet_operations caif_net_ops = {
541 	.init = caif_init_net,
542 	.exit = caif_exit_net,
543 	.id   = &caif_net_id,
544 	.size = sizeof(struct caif_net),
545 };
546 
547 /* Initialize Caif devices list */
548 static int __init caif_device_init(void)
549 {
550 	int result;
551 
552 	result = register_pernet_subsys(&caif_net_ops);
553 
554 	if (result)
555 		return result;
556 
557 	register_netdevice_notifier(&caif_device_notifier);
558 	dev_add_pack(&caif_packet_type);
559 
560 	return result;
561 }
562 
563 static void __exit caif_device_exit(void)
564 {
565 	unregister_pernet_subsys(&caif_net_ops);
566 	unregister_netdevice_notifier(&caif_device_notifier);
567 	dev_remove_pack(&caif_packet_type);
568 }
569 
570 module_init(caif_device_init);
571 module_exit(caif_device_exit);
572