Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
[linux-3.10.git] / net / caif / caif_dev.c
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 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);