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Linux/net/caif/caif_dev.c

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  1 /*
  2  * CAIF Interface registration.
  3  * Copyright (C) ST-Ericsson AB 2010
  4  * Author:      Sjur Brendeland
  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/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                 if (caifd->netdev == dev)
117                         return caifd;
118         }
119         return NULL;
120 }
121 
122 static void caif_flow_cb(struct sk_buff *skb)
123 {
124         struct caif_device_entry *caifd;
125         void (*dtor)(struct sk_buff *skb) = NULL;
126         bool send_xoff;
127 
128         WARN_ON(skb->dev == NULL);
129 
130         rcu_read_lock();
131         caifd = caif_get(skb->dev);
132 
133         WARN_ON(caifd == NULL);
134         if (caifd == NULL)
135                 return;
136 
137         caifd_hold(caifd);
138         rcu_read_unlock();
139 
140         spin_lock_bh(&caifd->flow_lock);
141         send_xoff = caifd->xoff;
142         caifd->xoff = 0;
143         dtor = caifd->xoff_skb_dtor;
144 
145         if (WARN_ON(caifd->xoff_skb != skb))
146                 skb = NULL;
147 
148         caifd->xoff_skb = NULL;
149         caifd->xoff_skb_dtor = NULL;
150 
151         spin_unlock_bh(&caifd->flow_lock);
152 
153         if (dtor && skb)
154                 dtor(skb);
155 
156         if (send_xoff)
157                 caifd->layer.up->
158                         ctrlcmd(caifd->layer.up,
159                                 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
160                                 caifd->layer.id);
161         caifd_put(caifd);
162 }
163 
164 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
165 {
166         int err, high = 0, qlen = 0;
167         struct caif_device_entry *caifd =
168             container_of(layer, struct caif_device_entry, layer);
169         struct sk_buff *skb;
170         struct netdev_queue *txq;
171 
172         rcu_read_lock_bh();
173 
174         skb = cfpkt_tonative(pkt);
175         skb->dev = caifd->netdev;
176         skb_reset_network_header(skb);
177         skb->protocol = htons(ETH_P_CAIF);
178 
179         /* Check if we need to handle xoff */
180         if (likely(caifd->netdev->priv_flags & IFF_NO_QUEUE))
181                 goto noxoff;
182 
183         if (unlikely(caifd->xoff))
184                 goto noxoff;
185 
186         if (likely(!netif_queue_stopped(caifd->netdev))) {
187                 /* If we run with a TX queue, check if the queue is too long*/
188                 txq = netdev_get_tx_queue(skb->dev, 0);
189                 qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
190 
191                 if (likely(qlen == 0))
192                         goto noxoff;
193 
194                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
195                 if (likely(qlen < high))
196                         goto noxoff;
197         }
198 
199         /* Hold lock while accessing xoff */
200         spin_lock_bh(&caifd->flow_lock);
201         if (caifd->xoff) {
202                 spin_unlock_bh(&caifd->flow_lock);
203                 goto noxoff;
204         }
205 
206         /*
207          * Handle flow off, we do this by temporary hi-jacking this
208          * skb's destructor function, and replace it with our own
209          * flow-on callback. The callback will set flow-on and call
210          * the original destructor.
211          */
212 
213         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
214                         netif_queue_stopped(caifd->netdev),
215                         qlen, high);
216         caifd->xoff = 1;
217         caifd->xoff_skb = skb;
218         caifd->xoff_skb_dtor = skb->destructor;
219         skb->destructor = caif_flow_cb;
220         spin_unlock_bh(&caifd->flow_lock);
221 
222         caifd->layer.up->ctrlcmd(caifd->layer.up,
223                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
224                                         caifd->layer.id);
225 noxoff:
226         rcu_read_unlock_bh();
227 
228         err = dev_queue_xmit(skb);
229         if (err > 0)
230                 err = -EIO;
231 
232         return err;
233 }
234 
235 /*
236  * Stuff received packets into the CAIF stack.
237  * On error, returns non-zero and releases the skb.
238  */
239 static int receive(struct sk_buff *skb, struct net_device *dev,
240                    struct packet_type *pkttype, struct net_device *orig_dev)
241 {
242         struct cfpkt *pkt;
243         struct caif_device_entry *caifd;
244         int err;
245 
246         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
247 
248         rcu_read_lock();
249         caifd = caif_get(dev);
250 
251         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
252                         !netif_oper_up(caifd->netdev)) {
253                 rcu_read_unlock();
254                 kfree_skb(skb);
255                 return NET_RX_DROP;
256         }
257 
258         /* Hold reference to netdevice while using CAIF stack */
259         caifd_hold(caifd);
260         rcu_read_unlock();
261 
262         err = caifd->layer.up->receive(caifd->layer.up, pkt);
263 
264         /* For -EILSEQ the packet is not freed so so it now */
265         if (err == -EILSEQ)
266                 cfpkt_destroy(pkt);
267 
268         /* Release reference to stack upwards */
269         caifd_put(caifd);
270 
271         if (err != 0)
272                 err = NET_RX_DROP;
273         return err;
274 }
275 
276 static struct packet_type caif_packet_type __read_mostly = {
277         .type = cpu_to_be16(ETH_P_CAIF),
278         .func = receive,
279 };
280 
281 static void dev_flowctrl(struct net_device *dev, int on)
282 {
283         struct caif_device_entry *caifd;
284 
285         rcu_read_lock();
286 
287         caifd = caif_get(dev);
288         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
289                 rcu_read_unlock();
290                 return;
291         }
292 
293         caifd_hold(caifd);
294         rcu_read_unlock();
295 
296         caifd->layer.up->ctrlcmd(caifd->layer.up,
297                                  on ?
298                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
299                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
300                                  caifd->layer.id);
301         caifd_put(caifd);
302 }
303 
304 void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
305                      struct cflayer *link_support, int head_room,
306                      struct cflayer **layer,
307                      int (**rcv_func)(struct sk_buff *, struct net_device *,
308                                       struct packet_type *,
309                                       struct net_device *))
310 {
311         struct caif_device_entry *caifd;
312         enum cfcnfg_phy_preference pref;
313         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
314         struct caif_device_entry_list *caifdevs;
315 
316         caifdevs = caif_device_list(dev_net(dev));
317         caifd = caif_device_alloc(dev);
318         if (!caifd)
319                 return;
320         *layer = &caifd->layer;
321         spin_lock_init(&caifd->flow_lock);
322 
323         switch (caifdev->link_select) {
324         case CAIF_LINK_HIGH_BANDW:
325                 pref = CFPHYPREF_HIGH_BW;
326                 break;
327         case CAIF_LINK_LOW_LATENCY:
328                 pref = CFPHYPREF_LOW_LAT;
329                 break;
330         default:
331                 pref = CFPHYPREF_HIGH_BW;
332                 break;
333         }
334         mutex_lock(&caifdevs->lock);
335         list_add_rcu(&caifd->list, &caifdevs->list);
336 
337         strlcpy(caifd->layer.name, dev->name,
338                 sizeof(caifd->layer.name));
339         caifd->layer.transmit = transmit;
340         cfcnfg_add_phy_layer(cfg,
341                                 dev,
342                                 &caifd->layer,
343                                 pref,
344                                 link_support,
345                                 caifdev->use_fcs,
346                                 head_room);
347         mutex_unlock(&caifdevs->lock);
348         if (rcv_func)
349                 *rcv_func = receive;
350 }
351 EXPORT_SYMBOL(caif_enroll_dev);
352 
353 /* notify Caif of device events */
354 static int caif_device_notify(struct notifier_block *me, unsigned long what,
355                               void *ptr)
356 {
357         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
358         struct caif_device_entry *caifd = NULL;
359         struct caif_dev_common *caifdev;
360         struct cfcnfg *cfg;
361         struct cflayer *layer, *link_support;
362         int head_room = 0;
363         struct caif_device_entry_list *caifdevs;
364 
365         cfg = get_cfcnfg(dev_net(dev));
366         caifdevs = caif_device_list(dev_net(dev));
367 
368         caifd = caif_get(dev);
369         if (caifd == NULL && dev->type != ARPHRD_CAIF)
370                 return 0;
371 
372         switch (what) {
373         case NETDEV_REGISTER:
374                 if (caifd != NULL)
375                         break;
376 
377                 caifdev = netdev_priv(dev);
378 
379                 link_support = NULL;
380                 if (caifdev->use_frag) {
381                         head_room = 1;
382                         link_support = cfserl_create(dev->ifindex,
383                                                         caifdev->use_stx);
384                         if (!link_support) {
385                                 pr_warn("Out of memory\n");
386                                 break;
387                         }
388                 }
389                 caif_enroll_dev(dev, caifdev, link_support, head_room,
390                                 &layer, NULL);
391                 caifdev->flowctrl = dev_flowctrl;
392                 break;
393 
394         case NETDEV_UP:
395                 rcu_read_lock();
396 
397                 caifd = caif_get(dev);
398                 if (caifd == NULL) {
399                         rcu_read_unlock();
400                         break;
401                 }
402 
403                 caifd->xoff = 0;
404                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
405                 rcu_read_unlock();
406 
407                 break;
408 
409         case NETDEV_DOWN:
410                 rcu_read_lock();
411 
412                 caifd = caif_get(dev);
413                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
414                         rcu_read_unlock();
415                         return -EINVAL;
416                 }
417 
418                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
419                 caifd_hold(caifd);
420                 rcu_read_unlock();
421 
422                 caifd->layer.up->ctrlcmd(caifd->layer.up,
423                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
424                                          caifd->layer.id);
425 
426                 spin_lock_bh(&caifd->flow_lock);
427 
428                 /*
429                  * Replace our xoff-destructor with original destructor.
430                  * We trust that skb->destructor *always* is called before
431                  * the skb reference is invalid. The hijacked SKB destructor
432                  * takes the flow_lock so manipulating the skb->destructor here
433                  * should be safe.
434                 */
435                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
436                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
437 
438                 caifd->xoff = 0;
439                 caifd->xoff_skb_dtor = NULL;
440                 caifd->xoff_skb = NULL;
441 
442                 spin_unlock_bh(&caifd->flow_lock);
443                 caifd_put(caifd);
444                 break;
445 
446         case NETDEV_UNREGISTER:
447                 mutex_lock(&caifdevs->lock);
448 
449                 caifd = caif_get(dev);
450                 if (caifd == NULL) {
451                         mutex_unlock(&caifdevs->lock);
452                         break;
453                 }
454                 list_del_rcu(&caifd->list);
455 
456                 /*
457                  * NETDEV_UNREGISTER is called repeatedly until all reference
458                  * counts for the net-device are released. If references to
459                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
460                  * the next call to NETDEV_UNREGISTER.
461                  *
462                  * If any packets are in flight down the CAIF Stack,
463                  * cfcnfg_del_phy_layer will return nonzero.
464                  * If no packets are in flight, the CAIF Stack associated
465                  * with the net-device un-registering is freed.
466                  */
467 
468                 if (caifd_refcnt_read(caifd) != 0 ||
469                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
470 
471                         pr_info("Wait for device inuse\n");
472                         /* Enrole device if CAIF Stack is still in use */
473                         list_add_rcu(&caifd->list, &caifdevs->list);
474                         mutex_unlock(&caifdevs->lock);
475                         break;
476                 }
477 
478                 synchronize_rcu();
479                 dev_put(caifd->netdev);
480                 free_percpu(caifd->pcpu_refcnt);
481                 kfree(caifd);
482 
483                 mutex_unlock(&caifdevs->lock);
484                 break;
485         }
486         return 0;
487 }
488 
489 static struct notifier_block caif_device_notifier = {
490         .notifier_call = caif_device_notify,
491         .priority = 0,
492 };
493 
494 /* Per-namespace Caif devices handling */
495 static int caif_init_net(struct net *net)
496 {
497         struct caif_net *caifn = net_generic(net, caif_net_id);
498         INIT_LIST_HEAD(&caifn->caifdevs.list);
499         mutex_init(&caifn->caifdevs.lock);
500 
501         caifn->cfg = cfcnfg_create();
502         if (!caifn->cfg)
503                 return -ENOMEM;
504 
505         return 0;
506 }
507 
508 static void caif_exit_net(struct net *net)
509 {
510         struct caif_device_entry *caifd, *tmp;
511         struct caif_device_entry_list *caifdevs =
512             caif_device_list(net);
513         struct cfcnfg *cfg =  get_cfcnfg(net);
514 
515         rtnl_lock();
516         mutex_lock(&caifdevs->lock);
517 
518         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
519                 int i = 0;
520                 list_del_rcu(&caifd->list);
521                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
522 
523                 while (i < 10 &&
524                         (caifd_refcnt_read(caifd) != 0 ||
525                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
526 
527                         pr_info("Wait for device inuse\n");
528                         msleep(250);
529                         i++;
530                 }
531                 synchronize_rcu();
532                 dev_put(caifd->netdev);
533                 free_percpu(caifd->pcpu_refcnt);
534                 kfree(caifd);
535         }
536         cfcnfg_remove(cfg);
537 
538         mutex_unlock(&caifdevs->lock);
539         rtnl_unlock();
540 }
541 
542 static struct pernet_operations caif_net_ops = {
543         .init = caif_init_net,
544         .exit = caif_exit_net,
545         .id   = &caif_net_id,
546         .size = sizeof(struct caif_net),
547 };
548 
549 /* Initialize Caif devices list */
550 static int __init caif_device_init(void)
551 {
552         int result;
553 
554         result = register_pernet_subsys(&caif_net_ops);
555 
556         if (result)
557                 return result;
558 
559         register_netdevice_notifier(&caif_device_notifier);
560         dev_add_pack(&caif_packet_type);
561 
562         return result;
563 }
564 
565 static void __exit caif_device_exit(void)
566 {
567         unregister_netdevice_notifier(&caif_device_notifier);
568         dev_remove_pack(&caif_packet_type);
569         unregister_pernet_subsys(&caif_net_ops);
570 }
571 
572 module_init(caif_device_init);
573 module_exit(caif_device_exit);
574 

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