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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/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,
306                      int (**rcv_func)(struct sk_buff *, struct net_device *,
307                                       struct packet_type *,
308                                       struct net_device *))
309 {
310         struct caif_device_entry *caifd;
311         enum cfcnfg_phy_preference pref;
312         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
313         struct caif_device_entry_list *caifdevs;
314 
315         caifdevs = caif_device_list(dev_net(dev));
316         caifd = caif_device_alloc(dev);
317         if (!caifd)
318                 return;
319         *layer = &caifd->layer;
320         spin_lock_init(&caifd->flow_lock);
321 
322         switch (caifdev->link_select) {
323         case CAIF_LINK_HIGH_BANDW:
324                 pref = CFPHYPREF_HIGH_BW;
325                 break;
326         case CAIF_LINK_LOW_LATENCY:
327                 pref = CFPHYPREF_LOW_LAT;
328                 break;
329         default:
330                 pref = CFPHYPREF_HIGH_BW;
331                 break;
332         }
333         mutex_lock(&caifdevs->lock);
334         list_add_rcu(&caifd->list, &caifdevs->list);
335 
336         strncpy(caifd->layer.name, dev->name,
337                 sizeof(caifd->layer.name) - 1);
338         caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
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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