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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 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->tx_queue_len == 0))
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         strncpy(caifd->layer.name, dev->name,
338                 sizeof(caifd->layer.name) - 1);
339         caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
340         caifd->layer.transmit = transmit;
341         cfcnfg_add_phy_layer(cfg,
342                                 dev,
343                                 &caifd->layer,
344                                 pref,
345                                 link_support,
346                                 caifdev->use_fcs,
347                                 head_room);
348         mutex_unlock(&caifdevs->lock);
349         if (rcv_func)
350                 *rcv_func = receive;
351 }
352 EXPORT_SYMBOL(caif_enroll_dev);
353 
354 /* notify Caif of device events */
355 static int caif_device_notify(struct notifier_block *me, unsigned long what,
356                               void *ptr)
357 {
358         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
359         struct caif_device_entry *caifd = NULL;
360         struct caif_dev_common *caifdev;
361         struct cfcnfg *cfg;
362         struct cflayer *layer, *link_support;
363         int head_room = 0;
364         struct caif_device_entry_list *caifdevs;
365 
366         cfg = get_cfcnfg(dev_net(dev));
367         caifdevs = caif_device_list(dev_net(dev));
368 
369         caifd = caif_get(dev);
370         if (caifd == NULL && dev->type != ARPHRD_CAIF)
371                 return 0;
372 
373         switch (what) {
374         case NETDEV_REGISTER:
375                 if (caifd != NULL)
376                         break;
377 
378                 caifdev = netdev_priv(dev);
379 
380                 link_support = NULL;
381                 if (caifdev->use_frag) {
382                         head_room = 1;
383                         link_support = cfserl_create(dev->ifindex,
384                                                         caifdev->use_stx);
385                         if (!link_support) {
386                                 pr_warn("Out of memory\n");
387                                 break;
388                         }
389                 }
390                 caif_enroll_dev(dev, caifdev, link_support, head_room,
391                                 &layer, NULL);
392                 caifdev->flowctrl = dev_flowctrl;
393                 break;
394 
395         case NETDEV_UP:
396                 rcu_read_lock();
397 
398                 caifd = caif_get(dev);
399                 if (caifd == NULL) {
400                         rcu_read_unlock();
401                         break;
402                 }
403 
404                 caifd->xoff = 0;
405                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
406                 rcu_read_unlock();
407 
408                 break;
409 
410         case NETDEV_DOWN:
411                 rcu_read_lock();
412 
413                 caifd = caif_get(dev);
414                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
415                         rcu_read_unlock();
416                         return -EINVAL;
417                 }
418 
419                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
420                 caifd_hold(caifd);
421                 rcu_read_unlock();
422 
423                 caifd->layer.up->ctrlcmd(caifd->layer.up,
424                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
425                                          caifd->layer.id);
426 
427                 spin_lock_bh(&caifd->flow_lock);
428 
429                 /*
430                  * Replace our xoff-destructor with original destructor.
431                  * We trust that skb->destructor *always* is called before
432                  * the skb reference is invalid. The hijacked SKB destructor
433                  * takes the flow_lock so manipulating the skb->destructor here
434                  * should be safe.
435                 */
436                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
437                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
438 
439                 caifd->xoff = 0;
440                 caifd->xoff_skb_dtor = NULL;
441                 caifd->xoff_skb = NULL;
442 
443                 spin_unlock_bh(&caifd->flow_lock);
444                 caifd_put(caifd);
445                 break;
446 
447         case NETDEV_UNREGISTER:
448                 mutex_lock(&caifdevs->lock);
449 
450                 caifd = caif_get(dev);
451                 if (caifd == NULL) {
452                         mutex_unlock(&caifdevs->lock);
453                         break;
454                 }
455                 list_del_rcu(&caifd->list);
456 
457                 /*
458                  * NETDEV_UNREGISTER is called repeatedly until all reference
459                  * counts for the net-device are released. If references to
460                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
461                  * the next call to NETDEV_UNREGISTER.
462                  *
463                  * If any packets are in flight down the CAIF Stack,
464                  * cfcnfg_del_phy_layer will return nonzero.
465                  * If no packets are in flight, the CAIF Stack associated
466                  * with the net-device un-registering is freed.
467                  */
468 
469                 if (caifd_refcnt_read(caifd) != 0 ||
470                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
471 
472                         pr_info("Wait for device inuse\n");
473                         /* Enrole device if CAIF Stack is still in use */
474                         list_add_rcu(&caifd->list, &caifdevs->list);
475                         mutex_unlock(&caifdevs->lock);
476                         break;
477                 }
478 
479                 synchronize_rcu();
480                 dev_put(caifd->netdev);
481                 free_percpu(caifd->pcpu_refcnt);
482                 kfree(caifd);
483 
484                 mutex_unlock(&caifdevs->lock);
485                 break;
486         }
487         return 0;
488 }
489 
490 static struct notifier_block caif_device_notifier = {
491         .notifier_call = caif_device_notify,
492         .priority = 0,
493 };
494 
495 /* Per-namespace Caif devices handling */
496 static int caif_init_net(struct net *net)
497 {
498         struct caif_net *caifn = net_generic(net, caif_net_id);
499         INIT_LIST_HEAD(&caifn->caifdevs.list);
500         mutex_init(&caifn->caifdevs.lock);
501 
502         caifn->cfg = cfcnfg_create();
503         if (!caifn->cfg)
504                 return -ENOMEM;
505 
506         return 0;
507 }
508 
509 static void caif_exit_net(struct net *net)
510 {
511         struct caif_device_entry *caifd, *tmp;
512         struct caif_device_entry_list *caifdevs =
513             caif_device_list(net);
514         struct cfcnfg *cfg =  get_cfcnfg(net);
515 
516         rtnl_lock();
517         mutex_lock(&caifdevs->lock);
518 
519         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
520                 int i = 0;
521                 list_del_rcu(&caifd->list);
522                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
523 
524                 while (i < 10 &&
525                         (caifd_refcnt_read(caifd) != 0 ||
526                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
527 
528                         pr_info("Wait for device inuse\n");
529                         msleep(250);
530                         i++;
531                 }
532                 synchronize_rcu();
533                 dev_put(caifd->netdev);
534                 free_percpu(caifd->pcpu_refcnt);
535                 kfree(caifd);
536         }
537         cfcnfg_remove(cfg);
538 
539         mutex_unlock(&caifdevs->lock);
540         rtnl_unlock();
541 }
542 
543 static struct pernet_operations caif_net_ops = {
544         .init = caif_init_net,
545         .exit = caif_exit_net,
546         .id   = &caif_net_id,
547         .size = sizeof(struct caif_net),
548 };
549 
550 /* Initialize Caif devices list */
551 static int __init caif_device_init(void)
552 {
553         int result;
554 
555         result = register_pernet_subsys(&caif_net_ops);
556 
557         if (result)
558                 return result;
559 
560         register_netdevice_notifier(&caif_device_notifier);
561         dev_add_pack(&caif_packet_type);
562 
563         return result;
564 }
565 
566 static void __exit caif_device_exit(void)
567 {
568         unregister_netdevice_notifier(&caif_device_notifier);
569         dev_remove_pack(&caif_packet_type);
570         unregister_pernet_subsys(&caif_net_ops);
571 }
572 
573 module_init(caif_device_init);
574 module_exit(caif_device_exit);
575 

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