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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) {
135                 rcu_read_unlock();
136                 return;
137         }
138 
139         caifd_hold(caifd);
140         rcu_read_unlock();
141 
142         spin_lock_bh(&caifd->flow_lock);
143         send_xoff = caifd->xoff;
144         caifd->xoff = 0;
145         dtor = caifd->xoff_skb_dtor;
146 
147         if (WARN_ON(caifd->xoff_skb != skb))
148                 skb = NULL;
149 
150         caifd->xoff_skb = NULL;
151         caifd->xoff_skb_dtor = NULL;
152 
153         spin_unlock_bh(&caifd->flow_lock);
154 
155         if (dtor && skb)
156                 dtor(skb);
157 
158         if (send_xoff)
159                 caifd->layer.up->
160                         ctrlcmd(caifd->layer.up,
161                                 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
162                                 caifd->layer.id);
163         caifd_put(caifd);
164 }
165 
166 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
167 {
168         int err, high = 0, qlen = 0;
169         struct caif_device_entry *caifd =
170             container_of(layer, struct caif_device_entry, layer);
171         struct sk_buff *skb;
172         struct netdev_queue *txq;
173 
174         rcu_read_lock_bh();
175 
176         skb = cfpkt_tonative(pkt);
177         skb->dev = caifd->netdev;
178         skb_reset_network_header(skb);
179         skb->protocol = htons(ETH_P_CAIF);
180 
181         /* Check if we need to handle xoff */
182         if (likely(caifd->netdev->priv_flags & IFF_NO_QUEUE))
183                 goto noxoff;
184 
185         if (unlikely(caifd->xoff))
186                 goto noxoff;
187 
188         if (likely(!netif_queue_stopped(caifd->netdev))) {
189                 /* If we run with a TX queue, check if the queue is too long*/
190                 txq = netdev_get_tx_queue(skb->dev, 0);
191                 qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
192 
193                 if (likely(qlen == 0))
194                         goto noxoff;
195 
196                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
197                 if (likely(qlen < high))
198                         goto noxoff;
199         }
200 
201         /* Hold lock while accessing xoff */
202         spin_lock_bh(&caifd->flow_lock);
203         if (caifd->xoff) {
204                 spin_unlock_bh(&caifd->flow_lock);
205                 goto noxoff;
206         }
207 
208         /*
209          * Handle flow off, we do this by temporary hi-jacking this
210          * skb's destructor function, and replace it with our own
211          * flow-on callback. The callback will set flow-on and call
212          * the original destructor.
213          */
214 
215         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
216                         netif_queue_stopped(caifd->netdev),
217                         qlen, high);
218         caifd->xoff = 1;
219         caifd->xoff_skb = skb;
220         caifd->xoff_skb_dtor = skb->destructor;
221         skb->destructor = caif_flow_cb;
222         spin_unlock_bh(&caifd->flow_lock);
223 
224         caifd->layer.up->ctrlcmd(caifd->layer.up,
225                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
226                                         caifd->layer.id);
227 noxoff:
228         rcu_read_unlock_bh();
229 
230         err = dev_queue_xmit(skb);
231         if (err > 0)
232                 err = -EIO;
233 
234         return err;
235 }
236 
237 /*
238  * Stuff received packets into the CAIF stack.
239  * On error, returns non-zero and releases the skb.
240  */
241 static int receive(struct sk_buff *skb, struct net_device *dev,
242                    struct packet_type *pkttype, struct net_device *orig_dev)
243 {
244         struct cfpkt *pkt;
245         struct caif_device_entry *caifd;
246         int err;
247 
248         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
249 
250         rcu_read_lock();
251         caifd = caif_get(dev);
252 
253         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
254                         !netif_oper_up(caifd->netdev)) {
255                 rcu_read_unlock();
256                 kfree_skb(skb);
257                 return NET_RX_DROP;
258         }
259 
260         /* Hold reference to netdevice while using CAIF stack */
261         caifd_hold(caifd);
262         rcu_read_unlock();
263 
264         err = caifd->layer.up->receive(caifd->layer.up, pkt);
265 
266         /* For -EILSEQ the packet is not freed so so it now */
267         if (err == -EILSEQ)
268                 cfpkt_destroy(pkt);
269 
270         /* Release reference to stack upwards */
271         caifd_put(caifd);
272 
273         if (err != 0)
274                 err = NET_RX_DROP;
275         return err;
276 }
277 
278 static struct packet_type caif_packet_type __read_mostly = {
279         .type = cpu_to_be16(ETH_P_CAIF),
280         .func = receive,
281 };
282 
283 static void dev_flowctrl(struct net_device *dev, int on)
284 {
285         struct caif_device_entry *caifd;
286 
287         rcu_read_lock();
288 
289         caifd = caif_get(dev);
290         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
291                 rcu_read_unlock();
292                 return;
293         }
294 
295         caifd_hold(caifd);
296         rcu_read_unlock();
297 
298         caifd->layer.up->ctrlcmd(caifd->layer.up,
299                                  on ?
300                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
301                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
302                                  caifd->layer.id);
303         caifd_put(caifd);
304 }
305 
306 void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
307                      struct cflayer *link_support, int head_room,
308                      struct cflayer **layer,
309                      int (**rcv_func)(struct sk_buff *, struct net_device *,
310                                       struct packet_type *,
311                                       struct net_device *))
312 {
313         struct caif_device_entry *caifd;
314         enum cfcnfg_phy_preference pref;
315         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
316         struct caif_device_entry_list *caifdevs;
317 
318         caifdevs = caif_device_list(dev_net(dev));
319         caifd = caif_device_alloc(dev);
320         if (!caifd)
321                 return;
322         *layer = &caifd->layer;
323         spin_lock_init(&caifd->flow_lock);
324 
325         switch (caifdev->link_select) {
326         case CAIF_LINK_HIGH_BANDW:
327                 pref = CFPHYPREF_HIGH_BW;
328                 break;
329         case CAIF_LINK_LOW_LATENCY:
330                 pref = CFPHYPREF_LOW_LAT;
331                 break;
332         default:
333                 pref = CFPHYPREF_HIGH_BW;
334                 break;
335         }
336         mutex_lock(&caifdevs->lock);
337         list_add_rcu(&caifd->list, &caifdevs->list);
338 
339         strlcpy(caifd->layer.name, dev->name,
340                 sizeof(caifd->layer.name));
341         caifd->layer.transmit = transmit;
342         cfcnfg_add_phy_layer(cfg,
343                                 dev,
344                                 &caifd->layer,
345                                 pref,
346                                 link_support,
347                                 caifdev->use_fcs,
348                                 head_room);
349         mutex_unlock(&caifdevs->lock);
350         if (rcv_func)
351                 *rcv_func = receive;
352 }
353 EXPORT_SYMBOL(caif_enroll_dev);
354 
355 /* notify Caif of device events */
356 static int caif_device_notify(struct notifier_block *me, unsigned long what,
357                               void *ptr)
358 {
359         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
360         struct caif_device_entry *caifd = NULL;
361         struct caif_dev_common *caifdev;
362         struct cfcnfg *cfg;
363         struct cflayer *layer, *link_support;
364         int head_room = 0;
365         struct caif_device_entry_list *caifdevs;
366 
367         cfg = get_cfcnfg(dev_net(dev));
368         caifdevs = caif_device_list(dev_net(dev));
369 
370         caifd = caif_get(dev);
371         if (caifd == NULL && dev->type != ARPHRD_CAIF)
372                 return 0;
373 
374         switch (what) {
375         case NETDEV_REGISTER:
376                 if (caifd != NULL)
377                         break;
378 
379                 caifdev = netdev_priv(dev);
380 
381                 link_support = NULL;
382                 if (caifdev->use_frag) {
383                         head_room = 1;
384                         link_support = cfserl_create(dev->ifindex,
385                                                         caifdev->use_stx);
386                         if (!link_support) {
387                                 pr_warn("Out of memory\n");
388                                 break;
389                         }
390                 }
391                 caif_enroll_dev(dev, caifdev, link_support, head_room,
392                                 &layer, NULL);
393                 caifdev->flowctrl = dev_flowctrl;
394                 break;
395 
396         case NETDEV_UP:
397                 rcu_read_lock();
398 
399                 caifd = caif_get(dev);
400                 if (caifd == NULL) {
401                         rcu_read_unlock();
402                         break;
403                 }
404 
405                 caifd->xoff = 0;
406                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
407                 rcu_read_unlock();
408 
409                 break;
410 
411         case NETDEV_DOWN:
412                 rcu_read_lock();
413 
414                 caifd = caif_get(dev);
415                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
416                         rcu_read_unlock();
417                         return -EINVAL;
418                 }
419 
420                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
421                 caifd_hold(caifd);
422                 rcu_read_unlock();
423 
424                 caifd->layer.up->ctrlcmd(caifd->layer.up,
425                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
426                                          caifd->layer.id);
427 
428                 spin_lock_bh(&caifd->flow_lock);
429 
430                 /*
431                  * Replace our xoff-destructor with original destructor.
432                  * We trust that skb->destructor *always* is called before
433                  * the skb reference is invalid. The hijacked SKB destructor
434                  * takes the flow_lock so manipulating the skb->destructor here
435                  * should be safe.
436                 */
437                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
438                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
439 
440                 caifd->xoff = 0;
441                 caifd->xoff_skb_dtor = NULL;
442                 caifd->xoff_skb = NULL;
443 
444                 spin_unlock_bh(&caifd->flow_lock);
445                 caifd_put(caifd);
446                 break;
447 
448         case NETDEV_UNREGISTER:
449                 mutex_lock(&caifdevs->lock);
450 
451                 caifd = caif_get(dev);
452                 if (caifd == NULL) {
453                         mutex_unlock(&caifdevs->lock);
454                         break;
455                 }
456                 list_del_rcu(&caifd->list);
457 
458                 /*
459                  * NETDEV_UNREGISTER is called repeatedly until all reference
460                  * counts for the net-device are released. If references to
461                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
462                  * the next call to NETDEV_UNREGISTER.
463                  *
464                  * If any packets are in flight down the CAIF Stack,
465                  * cfcnfg_del_phy_layer will return nonzero.
466                  * If no packets are in flight, the CAIF Stack associated
467                  * with the net-device un-registering is freed.
468                  */
469 
470                 if (caifd_refcnt_read(caifd) != 0 ||
471                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
472 
473                         pr_info("Wait for device inuse\n");
474                         /* Enrole device if CAIF Stack is still in use */
475                         list_add_rcu(&caifd->list, &caifdevs->list);
476                         mutex_unlock(&caifdevs->lock);
477                         break;
478                 }
479 
480                 synchronize_rcu();
481                 dev_put(caifd->netdev);
482                 free_percpu(caifd->pcpu_refcnt);
483                 kfree(caifd);
484 
485                 mutex_unlock(&caifdevs->lock);
486                 break;
487         }
488         return 0;
489 }
490 
491 static struct notifier_block caif_device_notifier = {
492         .notifier_call = caif_device_notify,
493         .priority = 0,
494 };
495 
496 /* Per-namespace Caif devices handling */
497 static int caif_init_net(struct net *net)
498 {
499         struct caif_net *caifn = net_generic(net, caif_net_id);
500         INIT_LIST_HEAD(&caifn->caifdevs.list);
501         mutex_init(&caifn->caifdevs.lock);
502 
503         caifn->cfg = cfcnfg_create();
504         if (!caifn->cfg)
505                 return -ENOMEM;
506 
507         return 0;
508 }
509 
510 static void caif_exit_net(struct net *net)
511 {
512         struct caif_device_entry *caifd, *tmp;
513         struct caif_device_entry_list *caifdevs =
514             caif_device_list(net);
515         struct cfcnfg *cfg =  get_cfcnfg(net);
516 
517         rtnl_lock();
518         mutex_lock(&caifdevs->lock);
519 
520         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
521                 int i = 0;
522                 list_del_rcu(&caifd->list);
523                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
524 
525                 while (i < 10 &&
526                         (caifd_refcnt_read(caifd) != 0 ||
527                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
528 
529                         pr_info("Wait for device inuse\n");
530                         msleep(250);
531                         i++;
532                 }
533                 synchronize_rcu();
534                 dev_put(caifd->netdev);
535                 free_percpu(caifd->pcpu_refcnt);
536                 kfree(caifd);
537         }
538         cfcnfg_remove(cfg);
539 
540         mutex_unlock(&caifdevs->lock);
541         rtnl_unlock();
542 }
543 
544 static struct pernet_operations caif_net_ops = {
545         .init = caif_init_net,
546         .exit = caif_exit_net,
547         .id   = &caif_net_id,
548         .size = sizeof(struct caif_net),
549 };
550 
551 /* Initialize Caif devices list */
552 static int __init caif_device_init(void)
553 {
554         int result;
555 
556         result = register_pernet_subsys(&caif_net_ops);
557 
558         if (result)
559                 return result;
560 
561         register_netdevice_notifier(&caif_device_notifier);
562         dev_add_pack(&caif_packet_type);
563 
564         return result;
565 }
566 
567 static void __exit caif_device_exit(void)
568 {
569         unregister_netdevice_notifier(&caif_device_notifier);
570         dev_remove_pack(&caif_packet_type);
571         unregister_pernet_subsys(&caif_net_ops);
572 }
573 
574 module_init(caif_device_init);
575 module_exit(caif_device_exit);
576 

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