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Linux/net/caif/caif_dev.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * CAIF Interface registration.
  4  * Copyright (C) ST-Ericsson AB 2010
  5  * Author:      Sjur Brendeland
  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                                 lockdep_rtnl_is_held()) {
117                 if (caifd->netdev == dev)
118                         return caifd;
119         }
120         return NULL;
121 }
122 
123 static void caif_flow_cb(struct sk_buff *skb)
124 {
125         struct caif_device_entry *caifd;
126         void (*dtor)(struct sk_buff *skb) = NULL;
127         bool send_xoff;
128 
129         WARN_ON(skb->dev == NULL);
130 
131         rcu_read_lock();
132         caifd = caif_get(skb->dev);
133 
134         WARN_ON(caifd == NULL);
135         if (!caifd) {
136                 rcu_read_unlock();
137                 return;
138         }
139 
140         caifd_hold(caifd);
141         rcu_read_unlock();
142 
143         spin_lock_bh(&caifd->flow_lock);
144         send_xoff = caifd->xoff;
145         caifd->xoff = false;
146         dtor = caifd->xoff_skb_dtor;
147 
148         if (WARN_ON(caifd->xoff_skb != skb))
149                 skb = NULL;
150 
151         caifd->xoff_skb = NULL;
152         caifd->xoff_skb_dtor = NULL;
153 
154         spin_unlock_bh(&caifd->flow_lock);
155 
156         if (dtor && skb)
157                 dtor(skb);
158 
159         if (send_xoff)
160                 caifd->layer.up->
161                         ctrlcmd(caifd->layer.up,
162                                 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
163                                 caifd->layer.id);
164         caifd_put(caifd);
165 }
166 
167 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
168 {
169         int err, high = 0, qlen = 0;
170         struct caif_device_entry *caifd =
171             container_of(layer, struct caif_device_entry, layer);
172         struct sk_buff *skb;
173         struct netdev_queue *txq;
174 
175         rcu_read_lock_bh();
176 
177         skb = cfpkt_tonative(pkt);
178         skb->dev = caifd->netdev;
179         skb_reset_network_header(skb);
180         skb->protocol = htons(ETH_P_CAIF);
181 
182         /* Check if we need to handle xoff */
183         if (likely(caifd->netdev->priv_flags & IFF_NO_QUEUE))
184                 goto noxoff;
185 
186         if (unlikely(caifd->xoff))
187                 goto noxoff;
188 
189         if (likely(!netif_queue_stopped(caifd->netdev))) {
190                 struct Qdisc *sch;
191 
192                 /* If we run with a TX queue, check if the queue is too long*/
193                 txq = netdev_get_tx_queue(skb->dev, 0);
194                 sch = rcu_dereference_bh(txq->qdisc);
195                 if (likely(qdisc_is_empty(sch)))
196                         goto noxoff;
197 
198                 /* can check for explicit qdisc len value only !NOLOCK,
199                  * always set flow off otherwise
200                  */
201                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
202                 if (!(sch->flags & TCQ_F_NOLOCK) && likely(sch->q.qlen < high))
203                         goto noxoff;
204         }
205 
206         /* Hold lock while accessing xoff */
207         spin_lock_bh(&caifd->flow_lock);
208         if (caifd->xoff) {
209                 spin_unlock_bh(&caifd->flow_lock);
210                 goto noxoff;
211         }
212 
213         /*
214          * Handle flow off, we do this by temporary hi-jacking this
215          * skb's destructor function, and replace it with our own
216          * flow-on callback. The callback will set flow-on and call
217          * the original destructor.
218          */
219 
220         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
221                         netif_queue_stopped(caifd->netdev),
222                         qlen, high);
223         caifd->xoff = true;
224         caifd->xoff_skb = skb;
225         caifd->xoff_skb_dtor = skb->destructor;
226         skb->destructor = caif_flow_cb;
227         spin_unlock_bh(&caifd->flow_lock);
228 
229         caifd->layer.up->ctrlcmd(caifd->layer.up,
230                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
231                                         caifd->layer.id);
232 noxoff:
233         rcu_read_unlock_bh();
234 
235         err = dev_queue_xmit(skb);
236         if (err > 0)
237                 err = -EIO;
238 
239         return err;
240 }
241 
242 /*
243  * Stuff received packets into the CAIF stack.
244  * On error, returns non-zero and releases the skb.
245  */
246 static int receive(struct sk_buff *skb, struct net_device *dev,
247                    struct packet_type *pkttype, struct net_device *orig_dev)
248 {
249         struct cfpkt *pkt;
250         struct caif_device_entry *caifd;
251         int err;
252 
253         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
254 
255         rcu_read_lock();
256         caifd = caif_get(dev);
257 
258         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
259                         !netif_oper_up(caifd->netdev)) {
260                 rcu_read_unlock();
261                 kfree_skb(skb);
262                 return NET_RX_DROP;
263         }
264 
265         /* Hold reference to netdevice while using CAIF stack */
266         caifd_hold(caifd);
267         rcu_read_unlock();
268 
269         err = caifd->layer.up->receive(caifd->layer.up, pkt);
270 
271         /* For -EILSEQ the packet is not freed so so it now */
272         if (err == -EILSEQ)
273                 cfpkt_destroy(pkt);
274 
275         /* Release reference to stack upwards */
276         caifd_put(caifd);
277 
278         if (err != 0)
279                 err = NET_RX_DROP;
280         return err;
281 }
282 
283 static struct packet_type caif_packet_type __read_mostly = {
284         .type = cpu_to_be16(ETH_P_CAIF),
285         .func = receive,
286 };
287 
288 static void dev_flowctrl(struct net_device *dev, int on)
289 {
290         struct caif_device_entry *caifd;
291 
292         rcu_read_lock();
293 
294         caifd = caif_get(dev);
295         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
296                 rcu_read_unlock();
297                 return;
298         }
299 
300         caifd_hold(caifd);
301         rcu_read_unlock();
302 
303         caifd->layer.up->ctrlcmd(caifd->layer.up,
304                                  on ?
305                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
306                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
307                                  caifd->layer.id);
308         caifd_put(caifd);
309 }
310 
311 int caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
312                      struct cflayer *link_support, int head_room,
313                      struct cflayer **layer,
314                      int (**rcv_func)(struct sk_buff *, struct net_device *,
315                                       struct packet_type *,
316                                       struct net_device *))
317 {
318         struct caif_device_entry *caifd;
319         enum cfcnfg_phy_preference pref;
320         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
321         struct caif_device_entry_list *caifdevs;
322         int res;
323 
324         caifdevs = caif_device_list(dev_net(dev));
325         caifd = caif_device_alloc(dev);
326         if (!caifd)
327                 return -ENOMEM;
328         *layer = &caifd->layer;
329         spin_lock_init(&caifd->flow_lock);
330 
331         switch (caifdev->link_select) {
332         case CAIF_LINK_HIGH_BANDW:
333                 pref = CFPHYPREF_HIGH_BW;
334                 break;
335         case CAIF_LINK_LOW_LATENCY:
336                 pref = CFPHYPREF_LOW_LAT;
337                 break;
338         default:
339                 pref = CFPHYPREF_HIGH_BW;
340                 break;
341         }
342         mutex_lock(&caifdevs->lock);
343         list_add_rcu(&caifd->list, &caifdevs->list);
344 
345         strlcpy(caifd->layer.name, dev->name,
346                 sizeof(caifd->layer.name));
347         caifd->layer.transmit = transmit;
348         res = cfcnfg_add_phy_layer(cfg,
349                                 dev,
350                                 &caifd->layer,
351                                 pref,
352                                 link_support,
353                                 caifdev->use_fcs,
354                                 head_room);
355         mutex_unlock(&caifdevs->lock);
356         if (rcv_func)
357                 *rcv_func = receive;
358         return res;
359 }
360 EXPORT_SYMBOL(caif_enroll_dev);
361 
362 /* notify Caif of device events */
363 static int caif_device_notify(struct notifier_block *me, unsigned long what,
364                               void *ptr)
365 {
366         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
367         struct caif_device_entry *caifd = NULL;
368         struct caif_dev_common *caifdev;
369         struct cfcnfg *cfg;
370         struct cflayer *layer, *link_support;
371         int head_room = 0;
372         struct caif_device_entry_list *caifdevs;
373         int res;
374 
375         cfg = get_cfcnfg(dev_net(dev));
376         caifdevs = caif_device_list(dev_net(dev));
377 
378         caifd = caif_get(dev);
379         if (caifd == NULL && dev->type != ARPHRD_CAIF)
380                 return 0;
381 
382         switch (what) {
383         case NETDEV_REGISTER:
384                 if (caifd != NULL)
385                         break;
386 
387                 caifdev = netdev_priv(dev);
388 
389                 link_support = NULL;
390                 if (caifdev->use_frag) {
391                         head_room = 1;
392                         link_support = cfserl_create(dev->ifindex,
393                                                         caifdev->use_stx);
394                         if (!link_support) {
395                                 pr_warn("Out of memory\n");
396                                 break;
397                         }
398                 }
399                 res = caif_enroll_dev(dev, caifdev, link_support, head_room,
400                                 &layer, NULL);
401                 if (res)
402                         cfserl_release(link_support);
403                 caifdev->flowctrl = dev_flowctrl;
404                 break;
405 
406         case NETDEV_UP:
407                 rcu_read_lock();
408 
409                 caifd = caif_get(dev);
410                 if (caifd == NULL) {
411                         rcu_read_unlock();
412                         break;
413                 }
414 
415                 caifd->xoff = false;
416                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
417                 rcu_read_unlock();
418 
419                 break;
420 
421         case NETDEV_DOWN:
422                 rcu_read_lock();
423 
424                 caifd = caif_get(dev);
425                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
426                         rcu_read_unlock();
427                         return -EINVAL;
428                 }
429 
430                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
431                 caifd_hold(caifd);
432                 rcu_read_unlock();
433 
434                 caifd->layer.up->ctrlcmd(caifd->layer.up,
435                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
436                                          caifd->layer.id);
437 
438                 spin_lock_bh(&caifd->flow_lock);
439 
440                 /*
441                  * Replace our xoff-destructor with original destructor.
442                  * We trust that skb->destructor *always* is called before
443                  * the skb reference is invalid. The hijacked SKB destructor
444                  * takes the flow_lock so manipulating the skb->destructor here
445                  * should be safe.
446                 */
447                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
448                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
449 
450                 caifd->xoff = false;
451                 caifd->xoff_skb_dtor = NULL;
452                 caifd->xoff_skb = NULL;
453 
454                 spin_unlock_bh(&caifd->flow_lock);
455                 caifd_put(caifd);
456                 break;
457 
458         case NETDEV_UNREGISTER:
459                 mutex_lock(&caifdevs->lock);
460 
461                 caifd = caif_get(dev);
462                 if (caifd == NULL) {
463                         mutex_unlock(&caifdevs->lock);
464                         break;
465                 }
466                 list_del_rcu(&caifd->list);
467 
468                 /*
469                  * NETDEV_UNREGISTER is called repeatedly until all reference
470                  * counts for the net-device are released. If references to
471                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
472                  * the next call to NETDEV_UNREGISTER.
473                  *
474                  * If any packets are in flight down the CAIF Stack,
475                  * cfcnfg_del_phy_layer will return nonzero.
476                  * If no packets are in flight, the CAIF Stack associated
477                  * with the net-device un-registering is freed.
478                  */
479 
480                 if (caifd_refcnt_read(caifd) != 0 ||
481                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
482 
483                         pr_info("Wait for device inuse\n");
484                         /* Enrole device if CAIF Stack is still in use */
485                         list_add_rcu(&caifd->list, &caifdevs->list);
486                         mutex_unlock(&caifdevs->lock);
487                         break;
488                 }
489 
490                 synchronize_rcu();
491                 dev_put(caifd->netdev);
492                 free_percpu(caifd->pcpu_refcnt);
493                 kfree(caifd);
494 
495                 mutex_unlock(&caifdevs->lock);
496                 break;
497         }
498         return 0;
499 }
500 
501 static struct notifier_block caif_device_notifier = {
502         .notifier_call = caif_device_notify,
503         .priority = 0,
504 };
505 
506 /* Per-namespace Caif devices handling */
507 static int caif_init_net(struct net *net)
508 {
509         struct caif_net *caifn = net_generic(net, caif_net_id);
510         INIT_LIST_HEAD(&caifn->caifdevs.list);
511         mutex_init(&caifn->caifdevs.lock);
512 
513         caifn->cfg = cfcnfg_create();
514         if (!caifn->cfg)
515                 return -ENOMEM;
516 
517         return 0;
518 }
519 
520 static void caif_exit_net(struct net *net)
521 {
522         struct caif_device_entry *caifd, *tmp;
523         struct caif_device_entry_list *caifdevs =
524             caif_device_list(net);
525         struct cfcnfg *cfg =  get_cfcnfg(net);
526 
527         rtnl_lock();
528         mutex_lock(&caifdevs->lock);
529 
530         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
531                 int i = 0;
532                 list_del_rcu(&caifd->list);
533                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
534 
535                 while (i < 10 &&
536                         (caifd_refcnt_read(caifd) != 0 ||
537                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
538 
539                         pr_info("Wait for device inuse\n");
540                         msleep(250);
541                         i++;
542                 }
543                 synchronize_rcu();
544                 dev_put(caifd->netdev);
545                 free_percpu(caifd->pcpu_refcnt);
546                 kfree(caifd);
547         }
548         cfcnfg_remove(cfg);
549 
550         mutex_unlock(&caifdevs->lock);
551         rtnl_unlock();
552 }
553 
554 static struct pernet_operations caif_net_ops = {
555         .init = caif_init_net,
556         .exit = caif_exit_net,
557         .id   = &caif_net_id,
558         .size = sizeof(struct caif_net),
559 };
560 
561 /* Initialize Caif devices list */
562 static int __init caif_device_init(void)
563 {
564         int result;
565 
566         result = register_pernet_subsys(&caif_net_ops);
567 
568         if (result)
569                 return result;
570 
571         register_netdevice_notifier(&caif_device_notifier);
572         dev_add_pack(&caif_packet_type);
573 
574         return result;
575 }
576 
577 static void __exit caif_device_exit(void)
578 {
579         unregister_netdevice_notifier(&caif_device_notifier);
580         dev_remove_pack(&caif_packet_type);
581         unregister_pernet_subsys(&caif_net_ops);
582 }
583 
584 module_init(caif_device_init);
585 module_exit(caif_device_exit);
586 

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