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

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