root/net/caif/caif_dev.c

DEFINITIONS

1. get_cfcnfg
2. caif_device_list
3. caifd_put
4. caifd_hold
5. caifd_refcnt_read
6. caif_device_alloc
7. caif_get
8. caif_flow_cb
9. transmit
10. receive
11. dev_flowctrl
12. caif_enroll_dev
13. caif_device_notify
14. caif_init_net
15. caif_exit_net
16. caif_device_init
17. caif_device_exit

   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);