net/caif/caif_dev.c

   1 /*
   2  * CAIF Interface registration.
   3  * Copyright (C) ST-Ericsson AB 2010
   4  * Author:      Sjur Brendeland/sjur.brandeland@stericsson.com
   5  * License terms: GNU General Public License (GPL) version 2
   6  *
   7  * Borrowed heavily from file: pn_dev.c. Thanks to
   8  *  Remi Denis-Courmont <remi.denis-courmont@nokia.com>
   9  *  and Sakari Ailus <sakari.ailus@nokia.com>
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
  13
  14 #include <linux/kernel.h>
  15 #include <linux/if_arp.h>
  16 #include <linux/net.h>
  17 #include <linux/netdevice.h>
  18 #include <linux/mutex.h>
  19 #include <linux/module.h>
  20 #include <linux/spinlock.h>
  21 #include <net/netns/generic.h>
  22 #include <net/net_namespace.h>
  23 #include <net/pkt_sched.h>
  24 #include <net/caif/caif_device.h>
  25 #include <net/caif/caif_layer.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         if (!caifn)
  63                 return NULL;
  64         return caifn->cfg;
  65 }
  66 EXPORT_SYMBOL(get_cfcnfg);
  67
  68 static struct caif_device_entry_list *caif_device_list(struct net *net)
  69 {
  70         struct caif_net *caifn;
  71         caifn = net_generic(net, caif_net_id);
  72         if (!caifn)
  73                 return NULL;
  74         return &caifn->caifdevs;
  75 }
  76
  77 static void caifd_put(struct caif_device_entry *e)
  78 {
  79         this_cpu_dec(*e->pcpu_refcnt);
  80 }
  81
  82 static void caifd_hold(struct caif_device_entry *e)
  83 {
  84         this_cpu_inc(*e->pcpu_refcnt);
  85 }
  86
  87 static int caifd_refcnt_read(struct caif_device_entry *e)
  88 {
  89         int i, refcnt = 0;
  90         for_each_possible_cpu(i)
  91                 refcnt += *per_cpu_ptr(e->pcpu_refcnt, i);
  92         return refcnt;
  93 }
  94
  95 /* Allocate new CAIF device. */
  96 static struct caif_device_entry *caif_device_alloc(struct net_device *dev)
  97 {
  98         struct caif_device_entry_list *caifdevs;
  99         struct caif_device_entry *caifd;
 100
 101         caifdevs = caif_device_list(dev_net(dev));
 102         if (!caifdevs)
 103                 return NULL;
 104
 105         caifd = kzalloc(sizeof(*caifd), GFP_KERNEL);
 106         if (!caifd)
 107                 return NULL;
 108         caifd->pcpu_refcnt = alloc_percpu(int);
 109         if (!caifd->pcpu_refcnt) {
 110                 kfree(caifd);
 111                 return NULL;
 112         }
 113         caifd->netdev = dev;
 114         dev_hold(dev);
 115         return caifd;
 116 }
 117
 118 static struct caif_device_entry *caif_get(struct net_device *dev)
 119 {
 120         struct caif_device_entry_list *caifdevs =
 121             caif_device_list(dev_net(dev));
 122         struct caif_device_entry *caifd;
 123         if (!caifdevs)
 124                 return NULL;
 125
 126         list_for_each_entry_rcu(caifd, &caifdevs->list, list) {
 127                 if (caifd->netdev == dev)
 128                         return caifd;
 129         }
 130         return NULL;
 131 }
 132
 133 void caif_flow_cb(struct sk_buff *skb)
 134 {
 135         struct caif_device_entry *caifd;
 136         void (*dtor)(struct sk_buff *skb) = NULL;
 137         bool send_xoff;
 138
 139         WARN_ON(skb->dev == NULL);
 140
 141         rcu_read_lock();
 142         caifd = caif_get(skb->dev);
 143         caifd_hold(caifd);
 144         rcu_read_unlock();
 145
 146         spin_lock_bh(&caifd->flow_lock);
 147         send_xoff = caifd->xoff;
 148         caifd->xoff = 0;
 149         dtor = caifd->xoff_skb_dtor;
 150
 151         if (WARN_ON(caifd->xoff_skb != skb))
 152                 skb = NULL;
 153
 154         caifd->xoff_skb = NULL;
 155         caifd->xoff_skb_dtor = NULL;
 156
 157         spin_unlock_bh(&caifd->flow_lock);
 158
 159         if (dtor && skb)
 160                 dtor(skb);
 161
 162         if (send_xoff)
 163                 caifd->layer.up->
 164                         ctrlcmd(caifd->layer.up,
 165                                 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
 166                                 caifd->layer.id);
 167         caifd_put(caifd);
 168 }
 169
 170 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
 171 {
 172         int err, high = 0, qlen = 0;
 173         struct caif_dev_common *caifdev;
 174         struct caif_device_entry *caifd =
 175             container_of(layer, struct caif_device_entry, layer);
 176         struct sk_buff *skb;
 177         struct netdev_queue *txq;
 178
 179         rcu_read_lock_bh();
 180
 181         skb = cfpkt_tonative(pkt);
 182         skb->dev = caifd->netdev;
 183         skb_reset_network_header(skb);
 184         skb->protocol = htons(ETH_P_CAIF);
 185         caifdev = netdev_priv(caifd->netdev);
 186
 187         /* Check if we need to handle xoff */
 188         if (likely(caifd->netdev->tx_queue_len == 0))
 189                 goto noxoff;
 190
 191         if (unlikely(caifd->xoff))
 192                 goto noxoff;
 193
 194         if (likely(!netif_queue_stopped(caifd->netdev))) {
 195                 /* If we run with a TX queue, check if the queue is too long*/
 196                 txq = netdev_get_tx_queue(skb->dev, 0);
 197                 qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
 198
 199                 if (likely(qlen == 0))
 200                         goto noxoff;
 201
 202                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
 203                 if (likely(qlen < high))
 204                         goto noxoff;
 205         }
 206
 207         /* Hold lock while accessing xoff */
 208         spin_lock_bh(&caifd->flow_lock);
 209         if (caifd->xoff) {
 210                 spin_unlock_bh(&caifd->flow_lock);
 211                 goto noxoff;
 212         }
 213
 214         /*
 215          * Handle flow off, we do this by temporary hi-jacking this
 216          * skb's destructor function, and replace it with our own
 217          * flow-on callback. The callback will set flow-on and call
 218          * the original destructor.
 219          */
 220
 221         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
 222                         netif_queue_stopped(caifd->netdev),
 223                         qlen, high);
 224         caifd->xoff = 1;
 225         caifd->xoff_skb = skb;
 226         caifd->xoff_skb_dtor = skb->destructor;
 227         skb->destructor = caif_flow_cb;
 228         spin_unlock_bh(&caifd->flow_lock);
 229
 230         caifd->layer.up->ctrlcmd(caifd->layer.up,
 231                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 232                                         caifd->layer.id);
 233 noxoff:
 234         rcu_read_unlock_bh();
 235
 236         err = dev_queue_xmit(skb);
 237         if (err > 0)
 238                 err = -EIO;
 239
 240         return err;
 241 }
 242
 243 /*
 244  * Stuff received packets into the CAIF stack.
 245  * On error, returns non-zero and releases the skb.
 246  */
 247 static int receive(struct sk_buff *skb, struct net_device *dev,
 248                    struct packet_type *pkttype, struct net_device *orig_dev)
 249 {
 250         struct cfpkt *pkt;
 251         struct caif_device_entry *caifd;
 252         int err;
 253
 254         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
 255
 256         rcu_read_lock();
 257         caifd = caif_get(dev);
 258
 259         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
 260                         !netif_oper_up(caifd->netdev)) {
 261                 rcu_read_unlock();
 262                 kfree_skb(skb);
 263                 return NET_RX_DROP;
 264         }
 265
 266         /* Hold reference to netdevice while using CAIF stack */
 267         caifd_hold(caifd);
 268         rcu_read_unlock();
 269
 270         err = caifd->layer.up->receive(caifd->layer.up, pkt);
 271
 272         /* For -EILSEQ the packet is not freed so so it now */
 273         if (err == -EILSEQ)
 274                 cfpkt_destroy(pkt);
 275
 276         /* Release reference to stack upwards */
 277         caifd_put(caifd);
 278
 279         if (err != 0)
 280                 err = NET_RX_DROP;
 281         return err;
 282 }
 283
 284 static struct packet_type caif_packet_type __read_mostly = {
 285         .type = cpu_to_be16(ETH_P_CAIF),
 286         .func = receive,
 287 };
 288
 289 static void dev_flowctrl(struct net_device *dev, int on)
 290 {
 291         struct caif_device_entry *caifd;
 292
 293         rcu_read_lock();
 294
 295         caifd = caif_get(dev);
 296         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 297                 rcu_read_unlock();
 298                 return;
 299         }
 300
 301         caifd_hold(caifd);
 302         rcu_read_unlock();
 303
 304         caifd->layer.up->ctrlcmd(caifd->layer.up,
 305                                  on ?
 306                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
 307                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 308                                  caifd->layer.id);
 309         caifd_put(caifd);
 310 }
 311
 312 void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 313                         struct cflayer *link_support, int head_room,
 314                         struct cflayer **layer, int (**rcv_func)(
 315                                 struct sk_buff *, struct net_device *,
 316                                 struct packet_type *, 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
 323         caifdevs = caif_device_list(dev_net(dev));
 324         if (!cfg || !caifdevs)
 325                 return;
 326         caifd = caif_device_alloc(dev);
 327         if (!caifd)
 328                 return;
 329         *layer = &caifd->layer;
 330         spin_lock_init(&caifd->flow_lock);
 331
 332         switch (caifdev->link_select) {
 333         case CAIF_LINK_HIGH_BANDW:
 334                 pref = CFPHYPREF_HIGH_BW;
 335                 break;
 336         case CAIF_LINK_LOW_LATENCY:
 337                 pref = CFPHYPREF_LOW_LAT;
 338                 break;
 339         default:
 340                 pref = CFPHYPREF_HIGH_BW;
 341                 break;
 342         }
 343         mutex_lock(&caifdevs->lock);
 344         list_add_rcu(&caifd->list, &caifdevs->list);
 345
 346         strncpy(caifd->layer.name, dev->name,
 347                 sizeof(caifd->layer.name) - 1);
 348         caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
 349         caifd->layer.transmit = transmit;
 350         cfcnfg_add_phy_layer(cfg,
 351                                 dev,
 352                                 &caifd->layer,
 353                                 pref,
 354                                 link_support,
 355                                 caifdev->use_fcs,
 356                                 head_room);
 357         mutex_unlock(&caifdevs->lock);
 358         if (rcv_func)
 359                 *rcv_func = receive;
 360 }
 361 EXPORT_SYMBOL(caif_enroll_dev);
 362
 363 /* notify Caif of device events */
 364 static int caif_device_notify(struct notifier_block *me, unsigned long what,
 365                               void *arg)
 366 {
 367         struct net_device *dev = arg;
 368         struct caif_device_entry *caifd = NULL;
 369         struct caif_dev_common *caifdev;
 370         struct cfcnfg *cfg;
 371         struct cflayer *layer, *link_support;
 372         int head_room = 0;
 373         struct caif_device_entry_list *caifdevs;
 374
 375         cfg = get_cfcnfg(dev_net(dev));
 376         caifdevs = caif_device_list(dev_net(dev));
 377         if (!cfg || !caifdevs)
 378                 return 0;
 379
 380         caifd = caif_get(dev);
 381         if (caifd == NULL && dev->type != ARPHRD_CAIF)
 382                 return 0;
 383
 384         switch (what) {
 385         case NETDEV_REGISTER:
 386                 if (caifd != NULL)
 387                         break;
 388
 389                 caifdev = netdev_priv(dev);
 390
 391                 link_support = NULL;
 392                 if (caifdev->use_frag) {
 393                         head_room = 1;
 394                         link_support = cfserl_create(dev->ifindex,
 395                                                         caifdev->use_stx);
 396                         if (!link_support) {
 397                                 pr_warn("Out of memory\n");
 398                                 break;
 399                         }
 400                 }
 401                 caif_enroll_dev(dev, caifdev, link_support, head_room,
 402                                 &layer, NULL);
 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 = 0;
 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 = 0;
 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         if (WARN_ON(!caifn))
 511                 return -EINVAL;
 512
 513         INIT_LIST_HEAD(&caifn->caifdevs.list);
 514         mutex_init(&caifn->caifdevs.lock);
 515
 516         caifn->cfg = cfcnfg_create();
 517         if (!caifn->cfg)
 518                 return -ENOMEM;
 519
 520         return 0;
 521 }
 522
 523 static void caif_exit_net(struct net *net)
 524 {
 525         struct caif_device_entry *caifd, *tmp;
 526         struct caif_device_entry_list *caifdevs =
 527             caif_device_list(net);
 528         struct cfcnfg *cfg =  get_cfcnfg(net);
 529
 530         if (!cfg || !caifdevs)
 531                 return;
 532
 533         rtnl_lock();
 534         mutex_lock(&caifdevs->lock);
 535
 536         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
 537                 int i = 0;
 538                 list_del_rcu(&caifd->list);
 539                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 540
 541                 while (i < 10 &&
 542                         (caifd_refcnt_read(caifd) != 0 ||
 543                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
 544
 545                         pr_info("Wait for device inuse\n");
 546                         msleep(250);
 547                         i++;
 548                 }
 549                 synchronize_rcu();
 550                 dev_put(caifd->netdev);
 551                 free_percpu(caifd->pcpu_refcnt);
 552                 kfree(caifd);
 553         }
 554         cfcnfg_remove(cfg);
 555
 556         mutex_unlock(&caifdevs->lock);
 557         rtnl_unlock();
 558 }
 559
 560 static struct pernet_operations caif_net_ops = {
 561         .init = caif_init_net,
 562         .exit = caif_exit_net,
 563         .id   = &caif_net_id,
 564         .size = sizeof(struct caif_net),
 565 };
 566
 567 /* Initialize Caif devices list */
 568 static int __init caif_device_init(void)
 569 {
 570         int result;
 571
 572         result = register_pernet_device(&caif_net_ops);
 573
 574         if (result)
 575                 return result;
 576
 577         register_netdevice_notifier(&caif_device_notifier);
 578         dev_add_pack(&caif_packet_type);
 579
 580         return result;
 581 }
 582
 583 static void __exit caif_device_exit(void)
 584 {
 585         unregister_pernet_device(&caif_net_ops);
 586         unregister_netdevice_notifier(&caif_device_notifier);
 587         dev_remove_pack(&caif_packet_type);
 588 }
 589
 590 module_init(caif_device_init);
 591 module_exit(caif_device_exit);