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         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_list *caifdevs;
  95         struct caif_device_entry *caifd;
  96
  97         caifdevs = caif_device_list(dev_net(dev));
  98
  99         caifd = kzalloc(sizeof(*caifd), GFP_KERNEL);
 100         if (!caifd)
 101                 return NULL;
 102         caifd->pcpu_refcnt = alloc_percpu(int);
 103         if (!caifd->pcpu_refcnt) {
 104                 kfree(caifd);
 105                 return NULL;
 106         }
 107         caifd->netdev = dev;
 108         dev_hold(dev);
 109         return caifd;
 110 }
 111
 112 static struct caif_device_entry *caif_get(struct net_device *dev)
 113 {
 114         struct caif_device_entry_list *caifdevs =
 115             caif_device_list(dev_net(dev));
 116         struct caif_device_entry *caifd;
 117
 118         list_for_each_entry_rcu(caifd, &caifdevs->list, list) {
 119                 if (caifd->netdev == dev)
 120                         return caifd;
 121         }
 122         return NULL;
 123 }
 124
 125 void caif_flow_cb(struct sk_buff *skb)
 126 {
 127         struct caif_device_entry *caifd;
 128         void (*dtor)(struct sk_buff *skb) = NULL;
 129         bool send_xoff;
 130
 131         WARN_ON(skb->dev == NULL);
 132
 133         rcu_read_lock();
 134         caifd = caif_get(skb->dev);
 135         caifd_hold(caifd);
 136         rcu_read_unlock();
 137
 138         spin_lock_bh(&caifd->flow_lock);
 139         send_xoff = caifd->xoff;
 140         caifd->xoff = 0;
 141         dtor = caifd->xoff_skb_dtor;
 142
 143         if (WARN_ON(caifd->xoff_skb != skb))
 144                 skb = NULL;
 145
 146         caifd->xoff_skb = NULL;
 147         caifd->xoff_skb_dtor = NULL;
 148
 149         spin_unlock_bh(&caifd->flow_lock);
 150
 151         if (dtor && skb)
 152                 dtor(skb);
 153
 154         if (send_xoff)
 155                 caifd->layer.up->
 156                         ctrlcmd(caifd->layer.up,
 157                                 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
 158                                 caifd->layer.id);
 159         caifd_put(caifd);
 160 }
 161
 162 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
 163 {
 164         int err, high = 0, qlen = 0;
 165         struct caif_device_entry *caifd =
 166             container_of(layer, struct caif_device_entry, layer);
 167         struct sk_buff *skb;
 168         struct netdev_queue *txq;
 169
 170         rcu_read_lock_bh();
 171
 172         skb = cfpkt_tonative(pkt);
 173         skb->dev = caifd->netdev;
 174         skb_reset_network_header(skb);
 175         skb->protocol = htons(ETH_P_CAIF);
 176
 177         /* Check if we need to handle xoff */
 178         if (likely(caifd->netdev->tx_queue_len == 0))
 179                 goto noxoff;
 180
 181         if (unlikely(caifd->xoff))
 182                 goto noxoff;
 183
 184         if (likely(!netif_queue_stopped(caifd->netdev))) {
 185                 /* If we run with a TX queue, check if the queue is too long*/
 186                 txq = netdev_get_tx_queue(skb->dev, 0);
 187                 qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
 188
 189                 if (likely(qlen == 0))
 190                         goto noxoff;
 191
 192                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
 193                 if (likely(qlen < high))
 194                         goto noxoff;
 195         }
 196
 197         /* Hold lock while accessing xoff */
 198         spin_lock_bh(&caifd->flow_lock);
 199         if (caifd->xoff) {
 200                 spin_unlock_bh(&caifd->flow_lock);
 201                 goto noxoff;
 202         }
 203
 204         /*
 205          * Handle flow off, we do this by temporary hi-jacking this
 206          * skb's destructor function, and replace it with our own
 207          * flow-on callback. The callback will set flow-on and call
 208          * the original destructor.
 209          */
 210
 211         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
 212                         netif_queue_stopped(caifd->netdev),
 213                         qlen, high);
 214         caifd->xoff = 1;
 215         caifd->xoff_skb = skb;
 216         caifd->xoff_skb_dtor = skb->destructor;
 217         skb->destructor = caif_flow_cb;
 218         spin_unlock_bh(&caifd->flow_lock);
 219
 220         caifd->layer.up->ctrlcmd(caifd->layer.up,
 221                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 222                                         caifd->layer.id);
 223 noxoff:
 224         rcu_read_unlock_bh();
 225
 226         err = dev_queue_xmit(skb);
 227         if (err > 0)
 228                 err = -EIO;
 229
 230         return err;
 231 }
 232
 233 /*
 234  * Stuff received packets into the CAIF stack.
 235  * On error, returns non-zero and releases the skb.
 236  */
 237 static int receive(struct sk_buff *skb, struct net_device *dev,
 238                    struct packet_type *pkttype, struct net_device *orig_dev)
 239 {
 240         struct cfpkt *pkt;
 241         struct caif_device_entry *caifd;
 242         int err;
 243
 244         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
 245
 246         rcu_read_lock();
 247         caifd = caif_get(dev);
 248
 249         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
 250                         !netif_oper_up(caifd->netdev)) {
 251                 rcu_read_unlock();
 252                 kfree_skb(skb);
 253                 return NET_RX_DROP;
 254         }
 255
 256         /* Hold reference to netdevice while using CAIF stack */
 257         caifd_hold(caifd);
 258         rcu_read_unlock();
 259
 260         err = caifd->layer.up->receive(caifd->layer.up, pkt);
 261
 262         /* For -EILSEQ the packet is not freed so so it now */
 263         if (err == -EILSEQ)
 264                 cfpkt_destroy(pkt);
 265
 266         /* Release reference to stack upwards */
 267         caifd_put(caifd);
 268
 269         if (err != 0)
 270                 err = NET_RX_DROP;
 271         return err;
 272 }
 273
 274 static struct packet_type caif_packet_type __read_mostly = {
 275         .type = cpu_to_be16(ETH_P_CAIF),
 276         .func = receive,
 277 };
 278
 279 static void dev_flowctrl(struct net_device *dev, int on)
 280 {
 281         struct caif_device_entry *caifd;
 282
 283         rcu_read_lock();
 284
 285         caifd = caif_get(dev);
 286         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 287                 rcu_read_unlock();
 288                 return;
 289         }
 290
 291         caifd_hold(caifd);
 292         rcu_read_unlock();
 293
 294         caifd->layer.up->ctrlcmd(caifd->layer.up,
 295                                  on ?
 296                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
 297                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 298                                  caifd->layer.id);
 299         caifd_put(caifd);
 300 }
 301
 302 void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 303                         struct cflayer *link_support, int head_room,
 304                         struct cflayer **layer, int (**rcv_func)(
 305                                 struct sk_buff *, struct net_device *,
 306                                 struct packet_type *, struct net_device *))
 307 {
 308         struct caif_device_entry *caifd;
 309         enum cfcnfg_phy_preference pref;
 310         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
 311         struct caif_device_entry_list *caifdevs;
 312
 313         caifdevs = caif_device_list(dev_net(dev));
 314         caifd = caif_device_alloc(dev);
 315         if (!caifd)
 316                 return;
 317         *layer = &caifd->layer;
 318         spin_lock_init(&caifd->flow_lock);
 319
 320         switch (caifdev->link_select) {
 321         case CAIF_LINK_HIGH_BANDW:
 322                 pref = CFPHYPREF_HIGH_BW;
 323                 break;
 324         case CAIF_LINK_LOW_LATENCY:
 325                 pref = CFPHYPREF_LOW_LAT;
 326                 break;
 327         default:
 328                 pref = CFPHYPREF_HIGH_BW;
 329                 break;
 330         }
 331         mutex_lock(&caifdevs->lock);
 332         list_add_rcu(&caifd->list, &caifdevs->list);
 333
 334         strncpy(caifd->layer.name, dev->name,
 335                 sizeof(caifd->layer.name) - 1);
 336         caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
 337         caifd->layer.transmit = transmit;
 338         cfcnfg_add_phy_layer(cfg,
 339                                 dev,
 340                                 &caifd->layer,
 341                                 pref,
 342                                 link_support,
 343                                 caifdev->use_fcs,
 344                                 head_room);
 345         mutex_unlock(&caifdevs->lock);
 346         if (rcv_func)
 347                 *rcv_func = receive;
 348 }
 349 EXPORT_SYMBOL(caif_enroll_dev);
 350
 351 /* notify Caif of device events */
 352 static int caif_device_notify(struct notifier_block *me, unsigned long what,
 353                               void *arg)
 354 {
 355         struct net_device *dev = arg;
 356         struct caif_device_entry *caifd = NULL;
 357         struct caif_dev_common *caifdev;
 358         struct cfcnfg *cfg;
 359         struct cflayer *layer, *link_support;
 360         int head_room = 0;
 361         struct caif_device_entry_list *caifdevs;
 362
 363         cfg = get_cfcnfg(dev_net(dev));
 364         caifdevs = caif_device_list(dev_net(dev));
 365
 366         caifd = caif_get(dev);
 367         if (caifd == NULL && dev->type != ARPHRD_CAIF)
 368                 return 0;
 369
 370         switch (what) {
 371         case NETDEV_REGISTER:
 372                 if (caifd != NULL)
 373                         break;
 374
 375                 caifdev = netdev_priv(dev);
 376
 377                 link_support = NULL;
 378                 if (caifdev->use_frag) {
 379                         head_room = 1;
 380                         link_support = cfserl_create(dev->ifindex,
 381                                                         caifdev->use_stx);
 382                         if (!link_support) {
 383                                 pr_warn("Out of memory\n");
 384                                 break;
 385                         }
 386                 }
 387                 caif_enroll_dev(dev, caifdev, link_support, head_room,
 388                                 &layer, NULL);
 389                 caifdev->flowctrl = dev_flowctrl;
 390                 break;
 391
 392         case NETDEV_UP:
 393                 rcu_read_lock();
 394
 395                 caifd = caif_get(dev);
 396                 if (caifd == NULL) {
 397                         rcu_read_unlock();
 398                         break;
 399                 }
 400
 401                 caifd->xoff = 0;
 402                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
 403                 rcu_read_unlock();
 404
 405                 break;
 406
 407         case NETDEV_DOWN:
 408                 rcu_read_lock();
 409
 410                 caifd = caif_get(dev);
 411                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 412                         rcu_read_unlock();
 413                         return -EINVAL;
 414                 }
 415
 416                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 417                 caifd_hold(caifd);
 418                 rcu_read_unlock();
 419
 420                 caifd->layer.up->ctrlcmd(caifd->layer.up,
 421                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
 422                                          caifd->layer.id);
 423
 424                 spin_lock_bh(&caifd->flow_lock);
 425
 426                 /*
 427                  * Replace our xoff-destructor with original destructor.
 428                  * We trust that skb->destructor *always* is called before
 429                  * the skb reference is invalid. The hijacked SKB destructor
 430                  * takes the flow_lock so manipulating the skb->destructor here
 431                  * should be safe.
 432                 */
 433                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
 434                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
 435
 436                 caifd->xoff = 0;
 437                 caifd->xoff_skb_dtor = NULL;
 438                 caifd->xoff_skb = NULL;
 439
 440                 spin_unlock_bh(&caifd->flow_lock);
 441                 caifd_put(caifd);
 442                 break;
 443
 444         case NETDEV_UNREGISTER:
 445                 mutex_lock(&caifdevs->lock);
 446
 447                 caifd = caif_get(dev);
 448                 if (caifd == NULL) {
 449                         mutex_unlock(&caifdevs->lock);
 450                         break;
 451                 }
 452                 list_del_rcu(&caifd->list);
 453
 454                 /*
 455                  * NETDEV_UNREGISTER is called repeatedly until all reference
 456                  * counts for the net-device are released. If references to
 457                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
 458                  * the next call to NETDEV_UNREGISTER.
 459                  *
 460                  * If any packets are in flight down the CAIF Stack,
 461                  * cfcnfg_del_phy_layer will return nonzero.
 462                  * If no packets are in flight, the CAIF Stack associated
 463                  * with the net-device un-registering is freed.
 464                  */
 465
 466                 if (caifd_refcnt_read(caifd) != 0 ||
 467                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
 468
 469                         pr_info("Wait for device inuse\n");
 470                         /* Enrole device if CAIF Stack is still in use */
 471                         list_add_rcu(&caifd->list, &caifdevs->list);
 472                         mutex_unlock(&caifdevs->lock);
 473                         break;
 474                 }
 475
 476                 synchronize_rcu();
 477                 dev_put(caifd->netdev);
 478                 free_percpu(caifd->pcpu_refcnt);
 479                 kfree(caifd);
 480
 481                 mutex_unlock(&caifdevs->lock);
 482                 break;
 483         }
 484         return 0;
 485 }
 486
 487 static struct notifier_block caif_device_notifier = {
 488         .notifier_call = caif_device_notify,
 489         .priority = 0,
 490 };
 491
 492 /* Per-namespace Caif devices handling */
 493 static int caif_init_net(struct net *net)
 494 {
 495         struct caif_net *caifn = net_generic(net, caif_net_id);
 496         INIT_LIST_HEAD(&caifn->caifdevs.list);
 497         mutex_init(&caifn->caifdevs.lock);
 498
 499         caifn->cfg = cfcnfg_create();
 500         if (!caifn->cfg)
 501                 return -ENOMEM;
 502
 503         return 0;
 504 }
 505
 506 static void caif_exit_net(struct net *net)
 507 {
 508         struct caif_device_entry *caifd, *tmp;
 509         struct caif_device_entry_list *caifdevs =
 510             caif_device_list(net);
 511         struct cfcnfg *cfg =  get_cfcnfg(net);
 512
 513         rtnl_lock();
 514         mutex_lock(&caifdevs->lock);
 515
 516         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
 517                 int i = 0;
 518                 list_del_rcu(&caifd->list);
 519                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 520
 521                 while (i < 10 &&
 522                         (caifd_refcnt_read(caifd) != 0 ||
 523                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
 524
 525                         pr_info("Wait for device inuse\n");
 526                         msleep(250);
 527                         i++;
 528                 }
 529                 synchronize_rcu();
 530                 dev_put(caifd->netdev);
 531                 free_percpu(caifd->pcpu_refcnt);
 532                 kfree(caifd);
 533         }
 534         cfcnfg_remove(cfg);
 535
 536         mutex_unlock(&caifdevs->lock);
 537         rtnl_unlock();
 538 }
 539
 540 static struct pernet_operations caif_net_ops = {
 541         .init = caif_init_net,
 542         .exit = caif_exit_net,
 543         .id   = &caif_net_id,
 544         .size = sizeof(struct caif_net),
 545 };
 546
 547 /* Initialize Caif devices list */
 548 static int __init caif_device_init(void)
 549 {
 550         int result;
 551
 552         result = register_pernet_subsys(&caif_net_ops);
 553
 554         if (result)
 555                 return result;
 556
 557         register_netdevice_notifier(&caif_device_notifier);
 558         dev_add_pack(&caif_packet_type);
 559
 560         return result;
 561 }
 562
 563 static void __exit caif_device_exit(void)
 564 {
 565         unregister_pernet_subsys(&caif_net_ops);
 566         unregister_netdevice_notifier(&caif_device_notifier);
 567         dev_remove_pack(&caif_packet_type);
 568 }
 569
 570 module_init(caif_device_init);
 571 module_exit(caif_device_exit);