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 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/cfpkt.h>
  26 #include <net/caif/cfcnfg.h>
  27 #include <net/caif/cfserl.h>
  28
  29 MODULE_LICENSE("GPL");
  30
  31 /* Used for local tracking of the CAIF net devices */
  32 struct caif_device_entry {
  33         struct cflayer layer;
  34         struct list_head list;
  35         struct net_device *netdev;
  36         int __percpu *pcpu_refcnt;
  37         spinlock_t flow_lock;
  38         struct sk_buff *xoff_skb;
  39         void (*xoff_skb_dtor)(struct sk_buff *skb);
  40         bool xoff;
  41 };
  42
  43 struct caif_device_entry_list {
  44         struct list_head list;
  45         /* Protects simulanous deletes in list */
  46         struct mutex lock;
  47 };
  48
  49 struct caif_net {
  50         struct cfcnfg *cfg;
  51         struct caif_device_entry_list caifdevs;
  52 };
  53
  54 static int caif_net_id;
  55 static int q_high = 50; /* Percent */
  56
  57 struct cfcnfg *get_cfcnfg(struct net *net)
  58 {
  59         struct caif_net *caifn;
  60         caifn = net_generic(net, caif_net_id);
  61         return caifn->cfg;
  62 }
  63 EXPORT_SYMBOL(get_cfcnfg);
  64
  65 static struct caif_device_entry_list *caif_device_list(struct net *net)
  66 {
  67         struct caif_net *caifn;
  68         caifn = net_generic(net, caif_net_id);
  69         return &caifn->caifdevs;
  70 }
  71
  72 static void caifd_put(struct caif_device_entry *e)
  73 {
  74         this_cpu_dec(*e->pcpu_refcnt);
  75 }
  76
  77 static void caifd_hold(struct caif_device_entry *e)
  78 {
  79         this_cpu_inc(*e->pcpu_refcnt);
  80 }
  81
  82 static int caifd_refcnt_read(struct caif_device_entry *e)
  83 {
  84         int i, refcnt = 0;
  85         for_each_possible_cpu(i)
  86                 refcnt += *per_cpu_ptr(e->pcpu_refcnt, i);
  87         return refcnt;
  88 }
  89
  90 /* Allocate new CAIF device. */
  91 static struct caif_device_entry *caif_device_alloc(struct net_device *dev)
  92 {
  93         struct caif_device_entry_list *caifdevs;
  94         struct caif_device_entry *caifd;
  95
  96         caifdevs = caif_device_list(dev_net(dev));
  97
  98         caifd = kzalloc(sizeof(*caifd), GFP_KERNEL);
  99         if (!caifd)
 100                 return NULL;
 101         caifd->pcpu_refcnt = alloc_percpu(int);
 102         if (!caifd->pcpu_refcnt) {
 103                 kfree(caifd);
 104                 return NULL;
 105         }
 106         caifd->netdev = dev;
 107         dev_hold(dev);
 108         return caifd;
 109 }
 110
 111 static struct caif_device_entry *caif_get(struct net_device *dev)
 112 {
 113         struct caif_device_entry_list *caifdevs =
 114             caif_device_list(dev_net(dev));
 115         struct caif_device_entry *caifd;
 116
 117         list_for_each_entry_rcu(caifd, &caifdevs->list, list) {
 118                 if (caifd->netdev == dev)
 119                         return caifd;
 120         }
 121         return NULL;
 122 }
 123
 124 void caif_flow_cb(struct sk_buff *skb)
 125 {
 126         struct caif_device_entry *caifd;
 127         void (*dtor)(struct sk_buff *skb) = NULL;
 128         bool send_xoff;
 129
 130         WARN_ON(skb->dev == NULL);
 131
 132         rcu_read_lock();
 133         caifd = caif_get(skb->dev);
 134         caifd_hold(caifd);
 135         rcu_read_unlock();
 136
 137         spin_lock_bh(&caifd->flow_lock);
 138         send_xoff = caifd->xoff;
 139         caifd->xoff = 0;
 140         dtor = caifd->xoff_skb_dtor;
 141
 142         if (WARN_ON(caifd->xoff_skb != skb))
 143                 skb = NULL;
 144
 145         caifd->xoff_skb = NULL;
 146         caifd->xoff_skb_dtor = NULL;
 147
 148         spin_unlock_bh(&caifd->flow_lock);
 149
 150         if (dtor && skb)
 151                 dtor(skb);
 152
 153         if (send_xoff)
 154                 caifd->layer.up->
 155                         ctrlcmd(caifd->layer.up,
 156                                 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
 157                                 caifd->layer.id);
 158         caifd_put(caifd);
 159 }
 160
 161 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
 162 {
 163         int err, high = 0, qlen = 0;
 164         struct caif_device_entry *caifd =
 165             container_of(layer, struct caif_device_entry, layer);
 166         struct sk_buff *skb;
 167         struct netdev_queue *txq;
 168
 169         rcu_read_lock_bh();
 170
 171         skb = cfpkt_tonative(pkt);
 172         skb->dev = caifd->netdev;
 173         skb_reset_network_header(skb);
 174         skb->protocol = htons(ETH_P_CAIF);
 175
 176         /* Check if we need to handle xoff */
 177         if (likely(caifd->netdev->tx_queue_len == 0))
 178                 goto noxoff;
 179
 180         if (unlikely(caifd->xoff))
 181                 goto noxoff;
 182
 183         if (likely(!netif_queue_stopped(caifd->netdev))) {
 184                 /* If we run with a TX queue, check if the queue is too long*/
 185                 txq = netdev_get_tx_queue(skb->dev, 0);
 186                 qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
 187
 188                 if (likely(qlen == 0))
 189                         goto noxoff;
 190
 191                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
 192                 if (likely(qlen < high))
 193                         goto noxoff;
 194         }
 195
 196         /* Hold lock while accessing xoff */
 197         spin_lock_bh(&caifd->flow_lock);
 198         if (caifd->xoff) {
 199                 spin_unlock_bh(&caifd->flow_lock);
 200                 goto noxoff;
 201         }
 202
 203         /*
 204          * Handle flow off, we do this by temporary hi-jacking this
 205          * skb's destructor function, and replace it with our own
 206          * flow-on callback. The callback will set flow-on and call
 207          * the original destructor.
 208          */
 209
 210         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
 211                         netif_queue_stopped(caifd->netdev),
 212                         qlen, high);
 213         caifd->xoff = 1;
 214         caifd->xoff_skb = skb;
 215         caifd->xoff_skb_dtor = skb->destructor;
 216         skb->destructor = caif_flow_cb;
 217         spin_unlock_bh(&caifd->flow_lock);
 218
 219         caifd->layer.up->ctrlcmd(caifd->layer.up,
 220                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 221                                         caifd->layer.id);
 222 noxoff:
 223         rcu_read_unlock_bh();
 224
 225         err = dev_queue_xmit(skb);
 226         if (err > 0)
 227                 err = -EIO;
 228
 229         return err;
 230 }
 231
 232 /*
 233  * Stuff received packets into the CAIF stack.
 234  * On error, returns non-zero and releases the skb.
 235  */
 236 static int receive(struct sk_buff *skb, struct net_device *dev,
 237                    struct packet_type *pkttype, struct net_device *orig_dev)
 238 {
 239         struct cfpkt *pkt;
 240         struct caif_device_entry *caifd;
 241         int err;
 242
 243         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
 244
 245         rcu_read_lock();
 246         caifd = caif_get(dev);
 247
 248         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
 249                         !netif_oper_up(caifd->netdev)) {
 250                 rcu_read_unlock();
 251                 kfree_skb(skb);
 252                 return NET_RX_DROP;
 253         }
 254
 255         /* Hold reference to netdevice while using CAIF stack */
 256         caifd_hold(caifd);
 257         rcu_read_unlock();
 258
 259         err = caifd->layer.up->receive(caifd->layer.up, pkt);
 260
 261         /* For -EILSEQ the packet is not freed so so it now */
 262         if (err == -EILSEQ)
 263                 cfpkt_destroy(pkt);
 264
 265         /* Release reference to stack upwards */
 266         caifd_put(caifd);
 267
 268         if (err != 0)
 269                 err = NET_RX_DROP;
 270         return err;
 271 }
 272
 273 static struct packet_type caif_packet_type __read_mostly = {
 274         .type = cpu_to_be16(ETH_P_CAIF),
 275         .func = receive,
 276 };
 277
 278 static void dev_flowctrl(struct net_device *dev, int on)
 279 {
 280         struct caif_device_entry *caifd;
 281
 282         rcu_read_lock();
 283
 284         caifd = caif_get(dev);
 285         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 286                 rcu_read_unlock();
 287                 return;
 288         }
 289
 290         caifd_hold(caifd);
 291         rcu_read_unlock();
 292
 293         caifd->layer.up->ctrlcmd(caifd->layer.up,
 294                                  on ?
 295                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
 296                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 297                                  caifd->layer.id);
 298         caifd_put(caifd);
 299 }
 300
 301 void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 302                         struct cflayer *link_support, int head_room,
 303                         struct cflayer **layer, int (**rcv_func)(
 304                                 struct sk_buff *, struct net_device *,
 305                                 struct packet_type *, struct net_device *))
 306 {
 307         struct caif_device_entry *caifd;
 308         enum cfcnfg_phy_preference pref;
 309         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
 310         struct caif_device_entry_list *caifdevs;
 311
 312         caifdevs = caif_device_list(dev_net(dev));
 313         caifd = caif_device_alloc(dev);
 314         if (!caifd)
 315                 return;
 316         *layer = &caifd->layer;
 317         spin_lock_init(&caifd->flow_lock);
 318
 319         switch (caifdev->link_select) {
 320         case CAIF_LINK_HIGH_BANDW:
 321                 pref = CFPHYPREF_HIGH_BW;
 322                 break;
 323         case CAIF_LINK_LOW_LATENCY:
 324                 pref = CFPHYPREF_LOW_LAT;
 325                 break;
 326         default:
 327                 pref = CFPHYPREF_HIGH_BW;
 328                 break;
 329         }
 330         mutex_lock(&caifdevs->lock);
 331         list_add_rcu(&caifd->list, &caifdevs->list);
 332
 333         strncpy(caifd->layer.name, dev->name,
 334                 sizeof(caifd->layer.name) - 1);
 335         caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
 336         caifd->layer.transmit = transmit;
 337         cfcnfg_add_phy_layer(cfg,
 338                                 dev,
 339                                 &caifd->layer,
 340                                 pref,
 341                                 link_support,
 342                                 caifdev->use_fcs,
 343                                 head_room);
 344         mutex_unlock(&caifdevs->lock);
 345         if (rcv_func)
 346                 *rcv_func = receive;
 347 }
 348 EXPORT_SYMBOL(caif_enroll_dev);
 349
 350 /* notify Caif of device events */
 351 static int caif_device_notify(struct notifier_block *me, unsigned long what,
 352                               void *arg)
 353 {
 354         struct net_device *dev = arg;
 355         struct caif_device_entry *caifd = NULL;
 356         struct caif_dev_common *caifdev;
 357         struct cfcnfg *cfg;
 358         struct cflayer *layer, *link_support;
 359         int head_room = 0;
 360         struct caif_device_entry_list *caifdevs;
 361
 362         cfg = get_cfcnfg(dev_net(dev));
 363         caifdevs = caif_device_list(dev_net(dev));
 364
 365         caifd = caif_get(dev);
 366         if (caifd == NULL && dev->type != ARPHRD_CAIF)
 367                 return 0;
 368
 369         switch (what) {
 370         case NETDEV_REGISTER:
 371                 if (caifd != NULL)
 372                         break;
 373
 374                 caifdev = netdev_priv(dev);
 375
 376                 link_support = NULL;
 377                 if (caifdev->use_frag) {
 378                         head_room = 1;
 379                         link_support = cfserl_create(dev->ifindex,
 380                                                         caifdev->use_stx);
 381                         if (!link_support) {
 382                                 pr_warn("Out of memory\n");
 383                                 break;
 384                         }
 385                 }
 386                 caif_enroll_dev(dev, caifdev, link_support, head_room,
 387                                 &layer, NULL);
 388                 caifdev->flowctrl = dev_flowctrl;
 389                 break;
 390
 391         case NETDEV_UP:
 392                 rcu_read_lock();
 393
 394                 caifd = caif_get(dev);
 395                 if (caifd == NULL) {
 396                         rcu_read_unlock();
 397                         break;
 398                 }
 399
 400                 caifd->xoff = 0;
 401                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
 402                 rcu_read_unlock();
 403
 404                 break;
 405
 406         case NETDEV_DOWN:
 407                 rcu_read_lock();
 408
 409                 caifd = caif_get(dev);
 410                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 411                         rcu_read_unlock();
 412                         return -EINVAL;
 413                 }
 414
 415                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 416                 caifd_hold(caifd);
 417                 rcu_read_unlock();
 418
 419                 caifd->layer.up->ctrlcmd(caifd->layer.up,
 420                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
 421                                          caifd->layer.id);
 422
 423                 spin_lock_bh(&caifd->flow_lock);
 424
 425                 /*
 426                  * Replace our xoff-destructor with original destructor.
 427                  * We trust that skb->destructor *always* is called before
 428                  * the skb reference is invalid. The hijacked SKB destructor
 429                  * takes the flow_lock so manipulating the skb->destructor here
 430                  * should be safe.
 431                 */
 432                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
 433                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
 434
 435                 caifd->xoff = 0;
 436                 caifd->xoff_skb_dtor = NULL;
 437                 caifd->xoff_skb = NULL;
 438
 439                 spin_unlock_bh(&caifd->flow_lock);
 440                 caifd_put(caifd);
 441                 break;
 442
 443         case NETDEV_UNREGISTER:
 444                 mutex_lock(&caifdevs->lock);
 445
 446                 caifd = caif_get(dev);
 447                 if (caifd == NULL) {
 448                         mutex_unlock(&caifdevs->lock);
 449                         break;
 450                 }
 451                 list_del_rcu(&caifd->list);
 452
 453                 /*
 454                  * NETDEV_UNREGISTER is called repeatedly until all reference
 455                  * counts for the net-device are released. If references to
 456                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
 457                  * the next call to NETDEV_UNREGISTER.
 458                  *
 459                  * If any packets are in flight down the CAIF Stack,
 460                  * cfcnfg_del_phy_layer will return nonzero.
 461                  * If no packets are in flight, the CAIF Stack associated
 462                  * with the net-device un-registering is freed.
 463                  */
 464
 465                 if (caifd_refcnt_read(caifd) != 0 ||
 466                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
 467
 468                         pr_info("Wait for device inuse\n");
 469                         /* Enrole device if CAIF Stack is still in use */
 470                         list_add_rcu(&caifd->list, &caifdevs->list);
 471                         mutex_unlock(&caifdevs->lock);
 472                         break;
 473                 }
 474
 475                 synchronize_rcu();
 476                 dev_put(caifd->netdev);
 477                 free_percpu(caifd->pcpu_refcnt);
 478                 kfree(caifd);
 479
 480                 mutex_unlock(&caifdevs->lock);
 481                 break;
 482         }
 483         return 0;
 484 }
 485
 486 static struct notifier_block caif_device_notifier = {
 487         .notifier_call = caif_device_notify,
 488         .priority = 0,
 489 };
 490
 491 /* Per-namespace Caif devices handling */
 492 static int caif_init_net(struct net *net)
 493 {
 494         struct caif_net *caifn = net_generic(net, caif_net_id);
 495         INIT_LIST_HEAD(&caifn->caifdevs.list);
 496         mutex_init(&caifn->caifdevs.lock);
 497
 498         caifn->cfg = cfcnfg_create();
 499         if (!caifn->cfg)
 500                 return -ENOMEM;
 501
 502         return 0;
 503 }
 504
 505 static void caif_exit_net(struct net *net)
 506 {
 507         struct caif_device_entry *caifd, *tmp;
 508         struct caif_device_entry_list *caifdevs =
 509             caif_device_list(net);
 510         struct cfcnfg *cfg =  get_cfcnfg(net);
 511
 512         rtnl_lock();
 513         mutex_lock(&caifdevs->lock);
 514
 515         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
 516                 int i = 0;
 517                 list_del_rcu(&caifd->list);
 518                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 519
 520                 while (i < 10 &&
 521                         (caifd_refcnt_read(caifd) != 0 ||
 522                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
 523
 524                         pr_info("Wait for device inuse\n");
 525                         msleep(250);
 526                         i++;
 527                 }
 528                 synchronize_rcu();
 529                 dev_put(caifd->netdev);
 530                 free_percpu(caifd->pcpu_refcnt);
 531                 kfree(caifd);
 532         }
 533         cfcnfg_remove(cfg);
 534
 535         mutex_unlock(&caifdevs->lock);
 536         rtnl_unlock();
 537 }
 538
 539 static struct pernet_operations caif_net_ops = {
 540         .init = caif_init_net,
 541         .exit = caif_exit_net,
 542         .id   = &caif_net_id,
 543         .size = sizeof(struct caif_net),
 544 };
 545
 546 /* Initialize Caif devices list */
 547 static int __init caif_device_init(void)
 548 {
 549         int result;
 550
 551         result = register_pernet_subsys(&caif_net_ops);
 552
 553         if (result)
 554                 return result;
 555
 556         register_netdevice_notifier(&caif_device_notifier);
 557         dev_add_pack(&caif_packet_type);
 558
 559         return result;
 560 }
 561
 562 static void __exit caif_device_exit(void)
 563 {
 564         unregister_pernet_subsys(&caif_net_ops);
 565         unregister_netdevice_notifier(&caif_device_notifier);
 566         dev_remove_pack(&caif_packet_type);
 567 }
 568
 569 module_init(caif_device_init);
 570 module_exit(caif_device_exit);