net/caif/caif_dev.c

   1 /*
   2  * CAIF Interface registration.
   3  * Copyright (C) ST-Ericsson AB 2010
   4  * Author:      Sjur Brendeland
   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/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 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 == NULL)
 135                 return;
 136
 137         caifd_hold(caifd);
 138         rcu_read_unlock();
 139
 140         spin_lock_bh(&caifd->flow_lock);
 141         send_xoff = caifd->xoff;
 142         caifd->xoff = 0;
 143         dtor = caifd->xoff_skb_dtor;
 144
 145         if (WARN_ON(caifd->xoff_skb != skb))
 146                 skb = NULL;
 147
 148         caifd->xoff_skb = NULL;
 149         caifd->xoff_skb_dtor = NULL;
 150
 151         spin_unlock_bh(&caifd->flow_lock);
 152
 153         if (dtor && skb)
 154                 dtor(skb);
 155
 156         if (send_xoff)
 157                 caifd->layer.up->
 158                         ctrlcmd(caifd->layer.up,
 159                                 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
 160                                 caifd->layer.id);
 161         caifd_put(caifd);
 162 }
 163
 164 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
 165 {
 166         int err, high = 0, qlen = 0;
 167         struct caif_device_entry *caifd =
 168             container_of(layer, struct caif_device_entry, layer);
 169         struct sk_buff *skb;
 170         struct netdev_queue *txq;
 171
 172         rcu_read_lock_bh();
 173
 174         skb = cfpkt_tonative(pkt);
 175         skb->dev = caifd->netdev;
 176         skb_reset_network_header(skb);
 177         skb->protocol = htons(ETH_P_CAIF);
 178
 179         /* Check if we need to handle xoff */
 180         if (likely(caifd->netdev->tx_queue_len == 0))
 181                 goto noxoff;
 182
 183         if (unlikely(caifd->xoff))
 184                 goto noxoff;
 185
 186         if (likely(!netif_queue_stopped(caifd->netdev))) {
 187                 /* If we run with a TX queue, check if the queue is too long*/
 188                 txq = netdev_get_tx_queue(skb->dev, 0);
 189                 qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
 190
 191                 if (likely(qlen == 0))
 192                         goto noxoff;
 193
 194                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
 195                 if (likely(qlen < high))
 196                         goto noxoff;
 197         }
 198
 199         /* Hold lock while accessing xoff */
 200         spin_lock_bh(&caifd->flow_lock);
 201         if (caifd->xoff) {
 202                 spin_unlock_bh(&caifd->flow_lock);
 203                 goto noxoff;
 204         }
 205
 206         /*
 207          * Handle flow off, we do this by temporary hi-jacking this
 208          * skb's destructor function, and replace it with our own
 209          * flow-on callback. The callback will set flow-on and call
 210          * the original destructor.
 211          */
 212
 213         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
 214                         netif_queue_stopped(caifd->netdev),
 215                         qlen, high);
 216         caifd->xoff = 1;
 217         caifd->xoff_skb = skb;
 218         caifd->xoff_skb_dtor = skb->destructor;
 219         skb->destructor = caif_flow_cb;
 220         spin_unlock_bh(&caifd->flow_lock);
 221
 222         caifd->layer.up->ctrlcmd(caifd->layer.up,
 223                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 224                                         caifd->layer.id);
 225 noxoff:
 226         rcu_read_unlock_bh();
 227
 228         err = dev_queue_xmit(skb);
 229         if (err > 0)
 230                 err = -EIO;
 231
 232         return err;
 233 }
 234
 235 /*
 236  * Stuff received packets into the CAIF stack.
 237  * On error, returns non-zero and releases the skb.
 238  */
 239 static int receive(struct sk_buff *skb, struct net_device *dev,
 240                    struct packet_type *pkttype, struct net_device *orig_dev)
 241 {
 242         struct cfpkt *pkt;
 243         struct caif_device_entry *caifd;
 244         int err;
 245
 246         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
 247
 248         rcu_read_lock();
 249         caifd = caif_get(dev);
 250
 251         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
 252                         !netif_oper_up(caifd->netdev)) {
 253                 rcu_read_unlock();
 254                 kfree_skb(skb);
 255                 return NET_RX_DROP;
 256         }
 257
 258         /* Hold reference to netdevice while using CAIF stack */
 259         caifd_hold(caifd);
 260         rcu_read_unlock();
 261
 262         err = caifd->layer.up->receive(caifd->layer.up, pkt);
 263
 264         /* For -EILSEQ the packet is not freed so so it now */
 265         if (err == -EILSEQ)
 266                 cfpkt_destroy(pkt);
 267
 268         /* Release reference to stack upwards */
 269         caifd_put(caifd);
 270
 271         if (err != 0)
 272                 err = NET_RX_DROP;
 273         return err;
 274 }
 275
 276 static struct packet_type caif_packet_type __read_mostly = {
 277         .type = cpu_to_be16(ETH_P_CAIF),
 278         .func = receive,
 279 };
 280
 281 static void dev_flowctrl(struct net_device *dev, int on)
 282 {
 283         struct caif_device_entry *caifd;
 284
 285         rcu_read_lock();
 286
 287         caifd = caif_get(dev);
 288         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 289                 rcu_read_unlock();
 290                 return;
 291         }
 292
 293         caifd_hold(caifd);
 294         rcu_read_unlock();
 295
 296         caifd->layer.up->ctrlcmd(caifd->layer.up,
 297                                  on ?
 298                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
 299                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 300                                  caifd->layer.id);
 301         caifd_put(caifd);
 302 }
 303
 304 void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 305                      struct cflayer *link_support, int head_room,
 306                      struct cflayer **layer,
 307                      int (**rcv_func)(struct sk_buff *, struct net_device *,
 308                                       struct packet_type *,
 309                                       struct net_device *))
 310 {
 311         struct caif_device_entry *caifd;
 312         enum cfcnfg_phy_preference pref;
 313         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
 314         struct caif_device_entry_list *caifdevs;
 315
 316         caifdevs = caif_device_list(dev_net(dev));
 317         caifd = caif_device_alloc(dev);
 318         if (!caifd)
 319                 return;
 320         *layer = &caifd->layer;
 321         spin_lock_init(&caifd->flow_lock);
 322
 323         switch (caifdev->link_select) {
 324         case CAIF_LINK_HIGH_BANDW:
 325                 pref = CFPHYPREF_HIGH_BW;
 326                 break;
 327         case CAIF_LINK_LOW_LATENCY:
 328                 pref = CFPHYPREF_LOW_LAT;
 329                 break;
 330         default:
 331                 pref = CFPHYPREF_HIGH_BW;
 332                 break;
 333         }
 334         mutex_lock(&caifdevs->lock);
 335         list_add_rcu(&caifd->list, &caifdevs->list);
 336
 337         strncpy(caifd->layer.name, dev->name,
 338                 sizeof(caifd->layer.name) - 1);
 339         caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
 340         caifd->layer.transmit = transmit;
 341         cfcnfg_add_phy_layer(cfg,
 342                                 dev,
 343                                 &caifd->layer,
 344                                 pref,
 345                                 link_support,
 346                                 caifdev->use_fcs,
 347                                 head_room);
 348         mutex_unlock(&caifdevs->lock);
 349         if (rcv_func)
 350                 *rcv_func = receive;
 351 }
 352 EXPORT_SYMBOL(caif_enroll_dev);
 353
 354 /* notify Caif of device events */
 355 static int caif_device_notify(struct notifier_block *me, unsigned long what,
 356                               void *ptr)
 357 {
 358         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 359         struct caif_device_entry *caifd = NULL;
 360         struct caif_dev_common *caifdev;
 361         struct cfcnfg *cfg;
 362         struct cflayer *layer, *link_support;
 363         int head_room = 0;
 364         struct caif_device_entry_list *caifdevs;
 365
 366         cfg = get_cfcnfg(dev_net(dev));
 367         caifdevs = caif_device_list(dev_net(dev));
 368
 369         caifd = caif_get(dev);
 370         if (caifd == NULL && dev->type != ARPHRD_CAIF)
 371                 return 0;
 372
 373         switch (what) {
 374         case NETDEV_REGISTER:
 375                 if (caifd != NULL)
 376                         break;
 377
 378                 caifdev = netdev_priv(dev);
 379
 380                 link_support = NULL;
 381                 if (caifdev->use_frag) {
 382                         head_room = 1;
 383                         link_support = cfserl_create(dev->ifindex,
 384                                                         caifdev->use_stx);
 385                         if (!link_support) {
 386                                 pr_warn("Out of memory\n");
 387                                 break;
 388                         }
 389                 }
 390                 caif_enroll_dev(dev, caifdev, link_support, head_room,
 391                                 &layer, NULL);
 392                 caifdev->flowctrl = dev_flowctrl;
 393                 break;
 394
 395         case NETDEV_UP:
 396                 rcu_read_lock();
 397
 398                 caifd = caif_get(dev);
 399                 if (caifd == NULL) {
 400                         rcu_read_unlock();
 401                         break;
 402                 }
 403
 404                 caifd->xoff = 0;
 405                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
 406                 rcu_read_unlock();
 407
 408                 break;
 409
 410         case NETDEV_DOWN:
 411                 rcu_read_lock();
 412
 413                 caifd = caif_get(dev);
 414                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 415                         rcu_read_unlock();
 416                         return -EINVAL;
 417                 }
 418
 419                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 420                 caifd_hold(caifd);
 421                 rcu_read_unlock();
 422
 423                 caifd->layer.up->ctrlcmd(caifd->layer.up,
 424                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
 425                                          caifd->layer.id);
 426
 427                 spin_lock_bh(&caifd->flow_lock);
 428
 429                 /*
 430                  * Replace our xoff-destructor with original destructor.
 431                  * We trust that skb->destructor *always* is called before
 432                  * the skb reference is invalid. The hijacked SKB destructor
 433                  * takes the flow_lock so manipulating the skb->destructor here
 434                  * should be safe.
 435                 */
 436                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
 437                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
 438
 439                 caifd->xoff = 0;
 440                 caifd->xoff_skb_dtor = NULL;
 441                 caifd->xoff_skb = NULL;
 442
 443                 spin_unlock_bh(&caifd->flow_lock);
 444                 caifd_put(caifd);
 445                 break;
 446
 447         case NETDEV_UNREGISTER:
 448                 mutex_lock(&caifdevs->lock);
 449
 450                 caifd = caif_get(dev);
 451                 if (caifd == NULL) {
 452                         mutex_unlock(&caifdevs->lock);
 453                         break;
 454                 }
 455                 list_del_rcu(&caifd->list);
 456
 457                 /*
 458                  * NETDEV_UNREGISTER is called repeatedly until all reference
 459                  * counts for the net-device are released. If references to
 460                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
 461                  * the next call to NETDEV_UNREGISTER.
 462                  *
 463                  * If any packets are in flight down the CAIF Stack,
 464                  * cfcnfg_del_phy_layer will return nonzero.
 465                  * If no packets are in flight, the CAIF Stack associated
 466                  * with the net-device un-registering is freed.
 467                  */
 468
 469                 if (caifd_refcnt_read(caifd) != 0 ||
 470                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
 471
 472                         pr_info("Wait for device inuse\n");
 473                         /* Enrole device if CAIF Stack is still in use */
 474                         list_add_rcu(&caifd->list, &caifdevs->list);
 475                         mutex_unlock(&caifdevs->lock);
 476                         break;
 477                 }
 478
 479                 synchronize_rcu();
 480                 dev_put(caifd->netdev);
 481                 free_percpu(caifd->pcpu_refcnt);
 482                 kfree(caifd);
 483
 484                 mutex_unlock(&caifdevs->lock);
 485                 break;
 486         }
 487         return 0;
 488 }
 489
 490 static struct notifier_block caif_device_notifier = {
 491         .notifier_call = caif_device_notify,
 492         .priority = 0,
 493 };
 494
 495 /* Per-namespace Caif devices handling */
 496 static int caif_init_net(struct net *net)
 497 {
 498         struct caif_net *caifn = net_generic(net, caif_net_id);
 499         INIT_LIST_HEAD(&caifn->caifdevs.list);
 500         mutex_init(&caifn->caifdevs.lock);
 501
 502         caifn->cfg = cfcnfg_create();
 503         if (!caifn->cfg)
 504                 return -ENOMEM;
 505
 506         return 0;
 507 }
 508
 509 static void caif_exit_net(struct net *net)
 510 {
 511         struct caif_device_entry *caifd, *tmp;
 512         struct caif_device_entry_list *caifdevs =
 513             caif_device_list(net);
 514         struct cfcnfg *cfg =  get_cfcnfg(net);
 515
 516         rtnl_lock();
 517         mutex_lock(&caifdevs->lock);
 518
 519         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
 520                 int i = 0;
 521                 list_del_rcu(&caifd->list);
 522                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 523
 524                 while (i < 10 &&
 525                         (caifd_refcnt_read(caifd) != 0 ||
 526                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
 527
 528                         pr_info("Wait for device inuse\n");
 529                         msleep(250);
 530                         i++;
 531                 }
 532                 synchronize_rcu();
 533                 dev_put(caifd->netdev);
 534                 free_percpu(caifd->pcpu_refcnt);
 535                 kfree(caifd);
 536         }
 537         cfcnfg_remove(cfg);
 538
 539         mutex_unlock(&caifdevs->lock);
 540         rtnl_unlock();
 541 }
 542
 543 static struct pernet_operations caif_net_ops = {
 544         .init = caif_init_net,
 545         .exit = caif_exit_net,
 546         .id   = &caif_net_id,
 547         .size = sizeof(struct caif_net),
 548 };
 549
 550 /* Initialize Caif devices list */
 551 static int __init caif_device_init(void)
 552 {
 553         int result;
 554
 555         result = register_pernet_subsys(&caif_net_ops);
 556
 557         if (result)
 558                 return result;
 559
 560         register_netdevice_notifier(&caif_device_notifier);
 561         dev_add_pack(&caif_packet_type);
 562
 563         return result;
 564 }
 565
 566 static void __exit caif_device_exit(void)
 567 {
 568         unregister_netdevice_notifier(&caif_device_notifier);
 569         dev_remove_pack(&caif_packet_type);
 570         unregister_pernet_subsys(&caif_net_ops);
 571 }
 572
 573 module_init(caif_device_init);
 574 module_exit(caif_device_exit);