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/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 *caifd;
  94
  95         caifd = kzalloc(sizeof(*caifd), GFP_KERNEL);
  96         if (!caifd)
  97                 return NULL;
  98         caifd->pcpu_refcnt = alloc_percpu(int);
  99         if (!caifd->pcpu_refcnt) {
 100                 kfree(caifd);
 101                 return NULL;
 102         }
 103         caifd->netdev = dev;
 104         dev_hold(dev);
 105         return caifd;
 106 }
 107
 108 static struct caif_device_entry *caif_get(struct net_device *dev)
 109 {
 110         struct caif_device_entry_list *caifdevs =
 111             caif_device_list(dev_net(dev));
 112         struct caif_device_entry *caifd;
 113
 114         list_for_each_entry_rcu(caifd, &caifdevs->list, list) {
 115                 if (caifd->netdev == dev)
 116                         return caifd;
 117         }
 118         return NULL;
 119 }
 120
 121 static void caif_flow_cb(struct sk_buff *skb)
 122 {
 123         struct caif_device_entry *caifd;
 124         void (*dtor)(struct sk_buff *skb) = NULL;
 125         bool send_xoff;
 126
 127         WARN_ON(skb->dev == NULL);
 128
 129         rcu_read_lock();
 130         caifd = caif_get(skb->dev);
 131
 132         WARN_ON(caifd == NULL);
 133         if (caifd == NULL)
 134                 return;
 135
 136         caifd_hold(caifd);
 137         rcu_read_unlock();
 138
 139         spin_lock_bh(&caifd->flow_lock);
 140         send_xoff = caifd->xoff;
 141         caifd->xoff = 0;
 142         dtor = caifd->xoff_skb_dtor;
 143
 144         if (WARN_ON(caifd->xoff_skb != skb))
 145                 skb = NULL;
 146
 147         caifd->xoff_skb = NULL;
 148         caifd->xoff_skb_dtor = NULL;
 149
 150         spin_unlock_bh(&caifd->flow_lock);
 151
 152         if (dtor && skb)
 153                 dtor(skb);
 154
 155         if (send_xoff)
 156                 caifd->layer.up->
 157                         ctrlcmd(caifd->layer.up,
 158                                 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
 159                                 caifd->layer.id);
 160         caifd_put(caifd);
 161 }
 162
 163 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
 164 {
 165         int err, high = 0, qlen = 0;
 166         struct caif_device_entry *caifd =
 167             container_of(layer, struct caif_device_entry, layer);
 168         struct sk_buff *skb;
 169         struct netdev_queue *txq;
 170
 171         rcu_read_lock_bh();
 172
 173         skb = cfpkt_tonative(pkt);
 174         skb->dev = caifd->netdev;
 175         skb_reset_network_header(skb);
 176         skb->protocol = htons(ETH_P_CAIF);
 177
 178         /* Check if we need to handle xoff */
 179         if (likely(caifd->netdev->tx_queue_len == 0))
 180                 goto noxoff;
 181
 182         if (unlikely(caifd->xoff))
 183                 goto noxoff;
 184
 185         if (likely(!netif_queue_stopped(caifd->netdev))) {
 186                 /* If we run with a TX queue, check if the queue is too long*/
 187                 txq = netdev_get_tx_queue(skb->dev, 0);
 188                 qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
 189
 190                 if (likely(qlen == 0))
 191                         goto noxoff;
 192
 193                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
 194                 if (likely(qlen < high))
 195                         goto noxoff;
 196         }
 197
 198         /* Hold lock while accessing xoff */
 199         spin_lock_bh(&caifd->flow_lock);
 200         if (caifd->xoff) {
 201                 spin_unlock_bh(&caifd->flow_lock);
 202                 goto noxoff;
 203         }
 204
 205         /*
 206          * Handle flow off, we do this by temporary hi-jacking this
 207          * skb's destructor function, and replace it with our own
 208          * flow-on callback. The callback will set flow-on and call
 209          * the original destructor.
 210          */
 211
 212         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
 213                         netif_queue_stopped(caifd->netdev),
 214                         qlen, high);
 215         caifd->xoff = 1;
 216         caifd->xoff_skb = skb;
 217         caifd->xoff_skb_dtor = skb->destructor;
 218         skb->destructor = caif_flow_cb;
 219         spin_unlock_bh(&caifd->flow_lock);
 220
 221         caifd->layer.up->ctrlcmd(caifd->layer.up,
 222                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 223                                         caifd->layer.id);
 224 noxoff:
 225         rcu_read_unlock_bh();
 226
 227         err = dev_queue_xmit(skb);
 228         if (err > 0)
 229                 err = -EIO;
 230
 231         return err;
 232 }
 233
 234 /*
 235  * Stuff received packets into the CAIF stack.
 236  * On error, returns non-zero and releases the skb.
 237  */
 238 static int receive(struct sk_buff *skb, struct net_device *dev,
 239                    struct packet_type *pkttype, struct net_device *orig_dev)
 240 {
 241         struct cfpkt *pkt;
 242         struct caif_device_entry *caifd;
 243         int err;
 244
 245         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
 246
 247         rcu_read_lock();
 248         caifd = caif_get(dev);
 249
 250         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
 251                         !netif_oper_up(caifd->netdev)) {
 252                 rcu_read_unlock();
 253                 kfree_skb(skb);
 254                 return NET_RX_DROP;
 255         }
 256
 257         /* Hold reference to netdevice while using CAIF stack */
 258         caifd_hold(caifd);
 259         rcu_read_unlock();
 260
 261         err = caifd->layer.up->receive(caifd->layer.up, pkt);
 262
 263         /* For -EILSEQ the packet is not freed so so it now */
 264         if (err == -EILSEQ)
 265                 cfpkt_destroy(pkt);
 266
 267         /* Release reference to stack upwards */
 268         caifd_put(caifd);
 269
 270         if (err != 0)
 271                 err = NET_RX_DROP;
 272         return err;
 273 }
 274
 275 static struct packet_type caif_packet_type __read_mostly = {
 276         .type = cpu_to_be16(ETH_P_CAIF),
 277         .func = receive,
 278 };
 279
 280 static void dev_flowctrl(struct net_device *dev, int on)
 281 {
 282         struct caif_device_entry *caifd;
 283
 284         rcu_read_lock();
 285
 286         caifd = caif_get(dev);
 287         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 288                 rcu_read_unlock();
 289                 return;
 290         }
 291
 292         caifd_hold(caifd);
 293         rcu_read_unlock();
 294
 295         caifd->layer.up->ctrlcmd(caifd->layer.up,
 296                                  on ?
 297                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
 298                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 299                                  caifd->layer.id);
 300         caifd_put(caifd);
 301 }
 302
 303 void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 304                      struct cflayer *link_support, int head_room,
 305                      struct cflayer **layer,
 306                      int (**rcv_func)(struct sk_buff *, struct net_device *,
 307                                       struct packet_type *,
 308                                       struct net_device *))
 309 {
 310         struct caif_device_entry *caifd;
 311         enum cfcnfg_phy_preference pref;
 312         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
 313         struct caif_device_entry_list *caifdevs;
 314
 315         caifdevs = caif_device_list(dev_net(dev));
 316         caifd = caif_device_alloc(dev);
 317         if (!caifd)
 318                 return;
 319         *layer = &caifd->layer;
 320         spin_lock_init(&caifd->flow_lock);
 321
 322         switch (caifdev->link_select) {
 323         case CAIF_LINK_HIGH_BANDW:
 324                 pref = CFPHYPREF_HIGH_BW;
 325                 break;
 326         case CAIF_LINK_LOW_LATENCY:
 327                 pref = CFPHYPREF_LOW_LAT;
 328                 break;
 329         default:
 330                 pref = CFPHYPREF_HIGH_BW;
 331                 break;
 332         }
 333         mutex_lock(&caifdevs->lock);
 334         list_add_rcu(&caifd->list, &caifdevs->list);
 335
 336         strncpy(caifd->layer.name, dev->name,
 337                 sizeof(caifd->layer.name) - 1);
 338         caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
 339         caifd->layer.transmit = transmit;
 340         cfcnfg_add_phy_layer(cfg,
 341                                 dev,
 342                                 &caifd->layer,
 343                                 pref,
 344                                 link_support,
 345                                 caifdev->use_fcs,
 346                                 head_room);
 347         mutex_unlock(&caifdevs->lock);
 348         if (rcv_func)
 349                 *rcv_func = receive;
 350 }
 351 EXPORT_SYMBOL(caif_enroll_dev);
 352
 353 /* notify Caif of device events */
 354 static int caif_device_notify(struct notifier_block *me, unsigned long what,
 355                               void *arg)
 356 {
 357         struct net_device *dev = arg;
 358         struct caif_device_entry *caifd = NULL;
 359         struct caif_dev_common *caifdev;
 360         struct cfcnfg *cfg;
 361         struct cflayer *layer, *link_support;
 362         int head_room = 0;
 363         struct caif_device_entry_list *caifdevs;
 364
 365         cfg = get_cfcnfg(dev_net(dev));
 366         caifdevs = caif_device_list(dev_net(dev));
 367
 368         caifd = caif_get(dev);
 369         if (caifd == NULL && dev->type != ARPHRD_CAIF)
 370                 return 0;
 371
 372         switch (what) {
 373         case NETDEV_REGISTER:
 374                 if (caifd != NULL)
 375                         break;
 376
 377                 caifdev = netdev_priv(dev);
 378
 379                 link_support = NULL;
 380                 if (caifdev->use_frag) {
 381                         head_room = 1;
 382                         link_support = cfserl_create(dev->ifindex,
 383                                                         caifdev->use_stx);
 384                         if (!link_support) {
 385                                 pr_warn("Out of memory\n");
 386                                 break;
 387                         }
 388                 }
 389                 caif_enroll_dev(dev, caifdev, link_support, head_room,
 390                                 &layer, NULL);
 391                 caifdev->flowctrl = dev_flowctrl;
 392                 break;
 393
 394         case NETDEV_UP:
 395                 rcu_read_lock();
 396
 397                 caifd = caif_get(dev);
 398                 if (caifd == NULL) {
 399                         rcu_read_unlock();
 400                         break;
 401                 }
 402
 403                 caifd->xoff = 0;
 404                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
 405                 rcu_read_unlock();
 406
 407                 break;
 408
 409         case NETDEV_DOWN:
 410                 rcu_read_lock();
 411
 412                 caifd = caif_get(dev);
 413                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 414                         rcu_read_unlock();
 415                         return -EINVAL;
 416                 }
 417
 418                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 419                 caifd_hold(caifd);
 420                 rcu_read_unlock();
 421
 422                 caifd->layer.up->ctrlcmd(caifd->layer.up,
 423                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
 424                                          caifd->layer.id);
 425
 426                 spin_lock_bh(&caifd->flow_lock);
 427
 428                 /*
 429                  * Replace our xoff-destructor with original destructor.
 430                  * We trust that skb->destructor *always* is called before
 431                  * the skb reference is invalid. The hijacked SKB destructor
 432                  * takes the flow_lock so manipulating the skb->destructor here
 433                  * should be safe.
 434                 */
 435                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
 436                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
 437
 438                 caifd->xoff = 0;
 439                 caifd->xoff_skb_dtor = NULL;
 440                 caifd->xoff_skb = NULL;
 441
 442                 spin_unlock_bh(&caifd->flow_lock);
 443                 caifd_put(caifd);
 444                 break;
 445
 446         case NETDEV_UNREGISTER:
 447                 mutex_lock(&caifdevs->lock);
 448
 449                 caifd = caif_get(dev);
 450                 if (caifd == NULL) {
 451                         mutex_unlock(&caifdevs->lock);
 452                         break;
 453                 }
 454                 list_del_rcu(&caifd->list);
 455
 456                 /*
 457                  * NETDEV_UNREGISTER is called repeatedly until all reference
 458                  * counts for the net-device are released. If references to
 459                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
 460                  * the next call to NETDEV_UNREGISTER.
 461                  *
 462                  * If any packets are in flight down the CAIF Stack,
 463                  * cfcnfg_del_phy_layer will return nonzero.
 464                  * If no packets are in flight, the CAIF Stack associated
 465                  * with the net-device un-registering is freed.
 466                  */
 467
 468                 if (caifd_refcnt_read(caifd) != 0 ||
 469                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
 470
 471                         pr_info("Wait for device inuse\n");
 472                         /* Enrole device if CAIF Stack is still in use */
 473                         list_add_rcu(&caifd->list, &caifdevs->list);
 474                         mutex_unlock(&caifdevs->lock);
 475                         break;
 476                 }
 477
 478                 synchronize_rcu();
 479                 dev_put(caifd->netdev);
 480                 free_percpu(caifd->pcpu_refcnt);
 481                 kfree(caifd);
 482
 483                 mutex_unlock(&caifdevs->lock);
 484                 break;
 485         }
 486         return 0;
 487 }
 488
 489 static struct notifier_block caif_device_notifier = {
 490         .notifier_call = caif_device_notify,
 491         .priority = 0,
 492 };
 493
 494 /* Per-namespace Caif devices handling */
 495 static int caif_init_net(struct net *net)
 496 {
 497         struct caif_net *caifn = net_generic(net, caif_net_id);
 498         INIT_LIST_HEAD(&caifn->caifdevs.list);
 499         mutex_init(&caifn->caifdevs.lock);
 500
 501         caifn->cfg = cfcnfg_create();
 502         if (!caifn->cfg)
 503                 return -ENOMEM;
 504
 505         return 0;
 506 }
 507
 508 static void caif_exit_net(struct net *net)
 509 {
 510         struct caif_device_entry *caifd, *tmp;
 511         struct caif_device_entry_list *caifdevs =
 512             caif_device_list(net);
 513         struct cfcnfg *cfg =  get_cfcnfg(net);
 514
 515         rtnl_lock();
 516         mutex_lock(&caifdevs->lock);
 517
 518         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
 519                 int i = 0;
 520                 list_del_rcu(&caifd->list);
 521                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 522
 523                 while (i < 10 &&
 524                         (caifd_refcnt_read(caifd) != 0 ||
 525                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
 526
 527                         pr_info("Wait for device inuse\n");
 528                         msleep(250);
 529                         i++;
 530                 }
 531                 synchronize_rcu();
 532                 dev_put(caifd->netdev);
 533                 free_percpu(caifd->pcpu_refcnt);
 534                 kfree(caifd);
 535         }
 536         cfcnfg_remove(cfg);
 537
 538         mutex_unlock(&caifdevs->lock);
 539         rtnl_unlock();
 540 }
 541
 542 static struct pernet_operations caif_net_ops = {
 543         .init = caif_init_net,
 544         .exit = caif_exit_net,
 545         .id   = &caif_net_id,
 546         .size = sizeof(struct caif_net),
 547 };
 548
 549 /* Initialize Caif devices list */
 550 static int __init caif_device_init(void)
 551 {
 552         int result;
 553
 554         result = register_pernet_subsys(&caif_net_ops);
 555
 556         if (result)
 557                 return result;
 558
 559         register_netdevice_notifier(&caif_device_notifier);
 560         dev_add_pack(&caif_packet_type);
 561
 562         return result;
 563 }
 564
 565 static void __exit caif_device_exit(void)
 566 {
 567         unregister_netdevice_notifier(&caif_device_notifier);
 568         dev_remove_pack(&caif_packet_type);
 569         unregister_pernet_subsys(&caif_net_ops);
 570 }
 571
 572 module_init(caif_device_init);
 573 module_exit(caif_device_exit);