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         if (!WARN_ON(caifd->xoff_skb_dtor == NULL)) {
 150                 WARN_ON(caifd->xoff_skb != skb);
 151                 dtor = caifd->xoff_skb_dtor;
 152                 caifd->xoff_skb = NULL;
 153                 caifd->xoff_skb_dtor = NULL;
 154         }
 155         spin_unlock_bh(&caifd->flow_lock);
 156
 157         if (dtor)
 158                 dtor(skb);
 159
 160         if (send_xoff)
 161                 caifd->layer.up->
 162                         ctrlcmd(caifd->layer.up,
 163                                 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
 164                                 caifd->layer.id);
 165         caifd_put(caifd);
 166 }
 167
 168 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
 169 {
 170         int err, high = 0, qlen = 0;
 171         struct caif_dev_common *caifdev;
 172         struct caif_device_entry *caifd =
 173             container_of(layer, struct caif_device_entry, layer);
 174         struct sk_buff *skb;
 175         struct netdev_queue *txq;
 176
 177         rcu_read_lock_bh();
 178
 179         skb = cfpkt_tonative(pkt);
 180         skb->dev = caifd->netdev;
 181         skb_reset_network_header(skb);
 182         skb->protocol = htons(ETH_P_CAIF);
 183         caifdev = netdev_priv(caifd->netdev);
 184
 185         /* Check if we need to handle xoff */
 186         if (likely(caifd->netdev->tx_queue_len == 0))
 187                 goto noxoff;
 188
 189         if (unlikely(caifd->xoff))
 190                 goto noxoff;
 191
 192         if (likely(!netif_queue_stopped(caifd->netdev))) {
 193                 /* If we run with a TX queue, check if the queue is too long*/
 194                 txq = netdev_get_tx_queue(skb->dev, 0);
 195                 qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
 196
 197                 if (likely(qlen == 0))
 198                         goto noxoff;
 199
 200                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
 201                 if (likely(qlen < high))
 202                         goto noxoff;
 203         }
 204
 205         /* Hold lock while accessing xoff */
 206         spin_lock_bh(&caifd->flow_lock);
 207         if (caifd->xoff) {
 208                 spin_unlock_bh(&caifd->flow_lock);
 209                 goto noxoff;
 210         }
 211
 212         /*
 213          * Handle flow off, we do this by temporary hi-jacking this
 214          * skb's destructor function, and replace it with our own
 215          * flow-on callback. The callback will set flow-on and call
 216          * the original destructor.
 217          */
 218
 219         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
 220                         netif_queue_stopped(caifd->netdev),
 221                         qlen, high);
 222         caifd->xoff = 1;
 223         caifd->xoff_skb = skb;
 224         caifd->xoff_skb_dtor = skb->destructor;
 225         skb->destructor = caif_flow_cb;
 226         spin_unlock_bh(&caifd->flow_lock);
 227
 228         caifd->layer.up->ctrlcmd(caifd->layer.up,
 229                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 230                                         caifd->layer.id);
 231 noxoff:
 232         rcu_read_unlock_bh();
 233
 234         err = dev_queue_xmit(skb);
 235         if (err > 0)
 236                 err = -EIO;
 237
 238         return err;
 239 }
 240
 241 /*
 242  * Stuff received packets into the CAIF stack.
 243  * On error, returns non-zero and releases the skb.
 244  */
 245 static int receive(struct sk_buff *skb, struct net_device *dev,
 246                    struct packet_type *pkttype, struct net_device *orig_dev)
 247 {
 248         struct cfpkt *pkt;
 249         struct caif_device_entry *caifd;
 250         int err;
 251
 252         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
 253
 254         rcu_read_lock();
 255         caifd = caif_get(dev);
 256
 257         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
 258                         !netif_oper_up(caifd->netdev)) {
 259                 rcu_read_unlock();
 260                 kfree_skb(skb);
 261                 return NET_RX_DROP;
 262         }
 263
 264         /* Hold reference to netdevice while using CAIF stack */
 265         caifd_hold(caifd);
 266         rcu_read_unlock();
 267
 268         err = caifd->layer.up->receive(caifd->layer.up, pkt);
 269
 270         /* For -EILSEQ the packet is not freed so so it now */
 271         if (err == -EILSEQ)
 272                 cfpkt_destroy(pkt);
 273
 274         /* Release reference to stack upwards */
 275         caifd_put(caifd);
 276
 277         if (err != 0)
 278                 err = NET_RX_DROP;
 279         return err;
 280 }
 281
 282 static struct packet_type caif_packet_type __read_mostly = {
 283         .type = cpu_to_be16(ETH_P_CAIF),
 284         .func = receive,
 285 };
 286
 287 static void dev_flowctrl(struct net_device *dev, int on)
 288 {
 289         struct caif_device_entry *caifd;
 290
 291         rcu_read_lock();
 292
 293         caifd = caif_get(dev);
 294         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 295                 rcu_read_unlock();
 296                 return;
 297         }
 298
 299         caifd_hold(caifd);
 300         rcu_read_unlock();
 301
 302         caifd->layer.up->ctrlcmd(caifd->layer.up,
 303                                  on ?
 304                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
 305                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 306                                  caifd->layer.id);
 307         caifd_put(caifd);
 308 }
 309
 310 void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 311                         struct cflayer *link_support, int head_room,
 312                         struct cflayer **layer, int (**rcv_func)(
 313                                 struct sk_buff *, struct net_device *,
 314                                 struct packet_type *, struct net_device *))
 315 {
 316         struct caif_device_entry *caifd;
 317         enum cfcnfg_phy_preference pref;
 318         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
 319         struct caif_device_entry_list *caifdevs;
 320
 321         caifdevs = caif_device_list(dev_net(dev));
 322         if (!cfg || !caifdevs)
 323                 return;
 324         caifd = caif_device_alloc(dev);
 325         if (!caifd)
 326                 return;
 327         *layer = &caifd->layer;
 328         spin_lock_init(&caifd->flow_lock);
 329
 330         switch (caifdev->link_select) {
 331         case CAIF_LINK_HIGH_BANDW:
 332                 pref = CFPHYPREF_HIGH_BW;
 333                 break;
 334         case CAIF_LINK_LOW_LATENCY:
 335                 pref = CFPHYPREF_LOW_LAT;
 336                 break;
 337         default:
 338                 pref = CFPHYPREF_HIGH_BW;
 339                 break;
 340         }
 341         mutex_lock(&caifdevs->lock);
 342         list_add_rcu(&caifd->list, &caifdevs->list);
 343
 344         strncpy(caifd->layer.name, dev->name,
 345                 sizeof(caifd->layer.name) - 1);
 346         caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
 347         caifd->layer.transmit = transmit;
 348         cfcnfg_add_phy_layer(cfg,
 349                                 dev,
 350                                 &caifd->layer,
 351                                 pref,
 352                                 link_support,
 353                                 caifdev->use_fcs,
 354                                 head_room);
 355         mutex_unlock(&caifdevs->lock);
 356         if (rcv_func)
 357                 *rcv_func = receive;
 358 }
 359 EXPORT_SYMBOL(caif_enroll_dev);
 360
 361 /* notify Caif of device events */
 362 static int caif_device_notify(struct notifier_block *me, unsigned long what,
 363                               void *arg)
 364 {
 365         struct net_device *dev = arg;
 366         struct caif_device_entry *caifd = NULL;
 367         struct caif_dev_common *caifdev;
 368         struct cfcnfg *cfg;
 369         struct cflayer *layer, *link_support;
 370         int head_room = 0;
 371         struct caif_device_entry_list *caifdevs;
 372
 373         cfg = get_cfcnfg(dev_net(dev));
 374         caifdevs = caif_device_list(dev_net(dev));
 375         if (!cfg || !caifdevs)
 376                 return 0;
 377
 378         caifd = caif_get(dev);
 379         if (caifd == NULL && dev->type != ARPHRD_CAIF)
 380                 return 0;
 381
 382         switch (what) {
 383         case NETDEV_REGISTER:
 384                 if (caifd != NULL)
 385                         break;
 386
 387                 caifdev = netdev_priv(dev);
 388
 389                 link_support = NULL;
 390                 if (caifdev->use_frag) {
 391                         head_room = 1;
 392                         link_support = cfserl_create(dev->ifindex,
 393                                                         caifdev->use_stx);
 394                         if (!link_support) {
 395                                 pr_warn("Out of memory\n");
 396                                 break;
 397                         }
 398                 }
 399                 caif_enroll_dev(dev, caifdev, link_support, head_room,
 400                                 &layer, NULL);
 401                 caifdev->flowctrl = dev_flowctrl;
 402                 break;
 403
 404         case NETDEV_UP:
 405                 rcu_read_lock();
 406
 407                 caifd = caif_get(dev);
 408                 if (caifd == NULL) {
 409                         rcu_read_unlock();
 410                         break;
 411                 }
 412
 413                 caifd->xoff = 0;
 414                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
 415                 rcu_read_unlock();
 416
 417                 break;
 418
 419         case NETDEV_DOWN:
 420                 rcu_read_lock();
 421
 422                 caifd = caif_get(dev);
 423                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 424                         rcu_read_unlock();
 425                         return -EINVAL;
 426                 }
 427
 428                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 429                 caifd_hold(caifd);
 430                 rcu_read_unlock();
 431
 432                 caifd->layer.up->ctrlcmd(caifd->layer.up,
 433                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
 434                                          caifd->layer.id);
 435
 436                 spin_lock_bh(&caifd->flow_lock);
 437
 438                 /*
 439                  * Replace our xoff-destructor with original destructor.
 440                  * We trust that skb->destructor *always* is called before
 441                  * the skb reference is invalid. The hijacked SKB destructor
 442                  * takes the flow_lock so manipulating the skb->destructor here
 443                  * should be safe.
 444                 */
 445                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
 446                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
 447
 448                 caifd->xoff = 0;
 449                 caifd->xoff_skb_dtor = NULL;
 450                 caifd->xoff_skb = NULL;
 451
 452                 spin_unlock_bh(&caifd->flow_lock);
 453                 caifd_put(caifd);
 454                 break;
 455
 456         case NETDEV_UNREGISTER:
 457                 mutex_lock(&caifdevs->lock);
 458
 459                 caifd = caif_get(dev);
 460                 if (caifd == NULL) {
 461                         mutex_unlock(&caifdevs->lock);
 462                         break;
 463                 }
 464                 list_del_rcu(&caifd->list);
 465
 466                 /*
 467                  * NETDEV_UNREGISTER is called repeatedly until all reference
 468                  * counts for the net-device are released. If references to
 469                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
 470                  * the next call to NETDEV_UNREGISTER.
 471                  *
 472                  * If any packets are in flight down the CAIF Stack,
 473                  * cfcnfg_del_phy_layer will return nonzero.
 474                  * If no packets are in flight, the CAIF Stack associated
 475                  * with the net-device un-registering is freed.
 476                  */
 477
 478                 if (caifd_refcnt_read(caifd) != 0 ||
 479                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
 480
 481                         pr_info("Wait for device inuse\n");
 482                         /* Enrole device if CAIF Stack is still in use */
 483                         list_add_rcu(&caifd->list, &caifdevs->list);
 484                         mutex_unlock(&caifdevs->lock);
 485                         break;
 486                 }
 487
 488                 synchronize_rcu();
 489                 dev_put(caifd->netdev);
 490                 free_percpu(caifd->pcpu_refcnt);
 491                 kfree(caifd);
 492
 493                 mutex_unlock(&caifdevs->lock);
 494                 break;
 495         }
 496         return 0;
 497 }
 498
 499 static struct notifier_block caif_device_notifier = {
 500         .notifier_call = caif_device_notify,
 501         .priority = 0,
 502 };
 503
 504 /* Per-namespace Caif devices handling */
 505 static int caif_init_net(struct net *net)
 506 {
 507         struct caif_net *caifn = net_generic(net, caif_net_id);
 508         if (WARN_ON(!caifn))
 509                 return -EINVAL;
 510
 511         INIT_LIST_HEAD(&caifn->caifdevs.list);
 512         mutex_init(&caifn->caifdevs.lock);
 513
 514         caifn->cfg = cfcnfg_create();
 515         if (!caifn->cfg)
 516                 return -ENOMEM;
 517
 518         return 0;
 519 }
 520
 521 static void caif_exit_net(struct net *net)
 522 {
 523         struct caif_device_entry *caifd, *tmp;
 524         struct caif_device_entry_list *caifdevs =
 525             caif_device_list(net);
 526         struct cfcnfg *cfg =  get_cfcnfg(net);
 527
 528         if (!cfg || !caifdevs)
 529                 return;
 530
 531         rtnl_lock();
 532         mutex_lock(&caifdevs->lock);
 533
 534         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
 535                 int i = 0;
 536                 list_del_rcu(&caifd->list);
 537                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 538
 539                 while (i < 10 &&
 540                         (caifd_refcnt_read(caifd) != 0 ||
 541                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
 542
 543                         pr_info("Wait for device inuse\n");
 544                         msleep(250);
 545                         i++;
 546                 }
 547                 synchronize_rcu();
 548                 dev_put(caifd->netdev);
 549                 free_percpu(caifd->pcpu_refcnt);
 550                 kfree(caifd);
 551         }
 552         cfcnfg_remove(cfg);
 553
 554         mutex_unlock(&caifdevs->lock);
 555         rtnl_unlock();
 556 }
 557
 558 static struct pernet_operations caif_net_ops = {
 559         .init = caif_init_net,
 560         .exit = caif_exit_net,
 561         .id   = &caif_net_id,
 562         .size = sizeof(struct caif_net),
 563 };
 564
 565 /* Initialize Caif devices list */
 566 static int __init caif_device_init(void)
 567 {
 568         int result;
 569
 570         result = register_pernet_device(&caif_net_ops);
 571
 572         if (result)
 573                 return result;
 574
 575         register_netdevice_notifier(&caif_device_notifier);
 576         dev_add_pack(&caif_packet_type);
 577
 578         return result;
 579 }
 580
 581 static void __exit caif_device_exit(void)
 582 {
 583         unregister_pernet_device(&caif_net_ops);
 584         unregister_netdevice_notifier(&caif_device_notifier);
 585         dev_remove_pack(&caif_packet_type);
 586 }
 587
 588 module_init(caif_device_init);
 589 module_exit(caif_device_exit);