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) {
 135                 rcu_read_unlock();
 136                 return;
 137         }
 138
 139         caifd_hold(caifd);
 140         rcu_read_unlock();
 141
 142         spin_lock_bh(&caifd->flow_lock);
 143         send_xoff = caifd->xoff;
 144         caifd->xoff = 0;
 145         dtor = caifd->xoff_skb_dtor;
 146
 147         if (WARN_ON(caifd->xoff_skb != skb))
 148                 skb = NULL;
 149
 150         caifd->xoff_skb = NULL;
 151         caifd->xoff_skb_dtor = NULL;
 152
 153         spin_unlock_bh(&caifd->flow_lock);
 154
 155         if (dtor && skb)
 156                 dtor(skb);
 157
 158         if (send_xoff)
 159                 caifd->layer.up->
 160                         ctrlcmd(caifd->layer.up,
 161                                 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
 162                                 caifd->layer.id);
 163         caifd_put(caifd);
 164 }
 165
 166 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
 167 {
 168         int err, high = 0, qlen = 0;
 169         struct caif_device_entry *caifd =
 170             container_of(layer, struct caif_device_entry, layer);
 171         struct sk_buff *skb;
 172         struct netdev_queue *txq;
 173
 174         rcu_read_lock_bh();
 175
 176         skb = cfpkt_tonative(pkt);
 177         skb->dev = caifd->netdev;
 178         skb_reset_network_header(skb);
 179         skb->protocol = htons(ETH_P_CAIF);
 180
 181         /* Check if we need to handle xoff */
 182         if (likely(caifd->netdev->priv_flags & IFF_NO_QUEUE))
 183                 goto noxoff;
 184
 185         if (unlikely(caifd->xoff))
 186                 goto noxoff;
 187
 188         if (likely(!netif_queue_stopped(caifd->netdev))) {
 189                 /* If we run with a TX queue, check if the queue is too long*/
 190                 txq = netdev_get_tx_queue(skb->dev, 0);
 191                 qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
 192
 193                 if (likely(qlen == 0))
 194                         goto noxoff;
 195
 196                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
 197                 if (likely(qlen < high))
 198                         goto noxoff;
 199         }
 200
 201         /* Hold lock while accessing xoff */
 202         spin_lock_bh(&caifd->flow_lock);
 203         if (caifd->xoff) {
 204                 spin_unlock_bh(&caifd->flow_lock);
 205                 goto noxoff;
 206         }
 207
 208         /*
 209          * Handle flow off, we do this by temporary hi-jacking this
 210          * skb's destructor function, and replace it with our own
 211          * flow-on callback. The callback will set flow-on and call
 212          * the original destructor.
 213          */
 214
 215         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
 216                         netif_queue_stopped(caifd->netdev),
 217                         qlen, high);
 218         caifd->xoff = 1;
 219         caifd->xoff_skb = skb;
 220         caifd->xoff_skb_dtor = skb->destructor;
 221         skb->destructor = caif_flow_cb;
 222         spin_unlock_bh(&caifd->flow_lock);
 223
 224         caifd->layer.up->ctrlcmd(caifd->layer.up,
 225                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 226                                         caifd->layer.id);
 227 noxoff:
 228         rcu_read_unlock_bh();
 229
 230         err = dev_queue_xmit(skb);
 231         if (err > 0)
 232                 err = -EIO;
 233
 234         return err;
 235 }
 236
 237 /*
 238  * Stuff received packets into the CAIF stack.
 239  * On error, returns non-zero and releases the skb.
 240  */
 241 static int receive(struct sk_buff *skb, struct net_device *dev,
 242                    struct packet_type *pkttype, struct net_device *orig_dev)
 243 {
 244         struct cfpkt *pkt;
 245         struct caif_device_entry *caifd;
 246         int err;
 247
 248         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
 249
 250         rcu_read_lock();
 251         caifd = caif_get(dev);
 252
 253         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
 254                         !netif_oper_up(caifd->netdev)) {
 255                 rcu_read_unlock();
 256                 kfree_skb(skb);
 257                 return NET_RX_DROP;
 258         }
 259
 260         /* Hold reference to netdevice while using CAIF stack */
 261         caifd_hold(caifd);
 262         rcu_read_unlock();
 263
 264         err = caifd->layer.up->receive(caifd->layer.up, pkt);
 265
 266         /* For -EILSEQ the packet is not freed so so it now */
 267         if (err == -EILSEQ)
 268                 cfpkt_destroy(pkt);
 269
 270         /* Release reference to stack upwards */
 271         caifd_put(caifd);
 272
 273         if (err != 0)
 274                 err = NET_RX_DROP;
 275         return err;
 276 }
 277
 278 static struct packet_type caif_packet_type __read_mostly = {
 279         .type = cpu_to_be16(ETH_P_CAIF),
 280         .func = receive,
 281 };
 282
 283 static void dev_flowctrl(struct net_device *dev, int on)
 284 {
 285         struct caif_device_entry *caifd;
 286
 287         rcu_read_lock();
 288
 289         caifd = caif_get(dev);
 290         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 291                 rcu_read_unlock();
 292                 return;
 293         }
 294
 295         caifd_hold(caifd);
 296         rcu_read_unlock();
 297
 298         caifd->layer.up->ctrlcmd(caifd->layer.up,
 299                                  on ?
 300                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
 301                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 302                                  caifd->layer.id);
 303         caifd_put(caifd);
 304 }
 305
 306 int caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 307                      struct cflayer *link_support, int head_room,
 308                      struct cflayer **layer,
 309                      int (**rcv_func)(struct sk_buff *, struct net_device *,
 310                                       struct packet_type *,
 311                                       struct net_device *))
 312 {
 313         struct caif_device_entry *caifd;
 314         enum cfcnfg_phy_preference pref;
 315         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
 316         struct caif_device_entry_list *caifdevs;
 317         int res;
 318
 319         caifdevs = caif_device_list(dev_net(dev));
 320         caifd = caif_device_alloc(dev);
 321         if (!caifd)
 322                 return -ENOMEM;
 323         *layer = &caifd->layer;
 324         spin_lock_init(&caifd->flow_lock);
 325
 326         switch (caifdev->link_select) {
 327         case CAIF_LINK_HIGH_BANDW:
 328                 pref = CFPHYPREF_HIGH_BW;
 329                 break;
 330         case CAIF_LINK_LOW_LATENCY:
 331                 pref = CFPHYPREF_LOW_LAT;
 332                 break;
 333         default:
 334                 pref = CFPHYPREF_HIGH_BW;
 335                 break;
 336         }
 337         mutex_lock(&caifdevs->lock);
 338         list_add_rcu(&caifd->list, &caifdevs->list);
 339
 340         strncpy(caifd->layer.name, dev->name,
 341                 sizeof(caifd->layer.name) - 1);
 342         caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
 343         caifd->layer.transmit = transmit;
 344         res = cfcnfg_add_phy_layer(cfg,
 345                                 dev,
 346                                 &caifd->layer,
 347                                 pref,
 348                                 link_support,
 349                                 caifdev->use_fcs,
 350                                 head_room);
 351         mutex_unlock(&caifdevs->lock);
 352         if (rcv_func)
 353                 *rcv_func = receive;
 354         return res;
 355 }
 356 EXPORT_SYMBOL(caif_enroll_dev);
 357
 358 /* notify Caif of device events */
 359 static int caif_device_notify(struct notifier_block *me, unsigned long what,
 360                               void *ptr)
 361 {
 362         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 363         struct caif_device_entry *caifd = NULL;
 364         struct caif_dev_common *caifdev;
 365         struct cfcnfg *cfg;
 366         struct cflayer *layer, *link_support;
 367         int head_room = 0;
 368         struct caif_device_entry_list *caifdevs;
 369         int res;
 370
 371         cfg = get_cfcnfg(dev_net(dev));
 372         caifdevs = caif_device_list(dev_net(dev));
 373
 374         caifd = caif_get(dev);
 375         if (caifd == NULL && dev->type != ARPHRD_CAIF)
 376                 return 0;
 377
 378         switch (what) {
 379         case NETDEV_REGISTER:
 380                 if (caifd != NULL)
 381                         break;
 382
 383                 caifdev = netdev_priv(dev);
 384
 385                 link_support = NULL;
 386                 if (caifdev->use_frag) {
 387                         head_room = 1;
 388                         link_support = cfserl_create(dev->ifindex,
 389                                                         caifdev->use_stx);
 390                         if (!link_support) {
 391                                 pr_warn("Out of memory\n");
 392                                 break;
 393                         }
 394                 }
 395                 res = caif_enroll_dev(dev, caifdev, link_support, head_room,
 396                                 &layer, NULL);
 397                 if (res)
 398                         cfserl_release(link_support);
 399                 caifdev->flowctrl = dev_flowctrl;
 400                 break;
 401
 402         case NETDEV_UP:
 403                 rcu_read_lock();
 404
 405                 caifd = caif_get(dev);
 406                 if (caifd == NULL) {
 407                         rcu_read_unlock();
 408                         break;
 409                 }
 410
 411                 caifd->xoff = 0;
 412                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
 413                 rcu_read_unlock();
 414
 415                 break;
 416
 417         case NETDEV_DOWN:
 418                 rcu_read_lock();
 419
 420                 caifd = caif_get(dev);
 421                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 422                         rcu_read_unlock();
 423                         return -EINVAL;
 424                 }
 425
 426                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 427                 caifd_hold(caifd);
 428                 rcu_read_unlock();
 429
 430                 caifd->layer.up->ctrlcmd(caifd->layer.up,
 431                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
 432                                          caifd->layer.id);
 433
 434                 spin_lock_bh(&caifd->flow_lock);
 435
 436                 /*
 437                  * Replace our xoff-destructor with original destructor.
 438                  * We trust that skb->destructor *always* is called before
 439                  * the skb reference is invalid. The hijacked SKB destructor
 440                  * takes the flow_lock so manipulating the skb->destructor here
 441                  * should be safe.
 442                 */
 443                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
 444                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
 445
 446                 caifd->xoff = 0;
 447                 caifd->xoff_skb_dtor = NULL;
 448                 caifd->xoff_skb = NULL;
 449
 450                 spin_unlock_bh(&caifd->flow_lock);
 451                 caifd_put(caifd);
 452                 break;
 453
 454         case NETDEV_UNREGISTER:
 455                 mutex_lock(&caifdevs->lock);
 456
 457                 caifd = caif_get(dev);
 458                 if (caifd == NULL) {
 459                         mutex_unlock(&caifdevs->lock);
 460                         break;
 461                 }
 462                 list_del_rcu(&caifd->list);
 463
 464                 /*
 465                  * NETDEV_UNREGISTER is called repeatedly until all reference
 466                  * counts for the net-device are released. If references to
 467                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
 468                  * the next call to NETDEV_UNREGISTER.
 469                  *
 470                  * If any packets are in flight down the CAIF Stack,
 471                  * cfcnfg_del_phy_layer will return nonzero.
 472                  * If no packets are in flight, the CAIF Stack associated
 473                  * with the net-device un-registering is freed.
 474                  */
 475
 476                 if (caifd_refcnt_read(caifd) != 0 ||
 477                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
 478
 479                         pr_info("Wait for device inuse\n");
 480                         /* Enrole device if CAIF Stack is still in use */
 481                         list_add_rcu(&caifd->list, &caifdevs->list);
 482                         mutex_unlock(&caifdevs->lock);
 483                         break;
 484                 }
 485
 486                 synchronize_rcu();
 487                 dev_put(caifd->netdev);
 488                 free_percpu(caifd->pcpu_refcnt);
 489                 kfree(caifd);
 490
 491                 mutex_unlock(&caifdevs->lock);
 492                 break;
 493         }
 494         return 0;
 495 }
 496
 497 static struct notifier_block caif_device_notifier = {
 498         .notifier_call = caif_device_notify,
 499         .priority = 0,
 500 };
 501
 502 /* Per-namespace Caif devices handling */
 503 static int caif_init_net(struct net *net)
 504 {
 505         struct caif_net *caifn = net_generic(net, caif_net_id);
 506         INIT_LIST_HEAD(&caifn->caifdevs.list);
 507         mutex_init(&caifn->caifdevs.lock);
 508
 509         caifn->cfg = cfcnfg_create();
 510         if (!caifn->cfg)
 511                 return -ENOMEM;
 512
 513         return 0;
 514 }
 515
 516 static void caif_exit_net(struct net *net)
 517 {
 518         struct caif_device_entry *caifd, *tmp;
 519         struct caif_device_entry_list *caifdevs =
 520             caif_device_list(net);
 521         struct cfcnfg *cfg =  get_cfcnfg(net);
 522
 523         rtnl_lock();
 524         mutex_lock(&caifdevs->lock);
 525
 526         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
 527                 int i = 0;
 528                 list_del_rcu(&caifd->list);
 529                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 530
 531                 while (i < 10 &&
 532                         (caifd_refcnt_read(caifd) != 0 ||
 533                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
 534
 535                         pr_info("Wait for device inuse\n");
 536                         msleep(250);
 537                         i++;
 538                 }
 539                 synchronize_rcu();
 540                 dev_put(caifd->netdev);
 541                 free_percpu(caifd->pcpu_refcnt);
 542                 kfree(caifd);
 543         }
 544         cfcnfg_remove(cfg);
 545
 546         mutex_unlock(&caifdevs->lock);
 547         rtnl_unlock();
 548 }
 549
 550 static struct pernet_operations caif_net_ops = {
 551         .init = caif_init_net,
 552         .exit = caif_exit_net,
 553         .id   = &caif_net_id,
 554         .size = sizeof(struct caif_net),
 555 };
 556
 557 /* Initialize Caif devices list */
 558 static int __init caif_device_init(void)
 559 {
 560         int result;
 561
 562         result = register_pernet_subsys(&caif_net_ops);
 563
 564         if (result)
 565                 return result;
 566
 567         register_netdevice_notifier(&caif_device_notifier);
 568         dev_add_pack(&caif_packet_type);
 569
 570         return result;
 571 }
 572
 573 static void __exit caif_device_exit(void)
 574 {
 575         unregister_netdevice_notifier(&caif_device_notifier);
 576         dev_remove_pack(&caif_packet_type);
 577         unregister_pernet_subsys(&caif_net_ops);
 578 }
 579
 580 module_init(caif_device_init);
 581 module_exit(caif_device_exit);