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