net/caif/caif_dev.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * CAIF Interface registration.
   4  * Copyright (C) ST-Ericsson AB 2010
   5  * Author:      Sjur Brendeland
   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 unsigned 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                                 lockdep_rtnl_is_held()) {
 117                 if (caifd->netdev == dev)
 118                         return caifd;
 119         }
 120         return NULL;
 121 }
 122
 123 static void caif_flow_cb(struct sk_buff *skb)
 124 {
 125         struct caif_device_entry *caifd;
 126         void (*dtor)(struct sk_buff *skb) = NULL;
 127         bool send_xoff;
 128
 129         WARN_ON(skb->dev == NULL);
 130
 131         rcu_read_lock();
 132         caifd = caif_get(skb->dev);
 133
 134         WARN_ON(caifd == NULL);
 135         if (!caifd) {
 136                 rcu_read_unlock();
 137                 return;
 138         }
 139
 140         caifd_hold(caifd);
 141         rcu_read_unlock();
 142
 143         spin_lock_bh(&caifd->flow_lock);
 144         send_xoff = caifd->xoff;
 145         caifd->xoff = false;
 146         dtor = caifd->xoff_skb_dtor;
 147
 148         if (WARN_ON(caifd->xoff_skb != skb))
 149                 skb = NULL;
 150
 151         caifd->xoff_skb = NULL;
 152         caifd->xoff_skb_dtor = NULL;
 153
 154         spin_unlock_bh(&caifd->flow_lock);
 155
 156         if (dtor && skb)
 157                 dtor(skb);
 158
 159         if (send_xoff)
 160                 caifd->layer.up->
 161                         ctrlcmd(caifd->layer.up,
 162                                 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
 163                                 caifd->layer.id);
 164         caifd_put(caifd);
 165 }
 166
 167 static int transmit(struct cflayer *layer, struct cfpkt *pkt)
 168 {
 169         int err, high = 0, qlen = 0;
 170         struct caif_device_entry *caifd =
 171             container_of(layer, struct caif_device_entry, layer);
 172         struct sk_buff *skb;
 173         struct netdev_queue *txq;
 174
 175         rcu_read_lock_bh();
 176
 177         skb = cfpkt_tonative(pkt);
 178         skb->dev = caifd->netdev;
 179         skb_reset_network_header(skb);
 180         skb->protocol = htons(ETH_P_CAIF);
 181
 182         /* Check if we need to handle xoff */
 183         if (likely(caifd->netdev->priv_flags & IFF_NO_QUEUE))
 184                 goto noxoff;
 185
 186         if (unlikely(caifd->xoff))
 187                 goto noxoff;
 188
 189         if (likely(!netif_queue_stopped(caifd->netdev))) {
 190                 struct Qdisc *sch;
 191
 192                 /* If we run with a TX queue, check if the queue is too long*/
 193                 txq = netdev_get_tx_queue(skb->dev, 0);
 194                 sch = rcu_dereference_bh(txq->qdisc);
 195                 if (likely(qdisc_is_empty(sch)))
 196                         goto noxoff;
 197
 198                 /* can check for explicit qdisc len value only !NOLOCK,
 199                  * always set flow off otherwise
 200                  */
 201                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
 202                 if (!(sch->flags & TCQ_F_NOLOCK) && likely(sch->q.qlen < high))
 203                         goto noxoff;
 204         }
 205
 206         /* Hold lock while accessing xoff */
 207         spin_lock_bh(&caifd->flow_lock);
 208         if (caifd->xoff) {
 209                 spin_unlock_bh(&caifd->flow_lock);
 210                 goto noxoff;
 211         }
 212
 213         /*
 214          * Handle flow off, we do this by temporary hi-jacking this
 215          * skb's destructor function, and replace it with our own
 216          * flow-on callback. The callback will set flow-on and call
 217          * the original destructor.
 218          */
 219
 220         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
 221                         netif_queue_stopped(caifd->netdev),
 222                         qlen, high);
 223         caifd->xoff = true;
 224         caifd->xoff_skb = skb;
 225         caifd->xoff_skb_dtor = skb->destructor;
 226         skb->destructor = caif_flow_cb;
 227         spin_unlock_bh(&caifd->flow_lock);
 228
 229         caifd->layer.up->ctrlcmd(caifd->layer.up,
 230                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 231                                         caifd->layer.id);
 232 noxoff:
 233         rcu_read_unlock_bh();
 234
 235         err = dev_queue_xmit(skb);
 236         if (err > 0)
 237                 err = -EIO;
 238
 239         return err;
 240 }
 241
 242 /*
 243  * Stuff received packets into the CAIF stack.
 244  * On error, returns non-zero and releases the skb.
 245  */
 246 static int receive(struct sk_buff *skb, struct net_device *dev,
 247                    struct packet_type *pkttype, struct net_device *orig_dev)
 248 {
 249         struct cfpkt *pkt;
 250         struct caif_device_entry *caifd;
 251         int err;
 252
 253         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
 254
 255         rcu_read_lock();
 256         caifd = caif_get(dev);
 257
 258         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
 259                         !netif_oper_up(caifd->netdev)) {
 260                 rcu_read_unlock();
 261                 kfree_skb(skb);
 262                 return NET_RX_DROP;
 263         }
 264
 265         /* Hold reference to netdevice while using CAIF stack */
 266         caifd_hold(caifd);
 267         rcu_read_unlock();
 268
 269         err = caifd->layer.up->receive(caifd->layer.up, pkt);
 270
 271         /* For -EILSEQ the packet is not freed so so it now */
 272         if (err == -EILSEQ)
 273                 cfpkt_destroy(pkt);
 274
 275         /* Release reference to stack upwards */
 276         caifd_put(caifd);
 277
 278         if (err != 0)
 279                 err = NET_RX_DROP;
 280         return err;
 281 }
 282
 283 static struct packet_type caif_packet_type __read_mostly = {
 284         .type = cpu_to_be16(ETH_P_CAIF),
 285         .func = receive,
 286 };
 287
 288 static void dev_flowctrl(struct net_device *dev, int on)
 289 {
 290         struct caif_device_entry *caifd;
 291
 292         rcu_read_lock();
 293
 294         caifd = caif_get(dev);
 295         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 296                 rcu_read_unlock();
 297                 return;
 298         }
 299
 300         caifd_hold(caifd);
 301         rcu_read_unlock();
 302
 303         caifd->layer.up->ctrlcmd(caifd->layer.up,
 304                                  on ?
 305                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
 306                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 307                                  caifd->layer.id);
 308         caifd_put(caifd);
 309 }
 310
 311 void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 312                      struct cflayer *link_support, int head_room,
 313                      struct cflayer **layer,
 314                      int (**rcv_func)(struct sk_buff *, struct net_device *,
 315                                       struct packet_type *,
 316                                       struct net_device *))
 317 {
 318         struct caif_device_entry *caifd;
 319         enum cfcnfg_phy_preference pref;
 320         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
 321         struct caif_device_entry_list *caifdevs;
 322
 323         caifdevs = caif_device_list(dev_net(dev));
 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         strlcpy(caifd->layer.name, dev->name,
 345                 sizeof(caifd->layer.name));
 346         caifd->layer.transmit = transmit;
 347         cfcnfg_add_phy_layer(cfg,
 348                                 dev,
 349                                 &caifd->layer,
 350                                 pref,
 351                                 link_support,
 352                                 caifdev->use_fcs,
 353                                 head_room);
 354         mutex_unlock(&caifdevs->lock);
 355         if (rcv_func)
 356                 *rcv_func = receive;
 357 }
 358 EXPORT_SYMBOL(caif_enroll_dev);
 359
 360 /* notify Caif of device events */
 361 static int caif_device_notify(struct notifier_block *me, unsigned long what,
 362                               void *ptr)
 363 {
 364         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 365         struct caif_device_entry *caifd = NULL;
 366         struct caif_dev_common *caifdev;
 367         struct cfcnfg *cfg;
 368         struct cflayer *layer, *link_support;
 369         int head_room = 0;
 370         struct caif_device_entry_list *caifdevs;
 371
 372         cfg = get_cfcnfg(dev_net(dev));
 373         caifdevs = caif_device_list(dev_net(dev));
 374
 375         caifd = caif_get(dev);
 376         if (caifd == NULL && dev->type != ARPHRD_CAIF)
 377                 return 0;
 378
 379         switch (what) {
 380         case NETDEV_REGISTER:
 381                 if (caifd != NULL)
 382                         break;
 383
 384                 caifdev = netdev_priv(dev);
 385
 386                 link_support = NULL;
 387                 if (caifdev->use_frag) {
 388                         head_room = 1;
 389                         link_support = cfserl_create(dev->ifindex,
 390                                                         caifdev->use_stx);
 391                         if (!link_support) {
 392                                 pr_warn("Out of memory\n");
 393                                 break;
 394                         }
 395                 }
 396                 caif_enroll_dev(dev, caifdev, link_support, head_room,
 397                                 &layer, NULL);
 398                 caifdev->flowctrl = dev_flowctrl;
 399                 break;
 400
 401         case NETDEV_UP:
 402                 rcu_read_lock();
 403
 404                 caifd = caif_get(dev);
 405                 if (caifd == NULL) {
 406                         rcu_read_unlock();
 407                         break;
 408                 }
 409
 410                 caifd->xoff = false;
 411                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
 412                 rcu_read_unlock();
 413
 414                 break;
 415
 416         case NETDEV_DOWN:
 417                 rcu_read_lock();
 418
 419                 caifd = caif_get(dev);
 420                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 421                         rcu_read_unlock();
 422                         return -EINVAL;
 423                 }
 424
 425                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 426                 caifd_hold(caifd);
 427                 rcu_read_unlock();
 428
 429                 caifd->layer.up->ctrlcmd(caifd->layer.up,
 430                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
 431                                          caifd->layer.id);
 432
 433                 spin_lock_bh(&caifd->flow_lock);
 434
 435                 /*
 436                  * Replace our xoff-destructor with original destructor.
 437                  * We trust that skb->destructor *always* is called before
 438                  * the skb reference is invalid. The hijacked SKB destructor
 439                  * takes the flow_lock so manipulating the skb->destructor here
 440                  * should be safe.
 441                 */
 442                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
 443                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
 444
 445                 caifd->xoff = false;
 446                 caifd->xoff_skb_dtor = NULL;
 447                 caifd->xoff_skb = NULL;
 448
 449                 spin_unlock_bh(&caifd->flow_lock);
 450                 caifd_put(caifd);
 451                 break;
 452
 453         case NETDEV_UNREGISTER:
 454                 mutex_lock(&caifdevs->lock);
 455
 456                 caifd = caif_get(dev);
 457                 if (caifd == NULL) {
 458                         mutex_unlock(&caifdevs->lock);
 459                         break;
 460                 }
 461                 list_del_rcu(&caifd->list);
 462
 463                 /*
 464                  * NETDEV_UNREGISTER is called repeatedly until all reference
 465                  * counts for the net-device are released. If references to
 466                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
 467                  * the next call to NETDEV_UNREGISTER.
 468                  *
 469                  * If any packets are in flight down the CAIF Stack,
 470                  * cfcnfg_del_phy_layer will return nonzero.
 471                  * If no packets are in flight, the CAIF Stack associated
 472                  * with the net-device un-registering is freed.
 473                  */
 474
 475                 if (caifd_refcnt_read(caifd) != 0 ||
 476                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
 477
 478                         pr_info("Wait for device inuse\n");
 479                         /* Enrole device if CAIF Stack is still in use */
 480                         list_add_rcu(&caifd->list, &caifdevs->list);
 481                         mutex_unlock(&caifdevs->lock);
 482                         break;
 483                 }
 484
 485                 synchronize_rcu();
 486                 dev_put(caifd->netdev);
 487                 free_percpu(caifd->pcpu_refcnt);
 488                 kfree(caifd);
 489
 490                 mutex_unlock(&caifdevs->lock);
 491                 break;
 492         }
 493         return 0;
 494 }
 495
 496 static struct notifier_block caif_device_notifier = {
 497         .notifier_call = caif_device_notify,
 498         .priority = 0,
 499 };
 500
 501 /* Per-namespace Caif devices handling */
 502 static int caif_init_net(struct net *net)
 503 {
 504         struct caif_net *caifn = net_generic(net, caif_net_id);
 505         INIT_LIST_HEAD(&caifn->caifdevs.list);
 506         mutex_init(&caifn->caifdevs.lock);
 507
 508         caifn->cfg = cfcnfg_create();
 509         if (!caifn->cfg)
 510                 return -ENOMEM;
 511
 512         return 0;
 513 }
 514
 515 static void caif_exit_net(struct net *net)
 516 {
 517         struct caif_device_entry *caifd, *tmp;
 518         struct caif_device_entry_list *caifdevs =
 519             caif_device_list(net);
 520         struct cfcnfg *cfg =  get_cfcnfg(net);
 521
 522         rtnl_lock();
 523         mutex_lock(&caifdevs->lock);
 524
 525         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
 526                 int i = 0;
 527                 list_del_rcu(&caifd->list);
 528                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 529
 530                 while (i < 10 &&
 531                         (caifd_refcnt_read(caifd) != 0 ||
 532                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
 533
 534                         pr_info("Wait for device inuse\n");
 535                         msleep(250);
 536                         i++;
 537                 }
 538                 synchronize_rcu();
 539                 dev_put(caifd->netdev);
 540                 free_percpu(caifd->pcpu_refcnt);
 541                 kfree(caifd);
 542         }
 543         cfcnfg_remove(cfg);
 544
 545         mutex_unlock(&caifdevs->lock);
 546         rtnl_unlock();
 547 }
 548
 549 static struct pernet_operations caif_net_ops = {
 550         .init = caif_init_net,
 551         .exit = caif_exit_net,
 552         .id   = &caif_net_id,
 553         .size = sizeof(struct caif_net),
 554 };
 555
 556 /* Initialize Caif devices list */
 557 static int __init caif_device_init(void)
 558 {
 559         int result;
 560
 561         result = register_pernet_subsys(&caif_net_ops);
 562
 563         if (result)
 564                 return result;
 565
 566         register_netdevice_notifier(&caif_device_notifier);
 567         dev_add_pack(&caif_packet_type);
 568
 569         return result;
 570 }
 571
 572 static void __exit caif_device_exit(void)
 573 {
 574         unregister_netdevice_notifier(&caif_device_notifier);
 575         dev_remove_pack(&caif_packet_type);
 576         unregister_pernet_subsys(&caif_net_ops);
 577 }
 578
 579 module_init(caif_device_init);
 580 module_exit(caif_device_exit);