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                 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                 struct Qdisc *sch;
 190
 191                 /* If we run with a TX queue, check if the queue is too long*/
 192                 txq = netdev_get_tx_queue(skb->dev, 0);
 193                 sch = rcu_dereference_bh(txq->qdisc);
 194                 if (likely(qdisc_is_empty(sch)))
 195                         goto noxoff;
 196
 197                 /* can check for explicit qdisc len value only !NOLOCK,
 198                  * always set flow off otherwise
 199                  */
 200                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
 201                 if (!(sch->flags & TCQ_F_NOLOCK) && likely(sch->q.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 int caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 311                      struct cflayer *link_support, int head_room,
 312                      struct cflayer **layer,
 313                      int (**rcv_func)(struct sk_buff *, struct net_device *,
 314                                       struct packet_type *,
 315                                       struct net_device *))
 316 {
 317         struct caif_device_entry *caifd;
 318         enum cfcnfg_phy_preference pref;
 319         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
 320         struct caif_device_entry_list *caifdevs;
 321         int res;
 322
 323         caifdevs = caif_device_list(dev_net(dev));
 324         caifd = caif_device_alloc(dev);
 325         if (!caifd)
 326                 return -ENOMEM;
 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         res = 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         return res;
 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 *ptr)
 364 {
 365         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 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         int res;
 373
 374         cfg = get_cfcnfg(dev_net(dev));
 375         caifdevs = caif_device_list(dev_net(dev));
 376
 377         caifd = caif_get(dev);
 378         if (caifd == NULL && dev->type != ARPHRD_CAIF)
 379                 return 0;
 380
 381         switch (what) {
 382         case NETDEV_REGISTER:
 383                 if (caifd != NULL)
 384                         break;
 385
 386                 caifdev = netdev_priv(dev);
 387
 388                 link_support = NULL;
 389                 if (caifdev->use_frag) {
 390                         head_room = 1;
 391                         link_support = cfserl_create(dev->ifindex,
 392                                                         caifdev->use_stx);
 393                         if (!link_support) {
 394                                 pr_warn("Out of memory\n");
 395                                 break;
 396                         }
 397                 }
 398                 res = caif_enroll_dev(dev, caifdev, link_support, head_room,
 399                                 &layer, NULL);
 400                 if (res)
 401                         cfserl_release(link_support);
 402                 caifdev->flowctrl = dev_flowctrl;
 403                 break;
 404
 405         case NETDEV_UP:
 406                 rcu_read_lock();
 407
 408                 caifd = caif_get(dev);
 409                 if (caifd == NULL) {
 410                         rcu_read_unlock();
 411                         break;
 412                 }
 413
 414                 caifd->xoff = 0;
 415                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
 416                 rcu_read_unlock();
 417
 418                 break;
 419
 420         case NETDEV_DOWN:
 421                 rcu_read_lock();
 422
 423                 caifd = caif_get(dev);
 424                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 425                         rcu_read_unlock();
 426                         return -EINVAL;
 427                 }
 428
 429                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 430                 caifd_hold(caifd);
 431                 rcu_read_unlock();
 432
 433                 caifd->layer.up->ctrlcmd(caifd->layer.up,
 434                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
 435                                          caifd->layer.id);
 436
 437                 spin_lock_bh(&caifd->flow_lock);
 438
 439                 /*
 440                  * Replace our xoff-destructor with original destructor.
 441                  * We trust that skb->destructor *always* is called before
 442                  * the skb reference is invalid. The hijacked SKB destructor
 443                  * takes the flow_lock so manipulating the skb->destructor here
 444                  * should be safe.
 445                 */
 446                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
 447                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
 448
 449                 caifd->xoff = 0;
 450                 caifd->xoff_skb_dtor = NULL;
 451                 caifd->xoff_skb = NULL;
 452
 453                 spin_unlock_bh(&caifd->flow_lock);
 454                 caifd_put(caifd);
 455                 break;
 456
 457         case NETDEV_UNREGISTER:
 458                 mutex_lock(&caifdevs->lock);
 459
 460                 caifd = caif_get(dev);
 461                 if (caifd == NULL) {
 462                         mutex_unlock(&caifdevs->lock);
 463                         break;
 464                 }
 465                 list_del_rcu(&caifd->list);
 466
 467                 /*
 468                  * NETDEV_UNREGISTER is called repeatedly until all reference
 469                  * counts for the net-device are released. If references to
 470                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
 471                  * the next call to NETDEV_UNREGISTER.
 472                  *
 473                  * If any packets are in flight down the CAIF Stack,
 474                  * cfcnfg_del_phy_layer will return nonzero.
 475                  * If no packets are in flight, the CAIF Stack associated
 476                  * with the net-device un-registering is freed.
 477                  */
 478
 479                 if (caifd_refcnt_read(caifd) != 0 ||
 480                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
 481
 482                         pr_info("Wait for device inuse\n");
 483                         /* Enrole device if CAIF Stack is still in use */
 484                         list_add_rcu(&caifd->list, &caifdevs->list);
 485                         mutex_unlock(&caifdevs->lock);
 486                         break;
 487                 }
 488
 489                 synchronize_rcu();
 490                 dev_put(caifd->netdev);
 491                 free_percpu(caifd->pcpu_refcnt);
 492                 kfree(caifd);
 493
 494                 mutex_unlock(&caifdevs->lock);
 495                 break;
 496         }
 497         return 0;
 498 }
 499
 500 static struct notifier_block caif_device_notifier = {
 501         .notifier_call = caif_device_notify,
 502         .priority = 0,
 503 };
 504
 505 /* Per-namespace Caif devices handling */
 506 static int caif_init_net(struct net *net)
 507 {
 508         struct caif_net *caifn = net_generic(net, caif_net_id);
 509         INIT_LIST_HEAD(&caifn->caifdevs.list);
 510         mutex_init(&caifn->caifdevs.lock);
 511
 512         caifn->cfg = cfcnfg_create();
 513         if (!caifn->cfg)
 514                 return -ENOMEM;
 515
 516         return 0;
 517 }
 518
 519 static void caif_exit_net(struct net *net)
 520 {
 521         struct caif_device_entry *caifd, *tmp;
 522         struct caif_device_entry_list *caifdevs =
 523             caif_device_list(net);
 524         struct cfcnfg *cfg =  get_cfcnfg(net);
 525
 526         rtnl_lock();
 527         mutex_lock(&caifdevs->lock);
 528
 529         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
 530                 int i = 0;
 531                 list_del_rcu(&caifd->list);
 532                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 533
 534                 while (i < 10 &&
 535                         (caifd_refcnt_read(caifd) != 0 ||
 536                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
 537
 538                         pr_info("Wait for device inuse\n");
 539                         msleep(250);
 540                         i++;
 541                 }
 542                 synchronize_rcu();
 543                 dev_put(caifd->netdev);
 544                 free_percpu(caifd->pcpu_refcnt);
 545                 kfree(caifd);
 546         }
 547         cfcnfg_remove(cfg);
 548
 549         mutex_unlock(&caifdevs->lock);
 550         rtnl_unlock();
 551 }
 552
 553 static struct pernet_operations caif_net_ops = {
 554         .init = caif_init_net,
 555         .exit = caif_exit_net,
 556         .id   = &caif_net_id,
 557         .size = sizeof(struct caif_net),
 558 };
 559
 560 /* Initialize Caif devices list */
 561 static int __init caif_device_init(void)
 562 {
 563         int result;
 564
 565         result = register_pernet_subsys(&caif_net_ops);
 566
 567         if (result)
 568                 return result;
 569
 570         register_netdevice_notifier(&caif_device_notifier);
 571         dev_add_pack(&caif_packet_type);
 572
 573         return result;
 574 }
 575
 576 static void __exit caif_device_exit(void)
 577 {
 578         unregister_netdevice_notifier(&caif_device_notifier);
 579         dev_remove_pack(&caif_packet_type);
 580         unregister_pernet_subsys(&caif_net_ops);
 581 }
 582
 583 module_init(caif_device_init);
 584 module_exit(caif_device_exit);