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_DESCRIPTION("ST-Ericsson CAIF modem protocol support");
  31 MODULE_LICENSE("GPL");
  32
  33 /* Used for local tracking of the CAIF net devices */
  34 struct caif_device_entry {
  35         struct cflayer layer;
  36         struct list_head list;
  37         struct net_device *netdev;
  38         int __percpu *pcpu_refcnt;
  39         spinlock_t flow_lock;
  40         struct sk_buff *xoff_skb;
  41         void (*xoff_skb_dtor)(struct sk_buff *skb);
  42         bool xoff;
  43 };
  44
  45 struct caif_device_entry_list {
  46         struct list_head list;
  47         /* Protects simulanous deletes in list */
  48         struct mutex lock;
  49 };
  50
  51 struct caif_net {
  52         struct cfcnfg *cfg;
  53         struct caif_device_entry_list caifdevs;
  54 };
  55
  56 static unsigned int caif_net_id;
  57 static int q_high = 50; /* Percent */
  58
  59 struct cfcnfg *get_cfcnfg(struct net *net)
  60 {
  61         struct caif_net *caifn;
  62         caifn = net_generic(net, caif_net_id);
  63         return caifn->cfg;
  64 }
  65 EXPORT_SYMBOL(get_cfcnfg);
  66
  67 static struct caif_device_entry_list *caif_device_list(struct net *net)
  68 {
  69         struct caif_net *caifn;
  70         caifn = net_generic(net, caif_net_id);
  71         return &caifn->caifdevs;
  72 }
  73
  74 static void caifd_put(struct caif_device_entry *e)
  75 {
  76         this_cpu_dec(*e->pcpu_refcnt);
  77 }
  78
  79 static void caifd_hold(struct caif_device_entry *e)
  80 {
  81         this_cpu_inc(*e->pcpu_refcnt);
  82 }
  83
  84 static int caifd_refcnt_read(struct caif_device_entry *e)
  85 {
  86         int i, refcnt = 0;
  87         for_each_possible_cpu(i)
  88                 refcnt += *per_cpu_ptr(e->pcpu_refcnt, i);
  89         return refcnt;
  90 }
  91
  92 /* Allocate new CAIF device. */
  93 static struct caif_device_entry *caif_device_alloc(struct net_device *dev)
  94 {
  95         struct caif_device_entry *caifd;
  96
  97         caifd = kzalloc(sizeof(*caifd), GFP_KERNEL);
  98         if (!caifd)
  99                 return NULL;
 100         caifd->pcpu_refcnt = alloc_percpu(int);
 101         if (!caifd->pcpu_refcnt) {
 102                 kfree(caifd);
 103                 return NULL;
 104         }
 105         caifd->netdev = dev;
 106         dev_hold(dev);
 107         return caifd;
 108 }
 109
 110 static struct caif_device_entry *caif_get(struct net_device *dev)
 111 {
 112         struct caif_device_entry_list *caifdevs =
 113             caif_device_list(dev_net(dev));
 114         struct caif_device_entry *caifd;
 115
 116         list_for_each_entry_rcu(caifd, &caifdevs->list, list,
 117                                 lockdep_rtnl_is_held()) {
 118                 if (caifd->netdev == dev)
 119                         return caifd;
 120         }
 121         return NULL;
 122 }
 123
 124 static void caif_flow_cb(struct sk_buff *skb)
 125 {
 126         struct caif_device_entry *caifd;
 127         void (*dtor)(struct sk_buff *skb) = NULL;
 128         bool send_xoff;
 129
 130         WARN_ON(skb->dev == NULL);
 131
 132         rcu_read_lock();
 133         caifd = caif_get(skb->dev);
 134
 135         WARN_ON(caifd == NULL);
 136         if (!caifd) {
 137                 rcu_read_unlock();
 138                 return;
 139         }
 140
 141         caifd_hold(caifd);
 142         rcu_read_unlock();
 143
 144         spin_lock_bh(&caifd->flow_lock);
 145         send_xoff = caifd->xoff;
 146         caifd->xoff = false;
 147         dtor = caifd->xoff_skb_dtor;
 148
 149         if (WARN_ON(caifd->xoff_skb != skb))
 150                 skb = NULL;
 151
 152         caifd->xoff_skb = NULL;
 153         caifd->xoff_skb_dtor = NULL;
 154
 155         spin_unlock_bh(&caifd->flow_lock);
 156
 157         if (dtor && skb)
 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_device_entry *caifd =
 172             container_of(layer, struct caif_device_entry, layer);
 173         struct sk_buff *skb;
 174         struct netdev_queue *txq;
 175
 176         rcu_read_lock_bh();
 177
 178         skb = cfpkt_tonative(pkt);
 179         skb->dev = caifd->netdev;
 180         skb_reset_network_header(skb);
 181         skb->protocol = htons(ETH_P_CAIF);
 182
 183         /* Check if we need to handle xoff */
 184         if (likely(caifd->netdev->priv_flags & IFF_NO_QUEUE))
 185                 goto noxoff;
 186
 187         if (unlikely(caifd->xoff))
 188                 goto noxoff;
 189
 190         if (likely(!netif_queue_stopped(caifd->netdev))) {
 191                 struct Qdisc *sch;
 192
 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                 sch = rcu_dereference_bh(txq->qdisc);
 196                 if (likely(qdisc_is_empty(sch)))
 197                         goto noxoff;
 198
 199                 /* can check for explicit qdisc len value only !NOLOCK,
 200                  * always set flow off otherwise
 201                  */
 202                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
 203                 if (!(sch->flags & TCQ_F_NOLOCK) && likely(sch->q.qlen < high))
 204                         goto noxoff;
 205         }
 206
 207         /* Hold lock while accessing xoff */
 208         spin_lock_bh(&caifd->flow_lock);
 209         if (caifd->xoff) {
 210                 spin_unlock_bh(&caifd->flow_lock);
 211                 goto noxoff;
 212         }
 213
 214         /*
 215          * Handle flow off, we do this by temporary hi-jacking this
 216          * skb's destructor function, and replace it with our own
 217          * flow-on callback. The callback will set flow-on and call
 218          * the original destructor.
 219          */
 220
 221         pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
 222                         netif_queue_stopped(caifd->netdev),
 223                         qlen, high);
 224         caifd->xoff = true;
 225         caifd->xoff_skb = skb;
 226         caifd->xoff_skb_dtor = skb->destructor;
 227         skb->destructor = caif_flow_cb;
 228         spin_unlock_bh(&caifd->flow_lock);
 229
 230         caifd->layer.up->ctrlcmd(caifd->layer.up,
 231                                         _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 232                                         caifd->layer.id);
 233 noxoff:
 234         rcu_read_unlock_bh();
 235
 236         err = dev_queue_xmit(skb);
 237         if (err > 0)
 238                 err = -EIO;
 239
 240         return err;
 241 }
 242
 243 /*
 244  * Stuff received packets into the CAIF stack.
 245  * On error, returns non-zero and releases the skb.
 246  */
 247 static int receive(struct sk_buff *skb, struct net_device *dev,
 248                    struct packet_type *pkttype, struct net_device *orig_dev)
 249 {
 250         struct cfpkt *pkt;
 251         struct caif_device_entry *caifd;
 252         int err;
 253
 254         pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
 255
 256         rcu_read_lock();
 257         caifd = caif_get(dev);
 258
 259         if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
 260                         !netif_oper_up(caifd->netdev)) {
 261                 rcu_read_unlock();
 262                 kfree_skb(skb);
 263                 return NET_RX_DROP;
 264         }
 265
 266         /* Hold reference to netdevice while using CAIF stack */
 267         caifd_hold(caifd);
 268         rcu_read_unlock();
 269
 270         err = caifd->layer.up->receive(caifd->layer.up, pkt);
 271
 272         /* For -EILSEQ the packet is not freed so free it now */
 273         if (err == -EILSEQ)
 274                 cfpkt_destroy(pkt);
 275
 276         /* Release reference to stack upwards */
 277         caifd_put(caifd);
 278
 279         if (err != 0)
 280                 err = NET_RX_DROP;
 281         return err;
 282 }
 283
 284 static struct packet_type caif_packet_type __read_mostly = {
 285         .type = cpu_to_be16(ETH_P_CAIF),
 286         .func = receive,
 287 };
 288
 289 static void dev_flowctrl(struct net_device *dev, int on)
 290 {
 291         struct caif_device_entry *caifd;
 292
 293         rcu_read_lock();
 294
 295         caifd = caif_get(dev);
 296         if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 297                 rcu_read_unlock();
 298                 return;
 299         }
 300
 301         caifd_hold(caifd);
 302         rcu_read_unlock();
 303
 304         caifd->layer.up->ctrlcmd(caifd->layer.up,
 305                                  on ?
 306                                  _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
 307                                  _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
 308                                  caifd->layer.id);
 309         caifd_put(caifd);
 310 }
 311
 312 int caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 313                      struct cflayer *link_support, int head_room,
 314                      struct cflayer **layer,
 315                      int (**rcv_func)(struct sk_buff *, struct net_device *,
 316                                       struct packet_type *,
 317                                       struct net_device *))
 318 {
 319         struct caif_device_entry *caifd;
 320         enum cfcnfg_phy_preference pref;
 321         struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
 322         struct caif_device_entry_list *caifdevs;
 323         int res;
 324
 325         caifdevs = caif_device_list(dev_net(dev));
 326         caifd = caif_device_alloc(dev);
 327         if (!caifd)
 328                 return -ENOMEM;
 329         *layer = &caifd->layer;
 330         spin_lock_init(&caifd->flow_lock);
 331
 332         switch (caifdev->link_select) {
 333         case CAIF_LINK_HIGH_BANDW:
 334                 pref = CFPHYPREF_HIGH_BW;
 335                 break;
 336         case CAIF_LINK_LOW_LATENCY:
 337                 pref = CFPHYPREF_LOW_LAT;
 338                 break;
 339         default:
 340                 pref = CFPHYPREF_HIGH_BW;
 341                 break;
 342         }
 343         mutex_lock(&caifdevs->lock);
 344         list_add_rcu(&caifd->list, &caifdevs->list);
 345
 346         strscpy(caifd->layer.name, dev->name,
 347                 sizeof(caifd->layer.name));
 348         caifd->layer.transmit = transmit;
 349         res = cfcnfg_add_phy_layer(cfg,
 350                                 dev,
 351                                 &caifd->layer,
 352                                 pref,
 353                                 link_support,
 354                                 caifdev->use_fcs,
 355                                 head_room);
 356         mutex_unlock(&caifdevs->lock);
 357         if (rcv_func)
 358                 *rcv_func = receive;
 359         return res;
 360 }
 361 EXPORT_SYMBOL(caif_enroll_dev);
 362
 363 /* notify Caif of device events */
 364 static int caif_device_notify(struct notifier_block *me, unsigned long what,
 365                               void *ptr)
 366 {
 367         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 368         struct caif_device_entry *caifd = NULL;
 369         struct caif_dev_common *caifdev;
 370         struct cfcnfg *cfg;
 371         struct cflayer *layer, *link_support;
 372         int head_room = 0;
 373         struct caif_device_entry_list *caifdevs;
 374         int res;
 375
 376         cfg = get_cfcnfg(dev_net(dev));
 377         caifdevs = caif_device_list(dev_net(dev));
 378
 379         caifd = caif_get(dev);
 380         if (caifd == NULL && dev->type != ARPHRD_CAIF)
 381                 return 0;
 382
 383         switch (what) {
 384         case NETDEV_REGISTER:
 385                 if (caifd != NULL)
 386                         break;
 387
 388                 caifdev = netdev_priv(dev);
 389
 390                 link_support = NULL;
 391                 if (caifdev->use_frag) {
 392                         head_room = 1;
 393                         link_support = cfserl_create(dev->ifindex,
 394                                                         caifdev->use_stx);
 395                         if (!link_support) {
 396                                 pr_warn("Out of memory\n");
 397                                 break;
 398                         }
 399                 }
 400                 res = caif_enroll_dev(dev, caifdev, link_support, head_room,
 401                                 &layer, NULL);
 402                 if (res)
 403                         cfserl_release(link_support);
 404                 caifdev->flowctrl = dev_flowctrl;
 405                 break;
 406
 407         case NETDEV_UP:
 408                 rcu_read_lock();
 409
 410                 caifd = caif_get(dev);
 411                 if (caifd == NULL) {
 412                         rcu_read_unlock();
 413                         break;
 414                 }
 415
 416                 caifd->xoff = false;
 417                 cfcnfg_set_phy_state(cfg, &caifd->layer, true);
 418                 rcu_read_unlock();
 419
 420                 break;
 421
 422         case NETDEV_DOWN:
 423                 rcu_read_lock();
 424
 425                 caifd = caif_get(dev);
 426                 if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
 427                         rcu_read_unlock();
 428                         return -EINVAL;
 429                 }
 430
 431                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 432                 caifd_hold(caifd);
 433                 rcu_read_unlock();
 434
 435                 caifd->layer.up->ctrlcmd(caifd->layer.up,
 436                                          _CAIF_CTRLCMD_PHYIF_DOWN_IND,
 437                                          caifd->layer.id);
 438
 439                 spin_lock_bh(&caifd->flow_lock);
 440
 441                 /*
 442                  * Replace our xoff-destructor with original destructor.
 443                  * We trust that skb->destructor *always* is called before
 444                  * the skb reference is invalid. The hijacked SKB destructor
 445                  * takes the flow_lock so manipulating the skb->destructor here
 446                  * should be safe.
 447                 */
 448                 if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
 449                         caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
 450
 451                 caifd->xoff = false;
 452                 caifd->xoff_skb_dtor = NULL;
 453                 caifd->xoff_skb = NULL;
 454
 455                 spin_unlock_bh(&caifd->flow_lock);
 456                 caifd_put(caifd);
 457                 break;
 458
 459         case NETDEV_UNREGISTER:
 460                 mutex_lock(&caifdevs->lock);
 461
 462                 caifd = caif_get(dev);
 463                 if (caifd == NULL) {
 464                         mutex_unlock(&caifdevs->lock);
 465                         break;
 466                 }
 467                 list_del_rcu(&caifd->list);
 468
 469                 /*
 470                  * NETDEV_UNREGISTER is called repeatedly until all reference
 471                  * counts for the net-device are released. If references to
 472                  * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
 473                  * the next call to NETDEV_UNREGISTER.
 474                  *
 475                  * If any packets are in flight down the CAIF Stack,
 476                  * cfcnfg_del_phy_layer will return nonzero.
 477                  * If no packets are in flight, the CAIF Stack associated
 478                  * with the net-device un-registering is freed.
 479                  */
 480
 481                 if (caifd_refcnt_read(caifd) != 0 ||
 482                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
 483
 484                         pr_info("Wait for device inuse\n");
 485                         /* Enrole device if CAIF Stack is still in use */
 486                         list_add_rcu(&caifd->list, &caifdevs->list);
 487                         mutex_unlock(&caifdevs->lock);
 488                         break;
 489                 }
 490
 491                 synchronize_rcu();
 492                 dev_put(caifd->netdev);
 493                 free_percpu(caifd->pcpu_refcnt);
 494                 kfree(caifd);
 495
 496                 mutex_unlock(&caifdevs->lock);
 497                 break;
 498         }
 499         return 0;
 500 }
 501
 502 static struct notifier_block caif_device_notifier = {
 503         .notifier_call = caif_device_notify,
 504         .priority = 0,
 505 };
 506
 507 /* Per-namespace Caif devices handling */
 508 static int caif_init_net(struct net *net)
 509 {
 510         struct caif_net *caifn = net_generic(net, caif_net_id);
 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         rtnl_lock();
 529         mutex_lock(&caifdevs->lock);
 530
 531         list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
 532                 int i = 0;
 533                 list_del_rcu(&caifd->list);
 534                 cfcnfg_set_phy_state(cfg, &caifd->layer, false);
 535
 536                 while (i < 10 &&
 537                         (caifd_refcnt_read(caifd) != 0 ||
 538                         cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
 539
 540                         pr_info("Wait for device inuse\n");
 541                         msleep(250);
 542                         i++;
 543                 }
 544                 synchronize_rcu();
 545                 dev_put(caifd->netdev);
 546                 free_percpu(caifd->pcpu_refcnt);
 547                 kfree(caifd);
 548         }
 549         cfcnfg_remove(cfg);
 550
 551         mutex_unlock(&caifdevs->lock);
 552         rtnl_unlock();
 553 }
 554
 555 static struct pernet_operations caif_net_ops = {
 556         .init = caif_init_net,
 557         .exit = caif_exit_net,
 558         .id   = &caif_net_id,
 559         .size = sizeof(struct caif_net),
 560 };
 561
 562 /* Initialize Caif devices list */
 563 static int __init caif_device_init(void)
 564 {
 565         int result;
 566
 567         result = register_pernet_subsys(&caif_net_ops);
 568
 569         if (result)
 570                 return result;
 571
 572         register_netdevice_notifier(&caif_device_notifier);
 573         dev_add_pack(&caif_packet_type);
 574
 575         return result;
 576 }
 577
 578 static void __exit caif_device_exit(void)
 579 {
 580         unregister_netdevice_notifier(&caif_device_notifier);
 581         dev_remove_pack(&caif_packet_type);
 582         unregister_pernet_subsys(&caif_net_ops);
 583 }
 584
 585 module_init(caif_device_init);
 586 module_exit(caif_device_exit);