net/core/netpoll.c

   1 /*
   2  * Common framework for low-level network console, dump, and debugger code
   3  *
   4  * Sep 8 2003  Matt Mackall <[email protected]>
   5  *
   6  * based on the netconsole code from:
   7  *
   8  * Copyright (C) 2001  Ingo Molnar <[email protected]>
   9  * Copyright (C) 2002  Red Hat, Inc.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/moduleparam.h>
  15 #include <linux/kernel.h>
  16 #include <linux/netdevice.h>
  17 #include <linux/etherdevice.h>
  18 #include <linux/string.h>
  19 #include <linux/if_arp.h>
  20 #include <linux/inetdevice.h>
  21 #include <linux/inet.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/netpoll.h>
  24 #include <linux/sched.h>
  25 #include <linux/delay.h>
  26 #include <linux/rcupdate.h>
  27 #include <linux/workqueue.h>
  28 #include <linux/slab.h>
  29 #include <linux/export.h>
  30 #include <linux/if_vlan.h>
  31 #include <net/tcp.h>
  32 #include <net/udp.h>
  33 #include <net/addrconf.h>
  34 #include <net/ndisc.h>
  35 #include <net/ip6_checksum.h>
  36 #include <asm/unaligned.h>
  37 #include <trace/events/napi.h>
  38
  39 /*
  40  * We maintain a small pool of fully-sized skbs, to make sure the
  41  * message gets out even in extreme OOM situations.
  42  */
  43
  44 #define MAX_UDP_CHUNK 1460
  45 #define MAX_SKBS 32
  46
  47 static struct sk_buff_head skb_pool;
  48
  49 DEFINE_STATIC_SRCU(netpoll_srcu);
  50
  51 #define USEC_PER_POLL   50
  52
  53 #define MAX_SKB_SIZE                                                    \
  54         (sizeof(struct ethhdr) +                                        \
  55          sizeof(struct iphdr) +                                         \
  56          sizeof(struct udphdr) +                                        \
  57          MAX_UDP_CHUNK)
  58
  59 static void zap_completion_queue(void);
  60 static void netpoll_async_cleanup(struct work_struct *work);
  61
  62 static unsigned int carrier_timeout = 4;
  63 module_param(carrier_timeout, uint, 0644);
  64
  65 #define np_info(np, fmt, ...)                           \
  66         pr_info("%s: " fmt, np->name, ##__VA_ARGS__)
  67 #define np_err(np, fmt, ...)                            \
  68         pr_err("%s: " fmt, np->name, ##__VA_ARGS__)
  69 #define np_notice(np, fmt, ...)                         \
  70         pr_notice("%s: " fmt, np->name, ##__VA_ARGS__)
  71
  72 static int netpoll_start_xmit(struct sk_buff *skb, struct net_device *dev,
  73                               struct netdev_queue *txq)
  74 {
  75         int status = NETDEV_TX_OK;
  76         netdev_features_t features;
  77
  78         features = netif_skb_features(skb);
  79
  80         if (vlan_tx_tag_present(skb) &&
  81             !vlan_hw_offload_capable(features, skb->vlan_proto)) {
  82                 skb = __vlan_put_tag(skb, skb->vlan_proto,
  83                                      vlan_tx_tag_get(skb));
  84                 if (unlikely(!skb)) {
  85                         /* This is actually a packet drop, but we
  86                          * don't want the code that calls this
  87                          * function to try and operate on a NULL skb.
  88                          */
  89                         goto out;
  90                 }
  91                 skb->vlan_tci = 0;
  92         }
  93
  94         status = netdev_start_xmit(skb, dev, txq, false);
  95
  96 out:
  97         return status;
  98 }
  99
 100 static void queue_process(struct work_struct *work)
 101 {
 102         struct netpoll_info *npinfo =
 103                 container_of(work, struct netpoll_info, tx_work.work);
 104         struct sk_buff *skb;
 105         unsigned long flags;
 106
 107         while ((skb = skb_dequeue(&npinfo->txq))) {
 108                 struct net_device *dev = skb->dev;
 109                 struct netdev_queue *txq;
 110
 111                 if (!netif_device_present(dev) || !netif_running(dev)) {
 112                         kfree_skb(skb);
 113                         continue;
 114                 }
 115
 116                 txq = skb_get_tx_queue(dev, skb);
 117
 118                 local_irq_save(flags);
 119                 HARD_TX_LOCK(dev, txq, smp_processor_id());
 120                 if (netif_xmit_frozen_or_stopped(txq) ||
 121                     netpoll_start_xmit(skb, dev, txq) != NETDEV_TX_OK) {
 122                         skb_queue_head(&npinfo->txq, skb);
 123                         HARD_TX_UNLOCK(dev, txq);
 124                         local_irq_restore(flags);
 125
 126                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
 127                         return;
 128                 }
 129                 HARD_TX_UNLOCK(dev, txq);
 130                 local_irq_restore(flags);
 131         }
 132 }
 133
 134 /*
 135  * Check whether delayed processing was scheduled for our NIC. If so,
 136  * we attempt to grab the poll lock and use ->poll() to pump the card.
 137  * If this fails, either we've recursed in ->poll() or it's already
 138  * running on another CPU.
 139  *
 140  * Note: we don't mask interrupts with this lock because we're using
 141  * trylock here and interrupts are already disabled in the softirq
 142  * case. Further, we test the poll_owner to avoid recursion on UP
 143  * systems where the lock doesn't exist.
 144  */
 145 static int poll_one_napi(struct napi_struct *napi, int budget)
 146 {
 147         int work;
 148
 149         /* net_rx_action's ->poll() invocations and our's are
 150          * synchronized by this test which is only made while
 151          * holding the napi->poll_lock.
 152          */
 153         if (!test_bit(NAPI_STATE_SCHED, &napi->state))
 154                 return budget;
 155
 156         set_bit(NAPI_STATE_NPSVC, &napi->state);
 157
 158         work = napi->poll(napi, budget);
 159         WARN_ONCE(work > budget, "%pF exceeded budget in poll\n", napi->poll);
 160         trace_napi_poll(napi);
 161
 162         clear_bit(NAPI_STATE_NPSVC, &napi->state);
 163
 164         return budget - work;
 165 }
 166
 167 static void poll_napi(struct net_device *dev, int budget)
 168 {
 169         struct napi_struct *napi;
 170
 171         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 172                 if (napi->poll_owner != smp_processor_id() &&
 173                     spin_trylock(&napi->poll_lock)) {
 174                         budget = poll_one_napi(napi, budget);
 175                         spin_unlock(&napi->poll_lock);
 176                 }
 177         }
 178 }
 179
 180 static void netpoll_poll_dev(struct net_device *dev)
 181 {
 182         const struct net_device_ops *ops;
 183         struct netpoll_info *ni = rcu_dereference_bh(dev->npinfo);
 184         int budget = 0;
 185
 186         /* Don't do any rx activity if the dev_lock mutex is held
 187          * the dev_open/close paths use this to block netpoll activity
 188          * while changing device state
 189          */
 190         if (down_trylock(&ni->dev_lock))
 191                 return;
 192
 193         if (!netif_running(dev)) {
 194                 up(&ni->dev_lock);
 195                 return;
 196         }
 197
 198         ops = dev->netdev_ops;
 199         if (!ops->ndo_poll_controller) {
 200                 up(&ni->dev_lock);
 201                 return;
 202         }
 203
 204         /* Process pending work on NIC */
 205         ops->ndo_poll_controller(dev);
 206
 207         poll_napi(dev, budget);
 208
 209         up(&ni->dev_lock);
 210
 211         zap_completion_queue();
 212 }
 213
 214 void netpoll_poll_disable(struct net_device *dev)
 215 {
 216         struct netpoll_info *ni;
 217         int idx;
 218         might_sleep();
 219         idx = srcu_read_lock(&netpoll_srcu);
 220         ni = srcu_dereference(dev->npinfo, &netpoll_srcu);
 221         if (ni)
 222                 down(&ni->dev_lock);
 223         srcu_read_unlock(&netpoll_srcu, idx);
 224 }
 225 EXPORT_SYMBOL(netpoll_poll_disable);
 226
 227 void netpoll_poll_enable(struct net_device *dev)
 228 {
 229         struct netpoll_info *ni;
 230         rcu_read_lock();
 231         ni = rcu_dereference(dev->npinfo);
 232         if (ni)
 233                 up(&ni->dev_lock);
 234         rcu_read_unlock();
 235 }
 236 EXPORT_SYMBOL(netpoll_poll_enable);
 237
 238 static void refill_skbs(void)
 239 {
 240         struct sk_buff *skb;
 241         unsigned long flags;
 242
 243         spin_lock_irqsave(&skb_pool.lock, flags);
 244         while (skb_pool.qlen < MAX_SKBS) {
 245                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
 246                 if (!skb)
 247                         break;
 248
 249                 __skb_queue_tail(&skb_pool, skb);
 250         }
 251         spin_unlock_irqrestore(&skb_pool.lock, flags);
 252 }
 253
 254 static void zap_completion_queue(void)
 255 {
 256         unsigned long flags;
 257         struct softnet_data *sd = &get_cpu_var(softnet_data);
 258
 259         if (sd->completion_queue) {
 260                 struct sk_buff *clist;
 261
 262                 local_irq_save(flags);
 263                 clist = sd->completion_queue;
 264                 sd->completion_queue = NULL;
 265                 local_irq_restore(flags);
 266
 267                 while (clist != NULL) {
 268                         struct sk_buff *skb = clist;
 269                         clist = clist->next;
 270                         if (!skb_irq_freeable(skb)) {
 271                                 atomic_inc(&skb->users);
 272                                 dev_kfree_skb_any(skb); /* put this one back */
 273                         } else {
 274                                 __kfree_skb(skb);
 275                         }
 276                 }
 277         }
 278
 279         put_cpu_var(softnet_data);
 280 }
 281
 282 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
 283 {
 284         int count = 0;
 285         struct sk_buff *skb;
 286
 287         zap_completion_queue();
 288         refill_skbs();
 289 repeat:
 290
 291         skb = alloc_skb(len, GFP_ATOMIC);
 292         if (!skb)
 293                 skb = skb_dequeue(&skb_pool);
 294
 295         if (!skb) {
 296                 if (++count < 10) {
 297                         netpoll_poll_dev(np->dev);
 298                         goto repeat;
 299                 }
 300                 return NULL;
 301         }
 302
 303         atomic_set(&skb->users, 1);
 304         skb_reserve(skb, reserve);
 305         return skb;
 306 }
 307
 308 static int netpoll_owner_active(struct net_device *dev)
 309 {
 310         struct napi_struct *napi;
 311
 312         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 313                 if (napi->poll_owner == smp_processor_id())
 314                         return 1;
 315         }
 316         return 0;
 317 }
 318
 319 /* call with IRQ disabled */
 320 void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
 321                              struct net_device *dev)
 322 {
 323         int status = NETDEV_TX_BUSY;
 324         unsigned long tries;
 325         /* It is up to the caller to keep npinfo alive. */
 326         struct netpoll_info *npinfo;
 327
 328         WARN_ON_ONCE(!irqs_disabled());
 329
 330         npinfo = rcu_dereference_bh(np->dev->npinfo);
 331         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
 332                 dev_kfree_skb_irq(skb);
 333                 return;
 334         }
 335
 336         /* don't get messages out of order, and no recursion */
 337         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
 338                 struct netdev_queue *txq;
 339
 340                 txq = netdev_pick_tx(dev, skb, NULL);
 341
 342                 /* try until next clock tick */
 343                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
 344                      tries > 0; --tries) {
 345                         if (HARD_TX_TRYLOCK(dev, txq)) {
 346                                 if (!netif_xmit_stopped(txq))
 347                                         status = netpoll_start_xmit(skb, dev, txq);
 348
 349                                 HARD_TX_UNLOCK(dev, txq);
 350
 351                                 if (status == NETDEV_TX_OK)
 352                                         break;
 353
 354                         }
 355
 356                         /* tickle device maybe there is some cleanup */
 357                         netpoll_poll_dev(np->dev);
 358
 359                         udelay(USEC_PER_POLL);
 360                 }
 361
 362                 WARN_ONCE(!irqs_disabled(),
 363                         "netpoll_send_skb_on_dev(): %s enabled interrupts in poll (%pF)\n",
 364                         dev->name, dev->netdev_ops->ndo_start_xmit);
 365
 366         }
 367
 368         if (status != NETDEV_TX_OK) {
 369                 skb_queue_tail(&npinfo->txq, skb);
 370                 schedule_delayed_work(&npinfo->tx_work,0);
 371         }
 372 }
 373 EXPORT_SYMBOL(netpoll_send_skb_on_dev);
 374
 375 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 376 {
 377         int total_len, ip_len, udp_len;
 378         struct sk_buff *skb;
 379         struct udphdr *udph;
 380         struct iphdr *iph;
 381         struct ethhdr *eth;
 382         static atomic_t ip_ident;
 383         struct ipv6hdr *ip6h;
 384
 385         udp_len = len + sizeof(*udph);
 386         if (np->ipv6)
 387                 ip_len = udp_len + sizeof(*ip6h);
 388         else
 389                 ip_len = udp_len + sizeof(*iph);
 390
 391         total_len = ip_len + LL_RESERVED_SPACE(np->dev);
 392
 393         skb = find_skb(np, total_len + np->dev->needed_tailroom,
 394                        total_len - len);
 395         if (!skb)
 396                 return;
 397
 398         skb_copy_to_linear_data(skb, msg, len);
 399         skb_put(skb, len);
 400
 401         skb_push(skb, sizeof(*udph));
 402         skb_reset_transport_header(skb);
 403         udph = udp_hdr(skb);
 404         udph->source = htons(np->local_port);
 405         udph->dest = htons(np->remote_port);
 406         udph->len = htons(udp_len);
 407
 408         if (np->ipv6) {
 409                 udph->check = 0;
 410                 udph->check = csum_ipv6_magic(&np->local_ip.in6,
 411                                               &np->remote_ip.in6,
 412                                               udp_len, IPPROTO_UDP,
 413                                               csum_partial(udph, udp_len, 0));
 414                 if (udph->check == 0)
 415                         udph->check = CSUM_MANGLED_0;
 416
 417                 skb_push(skb, sizeof(*ip6h));
 418                 skb_reset_network_header(skb);
 419                 ip6h = ipv6_hdr(skb);
 420
 421                 /* ip6h->version = 6; ip6h->priority = 0; */
 422                 put_unaligned(0x60, (unsigned char *)ip6h);
 423                 ip6h->flow_lbl[0] = 0;
 424                 ip6h->flow_lbl[1] = 0;
 425                 ip6h->flow_lbl[2] = 0;
 426
 427                 ip6h->payload_len = htons(sizeof(struct udphdr) + len);
 428                 ip6h->nexthdr = IPPROTO_UDP;
 429                 ip6h->hop_limit = 32;
 430                 ip6h->saddr = np->local_ip.in6;
 431                 ip6h->daddr = np->remote_ip.in6;
 432
 433                 eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 434                 skb_reset_mac_header(skb);
 435                 skb->protocol = eth->h_proto = htons(ETH_P_IPV6);
 436         } else {
 437                 udph->check = 0;
 438                 udph->check = csum_tcpudp_magic(np->local_ip.ip,
 439                                                 np->remote_ip.ip,
 440                                                 udp_len, IPPROTO_UDP,
 441                                                 csum_partial(udph, udp_len, 0));
 442                 if (udph->check == 0)
 443                         udph->check = CSUM_MANGLED_0;
 444
 445                 skb_push(skb, sizeof(*iph));
 446                 skb_reset_network_header(skb);
 447                 iph = ip_hdr(skb);
 448
 449                 /* iph->version = 4; iph->ihl = 5; */
 450                 put_unaligned(0x45, (unsigned char *)iph);
 451                 iph->tos      = 0;
 452                 put_unaligned(htons(ip_len), &(iph->tot_len));
 453                 iph->id       = htons(atomic_inc_return(&ip_ident));
 454                 iph->frag_off = 0;
 455                 iph->ttl      = 64;
 456                 iph->protocol = IPPROTO_UDP;
 457                 iph->check    = 0;
 458                 put_unaligned(np->local_ip.ip, &(iph->saddr));
 459                 put_unaligned(np->remote_ip.ip, &(iph->daddr));
 460                 iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 461
 462                 eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 463                 skb_reset_mac_header(skb);
 464                 skb->protocol = eth->h_proto = htons(ETH_P_IP);
 465         }
 466
 467         ether_addr_copy(eth->h_source, np->dev->dev_addr);
 468         ether_addr_copy(eth->h_dest, np->remote_mac);
 469
 470         skb->dev = np->dev;
 471
 472         netpoll_send_skb(np, skb);
 473 }
 474 EXPORT_SYMBOL(netpoll_send_udp);
 475
 476 void netpoll_print_options(struct netpoll *np)
 477 {
 478         np_info(np, "local port %d\n", np->local_port);
 479         if (np->ipv6)
 480                 np_info(np, "local IPv6 address %pI6c\n", &np->local_ip.in6);
 481         else
 482                 np_info(np, "local IPv4 address %pI4\n", &np->local_ip.ip);
 483         np_info(np, "interface '%s'\n", np->dev_name);
 484         np_info(np, "remote port %d\n", np->remote_port);
 485         if (np->ipv6)
 486                 np_info(np, "remote IPv6 address %pI6c\n", &np->remote_ip.in6);
 487         else
 488                 np_info(np, "remote IPv4 address %pI4\n", &np->remote_ip.ip);
 489         np_info(np, "remote ethernet address %pM\n", np->remote_mac);
 490 }
 491 EXPORT_SYMBOL(netpoll_print_options);
 492
 493 static int netpoll_parse_ip_addr(const char *str, union inet_addr *addr)
 494 {
 495         const char *end;
 496
 497         if (!strchr(str, ':') &&
 498             in4_pton(str, -1, (void *)addr, -1, &end) > 0) {
 499                 if (!*end)
 500                         return 0;
 501         }
 502         if (in6_pton(str, -1, addr->in6.s6_addr, -1, &end) > 0) {
 503 #if IS_ENABLED(CONFIG_IPV6)
 504                 if (!*end)
 505                         return 1;
 506 #else
 507                 return -1;
 508 #endif
 509         }
 510         return -1;
 511 }
 512
 513 int netpoll_parse_options(struct netpoll *np, char *opt)
 514 {
 515         char *cur=opt, *delim;
 516         int ipv6;
 517         bool ipversion_set = false;
 518
 519         if (*cur != '@') {
 520                 if ((delim = strchr(cur, '@')) == NULL)
 521                         goto parse_failed;
 522                 *delim = 0;
 523                 if (kstrtou16(cur, 10, &np->local_port))
 524                         goto parse_failed;
 525                 cur = delim;
 526         }
 527         cur++;
 528
 529         if (*cur != '/') {
 530                 ipversion_set = true;
 531                 if ((delim = strchr(cur, '/')) == NULL)
 532                         goto parse_failed;
 533                 *delim = 0;
 534                 ipv6 = netpoll_parse_ip_addr(cur, &np->local_ip);
 535                 if (ipv6 < 0)
 536                         goto parse_failed;
 537                 else
 538                         np->ipv6 = (bool)ipv6;
 539                 cur = delim;
 540         }
 541         cur++;
 542
 543         if (*cur != ',') {
 544                 /* parse out dev name */
 545                 if ((delim = strchr(cur, ',')) == NULL)
 546                         goto parse_failed;
 547                 *delim = 0;
 548                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 549                 cur = delim;
 550         }
 551         cur++;
 552
 553         if (*cur != '@') {
 554                 /* dst port */
 555                 if ((delim = strchr(cur, '@')) == NULL)
 556                         goto parse_failed;
 557                 *delim = 0;
 558                 if (*cur == ' ' || *cur == '\t')
 559                         np_info(np, "warning: whitespace is not allowed\n");
 560                 if (kstrtou16(cur, 10, &np->remote_port))
 561                         goto parse_failed;
 562                 cur = delim;
 563         }
 564         cur++;
 565
 566         /* dst ip */
 567         if ((delim = strchr(cur, '/')) == NULL)
 568                 goto parse_failed;
 569         *delim = 0;
 570         ipv6 = netpoll_parse_ip_addr(cur, &np->remote_ip);
 571         if (ipv6 < 0)
 572                 goto parse_failed;
 573         else if (ipversion_set && np->ipv6 != (bool)ipv6)
 574                 goto parse_failed;
 575         else
 576                 np->ipv6 = (bool)ipv6;
 577         cur = delim + 1;
 578
 579         if (*cur != 0) {
 580                 /* MAC address */
 581                 if (!mac_pton(cur, np->remote_mac))
 582                         goto parse_failed;
 583         }
 584
 585         netpoll_print_options(np);
 586
 587         return 0;
 588
 589  parse_failed:
 590         np_info(np, "couldn't parse config at '%s'!\n", cur);
 591         return -1;
 592 }
 593 EXPORT_SYMBOL(netpoll_parse_options);
 594
 595 int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
 596 {
 597         struct netpoll_info *npinfo;
 598         const struct net_device_ops *ops;
 599         int err;
 600
 601         np->dev = ndev;
 602         strlcpy(np->dev_name, ndev->name, IFNAMSIZ);
 603         INIT_WORK(&np->cleanup_work, netpoll_async_cleanup);
 604
 605         if ((ndev->priv_flags & IFF_DISABLE_NETPOLL) ||
 606             !ndev->netdev_ops->ndo_poll_controller) {
 607                 np_err(np, "%s doesn't support polling, aborting\n",
 608                        np->dev_name);
 609                 err = -ENOTSUPP;
 610                 goto out;
 611         }
 612
 613         if (!ndev->npinfo) {
 614                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
 615                 if (!npinfo) {
 616                         err = -ENOMEM;
 617                         goto out;
 618                 }
 619
 620                 sema_init(&npinfo->dev_lock, 1);
 621                 skb_queue_head_init(&npinfo->txq);
 622                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
 623
 624                 atomic_set(&npinfo->refcnt, 1);
 625
 626                 ops = np->dev->netdev_ops;
 627                 if (ops->ndo_netpoll_setup) {
 628                         err = ops->ndo_netpoll_setup(ndev, npinfo);
 629                         if (err)
 630                                 goto free_npinfo;
 631                 }
 632         } else {
 633                 npinfo = rtnl_dereference(ndev->npinfo);
 634                 atomic_inc(&npinfo->refcnt);
 635         }
 636
 637         npinfo->netpoll = np;
 638
 639         /* last thing to do is link it to the net device structure */
 640         rcu_assign_pointer(ndev->npinfo, npinfo);
 641
 642         return 0;
 643
 644 free_npinfo:
 645         kfree(npinfo);
 646 out:
 647         return err;
 648 }
 649 EXPORT_SYMBOL_GPL(__netpoll_setup);
 650
 651 int netpoll_setup(struct netpoll *np)
 652 {
 653         struct net_device *ndev = NULL;
 654         struct in_device *in_dev;
 655         int err;
 656
 657         rtnl_lock();
 658         if (np->dev_name) {
 659                 struct net *net = current->nsproxy->net_ns;
 660                 ndev = __dev_get_by_name(net, np->dev_name);
 661         }
 662         if (!ndev) {
 663                 np_err(np, "%s doesn't exist, aborting\n", np->dev_name);
 664                 err = -ENODEV;
 665                 goto unlock;
 666         }
 667         dev_hold(ndev);
 668
 669         if (netdev_master_upper_dev_get(ndev)) {
 670                 np_err(np, "%s is a slave device, aborting\n", np->dev_name);
 671                 err = -EBUSY;
 672                 goto put;
 673         }
 674
 675         if (!netif_running(ndev)) {
 676                 unsigned long atmost, atleast;
 677
 678                 np_info(np, "device %s not up yet, forcing it\n", np->dev_name);
 679
 680                 err = dev_open(ndev);
 681
 682                 if (err) {
 683                         np_err(np, "failed to open %s\n", ndev->name);
 684                         goto put;
 685                 }
 686
 687                 rtnl_unlock();
 688                 atleast = jiffies + HZ/10;
 689                 atmost = jiffies + carrier_timeout * HZ;
 690                 while (!netif_carrier_ok(ndev)) {
 691                         if (time_after(jiffies, atmost)) {
 692                                 np_notice(np, "timeout waiting for carrier\n");
 693                                 break;
 694                         }
 695                         msleep(1);
 696                 }
 697
 698                 /* If carrier appears to come up instantly, we don't
 699                  * trust it and pause so that we don't pump all our
 700                  * queued console messages into the bitbucket.
 701                  */
 702
 703                 if (time_before(jiffies, atleast)) {
 704                         np_notice(np, "carrier detect appears untrustworthy, waiting 4 seconds\n");
 705                         msleep(4000);
 706                 }
 707                 rtnl_lock();
 708         }
 709
 710         if (!np->local_ip.ip) {
 711                 if (!np->ipv6) {
 712                         in_dev = __in_dev_get_rtnl(ndev);
 713
 714                         if (!in_dev || !in_dev->ifa_list) {
 715                                 np_err(np, "no IP address for %s, aborting\n",
 716                                        np->dev_name);
 717                                 err = -EDESTADDRREQ;
 718                                 goto put;
 719                         }
 720
 721                         np->local_ip.ip = in_dev->ifa_list->ifa_local;
 722                         np_info(np, "local IP %pI4\n", &np->local_ip.ip);
 723                 } else {
 724 #if IS_ENABLED(CONFIG_IPV6)
 725                         struct inet6_dev *idev;
 726
 727                         err = -EDESTADDRREQ;
 728                         idev = __in6_dev_get(ndev);
 729                         if (idev) {
 730                                 struct inet6_ifaddr *ifp;
 731
 732                                 read_lock_bh(&idev->lock);
 733                                 list_for_each_entry(ifp, &idev->addr_list, if_list) {
 734                                         if (ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL)
 735                                                 continue;
 736                                         np->local_ip.in6 = ifp->addr;
 737                                         err = 0;
 738                                         break;
 739                                 }
 740                                 read_unlock_bh(&idev->lock);
 741                         }
 742                         if (err) {
 743                                 np_err(np, "no IPv6 address for %s, aborting\n",
 744                                        np->dev_name);
 745                                 goto put;
 746                         } else
 747                                 np_info(np, "local IPv6 %pI6c\n", &np->local_ip.in6);
 748 #else
 749                         np_err(np, "IPv6 is not supported %s, aborting\n",
 750                                np->dev_name);
 751                         err = -EINVAL;
 752                         goto put;
 753 #endif
 754                 }
 755         }
 756
 757         /* fill up the skb queue */
 758         refill_skbs();
 759
 760         err = __netpoll_setup(np, ndev);
 761         if (err)
 762                 goto put;
 763
 764         rtnl_unlock();
 765         return 0;
 766
 767 put:
 768         dev_put(ndev);
 769 unlock:
 770         rtnl_unlock();
 771         return err;
 772 }
 773 EXPORT_SYMBOL(netpoll_setup);
 774
 775 static int __init netpoll_init(void)
 776 {
 777         skb_queue_head_init(&skb_pool);
 778         return 0;
 779 }
 780 core_initcall(netpoll_init);
 781
 782 static void rcu_cleanup_netpoll_info(struct rcu_head *rcu_head)
 783 {
 784         struct netpoll_info *npinfo =
 785                         container_of(rcu_head, struct netpoll_info, rcu);
 786
 787         skb_queue_purge(&npinfo->txq);
 788
 789         /* we can't call cancel_delayed_work_sync here, as we are in softirq */
 790         cancel_delayed_work(&npinfo->tx_work);
 791
 792         /* clean after last, unfinished work */
 793         __skb_queue_purge(&npinfo->txq);
 794         /* now cancel it again */
 795         cancel_delayed_work(&npinfo->tx_work);
 796         kfree(npinfo);
 797 }
 798
 799 void __netpoll_cleanup(struct netpoll *np)
 800 {
 801         struct netpoll_info *npinfo;
 802
 803         /* rtnl_dereference would be preferable here but
 804          * rcu_cleanup_netpoll path can put us in here safely without
 805          * holding the rtnl, so plain rcu_dereference it is
 806          */
 807         npinfo = rtnl_dereference(np->dev->npinfo);
 808         if (!npinfo)
 809                 return;
 810
 811         synchronize_srcu(&netpoll_srcu);
 812
 813         if (atomic_dec_and_test(&npinfo->refcnt)) {
 814                 const struct net_device_ops *ops;
 815
 816                 ops = np->dev->netdev_ops;
 817                 if (ops->ndo_netpoll_cleanup)
 818                         ops->ndo_netpoll_cleanup(np->dev);
 819
 820                 RCU_INIT_POINTER(np->dev->npinfo, NULL);
 821                 call_rcu_bh(&npinfo->rcu, rcu_cleanup_netpoll_info);
 822         } else
 823                 RCU_INIT_POINTER(np->dev->npinfo, NULL);
 824 }
 825 EXPORT_SYMBOL_GPL(__netpoll_cleanup);
 826
 827 static void netpoll_async_cleanup(struct work_struct *work)
 828 {
 829         struct netpoll *np = container_of(work, struct netpoll, cleanup_work);
 830
 831         rtnl_lock();
 832         __netpoll_cleanup(np);
 833         rtnl_unlock();
 834         kfree(np);
 835 }
 836
 837 void __netpoll_free_async(struct netpoll *np)
 838 {
 839         schedule_work(&np->cleanup_work);
 840 }
 841 EXPORT_SYMBOL_GPL(__netpoll_free_async);
 842
 843 void netpoll_cleanup(struct netpoll *np)
 844 {
 845         rtnl_lock();
 846         if (!np->dev)
 847                 goto out;
 848         __netpoll_cleanup(np);
 849         dev_put(np->dev);
 850         np->dev = NULL;
 851 out:
 852         rtnl_unlock();
 853 }
 854 EXPORT_SYMBOL(netpoll_cleanup);