net/core/netpoll.c

   1 /*
   2  * Common framework for low-level network console, dump, and debugger code
   3  *
   4  * Sep 8 2003  Matt Mackall <mpm@selenic.com>
   5  *
   6  * based on the netconsole code from:
   7  *
   8  * Copyright (C) 2001  Ingo Molnar <mingo@redhat.com>
   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 static atomic_t trapped;
  50
  51 DEFINE_STATIC_SRCU(netpoll_srcu);
  52
  53 #define USEC_PER_POLL   50
  54
  55 #define MAX_SKB_SIZE                                                    \
  56         (sizeof(struct ethhdr) +                                        \
  57          sizeof(struct iphdr) +                                         \
  58          sizeof(struct udphdr) +                                        \
  59          MAX_UDP_CHUNK)
  60
  61 static void zap_completion_queue(void);
  62 static void netpoll_neigh_reply(struct sk_buff *skb, struct netpoll_info *npinfo);
  63 static void netpoll_async_cleanup(struct work_struct *work);
  64
  65 static unsigned int carrier_timeout = 4;
  66 module_param(carrier_timeout, uint, 0644);
  67
  68 #define np_info(np, fmt, ...)                           \
  69         pr_info("%s: " fmt, np->name, ##__VA_ARGS__)
  70 #define np_err(np, fmt, ...)                            \
  71         pr_err("%s: " fmt, np->name, ##__VA_ARGS__)
  72 #define np_notice(np, fmt, ...)                         \
  73         pr_notice("%s: " fmt, np->name, ##__VA_ARGS__)
  74
  75 static void queue_process(struct work_struct *work)
  76 {
  77         struct netpoll_info *npinfo =
  78                 container_of(work, struct netpoll_info, tx_work.work);
  79         struct sk_buff *skb;
  80         unsigned long flags;
  81
  82         while ((skb = skb_dequeue(&npinfo->txq))) {
  83                 struct net_device *dev = skb->dev;
  84                 const struct net_device_ops *ops = dev->netdev_ops;
  85                 struct netdev_queue *txq;
  86
  87                 if (!netif_device_present(dev) || !netif_running(dev)) {
  88                         __kfree_skb(skb);
  89                         continue;
  90                 }
  91
  92                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
  93
  94                 local_irq_save(flags);
  95                 __netif_tx_lock(txq, smp_processor_id());
  96                 if (netif_xmit_frozen_or_stopped(txq) ||
  97                     ops->ndo_start_xmit(skb, dev) != NETDEV_TX_OK) {
  98                         skb_queue_head(&npinfo->txq, skb);
  99                         __netif_tx_unlock(txq);
 100                         local_irq_restore(flags);
 101
 102                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
 103                         return;
 104                 }
 105                 __netif_tx_unlock(txq);
 106                 local_irq_restore(flags);
 107         }
 108 }
 109
 110 static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
 111                             unsigned short ulen, __be32 saddr, __be32 daddr)
 112 {
 113         __wsum psum;
 114
 115         if (uh->check == 0 || skb_csum_unnecessary(skb))
 116                 return 0;
 117
 118         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
 119
 120         if (skb->ip_summed == CHECKSUM_COMPLETE &&
 121             !csum_fold(csum_add(psum, skb->csum)))
 122                 return 0;
 123
 124         skb->csum = psum;
 125
 126         return __skb_checksum_complete(skb);
 127 }
 128
 129 /*
 130  * Check whether delayed processing was scheduled for our NIC. If so,
 131  * we attempt to grab the poll lock and use ->poll() to pump the card.
 132  * If this fails, either we've recursed in ->poll() or it's already
 133  * running on another CPU.
 134  *
 135  * Note: we don't mask interrupts with this lock because we're using
 136  * trylock here and interrupts are already disabled in the softirq
 137  * case. Further, we test the poll_owner to avoid recursion on UP
 138  * systems where the lock doesn't exist.
 139  *
 140  * In cases where there is bi-directional communications, reading only
 141  * one message at a time can lead to packets being dropped by the
 142  * network adapter, forcing superfluous retries and possibly timeouts.
 143  * Thus, we set our budget to greater than 1.
 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 service_neigh_queue(struct netpoll_info *npi)
 181 {
 182         if (npi) {
 183                 struct sk_buff *skb;
 184
 185                 while ((skb = skb_dequeue(&npi->neigh_tx)))
 186                         netpoll_neigh_reply(skb, npi);
 187         }
 188 }
 189
 190 static void netpoll_poll_dev(struct net_device *dev)
 191 {
 192         const struct net_device_ops *ops;
 193         struct netpoll_info *ni = rcu_dereference_bh(dev->npinfo);
 194         bool rx_processing = netpoll_rx_processing(ni);
 195         int budget = rx_processing? 16 : 0;
 196
 197         /* Don't do any rx activity if the dev_lock mutex is held
 198          * the dev_open/close paths use this to block netpoll activity
 199          * while changing device state
 200          */
 201         if (down_trylock(&ni->dev_lock))
 202                 return;
 203
 204         if (!netif_running(dev)) {
 205                 up(&ni->dev_lock);
 206                 return;
 207         }
 208
 209         if (rx_processing)
 210                 atomic_inc(&trapped);
 211
 212         ops = dev->netdev_ops;
 213         if (!ops->ndo_poll_controller) {
 214                 up(&ni->dev_lock);
 215                 return;
 216         }
 217
 218         /* Process pending work on NIC */
 219         ops->ndo_poll_controller(dev);
 220
 221         poll_napi(dev, budget);
 222
 223         if (rx_processing)
 224                 atomic_dec(&trapped);
 225
 226         up(&ni->dev_lock);
 227
 228         if (dev->flags & IFF_SLAVE) {
 229                 if (ni) {
 230                         struct net_device *bond_dev;
 231                         struct sk_buff *skb;
 232                         struct netpoll_info *bond_ni;
 233
 234                         bond_dev = netdev_master_upper_dev_get_rcu(dev);
 235                         bond_ni = rcu_dereference_bh(bond_dev->npinfo);
 236                         while ((skb = skb_dequeue(&ni->neigh_tx))) {
 237                                 skb->dev = bond_dev;
 238                                 skb_queue_tail(&bond_ni->neigh_tx, skb);
 239                         }
 240                 }
 241         }
 242
 243         service_neigh_queue(ni);
 244
 245         zap_completion_queue();
 246 }
 247
 248 void netpoll_rx_disable(struct net_device *dev)
 249 {
 250         struct netpoll_info *ni;
 251         int idx;
 252         might_sleep();
 253         idx = srcu_read_lock(&netpoll_srcu);
 254         ni = srcu_dereference(dev->npinfo, &netpoll_srcu);
 255         if (ni)
 256                 down(&ni->dev_lock);
 257         srcu_read_unlock(&netpoll_srcu, idx);
 258 }
 259 EXPORT_SYMBOL(netpoll_rx_disable);
 260
 261 void netpoll_rx_enable(struct net_device *dev)
 262 {
 263         struct netpoll_info *ni;
 264         rcu_read_lock();
 265         ni = rcu_dereference(dev->npinfo);
 266         if (ni)
 267                 up(&ni->dev_lock);
 268         rcu_read_unlock();
 269 }
 270 EXPORT_SYMBOL(netpoll_rx_enable);
 271
 272 static void refill_skbs(void)
 273 {
 274         struct sk_buff *skb;
 275         unsigned long flags;
 276
 277         spin_lock_irqsave(&skb_pool.lock, flags);
 278         while (skb_pool.qlen < MAX_SKBS) {
 279                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
 280                 if (!skb)
 281                         break;
 282
 283                 __skb_queue_tail(&skb_pool, skb);
 284         }
 285         spin_unlock_irqrestore(&skb_pool.lock, flags);
 286 }
 287
 288 static void zap_completion_queue(void)
 289 {
 290         unsigned long flags;
 291         struct softnet_data *sd = &get_cpu_var(softnet_data);
 292
 293         if (sd->completion_queue) {
 294                 struct sk_buff *clist;
 295
 296                 local_irq_save(flags);
 297                 clist = sd->completion_queue;
 298                 sd->completion_queue = NULL;
 299                 local_irq_restore(flags);
 300
 301                 while (clist != NULL) {
 302                         struct sk_buff *skb = clist;
 303                         clist = clist->next;
 304                         if (skb->destructor) {
 305                                 atomic_inc(&skb->users);
 306                                 dev_kfree_skb_any(skb); /* put this one back */
 307                         } else {
 308                                 __kfree_skb(skb);
 309                         }
 310                 }
 311         }
 312
 313         put_cpu_var(softnet_data);
 314 }
 315
 316 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
 317 {
 318         int count = 0;
 319         struct sk_buff *skb;
 320
 321         zap_completion_queue();
 322         refill_skbs();
 323 repeat:
 324
 325         skb = alloc_skb(len, GFP_ATOMIC);
 326         if (!skb)
 327                 skb = skb_dequeue(&skb_pool);
 328
 329         if (!skb) {
 330                 if (++count < 10) {
 331                         netpoll_poll_dev(np->dev);
 332                         goto repeat;
 333                 }
 334                 return NULL;
 335         }
 336
 337         atomic_set(&skb->users, 1);
 338         skb_reserve(skb, reserve);
 339         return skb;
 340 }
 341
 342 static int netpoll_owner_active(struct net_device *dev)
 343 {
 344         struct napi_struct *napi;
 345
 346         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 347                 if (napi->poll_owner == smp_processor_id())
 348                         return 1;
 349         }
 350         return 0;
 351 }
 352
 353 /* call with IRQ disabled */
 354 void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
 355                              struct net_device *dev)
 356 {
 357         int status = NETDEV_TX_BUSY;
 358         unsigned long tries;
 359         const struct net_device_ops *ops = dev->netdev_ops;
 360         /* It is up to the caller to keep npinfo alive. */
 361         struct netpoll_info *npinfo;
 362
 363         WARN_ON_ONCE(!irqs_disabled());
 364
 365         npinfo = rcu_dereference_bh(np->dev->npinfo);
 366         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
 367                 __kfree_skb(skb);
 368                 return;
 369         }
 370
 371         /* don't get messages out of order, and no recursion */
 372         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
 373                 struct netdev_queue *txq;
 374
 375                 txq = netdev_pick_tx(dev, skb, NULL);
 376
 377                 /* try until next clock tick */
 378                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
 379                      tries > 0; --tries) {
 380                         if (__netif_tx_trylock(txq)) {
 381                                 if (!netif_xmit_stopped(txq)) {
 382                                         if (vlan_tx_tag_present(skb) &&
 383                                             !vlan_hw_offload_capable(netif_skb_features(skb),
 384                                                                      skb->vlan_proto)) {
 385                                                 skb = __vlan_put_tag(skb, skb->vlan_proto, vlan_tx_tag_get(skb));
 386                                                 if (unlikely(!skb)) {
 387                                                         /* This is actually a packet drop, but we
 388                                                          * don't want the code at the end of this
 389                                                          * function to try and re-queue a NULL skb.
 390                                                          */
 391                                                         status = NETDEV_TX_OK;
 392                                                         goto unlock_txq;
 393                                                 }
 394                                                 skb->vlan_tci = 0;
 395                                         }
 396
 397                                         status = ops->ndo_start_xmit(skb, dev);
 398                                         if (status == NETDEV_TX_OK)
 399                                                 txq_trans_update(txq);
 400                                 }
 401                         unlock_txq:
 402                                 __netif_tx_unlock(txq);
 403
 404                                 if (status == NETDEV_TX_OK)
 405                                         break;
 406
 407                         }
 408
 409                         /* tickle device maybe there is some cleanup */
 410                         netpoll_poll_dev(np->dev);
 411
 412                         udelay(USEC_PER_POLL);
 413                 }
 414
 415                 WARN_ONCE(!irqs_disabled(),
 416                         "netpoll_send_skb_on_dev(): %s enabled interrupts in poll (%pF)\n",
 417                         dev->name, ops->ndo_start_xmit);
 418
 419         }
 420
 421         if (status != NETDEV_TX_OK) {
 422                 skb_queue_tail(&npinfo->txq, skb);
 423                 schedule_delayed_work(&npinfo->tx_work,0);
 424         }
 425 }
 426 EXPORT_SYMBOL(netpoll_send_skb_on_dev);
 427
 428 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 429 {
 430         int total_len, ip_len, udp_len;
 431         struct sk_buff *skb;
 432         struct udphdr *udph;
 433         struct iphdr *iph;
 434         struct ethhdr *eth;
 435         static atomic_t ip_ident;
 436         struct ipv6hdr *ip6h;
 437
 438         udp_len = len + sizeof(*udph);
 439         if (np->ipv6)
 440                 ip_len = udp_len + sizeof(*ip6h);
 441         else
 442                 ip_len = udp_len + sizeof(*iph);
 443
 444         total_len = ip_len + LL_RESERVED_SPACE(np->dev);
 445
 446         skb = find_skb(np, total_len + np->dev->needed_tailroom,
 447                        total_len - len);
 448         if (!skb)
 449                 return;
 450
 451         skb_copy_to_linear_data(skb, msg, len);
 452         skb_put(skb, len);
 453
 454         skb_push(skb, sizeof(*udph));
 455         skb_reset_transport_header(skb);
 456         udph = udp_hdr(skb);
 457         udph->source = htons(np->local_port);
 458         udph->dest = htons(np->remote_port);
 459         udph->len = htons(udp_len);
 460
 461         if (np->ipv6) {
 462                 udph->check = 0;
 463                 udph->check = csum_ipv6_magic(&np->local_ip.in6,
 464                                               &np->remote_ip.in6,
 465                                               udp_len, IPPROTO_UDP,
 466                                               csum_partial(udph, udp_len, 0));
 467                 if (udph->check == 0)
 468                         udph->check = CSUM_MANGLED_0;
 469
 470                 skb_push(skb, sizeof(*ip6h));
 471                 skb_reset_network_header(skb);
 472                 ip6h = ipv6_hdr(skb);
 473
 474                 /* ip6h->version = 6; ip6h->priority = 0; */
 475                 put_unaligned(0x60, (unsigned char *)ip6h);
 476                 ip6h->flow_lbl[0] = 0;
 477                 ip6h->flow_lbl[1] = 0;
 478                 ip6h->flow_lbl[2] = 0;
 479
 480                 ip6h->payload_len = htons(sizeof(struct udphdr) + len);
 481                 ip6h->nexthdr = IPPROTO_UDP;
 482                 ip6h->hop_limit = 32;
 483                 ip6h->saddr = np->local_ip.in6;
 484                 ip6h->daddr = np->remote_ip.in6;
 485
 486                 eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 487                 skb_reset_mac_header(skb);
 488                 skb->protocol = eth->h_proto = htons(ETH_P_IPV6);
 489         } else {
 490                 udph->check = 0;
 491                 udph->check = csum_tcpudp_magic(np->local_ip.ip,
 492                                                 np->remote_ip.ip,
 493                                                 udp_len, IPPROTO_UDP,
 494                                                 csum_partial(udph, udp_len, 0));
 495                 if (udph->check == 0)
 496                         udph->check = CSUM_MANGLED_0;
 497
 498                 skb_push(skb, sizeof(*iph));
 499                 skb_reset_network_header(skb);
 500                 iph = ip_hdr(skb);
 501
 502                 /* iph->version = 4; iph->ihl = 5; */
 503                 put_unaligned(0x45, (unsigned char *)iph);
 504                 iph->tos      = 0;
 505                 put_unaligned(htons(ip_len), &(iph->tot_len));
 506                 iph->id       = htons(atomic_inc_return(&ip_ident));
 507                 iph->frag_off = 0;
 508                 iph->ttl      = 64;
 509                 iph->protocol = IPPROTO_UDP;
 510                 iph->check    = 0;
 511                 put_unaligned(np->local_ip.ip, &(iph->saddr));
 512                 put_unaligned(np->remote_ip.ip, &(iph->daddr));
 513                 iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 514
 515                 eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 516                 skb_reset_mac_header(skb);
 517                 skb->protocol = eth->h_proto = htons(ETH_P_IP);
 518         }
 519
 520         ether_addr_copy(eth->h_source, np->dev->dev_addr);
 521         ether_addr_copy(eth->h_dest, np->remote_mac);
 522
 523         skb->dev = np->dev;
 524
 525         netpoll_send_skb(np, skb);
 526 }
 527 EXPORT_SYMBOL(netpoll_send_udp);
 528
 529 static void netpoll_neigh_reply(struct sk_buff *skb, struct netpoll_info *npinfo)
 530 {
 531         int size, type = ARPOP_REPLY;
 532         __be32 sip, tip;
 533         unsigned char *sha;
 534         struct sk_buff *send_skb;
 535         struct netpoll *np, *tmp;
 536         unsigned long flags;
 537         int hlen, tlen;
 538         int hits = 0, proto;
 539
 540         if (!netpoll_rx_processing(npinfo))
 541                 return;
 542
 543         /* Before checking the packet, we do some early
 544            inspection whether this is interesting at all */
 545         spin_lock_irqsave(&npinfo->rx_lock, flags);
 546         list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
 547                 if (np->dev == skb->dev)
 548                         hits++;
 549         }
 550         spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 551
 552         /* No netpoll struct is using this dev */
 553         if (!hits)
 554                 return;
 555
 556         proto = ntohs(eth_hdr(skb)->h_proto);
 557         if (proto == ETH_P_ARP) {
 558                 struct arphdr *arp;
 559                 unsigned char *arp_ptr;
 560                 /* No arp on this interface */
 561                 if (skb->dev->flags & IFF_NOARP)
 562                         return;
 563
 564                 if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
 565                         return;
 566
 567                 skb_reset_network_header(skb);
 568                 skb_reset_transport_header(skb);
 569                 arp = arp_hdr(skb);
 570
 571                 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 572                      arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 573                     arp->ar_pro != htons(ETH_P_IP) ||
 574                     arp->ar_op != htons(ARPOP_REQUEST))
 575                         return;
 576
 577                 arp_ptr = (unsigned char *)(arp+1);
 578                 /* save the location of the src hw addr */
 579                 sha = arp_ptr;
 580                 arp_ptr += skb->dev->addr_len;
 581                 memcpy(&sip, arp_ptr, 4);
 582                 arp_ptr += 4;
 583                 /* If we actually cared about dst hw addr,
 584                    it would get copied here */
 585                 arp_ptr += skb->dev->addr_len;
 586                 memcpy(&tip, arp_ptr, 4);
 587
 588                 /* Should we ignore arp? */
 589                 if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
 590                         return;
 591
 592                 size = arp_hdr_len(skb->dev);
 593
 594                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 595                 list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
 596                         if (tip != np->local_ip.ip)
 597                                 continue;
 598
 599                         hlen = LL_RESERVED_SPACE(np->dev);
 600                         tlen = np->dev->needed_tailroom;
 601                         send_skb = find_skb(np, size + hlen + tlen, hlen);
 602                         if (!send_skb)
 603                                 continue;
 604
 605                         skb_reset_network_header(send_skb);
 606                         arp = (struct arphdr *) skb_put(send_skb, size);
 607                         send_skb->dev = skb->dev;
 608                         send_skb->protocol = htons(ETH_P_ARP);
 609
 610                         /* Fill the device header for the ARP frame */
 611                         if (dev_hard_header(send_skb, skb->dev, ETH_P_ARP,
 612                                             sha, np->dev->dev_addr,
 613                                             send_skb->len) < 0) {
 614                                 kfree_skb(send_skb);
 615                                 continue;
 616                         }
 617
 618                         /*
 619                          * Fill out the arp protocol part.
 620                          *
 621                          * we only support ethernet device type,
 622                          * which (according to RFC 1390) should
 623                          * always equal 1 (Ethernet).
 624                          */
 625
 626                         arp->ar_hrd = htons(np->dev->type);
 627                         arp->ar_pro = htons(ETH_P_IP);
 628                         arp->ar_hln = np->dev->addr_len;
 629                         arp->ar_pln = 4;
 630                         arp->ar_op = htons(type);
 631
 632                         arp_ptr = (unsigned char *)(arp + 1);
 633                         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
 634                         arp_ptr += np->dev->addr_len;
 635                         memcpy(arp_ptr, &tip, 4);
 636                         arp_ptr += 4;
 637                         memcpy(arp_ptr, sha, np->dev->addr_len);
 638                         arp_ptr += np->dev->addr_len;
 639                         memcpy(arp_ptr, &sip, 4);
 640
 641                         netpoll_send_skb(np, send_skb);
 642
 643                         /* If there are several rx_skb_hooks for the same
 644                          * address we're fine by sending a single reply
 645                          */
 646                         break;
 647                 }
 648                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 649         } else if( proto == ETH_P_IPV6) {
 650 #if IS_ENABLED(CONFIG_IPV6)
 651                 struct nd_msg *msg;
 652                 u8 *lladdr = NULL;
 653                 struct ipv6hdr *hdr;
 654                 struct icmp6hdr *icmp6h;
 655                 const struct in6_addr *saddr;
 656                 const struct in6_addr *daddr;
 657                 struct inet6_dev *in6_dev = NULL;
 658                 struct in6_addr *target;
 659
 660                 in6_dev = in6_dev_get(skb->dev);
 661                 if (!in6_dev || !in6_dev->cnf.accept_ra)
 662                         return;
 663
 664                 if (!pskb_may_pull(skb, skb->len))
 665                         return;
 666
 667                 msg = (struct nd_msg *)skb_transport_header(skb);
 668
 669                 __skb_push(skb, skb->data - skb_transport_header(skb));
 670
 671                 if (ipv6_hdr(skb)->hop_limit != 255)
 672                         return;
 673                 if (msg->icmph.icmp6_code != 0)
 674                         return;
 675                 if (msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)
 676                         return;
 677
 678                 saddr = &ipv6_hdr(skb)->saddr;
 679                 daddr = &ipv6_hdr(skb)->daddr;
 680
 681                 size = sizeof(struct icmp6hdr) + sizeof(struct in6_addr);
 682
 683                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 684                 list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
 685                         if (!ipv6_addr_equal(daddr, &np->local_ip.in6))
 686                                 continue;
 687
 688                         hlen = LL_RESERVED_SPACE(np->dev);
 689                         tlen = np->dev->needed_tailroom;
 690                         send_skb = find_skb(np, size + hlen + tlen, hlen);
 691                         if (!send_skb)
 692                                 continue;
 693
 694                         send_skb->protocol = htons(ETH_P_IPV6);
 695                         send_skb->dev = skb->dev;
 696
 697                         skb_reset_network_header(send_skb);
 698                         hdr = (struct ipv6hdr *) skb_put(send_skb, sizeof(struct ipv6hdr));
 699                         *(__be32*)hdr = htonl(0x60000000);
 700                         hdr->payload_len = htons(size);
 701                         hdr->nexthdr = IPPROTO_ICMPV6;
 702                         hdr->hop_limit = 255;
 703                         hdr->saddr = *saddr;
 704                         hdr->daddr = *daddr;
 705
 706                         icmp6h = (struct icmp6hdr *) skb_put(send_skb, sizeof(struct icmp6hdr));
 707                         icmp6h->icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT;
 708                         icmp6h->icmp6_router = 0;
 709                         icmp6h->icmp6_solicited = 1;
 710
 711                         target = (struct in6_addr *) skb_put(send_skb, sizeof(struct in6_addr));
 712                         *target = msg->target;
 713                         icmp6h->icmp6_cksum = csum_ipv6_magic(saddr, daddr, size,
 714                                                               IPPROTO_ICMPV6,
 715                                                               csum_partial(icmp6h,
 716                                                                            size, 0));
 717
 718                         if (dev_hard_header(send_skb, skb->dev, ETH_P_IPV6,
 719                                             lladdr, np->dev->dev_addr,
 720                                             send_skb->len) < 0) {
 721                                 kfree_skb(send_skb);
 722                                 continue;
 723                         }
 724
 725                         netpoll_send_skb(np, send_skb);
 726
 727                         /* If there are several rx_skb_hooks for the same
 728                          * address, we're fine by sending a single reply
 729                          */
 730                         break;
 731                 }
 732                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 733 #endif
 734         }
 735 }
 736
 737 static bool pkt_is_ns(struct sk_buff *skb)
 738 {
 739         struct nd_msg *msg;
 740         struct ipv6hdr *hdr;
 741
 742         if (skb->protocol != htons(ETH_P_ARP))
 743                 return false;
 744         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + sizeof(struct nd_msg)))
 745                 return false;
 746
 747         msg = (struct nd_msg *)skb_transport_header(skb);
 748         __skb_push(skb, skb->data - skb_transport_header(skb));
 749         hdr = ipv6_hdr(skb);
 750
 751         if (hdr->nexthdr != IPPROTO_ICMPV6)
 752                 return false;
 753         if (hdr->hop_limit != 255)
 754                 return false;
 755         if (msg->icmph.icmp6_code != 0)
 756                 return false;
 757         if (msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)
 758                 return false;
 759
 760         return true;
 761 }
 762
 763 int __netpoll_rx(struct sk_buff *skb, struct netpoll_info *npinfo)
 764 {
 765         int proto, len, ulen, data_len;
 766         int hits = 0, offset;
 767         const struct iphdr *iph;
 768         struct udphdr *uh;
 769         struct netpoll *np, *tmp;
 770         uint16_t source;
 771
 772         if (!netpoll_rx_processing(npinfo))
 773                 goto out;
 774
 775         if (skb->dev->type != ARPHRD_ETHER)
 776                 goto out;
 777
 778         /* check if netpoll clients need ARP */
 779         if (skb->protocol == htons(ETH_P_ARP) && atomic_read(&trapped)) {
 780                 skb_queue_tail(&npinfo->neigh_tx, skb);
 781                 return 1;
 782         } else if (pkt_is_ns(skb) && atomic_read(&trapped)) {
 783                 skb_queue_tail(&npinfo->neigh_tx, skb);
 784                 return 1;
 785         }
 786
 787         if (skb->protocol == cpu_to_be16(ETH_P_8021Q)) {
 788                 skb = vlan_untag(skb);
 789                 if (unlikely(!skb))
 790                         goto out;
 791         }
 792
 793         proto = ntohs(eth_hdr(skb)->h_proto);
 794         if (proto != ETH_P_IP && proto != ETH_P_IPV6)
 795                 goto out;
 796         if (skb->pkt_type == PACKET_OTHERHOST)
 797                 goto out;
 798         if (skb_shared(skb))
 799                 goto out;
 800
 801         if (proto == ETH_P_IP) {
 802                 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 803                         goto out;
 804                 iph = (struct iphdr *)skb->data;
 805                 if (iph->ihl < 5 || iph->version != 4)
 806                         goto out;
 807                 if (!pskb_may_pull(skb, iph->ihl*4))
 808                         goto out;
 809                 iph = (struct iphdr *)skb->data;
 810                 if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
 811                         goto out;
 812
 813                 len = ntohs(iph->tot_len);
 814                 if (skb->len < len || len < iph->ihl*4)
 815                         goto out;
 816
 817                 /*
 818                  * Our transport medium may have padded the buffer out.
 819                  * Now We trim to the true length of the frame.
 820                  */
 821                 if (pskb_trim_rcsum(skb, len))
 822                         goto out;
 823
 824                 iph = (struct iphdr *)skb->data;
 825                 if (iph->protocol != IPPROTO_UDP)
 826                         goto out;
 827
 828                 len -= iph->ihl*4;
 829                 uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
 830                 offset = (unsigned char *)(uh + 1) - skb->data;
 831                 ulen = ntohs(uh->len);
 832                 data_len = skb->len - offset;
 833                 source = ntohs(uh->source);
 834
 835                 if (ulen != len)
 836                         goto out;
 837                 if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
 838                         goto out;
 839                 list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
 840                         if (np->local_ip.ip && np->local_ip.ip != iph->daddr)
 841                                 continue;
 842                         if (np->remote_ip.ip && np->remote_ip.ip != iph->saddr)
 843                                 continue;
 844                         if (np->local_port && np->local_port != ntohs(uh->dest))
 845                                 continue;
 846
 847                         np->rx_skb_hook(np, source, skb, offset, data_len);
 848                         hits++;
 849                 }
 850         } else {
 851 #if IS_ENABLED(CONFIG_IPV6)
 852                 const struct ipv6hdr *ip6h;
 853
 854                 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 855                         goto out;
 856                 ip6h = (struct ipv6hdr *)skb->data;
 857                 if (ip6h->version != 6)
 858                         goto out;
 859                 len = ntohs(ip6h->payload_len);
 860                 if (!len)
 861                         goto out;
 862                 if (len + sizeof(struct ipv6hdr) > skb->len)
 863                         goto out;
 864                 if (pskb_trim_rcsum(skb, len + sizeof(struct ipv6hdr)))
 865                         goto out;
 866                 ip6h = ipv6_hdr(skb);
 867                 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
 868                         goto out;
 869                 uh = udp_hdr(skb);
 870                 offset = (unsigned char *)(uh + 1) - skb->data;
 871                 ulen = ntohs(uh->len);
 872                 data_len = skb->len - offset;
 873                 source = ntohs(uh->source);
 874                 if (ulen != skb->len)
 875                         goto out;
 876                 if (udp6_csum_init(skb, uh, IPPROTO_UDP))
 877                         goto out;
 878                 list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
 879                         if (!ipv6_addr_equal(&np->local_ip.in6, &ip6h->daddr))
 880                                 continue;
 881                         if (!ipv6_addr_equal(&np->remote_ip.in6, &ip6h->saddr))
 882                                 continue;
 883                         if (np->local_port && np->local_port != ntohs(uh->dest))
 884                                 continue;
 885
 886                         np->rx_skb_hook(np, source, skb, offset, data_len);
 887                         hits++;
 888                 }
 889 #endif
 890         }
 891
 892         if (!hits)
 893                 goto out;
 894
 895         kfree_skb(skb);
 896         return 1;
 897
 898 out:
 899         if (atomic_read(&trapped)) {
 900                 kfree_skb(skb);
 901                 return 1;
 902         }
 903
 904         return 0;
 905 }
 906
 907 void netpoll_print_options(struct netpoll *np)
 908 {
 909         np_info(np, "local port %d\n", np->local_port);
 910         if (np->ipv6)
 911                 np_info(np, "local IPv6 address %pI6c\n", &np->local_ip.in6);
 912         else
 913                 np_info(np, "local IPv4 address %pI4\n", &np->local_ip.ip);
 914         np_info(np, "interface '%s'\n", np->dev_name);
 915         np_info(np, "remote port %d\n", np->remote_port);
 916         if (np->ipv6)
 917                 np_info(np, "remote IPv6 address %pI6c\n", &np->remote_ip.in6);
 918         else
 919                 np_info(np, "remote IPv4 address %pI4\n", &np->remote_ip.ip);
 920         np_info(np, "remote ethernet address %pM\n", np->remote_mac);
 921 }
 922 EXPORT_SYMBOL(netpoll_print_options);
 923
 924 static int netpoll_parse_ip_addr(const char *str, union inet_addr *addr)
 925 {
 926         const char *end;
 927
 928         if (!strchr(str, ':') &&
 929             in4_pton(str, -1, (void *)addr, -1, &end) > 0) {
 930                 if (!*end)
 931                         return 0;
 932         }
 933         if (in6_pton(str, -1, addr->in6.s6_addr, -1, &end) > 0) {
 934 #if IS_ENABLED(CONFIG_IPV6)
 935                 if (!*end)
 936                         return 1;
 937 #else
 938                 return -1;
 939 #endif
 940         }
 941         return -1;
 942 }
 943
 944 int netpoll_parse_options(struct netpoll *np, char *opt)
 945 {
 946         char *cur=opt, *delim;
 947         int ipv6;
 948         bool ipversion_set = false;
 949
 950         if (*cur != '@') {
 951                 if ((delim = strchr(cur, '@')) == NULL)
 952                         goto parse_failed;
 953                 *delim = 0;
 954                 if (kstrtou16(cur, 10, &np->local_port))
 955                         goto parse_failed;
 956                 cur = delim;
 957         }
 958         cur++;
 959
 960         if (*cur != '/') {
 961                 ipversion_set = true;
 962                 if ((delim = strchr(cur, '/')) == NULL)
 963                         goto parse_failed;
 964                 *delim = 0;
 965                 ipv6 = netpoll_parse_ip_addr(cur, &np->local_ip);
 966                 if (ipv6 < 0)
 967                         goto parse_failed;
 968                 else
 969                         np->ipv6 = (bool)ipv6;
 970                 cur = delim;
 971         }
 972         cur++;
 973
 974         if (*cur != ',') {
 975                 /* parse out dev name */
 976                 if ((delim = strchr(cur, ',')) == NULL)
 977                         goto parse_failed;
 978                 *delim = 0;
 979                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 980                 cur = delim;
 981         }
 982         cur++;
 983
 984         if (*cur != '@') {
 985                 /* dst port */
 986                 if ((delim = strchr(cur, '@')) == NULL)
 987                         goto parse_failed;
 988                 *delim = 0;
 989                 if (*cur == ' ' || *cur == '\t')
 990                         np_info(np, "warning: whitespace is not allowed\n");
 991                 if (kstrtou16(cur, 10, &np->remote_port))
 992                         goto parse_failed;
 993                 cur = delim;
 994         }
 995         cur++;
 996
 997         /* dst ip */
 998         if ((delim = strchr(cur, '/')) == NULL)
 999                 goto parse_failed;
1000         *delim = 0;
1001         ipv6 = netpoll_parse_ip_addr(cur, &np->remote_ip);
1002         if (ipv6 < 0)
1003                 goto parse_failed;
1004         else if (ipversion_set && np->ipv6 != (bool)ipv6)
1005                 goto parse_failed;
1006         else
1007                 np->ipv6 = (bool)ipv6;
1008         cur = delim + 1;
1009
1010         if (*cur != 0) {
1011                 /* MAC address */
1012                 if (!mac_pton(cur, np->remote_mac))
1013                         goto parse_failed;
1014         }
1015
1016         netpoll_print_options(np);
1017
1018         return 0;
1019
1020  parse_failed:
1021         np_info(np, "couldn't parse config at '%s'!\n", cur);
1022         return -1;
1023 }
1024 EXPORT_SYMBOL(netpoll_parse_options);
1025
1026 int __netpoll_setup(struct netpoll *np, struct net_device *ndev, gfp_t gfp)
1027 {
1028         struct netpoll_info *npinfo;
1029         const struct net_device_ops *ops;
1030         unsigned long flags;
1031         int err;
1032
1033         np->dev = ndev;
1034         strlcpy(np->dev_name, ndev->name, IFNAMSIZ);
1035         INIT_WORK(&np->cleanup_work, netpoll_async_cleanup);
1036
1037         if ((ndev->priv_flags & IFF_DISABLE_NETPOLL) ||
1038             !ndev->netdev_ops->ndo_poll_controller) {
1039                 np_err(np, "%s doesn't support polling, aborting\n",
1040                        np->dev_name);
1041                 err = -ENOTSUPP;
1042                 goto out;
1043         }
1044
1045         if (!ndev->npinfo) {
1046                 npinfo = kmalloc(sizeof(*npinfo), gfp);
1047                 if (!npinfo) {
1048                         err = -ENOMEM;
1049                         goto out;
1050                 }
1051
1052                 INIT_LIST_HEAD(&npinfo->rx_np);
1053
1054                 spin_lock_init(&npinfo->rx_lock);
1055                 sema_init(&npinfo->dev_lock, 1);
1056                 skb_queue_head_init(&npinfo->neigh_tx);
1057                 skb_queue_head_init(&npinfo->txq);
1058                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
1059
1060                 atomic_set(&npinfo->refcnt, 1);
1061
1062                 ops = np->dev->netdev_ops;
1063                 if (ops->ndo_netpoll_setup) {
1064                         err = ops->ndo_netpoll_setup(ndev, npinfo, gfp);
1065                         if (err)
1066                                 goto free_npinfo;
1067                 }
1068         } else {
1069                 npinfo = rtnl_dereference(ndev->npinfo);
1070                 atomic_inc(&npinfo->refcnt);
1071         }
1072
1073         npinfo->netpoll = np;
1074
1075         if (np->rx_skb_hook) {
1076                 spin_lock_irqsave(&npinfo->rx_lock, flags);
1077                 list_add_tail(&np->rx, &npinfo->rx_np);
1078                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
1079         }
1080
1081         /* last thing to do is link it to the net device structure */
1082         rcu_assign_pointer(ndev->npinfo, npinfo);
1083
1084         return 0;
1085
1086 free_npinfo:
1087         kfree(npinfo);
1088 out:
1089         return err;
1090 }
1091 EXPORT_SYMBOL_GPL(__netpoll_setup);
1092
1093 int netpoll_setup(struct netpoll *np)
1094 {
1095         struct net_device *ndev = NULL;
1096         struct in_device *in_dev;
1097         int err;
1098
1099         rtnl_lock();
1100         if (np->dev_name) {
1101                 struct net *net = current->nsproxy->net_ns;
1102                 ndev = __dev_get_by_name(net, np->dev_name);
1103         }
1104         if (!ndev) {
1105                 np_err(np, "%s doesn't exist, aborting\n", np->dev_name);
1106                 err = -ENODEV;
1107                 goto unlock;
1108         }
1109         dev_hold(ndev);
1110
1111         if (netdev_master_upper_dev_get(ndev)) {
1112                 np_err(np, "%s is a slave device, aborting\n", np->dev_name);
1113                 err = -EBUSY;
1114                 goto put;
1115         }
1116
1117         if (!netif_running(ndev)) {
1118                 unsigned long atmost, atleast;
1119
1120                 np_info(np, "device %s not up yet, forcing it\n", np->dev_name);
1121
1122                 err = dev_open(ndev);
1123
1124                 if (err) {
1125                         np_err(np, "failed to open %s\n", ndev->name);
1126                         goto put;
1127                 }
1128
1129                 rtnl_unlock();
1130                 atleast = jiffies + HZ/10;
1131                 atmost = jiffies + carrier_timeout * HZ;
1132                 while (!netif_carrier_ok(ndev)) {
1133                         if (time_after(jiffies, atmost)) {
1134                                 np_notice(np, "timeout waiting for carrier\n");
1135                                 break;
1136                         }
1137                         msleep(1);
1138                 }
1139
1140                 /* If carrier appears to come up instantly, we don't
1141                  * trust it and pause so that we don't pump all our
1142                  * queued console messages into the bitbucket.
1143                  */
1144
1145                 if (time_before(jiffies, atleast)) {
1146                         np_notice(np, "carrier detect appears untrustworthy, waiting 4 seconds\n");
1147                         msleep(4000);
1148                 }
1149                 rtnl_lock();
1150         }
1151
1152         if (!np->local_ip.ip) {
1153                 if (!np->ipv6) {
1154                         in_dev = __in_dev_get_rtnl(ndev);
1155
1156                         if (!in_dev || !in_dev->ifa_list) {
1157                                 np_err(np, "no IP address for %s, aborting\n",
1158                                        np->dev_name);
1159                                 err = -EDESTADDRREQ;
1160                                 goto put;
1161                         }
1162
1163                         np->local_ip.ip = in_dev->ifa_list->ifa_local;
1164                         np_info(np, "local IP %pI4\n", &np->local_ip.ip);
1165                 } else {
1166 #if IS_ENABLED(CONFIG_IPV6)
1167                         struct inet6_dev *idev;
1168
1169                         err = -EDESTADDRREQ;
1170                         idev = __in6_dev_get(ndev);
1171                         if (idev) {
1172                                 struct inet6_ifaddr *ifp;
1173
1174                                 read_lock_bh(&idev->lock);
1175                                 list_for_each_entry(ifp, &idev->addr_list, if_list) {
1176                                         if (ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL)
1177                                                 continue;
1178                                         np->local_ip.in6 = ifp->addr;
1179                                         err = 0;
1180                                         break;
1181                                 }
1182                                 read_unlock_bh(&idev->lock);
1183                         }
1184                         if (err) {
1185                                 np_err(np, "no IPv6 address for %s, aborting\n",
1186                                        np->dev_name);
1187                                 goto put;
1188                         } else
1189                                 np_info(np, "local IPv6 %pI6c\n", &np->local_ip.in6);
1190 #else
1191                         np_err(np, "IPv6 is not supported %s, aborting\n",
1192                                np->dev_name);
1193                         err = -EINVAL;
1194                         goto put;
1195 #endif
1196                 }
1197         }
1198
1199         /* fill up the skb queue */
1200         refill_skbs();
1201
1202         err = __netpoll_setup(np, ndev, GFP_KERNEL);
1203         if (err)
1204                 goto put;
1205
1206         rtnl_unlock();
1207         return 0;
1208
1209 put:
1210         dev_put(ndev);
1211 unlock:
1212         rtnl_unlock();
1213         return err;
1214 }
1215 EXPORT_SYMBOL(netpoll_setup);
1216
1217 static int __init netpoll_init(void)
1218 {
1219         skb_queue_head_init(&skb_pool);
1220         return 0;
1221 }
1222 core_initcall(netpoll_init);
1223
1224 static void rcu_cleanup_netpoll_info(struct rcu_head *rcu_head)
1225 {
1226         struct netpoll_info *npinfo =
1227                         container_of(rcu_head, struct netpoll_info, rcu);
1228
1229         skb_queue_purge(&npinfo->neigh_tx);
1230         skb_queue_purge(&npinfo->txq);
1231
1232         /* we can't call cancel_delayed_work_sync here, as we are in softirq */
1233         cancel_delayed_work(&npinfo->tx_work);
1234
1235         /* clean after last, unfinished work */
1236         __skb_queue_purge(&npinfo->txq);
1237         /* now cancel it again */
1238         cancel_delayed_work(&npinfo->tx_work);
1239         kfree(npinfo);
1240 }
1241
1242 void __netpoll_cleanup(struct netpoll *np)
1243 {
1244         struct netpoll_info *npinfo;
1245         unsigned long flags;
1246
1247         /* rtnl_dereference would be preferable here but
1248          * rcu_cleanup_netpoll path can put us in here safely without
1249          * holding the rtnl, so plain rcu_dereference it is
1250          */
1251         npinfo = rtnl_dereference(np->dev->npinfo);
1252         if (!npinfo)
1253                 return;
1254
1255         if (!list_empty(&npinfo->rx_np)) {
1256                 spin_lock_irqsave(&npinfo->rx_lock, flags);
1257                 list_del(&np->rx);
1258                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
1259         }
1260
1261         synchronize_srcu(&netpoll_srcu);
1262
1263         if (atomic_dec_and_test(&npinfo->refcnt)) {
1264                 const struct net_device_ops *ops;
1265
1266                 ops = np->dev->netdev_ops;
1267                 if (ops->ndo_netpoll_cleanup)
1268                         ops->ndo_netpoll_cleanup(np->dev);
1269
1270                 rcu_assign_pointer(np->dev->npinfo, NULL);
1271                 call_rcu_bh(&npinfo->rcu, rcu_cleanup_netpoll_info);
1272         }
1273 }
1274 EXPORT_SYMBOL_GPL(__netpoll_cleanup);
1275
1276 static void netpoll_async_cleanup(struct work_struct *work)
1277 {
1278         struct netpoll *np = container_of(work, struct netpoll, cleanup_work);
1279
1280         rtnl_lock();
1281         __netpoll_cleanup(np);
1282         rtnl_unlock();
1283         kfree(np);
1284 }
1285
1286 void __netpoll_free_async(struct netpoll *np)
1287 {
1288         schedule_work(&np->cleanup_work);
1289 }
1290 EXPORT_SYMBOL_GPL(__netpoll_free_async);
1291
1292 void netpoll_cleanup(struct netpoll *np)
1293 {
1294         rtnl_lock();
1295         if (!np->dev)
1296                 goto out;
1297         __netpoll_cleanup(np);
1298         dev_put(np->dev);
1299         np->dev = NULL;
1300 out:
1301         rtnl_unlock();
1302 }
1303 EXPORT_SYMBOL(netpoll_cleanup);
1304
1305 int netpoll_trap(void)
1306 {
1307         return atomic_read(&trapped);
1308 }
1309 EXPORT_SYMBOL(netpoll_trap);
1310
1311 void netpoll_set_trap(int trap)
1312 {
1313         if (trap)
1314                 atomic_inc(&trapped);
1315         else
1316                 atomic_dec(&trapped);
1317 }
1318 EXPORT_SYMBOL(netpoll_set_trap);