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/netdevice.h>
  16 #include <linux/etherdevice.h>
  17 #include <linux/string.h>
  18 #include <linux/if_arp.h>
  19 #include <linux/inetdevice.h>
  20 #include <linux/inet.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/netpoll.h>
  23 #include <linux/sched.h>
  24 #include <linux/delay.h>
  25 #include <linux/rcupdate.h>
  26 #include <linux/workqueue.h>
  27 #include <linux/slab.h>
  28 #include <linux/export.h>
  29 #include <linux/if_vlan.h>
  30 #include <net/tcp.h>
  31 #include <net/udp.h>
  32 #include <net/addrconf.h>
  33 #include <net/ndisc.h>
  34 #include <net/ip6_checksum.h>
  35 #include <asm/unaligned.h>
  36 #include <trace/events/napi.h>
  37
  38 /*
  39  * We maintain a small pool of fully-sized skbs, to make sure the
  40  * message gets out even in extreme OOM situations.
  41  */
  42
  43 #define MAX_UDP_CHUNK 1460
  44 #define MAX_SKBS 32
  45
  46 static struct sk_buff_head skb_pool;
  47
  48 static atomic_t trapped;
  49
  50 static struct srcu_struct netpoll_srcu;
  51
  52 #define USEC_PER_POLL   50
  53 #define NETPOLL_RX_ENABLED  1
  54 #define NETPOLL_RX_DROP     2
  55
  56 #define MAX_SKB_SIZE                                                    \
  57         (sizeof(struct ethhdr) +                                        \
  58          sizeof(struct iphdr) +                                         \
  59          sizeof(struct udphdr) +                                        \
  60          MAX_UDP_CHUNK)
  61
  62 static void zap_completion_queue(void);
  63 static void netpoll_neigh_reply(struct sk_buff *skb, struct netpoll_info *npinfo);
  64 static void netpoll_async_cleanup(struct work_struct *work);
  65
  66 static unsigned int carrier_timeout = 4;
  67 module_param(carrier_timeout, uint, 0644);
  68
  69 #define np_info(np, fmt, ...)                           \
  70         pr_info("%s: " fmt, np->name, ##__VA_ARGS__)
  71 #define np_err(np, fmt, ...)                            \
  72         pr_err("%s: " fmt, np->name, ##__VA_ARGS__)
  73 #define np_notice(np, fmt, ...)                         \
  74         pr_notice("%s: " fmt, np->name, ##__VA_ARGS__)
  75
  76 static void queue_process(struct work_struct *work)
  77 {
  78         struct netpoll_info *npinfo =
  79                 container_of(work, struct netpoll_info, tx_work.work);
  80         struct sk_buff *skb;
  81         unsigned long flags;
  82
  83         while ((skb = skb_dequeue(&npinfo->txq))) {
  84                 struct net_device *dev = skb->dev;
  85                 const struct net_device_ops *ops = dev->netdev_ops;
  86                 struct netdev_queue *txq;
  87
  88                 if (!netif_device_present(dev) || !netif_running(dev)) {
  89                         __kfree_skb(skb);
  90                         continue;
  91                 }
  92
  93                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
  94
  95                 local_irq_save(flags);
  96                 __netif_tx_lock(txq, smp_processor_id());
  97                 if (netif_xmit_frozen_or_stopped(txq) ||
  98                     ops->ndo_start_xmit(skb, dev) != NETDEV_TX_OK) {
  99                         skb_queue_head(&npinfo->txq, skb);
 100                         __netif_tx_unlock(txq);
 101                         local_irq_restore(flags);
 102
 103                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
 104                         return;
 105                 }
 106                 __netif_tx_unlock(txq);
 107                 local_irq_restore(flags);
 108         }
 109 }
 110
 111 static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
 112                             unsigned short ulen, __be32 saddr, __be32 daddr)
 113 {
 114         __wsum psum;
 115
 116         if (uh->check == 0 || skb_csum_unnecessary(skb))
 117                 return 0;
 118
 119         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
 120
 121         if (skb->ip_summed == CHECKSUM_COMPLETE &&
 122             !csum_fold(csum_add(psum, skb->csum)))
 123                 return 0;
 124
 125         skb->csum = psum;
 126
 127         return __skb_checksum_complete(skb);
 128 }
 129
 130 /*
 131  * Check whether delayed processing was scheduled for our NIC. If so,
 132  * we attempt to grab the poll lock and use ->poll() to pump the card.
 133  * If this fails, either we've recursed in ->poll() or it's already
 134  * running on another CPU.
 135  *
 136  * Note: we don't mask interrupts with this lock because we're using
 137  * trylock here and interrupts are already disabled in the softirq
 138  * case. Further, we test the poll_owner to avoid recursion on UP
 139  * systems where the lock doesn't exist.
 140  *
 141  * In cases where there is bi-directional communications, reading only
 142  * one message at a time can lead to packets being dropped by the
 143  * network adapter, forcing superfluous retries and possibly timeouts.
 144  * Thus, we set our budget to greater than 1.
 145  */
 146 static int poll_one_napi(struct netpoll_info *npinfo,
 147                          struct napi_struct *napi, int budget)
 148 {
 149         int work;
 150
 151         /* net_rx_action's ->poll() invocations and our's are
 152          * synchronized by this test which is only made while
 153          * holding the napi->poll_lock.
 154          */
 155         if (!test_bit(NAPI_STATE_SCHED, &napi->state))
 156                 return budget;
 157
 158         npinfo->rx_flags |= NETPOLL_RX_DROP;
 159         atomic_inc(&trapped);
 160         set_bit(NAPI_STATE_NPSVC, &napi->state);
 161
 162         work = napi->poll(napi, budget);
 163         trace_napi_poll(napi);
 164
 165         clear_bit(NAPI_STATE_NPSVC, &napi->state);
 166         atomic_dec(&trapped);
 167         npinfo->rx_flags &= ~NETPOLL_RX_DROP;
 168
 169         return budget - work;
 170 }
 171
 172 static void poll_napi(struct net_device *dev)
 173 {
 174         struct napi_struct *napi;
 175         int budget = 16;
 176
 177         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 178                 if (napi->poll_owner != smp_processor_id() &&
 179                     spin_trylock(&napi->poll_lock)) {
 180                         budget = poll_one_napi(rcu_dereference_bh(dev->npinfo),
 181                                                napi, budget);
 182                         spin_unlock(&napi->poll_lock);
 183
 184                         if (!budget)
 185                                 break;
 186                 }
 187         }
 188 }
 189
 190 static void service_neigh_queue(struct netpoll_info *npi)
 191 {
 192         if (npi) {
 193                 struct sk_buff *skb;
 194
 195                 while ((skb = skb_dequeue(&npi->neigh_tx)))
 196                         netpoll_neigh_reply(skb, npi);
 197         }
 198 }
 199
 200 static void netpoll_poll_dev(struct net_device *dev)
 201 {
 202         const struct net_device_ops *ops;
 203         struct netpoll_info *ni = rcu_dereference_bh(dev->npinfo);
 204
 205         /* Don't do any rx activity if the dev_lock mutex is held
 206          * the dev_open/close paths use this to block netpoll activity
 207          * while changing device state
 208          */
 209         if (!mutex_trylock(&ni->dev_lock))
 210                 return;
 211
 212         if (!netif_running(dev)) {
 213                 mutex_unlock(&ni->dev_lock);
 214                 return;
 215         }
 216
 217         ops = dev->netdev_ops;
 218         if (!ops->ndo_poll_controller) {
 219                 mutex_unlock(&ni->dev_lock);
 220                 return;
 221         }
 222
 223         /* Process pending work on NIC */
 224         ops->ndo_poll_controller(dev);
 225
 226         poll_napi(dev);
 227
 228         mutex_unlock(&ni->dev_lock);
 229
 230         if (dev->flags & IFF_SLAVE) {
 231                 if (ni) {
 232                         struct net_device *bond_dev;
 233                         struct sk_buff *skb;
 234                         struct netpoll_info *bond_ni;
 235
 236                         bond_dev = netdev_master_upper_dev_get_rcu(dev);
 237                         bond_ni = rcu_dereference_bh(bond_dev->npinfo);
 238                         while ((skb = skb_dequeue(&ni->neigh_tx))) {
 239                                 skb->dev = bond_dev;
 240                                 skb_queue_tail(&bond_ni->neigh_tx, skb);
 241                         }
 242                 }
 243         }
 244
 245         service_neigh_queue(ni);
 246
 247         zap_completion_queue();
 248 }
 249
 250 int netpoll_rx_disable(struct net_device *dev)
 251 {
 252         struct netpoll_info *ni;
 253         int idx;
 254         might_sleep();
 255         idx = srcu_read_lock(&netpoll_srcu);
 256         ni = srcu_dereference(dev->npinfo, &netpoll_srcu);
 257         if (ni)
 258                 mutex_lock(&ni->dev_lock);
 259         srcu_read_unlock(&netpoll_srcu, idx);
 260         return 0;
 261 }
 262 EXPORT_SYMBOL(netpoll_rx_disable);
 263
 264 void netpoll_rx_enable(struct net_device *dev)
 265 {
 266         struct netpoll_info *ni;
 267         rcu_read_lock();
 268         ni = rcu_dereference(dev->npinfo);
 269         if (ni)
 270                 mutex_unlock(&ni->dev_lock);
 271         rcu_read_unlock();
 272 }
 273 EXPORT_SYMBOL(netpoll_rx_enable);
 274
 275 static void refill_skbs(void)
 276 {
 277         struct sk_buff *skb;
 278         unsigned long flags;
 279
 280         spin_lock_irqsave(&skb_pool.lock, flags);
 281         while (skb_pool.qlen < MAX_SKBS) {
 282                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
 283                 if (!skb)
 284                         break;
 285
 286                 __skb_queue_tail(&skb_pool, skb);
 287         }
 288         spin_unlock_irqrestore(&skb_pool.lock, flags);
 289 }
 290
 291 static void zap_completion_queue(void)
 292 {
 293         unsigned long flags;
 294         struct softnet_data *sd = &get_cpu_var(softnet_data);
 295
 296         if (sd->completion_queue) {
 297                 struct sk_buff *clist;
 298
 299                 local_irq_save(flags);
 300                 clist = sd->completion_queue;
 301                 sd->completion_queue = NULL;
 302                 local_irq_restore(flags);
 303
 304                 while (clist != NULL) {
 305                         struct sk_buff *skb = clist;
 306                         clist = clist->next;
 307                         if (skb->destructor) {
 308                                 atomic_inc(&skb->users);
 309                                 dev_kfree_skb_any(skb); /* put this one back */
 310                         } else {
 311                                 __kfree_skb(skb);
 312                         }
 313                 }
 314         }
 315
 316         put_cpu_var(softnet_data);
 317 }
 318
 319 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
 320 {
 321         int count = 0;
 322         struct sk_buff *skb;
 323
 324         zap_completion_queue();
 325         refill_skbs();
 326 repeat:
 327
 328         skb = alloc_skb(len, GFP_ATOMIC);
 329         if (!skb)
 330                 skb = skb_dequeue(&skb_pool);
 331
 332         if (!skb) {
 333                 if (++count < 10) {
 334                         netpoll_poll_dev(np->dev);
 335                         goto repeat;
 336                 }
 337                 return NULL;
 338         }
 339
 340         atomic_set(&skb->users, 1);
 341         skb_reserve(skb, reserve);
 342         return skb;
 343 }
 344
 345 static int netpoll_owner_active(struct net_device *dev)
 346 {
 347         struct napi_struct *napi;
 348
 349         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 350                 if (napi->poll_owner == smp_processor_id())
 351                         return 1;
 352         }
 353         return 0;
 354 }
 355
 356 /* call with IRQ disabled */
 357 void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
 358                              struct net_device *dev)
 359 {
 360         int status = NETDEV_TX_BUSY;
 361         unsigned long tries;
 362         const struct net_device_ops *ops = dev->netdev_ops;
 363         /* It is up to the caller to keep npinfo alive. */
 364         struct netpoll_info *npinfo;
 365
 366         WARN_ON_ONCE(!irqs_disabled());
 367
 368         npinfo = rcu_dereference_bh(np->dev->npinfo);
 369         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
 370                 __kfree_skb(skb);
 371                 return;
 372         }
 373
 374         /* don't get messages out of order, and no recursion */
 375         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
 376                 struct netdev_queue *txq;
 377
 378                 txq = netdev_pick_tx(dev, skb);
 379
 380                 /* try until next clock tick */
 381                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
 382                      tries > 0; --tries) {
 383                         if (__netif_tx_trylock(txq)) {
 384                                 if (!netif_xmit_stopped(txq)) {
 385                                         if (vlan_tx_tag_present(skb) &&
 386                                             !(netif_skb_features(skb) & NETIF_F_HW_VLAN_TX)) {
 387                                                 skb = __vlan_put_tag(skb, vlan_tx_tag_get(skb));
 388                                                 if (unlikely(!skb))
 389                                                         break;
 390                                                 skb->vlan_tci = 0;
 391                                         }
 392
 393                                         status = ops->ndo_start_xmit(skb, dev);
 394                                         if (status == NETDEV_TX_OK)
 395                                                 txq_trans_update(txq);
 396                                 }
 397                                 __netif_tx_unlock(txq);
 398
 399                                 if (status == NETDEV_TX_OK)
 400                                         break;
 401
 402                         }
 403
 404                         /* tickle device maybe there is some cleanup */
 405                         netpoll_poll_dev(np->dev);
 406
 407                         udelay(USEC_PER_POLL);
 408                 }
 409
 410                 WARN_ONCE(!irqs_disabled(),
 411                         "netpoll_send_skb_on_dev(): %s enabled interrupts in poll (%pF)\n",
 412                         dev->name, ops->ndo_start_xmit);
 413
 414         }
 415
 416         if (status != NETDEV_TX_OK) {
 417                 skb_queue_tail(&npinfo->txq, skb);
 418                 schedule_delayed_work(&npinfo->tx_work,0);
 419         }
 420 }
 421 EXPORT_SYMBOL(netpoll_send_skb_on_dev);
 422
 423 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 424 {
 425         int total_len, ip_len, udp_len;
 426         struct sk_buff *skb;
 427         struct udphdr *udph;
 428         struct iphdr *iph;
 429         struct ethhdr *eth;
 430         static atomic_t ip_ident;
 431         struct ipv6hdr *ip6h;
 432
 433         udp_len = len + sizeof(*udph);
 434         if (np->ipv6)
 435                 ip_len = udp_len + sizeof(*ip6h);
 436         else
 437                 ip_len = udp_len + sizeof(*iph);
 438
 439         total_len = ip_len + LL_RESERVED_SPACE(np->dev);
 440
 441         skb = find_skb(np, total_len + np->dev->needed_tailroom,
 442                        total_len - len);
 443         if (!skb)
 444                 return;
 445
 446         skb_copy_to_linear_data(skb, msg, len);
 447         skb_put(skb, len);
 448
 449         skb_push(skb, sizeof(*udph));
 450         skb_reset_transport_header(skb);
 451         udph = udp_hdr(skb);
 452         udph->source = htons(np->local_port);
 453         udph->dest = htons(np->remote_port);
 454         udph->len = htons(udp_len);
 455
 456         if (np->ipv6) {
 457                 udph->check = 0;
 458                 udph->check = csum_ipv6_magic(&np->local_ip.in6,
 459                                               &np->remote_ip.in6,
 460                                               udp_len, IPPROTO_UDP,
 461                                               csum_partial(udph, udp_len, 0));
 462                 if (udph->check == 0)
 463                         udph->check = CSUM_MANGLED_0;
 464
 465                 skb_push(skb, sizeof(*ip6h));
 466                 skb_reset_network_header(skb);
 467                 ip6h = ipv6_hdr(skb);
 468
 469                 /* ip6h->version = 6; ip6h->priority = 0; */
 470                 put_unaligned(0x60, (unsigned char *)ip6h);
 471                 ip6h->flow_lbl[0] = 0;
 472                 ip6h->flow_lbl[1] = 0;
 473                 ip6h->flow_lbl[2] = 0;
 474
 475                 ip6h->payload_len = htons(sizeof(struct udphdr) + len);
 476                 ip6h->nexthdr = IPPROTO_UDP;
 477                 ip6h->hop_limit = 32;
 478                 ip6h->saddr = np->local_ip.in6;
 479                 ip6h->daddr = np->remote_ip.in6;
 480
 481                 eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 482                 skb_reset_mac_header(skb);
 483                 skb->protocol = eth->h_proto = htons(ETH_P_IPV6);
 484         } else {
 485                 udph->check = 0;
 486                 udph->check = csum_tcpudp_magic(np->local_ip.ip,
 487                                                 np->remote_ip.ip,
 488                                                 udp_len, IPPROTO_UDP,
 489                                                 csum_partial(udph, udp_len, 0));
 490                 if (udph->check == 0)
 491                         udph->check = CSUM_MANGLED_0;
 492
 493                 skb_push(skb, sizeof(*iph));
 494                 skb_reset_network_header(skb);
 495                 iph = ip_hdr(skb);
 496
 497                 /* iph->version = 4; iph->ihl = 5; */
 498                 put_unaligned(0x45, (unsigned char *)iph);
 499                 iph->tos      = 0;
 500                 put_unaligned(htons(ip_len), &(iph->tot_len));
 501                 iph->id       = htons(atomic_inc_return(&ip_ident));
 502                 iph->frag_off = 0;
 503                 iph->ttl      = 64;
 504                 iph->protocol = IPPROTO_UDP;
 505                 iph->check    = 0;
 506                 put_unaligned(np->local_ip.ip, &(iph->saddr));
 507                 put_unaligned(np->remote_ip.ip, &(iph->daddr));
 508                 iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 509
 510                 eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 511                 skb_reset_mac_header(skb);
 512                 skb->protocol = eth->h_proto = htons(ETH_P_IP);
 513         }
 514
 515         memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN);
 516         memcpy(eth->h_dest, np->remote_mac, ETH_ALEN);
 517
 518         skb->dev = np->dev;
 519
 520         netpoll_send_skb(np, skb);
 521 }
 522 EXPORT_SYMBOL(netpoll_send_udp);
 523
 524 static void netpoll_neigh_reply(struct sk_buff *skb, struct netpoll_info *npinfo)
 525 {
 526         int size, type = ARPOP_REPLY;
 527         __be32 sip, tip;
 528         unsigned char *sha;
 529         struct sk_buff *send_skb;
 530         struct netpoll *np, *tmp;
 531         unsigned long flags;
 532         int hlen, tlen;
 533         int hits = 0, proto;
 534
 535         if (list_empty(&npinfo->rx_np))
 536                 return;
 537
 538         /* Before checking the packet, we do some early
 539            inspection whether this is interesting at all */
 540         spin_lock_irqsave(&npinfo->rx_lock, flags);
 541         list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
 542                 if (np->dev == skb->dev)
 543                         hits++;
 544         }
 545         spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 546
 547         /* No netpoll struct is using this dev */
 548         if (!hits)
 549                 return;
 550
 551         proto = ntohs(eth_hdr(skb)->h_proto);
 552         if (proto == ETH_P_IP) {
 553                 struct arphdr *arp;
 554                 unsigned char *arp_ptr;
 555                 /* No arp on this interface */
 556                 if (skb->dev->flags & IFF_NOARP)
 557                         return;
 558
 559                 if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
 560                         return;
 561
 562                 skb_reset_network_header(skb);
 563                 skb_reset_transport_header(skb);
 564                 arp = arp_hdr(skb);
 565
 566                 if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 567                      arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 568                     arp->ar_pro != htons(ETH_P_IP) ||
 569                     arp->ar_op != htons(ARPOP_REQUEST))
 570                         return;
 571
 572                 arp_ptr = (unsigned char *)(arp+1);
 573                 /* save the location of the src hw addr */
 574                 sha = arp_ptr;
 575                 arp_ptr += skb->dev->addr_len;
 576                 memcpy(&sip, arp_ptr, 4);
 577                 arp_ptr += 4;
 578                 /* If we actually cared about dst hw addr,
 579                    it would get copied here */
 580                 arp_ptr += skb->dev->addr_len;
 581                 memcpy(&tip, arp_ptr, 4);
 582
 583                 /* Should we ignore arp? */
 584                 if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
 585                         return;
 586
 587                 size = arp_hdr_len(skb->dev);
 588
 589                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 590                 list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
 591                         if (tip != np->local_ip.ip)
 592                                 continue;
 593
 594                         hlen = LL_RESERVED_SPACE(np->dev);
 595                         tlen = np->dev->needed_tailroom;
 596                         send_skb = find_skb(np, size + hlen + tlen, hlen);
 597                         if (!send_skb)
 598                                 continue;
 599
 600                         skb_reset_network_header(send_skb);
 601                         arp = (struct arphdr *) skb_put(send_skb, size);
 602                         send_skb->dev = skb->dev;
 603                         send_skb->protocol = htons(ETH_P_ARP);
 604
 605                         /* Fill the device header for the ARP frame */
 606                         if (dev_hard_header(send_skb, skb->dev, ETH_P_ARP,
 607                                             sha, np->dev->dev_addr,
 608                                             send_skb->len) < 0) {
 609                                 kfree_skb(send_skb);
 610                                 continue;
 611                         }
 612
 613                         /*
 614                          * Fill out the arp protocol part.
 615                          *
 616                          * we only support ethernet device type,
 617                          * which (according to RFC 1390) should
 618                          * always equal 1 (Ethernet).
 619                          */
 620
 621                         arp->ar_hrd = htons(np->dev->type);
 622                         arp->ar_pro = htons(ETH_P_IP);
 623                         arp->ar_hln = np->dev->addr_len;
 624                         arp->ar_pln = 4;
 625                         arp->ar_op = htons(type);
 626
 627                         arp_ptr = (unsigned char *)(arp + 1);
 628                         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
 629                         arp_ptr += np->dev->addr_len;
 630                         memcpy(arp_ptr, &tip, 4);
 631                         arp_ptr += 4;
 632                         memcpy(arp_ptr, sha, np->dev->addr_len);
 633                         arp_ptr += np->dev->addr_len;
 634                         memcpy(arp_ptr, &sip, 4);
 635
 636                         netpoll_send_skb(np, send_skb);
 637
 638                         /* If there are several rx_hooks for the same address,
 639                            we're fine by sending a single reply */
 640                         break;
 641                 }
 642                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 643         } else if( proto == ETH_P_IPV6) {
 644 #if IS_ENABLED(CONFIG_IPV6)
 645                 struct nd_msg *msg;
 646                 u8 *lladdr = NULL;
 647                 struct ipv6hdr *hdr;
 648                 struct icmp6hdr *icmp6h;
 649                 const struct in6_addr *saddr;
 650                 const struct in6_addr *daddr;
 651                 struct inet6_dev *in6_dev = NULL;
 652                 struct in6_addr *target;
 653
 654                 in6_dev = in6_dev_get(skb->dev);
 655                 if (!in6_dev || !in6_dev->cnf.accept_ra)
 656                         return;
 657
 658                 if (!pskb_may_pull(skb, skb->len))
 659                         return;
 660
 661                 msg = (struct nd_msg *)skb_transport_header(skb);
 662
 663                 __skb_push(skb, skb->data - skb_transport_header(skb));
 664
 665                 if (ipv6_hdr(skb)->hop_limit != 255)
 666                         return;
 667                 if (msg->icmph.icmp6_code != 0)
 668                         return;
 669                 if (msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)
 670                         return;
 671
 672                 saddr = &ipv6_hdr(skb)->saddr;
 673                 daddr = &ipv6_hdr(skb)->daddr;
 674
 675                 size = sizeof(struct icmp6hdr) + sizeof(struct in6_addr);
 676
 677                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 678                 list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
 679                         if (!ipv6_addr_equal(daddr, &np->local_ip.in6))
 680                                 continue;
 681
 682                         hlen = LL_RESERVED_SPACE(np->dev);
 683                         tlen = np->dev->needed_tailroom;
 684                         send_skb = find_skb(np, size + hlen + tlen, hlen);
 685                         if (!send_skb)
 686                                 continue;
 687
 688                         send_skb->protocol = htons(ETH_P_IPV6);
 689                         send_skb->dev = skb->dev;
 690
 691                         skb_reset_network_header(send_skb);
 692                         skb_put(send_skb, sizeof(struct ipv6hdr));
 693                         hdr = ipv6_hdr(send_skb);
 694
 695                         *(__be32*)hdr = htonl(0x60000000);
 696
 697                         hdr->payload_len = htons(size);
 698                         hdr->nexthdr = IPPROTO_ICMPV6;
 699                         hdr->hop_limit = 255;
 700                         hdr->saddr = *saddr;
 701                         hdr->daddr = *daddr;
 702
 703                         send_skb->transport_header = send_skb->tail;
 704                         skb_put(send_skb, size);
 705
 706                         icmp6h = (struct icmp6hdr *)skb_transport_header(skb);
 707                         icmp6h->icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT;
 708                         icmp6h->icmp6_router = 0;
 709                         icmp6h->icmp6_solicited = 1;
 710                         target = (struct in6_addr *)(skb_transport_header(send_skb) + sizeof(struct icmp6hdr));
 711                         *target = msg->target;
 712                         icmp6h->icmp6_cksum = csum_ipv6_magic(saddr, daddr, size,
 713                                                               IPPROTO_ICMPV6,
 714                                                               csum_partial(icmp6h,
 715                                                                            size, 0));
 716
 717                         if (dev_hard_header(send_skb, skb->dev, ETH_P_IPV6,
 718                                             lladdr, np->dev->dev_addr,
 719                                             send_skb->len) < 0) {
 720                                 kfree_skb(send_skb);
 721                                 continue;
 722                         }
 723
 724                         netpoll_send_skb(np, send_skb);
 725
 726                         /* If there are several rx_hooks for the same address,
 727                            we're fine by sending a single reply */
 728                         break;
 729                 }
 730                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 731 #endif
 732         }
 733 }
 734
 735 static bool pkt_is_ns(struct sk_buff *skb)
 736 {
 737         struct nd_msg *msg;
 738         struct ipv6hdr *hdr;
 739
 740         if (skb->protocol != htons(ETH_P_ARP))
 741                 return false;
 742         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + sizeof(struct nd_msg)))
 743                 return false;
 744
 745         msg = (struct nd_msg *)skb_transport_header(skb);
 746         __skb_push(skb, skb->data - skb_transport_header(skb));
 747         hdr = ipv6_hdr(skb);
 748
 749         if (hdr->nexthdr != IPPROTO_ICMPV6)
 750                 return false;
 751         if (hdr->hop_limit != 255)
 752                 return false;
 753         if (msg->icmph.icmp6_code != 0)
 754                 return false;
 755         if (msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)
 756                 return false;
 757
 758         return true;
 759 }
 760
 761 int __netpoll_rx(struct sk_buff *skb, struct netpoll_info *npinfo)
 762 {
 763         int proto, len, ulen;
 764         int hits = 0;
 765         const struct iphdr *iph;
 766         struct udphdr *uh;
 767         struct netpoll *np, *tmp;
 768
 769         if (list_empty(&npinfo->rx_np))
 770                 goto out;
 771
 772         if (skb->dev->type != ARPHRD_ETHER)
 773                 goto out;
 774
 775         /* check if netpoll clients need ARP */
 776         if (skb->protocol == htons(ETH_P_ARP) && atomic_read(&trapped)) {
 777                 skb_queue_tail(&npinfo->neigh_tx, skb);
 778                 return 1;
 779         } else if (pkt_is_ns(skb) && atomic_read(&trapped)) {
 780                 skb_queue_tail(&npinfo->neigh_tx, skb);
 781                 return 1;
 782         }
 783
 784         if (skb->protocol == cpu_to_be16(ETH_P_8021Q)) {
 785                 skb = vlan_untag(skb);
 786                 if (unlikely(!skb))
 787                         goto out;
 788         }
 789
 790         proto = ntohs(eth_hdr(skb)->h_proto);
 791         if (proto != ETH_P_IP && proto != ETH_P_IPV6)
 792                 goto out;
 793         if (skb->pkt_type == PACKET_OTHERHOST)
 794                 goto out;
 795         if (skb_shared(skb))
 796                 goto out;
 797
 798         if (proto == ETH_P_IP) {
 799                 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 800                         goto out;
 801                 iph = (struct iphdr *)skb->data;
 802                 if (iph->ihl < 5 || iph->version != 4)
 803                         goto out;
 804                 if (!pskb_may_pull(skb, iph->ihl*4))
 805                         goto out;
 806                 iph = (struct iphdr *)skb->data;
 807                 if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
 808                         goto out;
 809
 810                 len = ntohs(iph->tot_len);
 811                 if (skb->len < len || len < iph->ihl*4)
 812                         goto out;
 813
 814                 /*
 815                  * Our transport medium may have padded the buffer out.
 816                  * Now We trim to the true length of the frame.
 817                  */
 818                 if (pskb_trim_rcsum(skb, len))
 819                         goto out;
 820
 821                 iph = (struct iphdr *)skb->data;
 822                 if (iph->protocol != IPPROTO_UDP)
 823                         goto out;
 824
 825                 len -= iph->ihl*4;
 826                 uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
 827                 ulen = ntohs(uh->len);
 828
 829                 if (ulen != len)
 830                         goto out;
 831                 if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
 832                         goto out;
 833                 list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
 834                         if (np->local_ip.ip && np->local_ip.ip != iph->daddr)
 835                                 continue;
 836                         if (np->remote_ip.ip && np->remote_ip.ip != iph->saddr)
 837                                 continue;
 838                         if (np->local_port && np->local_port != ntohs(uh->dest))
 839                                 continue;
 840
 841                         np->rx_hook(np, ntohs(uh->source),
 842                                        (char *)(uh+1),
 843                                        ulen - sizeof(struct udphdr));
 844                         hits++;
 845                 }
 846         } else {
 847 #if IS_ENABLED(CONFIG_IPV6)
 848                 const struct ipv6hdr *ip6h;
 849
 850                 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 851                         goto out;
 852                 ip6h = (struct ipv6hdr *)skb->data;
 853                 if (ip6h->version != 6)
 854                         goto out;
 855                 len = ntohs(ip6h->payload_len);
 856                 if (!len)
 857                         goto out;
 858                 if (len + sizeof(struct ipv6hdr) > skb->len)
 859                         goto out;
 860                 if (pskb_trim_rcsum(skb, len + sizeof(struct ipv6hdr)))
 861                         goto out;
 862                 ip6h = ipv6_hdr(skb);
 863                 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
 864                         goto out;
 865                 uh = udp_hdr(skb);
 866                 ulen = ntohs(uh->len);
 867                 if (ulen != skb->len)
 868                         goto out;
 869                 if (udp6_csum_init(skb, uh, IPPROTO_UDP))
 870                         goto out;
 871                 list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
 872                         if (!ipv6_addr_equal(&np->local_ip.in6, &ip6h->daddr))
 873                                 continue;
 874                         if (!ipv6_addr_equal(&np->remote_ip.in6, &ip6h->saddr))
 875                                 continue;
 876                         if (np->local_port && np->local_port != ntohs(uh->dest))
 877                                 continue;
 878
 879                         np->rx_hook(np, ntohs(uh->source),
 880                                        (char *)(uh+1),
 881                                        ulen - sizeof(struct udphdr));
 882                         hits++;
 883                 }
 884 #endif
 885         }
 886
 887         if (!hits)
 888                 goto out;
 889
 890         kfree_skb(skb);
 891         return 1;
 892
 893 out:
 894         if (atomic_read(&trapped)) {
 895                 kfree_skb(skb);
 896                 return 1;
 897         }
 898
 899         return 0;
 900 }
 901
 902 void netpoll_print_options(struct netpoll *np)
 903 {
 904         np_info(np, "local port %d\n", np->local_port);
 905         if (np->ipv6)
 906                 np_info(np, "local IPv6 address %pI6c\n", &np->local_ip.in6);
 907         else
 908                 np_info(np, "local IPv4 address %pI4\n", &np->local_ip.ip);
 909         np_info(np, "interface '%s'\n", np->dev_name);
 910         np_info(np, "remote port %d\n", np->remote_port);
 911         if (np->ipv6)
 912                 np_info(np, "remote IPv6 address %pI6c\n", &np->remote_ip.in6);
 913         else
 914                 np_info(np, "remote IPv4 address %pI4\n", &np->remote_ip.ip);
 915         np_info(np, "remote ethernet address %pM\n", np->remote_mac);
 916 }
 917 EXPORT_SYMBOL(netpoll_print_options);
 918
 919 static int netpoll_parse_ip_addr(const char *str, union inet_addr *addr)
 920 {
 921         const char *end;
 922
 923         if (!strchr(str, ':') &&
 924             in4_pton(str, -1, (void *)addr, -1, &end) > 0) {
 925                 if (!*end)
 926                         return 0;
 927         }
 928         if (in6_pton(str, -1, addr->in6.s6_addr, -1, &end) > 0) {
 929 #if IS_ENABLED(CONFIG_IPV6)
 930                 if (!*end)
 931                         return 1;
 932 #else
 933                 return -1;
 934 #endif
 935         }
 936         return -1;
 937 }
 938
 939 int netpoll_parse_options(struct netpoll *np, char *opt)
 940 {
 941         char *cur=opt, *delim;
 942         int ipv6;
 943
 944         if (*cur != '@') {
 945                 if ((delim = strchr(cur, '@')) == NULL)
 946                         goto parse_failed;
 947                 *delim = 0;
 948                 if (kstrtou16(cur, 10, &np->local_port))
 949                         goto parse_failed;
 950                 cur = delim;
 951         }
 952         cur++;
 953
 954         if (*cur != '/') {
 955                 if ((delim = strchr(cur, '/')) == NULL)
 956                         goto parse_failed;
 957                 *delim = 0;
 958                 ipv6 = netpoll_parse_ip_addr(cur, &np->local_ip);
 959                 if (ipv6 < 0)
 960                         goto parse_failed;
 961                 else
 962                         np->ipv6 = (bool)ipv6;
 963                 cur = delim;
 964         }
 965         cur++;
 966
 967         if (*cur != ',') {
 968                 /* parse out dev name */
 969                 if ((delim = strchr(cur, ',')) == NULL)
 970                         goto parse_failed;
 971                 *delim = 0;
 972                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 973                 cur = delim;
 974         }
 975         cur++;
 976
 977         if (*cur != '@') {
 978                 /* dst port */
 979                 if ((delim = strchr(cur, '@')) == NULL)
 980                         goto parse_failed;
 981                 *delim = 0;
 982                 if (*cur == ' ' || *cur == '\t')
 983                         np_info(np, "warning: whitespace is not allowed\n");
 984                 if (kstrtou16(cur, 10, &np->remote_port))
 985                         goto parse_failed;
 986                 cur = delim;
 987         }
 988         cur++;
 989
 990         /* dst ip */
 991         if ((delim = strchr(cur, '/')) == NULL)
 992                 goto parse_failed;
 993         *delim = 0;
 994         ipv6 = netpoll_parse_ip_addr(cur, &np->remote_ip);
 995         if (ipv6 < 0)
 996                 goto parse_failed;
 997         else if (np->ipv6 != (bool)ipv6)
 998                 goto parse_failed;
 999         else
1000                 np->ipv6 = (bool)ipv6;
1001         cur = delim + 1;
1002
1003         if (*cur != 0) {
1004                 /* MAC address */
1005                 if (!mac_pton(cur, np->remote_mac))
1006                         goto parse_failed;
1007         }
1008
1009         netpoll_print_options(np);
1010
1011         return 0;
1012
1013  parse_failed:
1014         np_info(np, "couldn't parse config at '%s'!\n", cur);
1015         return -1;
1016 }
1017 EXPORT_SYMBOL(netpoll_parse_options);
1018
1019 int __netpoll_setup(struct netpoll *np, struct net_device *ndev, gfp_t gfp)
1020 {
1021         struct netpoll_info *npinfo;
1022         const struct net_device_ops *ops;
1023         unsigned long flags;
1024         int err;
1025
1026         np->dev = ndev;
1027         strlcpy(np->dev_name, ndev->name, IFNAMSIZ);
1028         INIT_WORK(&np->cleanup_work, netpoll_async_cleanup);
1029
1030         if ((ndev->priv_flags & IFF_DISABLE_NETPOLL) ||
1031             !ndev->netdev_ops->ndo_poll_controller) {
1032                 np_err(np, "%s doesn't support polling, aborting\n",
1033                        np->dev_name);
1034                 err = -ENOTSUPP;
1035                 goto out;
1036         }
1037
1038         if (!ndev->npinfo) {
1039                 npinfo = kmalloc(sizeof(*npinfo), gfp);
1040                 if (!npinfo) {
1041                         err = -ENOMEM;
1042                         goto out;
1043                 }
1044
1045                 npinfo->rx_flags = 0;
1046                 INIT_LIST_HEAD(&npinfo->rx_np);
1047
1048                 spin_lock_init(&npinfo->rx_lock);
1049                 mutex_init(&npinfo->dev_lock);
1050                 skb_queue_head_init(&npinfo->neigh_tx);
1051                 skb_queue_head_init(&npinfo->txq);
1052                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
1053
1054                 atomic_set(&npinfo->refcnt, 1);
1055
1056                 ops = np->dev->netdev_ops;
1057                 if (ops->ndo_netpoll_setup) {
1058                         err = ops->ndo_netpoll_setup(ndev, npinfo, gfp);
1059                         if (err)
1060                                 goto free_npinfo;
1061                 }
1062         } else {
1063                 npinfo = rtnl_dereference(ndev->npinfo);
1064                 atomic_inc(&npinfo->refcnt);
1065         }
1066
1067         npinfo->netpoll = np;
1068
1069         if (np->rx_hook) {
1070                 spin_lock_irqsave(&npinfo->rx_lock, flags);
1071                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
1072                 list_add_tail(&np->rx, &npinfo->rx_np);
1073                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
1074         }
1075
1076         /* last thing to do is link it to the net device structure */
1077         rcu_assign_pointer(ndev->npinfo, npinfo);
1078
1079         return 0;
1080
1081 free_npinfo:
1082         kfree(npinfo);
1083 out:
1084         return err;
1085 }
1086 EXPORT_SYMBOL_GPL(__netpoll_setup);
1087
1088 int netpoll_setup(struct netpoll *np)
1089 {
1090         struct net_device *ndev = NULL;
1091         struct in_device *in_dev;
1092         int err;
1093
1094         rtnl_lock();
1095         if (np->dev_name) {
1096                 struct net *net = current->nsproxy->net_ns;
1097                 ndev = __dev_get_by_name(net, np->dev_name);
1098         }
1099         if (!ndev) {
1100                 np_err(np, "%s doesn't exist, aborting\n", np->dev_name);
1101                 err = -ENODEV;
1102                 goto unlock;
1103         }
1104         dev_hold(ndev);
1105
1106         if (netdev_master_upper_dev_get(ndev)) {
1107                 np_err(np, "%s is a slave device, aborting\n", np->dev_name);
1108                 err = -EBUSY;
1109                 goto put;
1110         }
1111
1112         if (!netif_running(ndev)) {
1113                 unsigned long atmost, atleast;
1114
1115                 np_info(np, "device %s not up yet, forcing it\n", np->dev_name);
1116
1117                 err = dev_open(ndev);
1118
1119                 if (err) {
1120                         np_err(np, "failed to open %s\n", ndev->name);
1121                         goto put;
1122                 }
1123
1124                 rtnl_unlock();
1125                 atleast = jiffies + HZ/10;
1126                 atmost = jiffies + carrier_timeout * HZ;
1127                 while (!netif_carrier_ok(ndev)) {
1128                         if (time_after(jiffies, atmost)) {
1129                                 np_notice(np, "timeout waiting for carrier\n");
1130                                 break;
1131                         }
1132                         msleep(1);
1133                 }
1134
1135                 /* If carrier appears to come up instantly, we don't
1136                  * trust it and pause so that we don't pump all our
1137                  * queued console messages into the bitbucket.
1138                  */
1139
1140                 if (time_before(jiffies, atleast)) {
1141                         np_notice(np, "carrier detect appears untrustworthy, waiting 4 seconds\n");
1142                         msleep(4000);
1143                 }
1144                 rtnl_lock();
1145         }
1146
1147         if (!np->local_ip.ip) {
1148                 if (!np->ipv6) {
1149                         in_dev = __in_dev_get_rtnl(ndev);
1150
1151                         if (!in_dev || !in_dev->ifa_list) {
1152                                 np_err(np, "no IP address for %s, aborting\n",
1153                                        np->dev_name);
1154                                 err = -EDESTADDRREQ;
1155                                 goto put;
1156                         }
1157
1158                         np->local_ip.ip = in_dev->ifa_list->ifa_local;
1159                         np_info(np, "local IP %pI4\n", &np->local_ip.ip);
1160                 } else {
1161 #if IS_ENABLED(CONFIG_IPV6)
1162                         struct inet6_dev *idev;
1163
1164                         err = -EDESTADDRREQ;
1165                         idev = __in6_dev_get(ndev);
1166                         if (idev) {
1167                                 struct inet6_ifaddr *ifp;
1168
1169                                 read_lock_bh(&idev->lock);
1170                                 list_for_each_entry(ifp, &idev->addr_list, if_list) {
1171                                         if (ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL)
1172                                                 continue;
1173                                         np->local_ip.in6 = ifp->addr;
1174                                         err = 0;
1175                                         break;
1176                                 }
1177                                 read_unlock_bh(&idev->lock);
1178                         }
1179                         if (err) {
1180                                 np_err(np, "no IPv6 address for %s, aborting\n",
1181                                        np->dev_name);
1182                                 goto put;
1183                         } else
1184                                 np_info(np, "local IPv6 %pI6c\n", &np->local_ip.in6);
1185 #else
1186                         np_err(np, "IPv6 is not supported %s, aborting\n",
1187                                np->dev_name);
1188                         err = -EINVAL;
1189                         goto put;
1190 #endif
1191                 }
1192         }
1193
1194         /* fill up the skb queue */
1195         refill_skbs();
1196
1197         err = __netpoll_setup(np, ndev, GFP_KERNEL);
1198         if (err)
1199                 goto put;
1200
1201         rtnl_unlock();
1202         return 0;
1203
1204 put:
1205         dev_put(ndev);
1206 unlock:
1207         rtnl_unlock();
1208         return err;
1209 }
1210 EXPORT_SYMBOL(netpoll_setup);
1211
1212 static int __init netpoll_init(void)
1213 {
1214         skb_queue_head_init(&skb_pool);
1215         init_srcu_struct(&netpoll_srcu);
1216         return 0;
1217 }
1218 core_initcall(netpoll_init);
1219
1220 static void rcu_cleanup_netpoll_info(struct rcu_head *rcu_head)
1221 {
1222         struct netpoll_info *npinfo =
1223                         container_of(rcu_head, struct netpoll_info, rcu);
1224
1225         skb_queue_purge(&npinfo->neigh_tx);
1226         skb_queue_purge(&npinfo->txq);
1227
1228         /* we can't call cancel_delayed_work_sync here, as we are in softirq */
1229         cancel_delayed_work(&npinfo->tx_work);
1230
1231         /* clean after last, unfinished work */
1232         __skb_queue_purge(&npinfo->txq);
1233         /* now cancel it again */
1234         cancel_delayed_work(&npinfo->tx_work);
1235         kfree(npinfo);
1236 }
1237
1238 void __netpoll_cleanup(struct netpoll *np)
1239 {
1240         struct netpoll_info *npinfo;
1241         unsigned long flags;
1242
1243         /* rtnl_dereference would be preferable here but
1244          * rcu_cleanup_netpoll path can put us in here safely without
1245          * holding the rtnl, so plain rcu_dereference it is
1246          */
1247         npinfo = rtnl_dereference(np->dev->npinfo);
1248         if (!npinfo)
1249                 return;
1250
1251         if (!list_empty(&npinfo->rx_np)) {
1252                 spin_lock_irqsave(&npinfo->rx_lock, flags);
1253                 list_del(&np->rx);
1254                 if (list_empty(&npinfo->rx_np))
1255                         npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
1256                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
1257         }
1258
1259         synchronize_srcu(&netpoll_srcu);
1260
1261         if (atomic_dec_and_test(&npinfo->refcnt)) {
1262                 const struct net_device_ops *ops;
1263
1264                 ops = np->dev->netdev_ops;
1265                 if (ops->ndo_netpoll_cleanup)
1266                         ops->ndo_netpoll_cleanup(np->dev);
1267
1268                 rcu_assign_pointer(np->dev->npinfo, NULL);
1269                 call_rcu_bh(&npinfo->rcu, rcu_cleanup_netpoll_info);
1270         }
1271 }
1272 EXPORT_SYMBOL_GPL(__netpoll_cleanup);
1273
1274 static void netpoll_async_cleanup(struct work_struct *work)
1275 {
1276         struct netpoll *np = container_of(work, struct netpoll, cleanup_work);
1277
1278         rtnl_lock();
1279         __netpoll_cleanup(np);
1280         rtnl_unlock();
1281         kfree(np);
1282 }
1283
1284 void __netpoll_free_async(struct netpoll *np)
1285 {
1286         schedule_work(&np->cleanup_work);
1287 }
1288 EXPORT_SYMBOL_GPL(__netpoll_free_async);
1289
1290 void netpoll_cleanup(struct netpoll *np)
1291 {
1292         if (!np->dev)
1293                 return;
1294
1295         rtnl_lock();
1296         __netpoll_cleanup(np);
1297         rtnl_unlock();
1298
1299         dev_put(np->dev);
1300         np->dev = NULL;
1301 }
1302 EXPORT_SYMBOL(netpoll_cleanup);
1303
1304 int netpoll_trap(void)
1305 {
1306         return atomic_read(&trapped);
1307 }
1308 EXPORT_SYMBOL(netpoll_trap);
1309
1310 void netpoll_set_trap(int trap)
1311 {
1312         if (trap)
1313                 atomic_inc(&trapped);
1314         else
1315                 atomic_dec(&trapped);
1316 }
1317 EXPORT_SYMBOL(netpoll_set_trap);