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