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 #include <linux/netdevice.h>
  13 #include <linux/etherdevice.h>
  14 #include <linux/string.h>
  15 #include <linux/if_arp.h>
  16 #include <linux/inetdevice.h>
  17 #include <linux/inet.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/netpoll.h>
  20 #include <linux/sched.h>
  21 #include <linux/delay.h>
  22 #include <linux/rcupdate.h>
  23 #include <linux/workqueue.h>
  24 #include <net/tcp.h>
  25 #include <net/udp.h>
  26 #include <asm/unaligned.h>
  27
  28 /*
  29  * We maintain a small pool of fully-sized skbs, to make sure the
  30  * message gets out even in extreme OOM situations.
  31  */
  32
  33 #define MAX_UDP_CHUNK 1460
  34 #define MAX_SKBS 32
  35 #define MAX_QUEUE_DEPTH (MAX_SKBS / 2)
  36
  37 static struct sk_buff_head skb_pool;
  38
  39 static atomic_t trapped;
  40
  41 #define USEC_PER_POLL   50
  42 #define NETPOLL_RX_ENABLED  1
  43 #define NETPOLL_RX_DROP     2
  44
  45 #define MAX_SKB_SIZE \
  46                 (MAX_UDP_CHUNK + sizeof(struct udphdr) + \
  47                                 sizeof(struct iphdr) + sizeof(struct ethhdr))
  48
  49 static void zap_completion_queue(void);
  50 static void arp_reply(struct sk_buff *skb);
  51
  52 static void queue_process(struct work_struct *work)
  53 {
  54         struct netpoll_info *npinfo =
  55                 container_of(work, struct netpoll_info, tx_work.work);
  56         struct sk_buff *skb;
  57         unsigned long flags;
  58
  59         while ((skb = skb_dequeue(&npinfo->txq))) {
  60                 struct net_device *dev = skb->dev;
  61                 struct netdev_queue *txq;
  62
  63                 if (!netif_device_present(dev) || !netif_running(dev)) {
  64                         __kfree_skb(skb);
  65                         continue;
  66                 }
  67
  68                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
  69
  70                 local_irq_save(flags);
  71                 __netif_tx_lock(txq, smp_processor_id());
  72                 if (netif_tx_queue_stopped(txq) ||
  73                     dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
  74                         skb_queue_head(&npinfo->txq, skb);
  75                         __netif_tx_unlock(txq);
  76                         local_irq_restore(flags);
  77
  78                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
  79                         return;
  80                 }
  81                 __netif_tx_unlock(txq);
  82                 local_irq_restore(flags);
  83         }
  84 }
  85
  86 static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
  87                             unsigned short ulen, __be32 saddr, __be32 daddr)
  88 {
  89         __wsum psum;
  90
  91         if (uh->check == 0 || skb_csum_unnecessary(skb))
  92                 return 0;
  93
  94         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
  95
  96         if (skb->ip_summed == CHECKSUM_COMPLETE &&
  97             !csum_fold(csum_add(psum, skb->csum)))
  98                 return 0;
  99
 100         skb->csum = psum;
 101
 102         return __skb_checksum_complete(skb);
 103 }
 104
 105 /*
 106  * Check whether delayed processing was scheduled for our NIC. If so,
 107  * we attempt to grab the poll lock and use ->poll() to pump the card.
 108  * If this fails, either we've recursed in ->poll() or it's already
 109  * running on another CPU.
 110  *
 111  * Note: we don't mask interrupts with this lock because we're using
 112  * trylock here and interrupts are already disabled in the softirq
 113  * case. Further, we test the poll_owner to avoid recursion on UP
 114  * systems where the lock doesn't exist.
 115  *
 116  * In cases where there is bi-directional communications, reading only
 117  * one message at a time can lead to packets being dropped by the
 118  * network adapter, forcing superfluous retries and possibly timeouts.
 119  * Thus, we set our budget to greater than 1.
 120  */
 121 static int poll_one_napi(struct netpoll_info *npinfo,
 122                          struct napi_struct *napi, int budget)
 123 {
 124         int work;
 125
 126         /* net_rx_action's ->poll() invocations and our's are
 127          * synchronized by this test which is only made while
 128          * holding the napi->poll_lock.
 129          */
 130         if (!test_bit(NAPI_STATE_SCHED, &napi->state))
 131                 return budget;
 132
 133         npinfo->rx_flags |= NETPOLL_RX_DROP;
 134         atomic_inc(&trapped);
 135
 136         work = napi->poll(napi, budget);
 137
 138         atomic_dec(&trapped);
 139         npinfo->rx_flags &= ~NETPOLL_RX_DROP;
 140
 141         return budget - work;
 142 }
 143
 144 static void poll_napi(struct net_device *dev)
 145 {
 146         struct napi_struct *napi;
 147         int budget = 16;
 148
 149         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 150                 if (napi->poll_owner != smp_processor_id() &&
 151                     spin_trylock(&napi->poll_lock)) {
 152                         budget = poll_one_napi(dev->npinfo, napi, budget);
 153                         spin_unlock(&napi->poll_lock);
 154
 155                         if (!budget)
 156                                 break;
 157                 }
 158         }
 159 }
 160
 161 static void service_arp_queue(struct netpoll_info *npi)
 162 {
 163         if (npi) {
 164                 struct sk_buff *skb;
 165
 166                 while ((skb = skb_dequeue(&npi->arp_tx)))
 167                         arp_reply(skb);
 168         }
 169 }
 170
 171 void netpoll_poll(struct netpoll *np)
 172 {
 173         struct net_device *dev = np->dev;
 174
 175         if (!dev || !netif_running(dev) || !dev->poll_controller)
 176                 return;
 177
 178         /* Process pending work on NIC */
 179         dev->poll_controller(dev);
 180
 181         poll_napi(dev);
 182
 183         service_arp_queue(dev->npinfo);
 184
 185         zap_completion_queue();
 186 }
 187
 188 static void refill_skbs(void)
 189 {
 190         struct sk_buff *skb;
 191         unsigned long flags;
 192
 193         spin_lock_irqsave(&skb_pool.lock, flags);
 194         while (skb_pool.qlen < MAX_SKBS) {
 195                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
 196                 if (!skb)
 197                         break;
 198
 199                 __skb_queue_tail(&skb_pool, skb);
 200         }
 201         spin_unlock_irqrestore(&skb_pool.lock, flags);
 202 }
 203
 204 static void zap_completion_queue(void)
 205 {
 206         unsigned long flags;
 207         struct softnet_data *sd = &get_cpu_var(softnet_data);
 208
 209         if (sd->completion_queue) {
 210                 struct sk_buff *clist;
 211
 212                 local_irq_save(flags);
 213                 clist = sd->completion_queue;
 214                 sd->completion_queue = NULL;
 215                 local_irq_restore(flags);
 216
 217                 while (clist != NULL) {
 218                         struct sk_buff *skb = clist;
 219                         clist = clist->next;
 220                         if (skb->destructor) {
 221                                 atomic_inc(&skb->users);
 222                                 dev_kfree_skb_any(skb); /* put this one back */
 223                         } else {
 224                                 __kfree_skb(skb);
 225                         }
 226                 }
 227         }
 228
 229         put_cpu_var(softnet_data);
 230 }
 231
 232 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
 233 {
 234         int count = 0;
 235         struct sk_buff *skb;
 236
 237         zap_completion_queue();
 238         refill_skbs();
 239 repeat:
 240
 241         skb = alloc_skb(len, GFP_ATOMIC);
 242         if (!skb)
 243                 skb = skb_dequeue(&skb_pool);
 244
 245         if (!skb) {
 246                 if (++count < 10) {
 247                         netpoll_poll(np);
 248                         goto repeat;
 249                 }
 250                 return NULL;
 251         }
 252
 253         atomic_set(&skb->users, 1);
 254         skb_reserve(skb, reserve);
 255         return skb;
 256 }
 257
 258 static int netpoll_owner_active(struct net_device *dev)
 259 {
 260         struct napi_struct *napi;
 261
 262         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 263                 if (napi->poll_owner == smp_processor_id())
 264                         return 1;
 265         }
 266         return 0;
 267 }
 268
 269 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 270 {
 271         int status = NETDEV_TX_BUSY;
 272         unsigned long tries;
 273         struct net_device *dev = np->dev;
 274         struct netpoll_info *npinfo = np->dev->npinfo;
 275
 276         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
 277                 __kfree_skb(skb);
 278                 return;
 279         }
 280
 281         /* don't get messages out of order, and no recursion */
 282         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
 283                 struct netdev_queue *txq;
 284                 unsigned long flags;
 285
 286                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
 287
 288                 local_irq_save(flags);
 289                 /* try until next clock tick */
 290                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
 291                      tries > 0; --tries) {
 292                         if (__netif_tx_trylock(txq)) {
 293                                 if (!netif_tx_queue_stopped(txq))
 294                                         status = dev->hard_start_xmit(skb, dev);
 295                                 __netif_tx_unlock(txq);
 296
 297                                 if (status == NETDEV_TX_OK)
 298                                         break;
 299
 300                         }
 301
 302                         /* tickle device maybe there is some cleanup */
 303                         netpoll_poll(np);
 304
 305                         udelay(USEC_PER_POLL);
 306                 }
 307                 local_irq_restore(flags);
 308         }
 309
 310         if (status != NETDEV_TX_OK) {
 311                 skb_queue_tail(&npinfo->txq, skb);
 312                 schedule_delayed_work(&npinfo->tx_work,0);
 313         }
 314 }
 315
 316 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 317 {
 318         int total_len, eth_len, ip_len, udp_len;
 319         struct sk_buff *skb;
 320         struct udphdr *udph;
 321         struct iphdr *iph;
 322         struct ethhdr *eth;
 323
 324         udp_len = len + sizeof(*udph);
 325         ip_len = eth_len = udp_len + sizeof(*iph);
 326         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
 327
 328         skb = find_skb(np, total_len, total_len - len);
 329         if (!skb)
 330                 return;
 331
 332         skb_copy_to_linear_data(skb, msg, len);
 333         skb->len += len;
 334
 335         skb_push(skb, sizeof(*udph));
 336         skb_reset_transport_header(skb);
 337         udph = udp_hdr(skb);
 338         udph->source = htons(np->local_port);
 339         udph->dest = htons(np->remote_port);
 340         udph->len = htons(udp_len);
 341         udph->check = 0;
 342         udph->check = csum_tcpudp_magic(htonl(np->local_ip),
 343                                         htonl(np->remote_ip),
 344                                         udp_len, IPPROTO_UDP,
 345                                         csum_partial((unsigned char *)udph, udp_len, 0));
 346         if (udph->check == 0)
 347                 udph->check = CSUM_MANGLED_0;
 348
 349         skb_push(skb, sizeof(*iph));
 350         skb_reset_network_header(skb);
 351         iph = ip_hdr(skb);
 352
 353         /* iph->version = 4; iph->ihl = 5; */
 354         put_unaligned(0x45, (unsigned char *)iph);
 355         iph->tos      = 0;
 356         put_unaligned(htons(ip_len), &(iph->tot_len));
 357         iph->id       = 0;
 358         iph->frag_off = 0;
 359         iph->ttl      = 64;
 360         iph->protocol = IPPROTO_UDP;
 361         iph->check    = 0;
 362         put_unaligned(htonl(np->local_ip), &(iph->saddr));
 363         put_unaligned(htonl(np->remote_ip), &(iph->daddr));
 364         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 365
 366         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 367         skb_reset_mac_header(skb);
 368         skb->protocol = eth->h_proto = htons(ETH_P_IP);
 369         memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN);
 370         memcpy(eth->h_dest, np->remote_mac, ETH_ALEN);
 371
 372         skb->dev = np->dev;
 373
 374         netpoll_send_skb(np, skb);
 375 }
 376
 377 static void arp_reply(struct sk_buff *skb)
 378 {
 379         struct netpoll_info *npinfo = skb->dev->npinfo;
 380         struct arphdr *arp;
 381         unsigned char *arp_ptr;
 382         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
 383         __be32 sip, tip;
 384         unsigned char *sha;
 385         struct sk_buff *send_skb;
 386         struct netpoll *np = NULL;
 387
 388         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
 389                 np = npinfo->rx_np;
 390         if (!np)
 391                 return;
 392
 393         /* No arp on this interface */
 394         if (skb->dev->flags & IFF_NOARP)
 395                 return;
 396
 397         if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
 398                 return;
 399
 400         skb_reset_network_header(skb);
 401         skb_reset_transport_header(skb);
 402         arp = arp_hdr(skb);
 403
 404         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 405              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 406             arp->ar_pro != htons(ETH_P_IP) ||
 407             arp->ar_op != htons(ARPOP_REQUEST))
 408                 return;
 409
 410         arp_ptr = (unsigned char *)(arp+1);
 411         /* save the location of the src hw addr */
 412         sha = arp_ptr;
 413         arp_ptr += skb->dev->addr_len;
 414         memcpy(&sip, arp_ptr, 4);
 415         arp_ptr += 4;
 416         /* if we actually cared about dst hw addr, it would get copied here */
 417         arp_ptr += skb->dev->addr_len;
 418         memcpy(&tip, arp_ptr, 4);
 419
 420         /* Should we ignore arp? */
 421         if (tip != htonl(np->local_ip) ||
 422             ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
 423                 return;
 424
 425         size = arp_hdr_len(skb->dev);
 426         send_skb = find_skb(np, size + LL_ALLOCATED_SPACE(np->dev),
 427                             LL_RESERVED_SPACE(np->dev));
 428
 429         if (!send_skb)
 430                 return;
 431
 432         skb_reset_network_header(send_skb);
 433         arp = (struct arphdr *) skb_put(send_skb, size);
 434         send_skb->dev = skb->dev;
 435         send_skb->protocol = htons(ETH_P_ARP);
 436
 437         /* Fill the device header for the ARP frame */
 438         if (dev_hard_header(send_skb, skb->dev, ptype,
 439                             sha, np->dev->dev_addr,
 440                             send_skb->len) < 0) {
 441                 kfree_skb(send_skb);
 442                 return;
 443         }
 444
 445         /*
 446          * Fill out the arp protocol part.
 447          *
 448          * we only support ethernet device type,
 449          * which (according to RFC 1390) should always equal 1 (Ethernet).
 450          */
 451
 452         arp->ar_hrd = htons(np->dev->type);
 453         arp->ar_pro = htons(ETH_P_IP);
 454         arp->ar_hln = np->dev->addr_len;
 455         arp->ar_pln = 4;
 456         arp->ar_op = htons(type);
 457
 458         arp_ptr=(unsigned char *)(arp + 1);
 459         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
 460         arp_ptr += np->dev->addr_len;
 461         memcpy(arp_ptr, &tip, 4);
 462         arp_ptr += 4;
 463         memcpy(arp_ptr, sha, np->dev->addr_len);
 464         arp_ptr += np->dev->addr_len;
 465         memcpy(arp_ptr, &sip, 4);
 466
 467         netpoll_send_skb(np, send_skb);
 468 }
 469
 470 int __netpoll_rx(struct sk_buff *skb)
 471 {
 472         int proto, len, ulen;
 473         struct iphdr *iph;
 474         struct udphdr *uh;
 475         struct netpoll_info *npi = skb->dev->npinfo;
 476         struct netpoll *np = npi->rx_np;
 477
 478         if (!np)
 479                 goto out;
 480         if (skb->dev->type != ARPHRD_ETHER)
 481                 goto out;
 482
 483         /* check if netpoll clients need ARP */
 484         if (skb->protocol == htons(ETH_P_ARP) &&
 485             atomic_read(&trapped)) {
 486                 skb_queue_tail(&npi->arp_tx, skb);
 487                 return 1;
 488         }
 489
 490         proto = ntohs(eth_hdr(skb)->h_proto);
 491         if (proto != ETH_P_IP)
 492                 goto out;
 493         if (skb->pkt_type == PACKET_OTHERHOST)
 494                 goto out;
 495         if (skb_shared(skb))
 496                 goto out;
 497
 498         iph = (struct iphdr *)skb->data;
 499         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 500                 goto out;
 501         if (iph->ihl < 5 || iph->version != 4)
 502                 goto out;
 503         if (!pskb_may_pull(skb, iph->ihl*4))
 504                 goto out;
 505         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
 506                 goto out;
 507
 508         len = ntohs(iph->tot_len);
 509         if (skb->len < len || len < iph->ihl*4)
 510                 goto out;
 511
 512         /*
 513          * Our transport medium may have padded the buffer out.
 514          * Now We trim to the true length of the frame.
 515          */
 516         if (pskb_trim_rcsum(skb, len))
 517                 goto out;
 518
 519         if (iph->protocol != IPPROTO_UDP)
 520                 goto out;
 521
 522         len -= iph->ihl*4;
 523         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
 524         ulen = ntohs(uh->len);
 525
 526         if (ulen != len)
 527                 goto out;
 528         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
 529                 goto out;
 530         if (np->local_ip && np->local_ip != ntohl(iph->daddr))
 531                 goto out;
 532         if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
 533                 goto out;
 534         if (np->local_port && np->local_port != ntohs(uh->dest))
 535                 goto out;
 536
 537         np->rx_hook(np, ntohs(uh->source),
 538                     (char *)(uh+1),
 539                     ulen - sizeof(struct udphdr));
 540
 541         kfree_skb(skb);
 542         return 1;
 543
 544 out:
 545         if (atomic_read(&trapped)) {
 546                 kfree_skb(skb);
 547                 return 1;
 548         }
 549
 550         return 0;
 551 }
 552
 553 void netpoll_print_options(struct netpoll *np)
 554 {
 555         DECLARE_MAC_BUF(mac);
 556         printk(KERN_INFO "%s: local port %d\n",
 557                          np->name, np->local_port);
 558         printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 559                          np->name, HIPQUAD(np->local_ip));
 560         printk(KERN_INFO "%s: interface %s\n",
 561                          np->name, np->dev_name);
 562         printk(KERN_INFO "%s: remote port %d\n",
 563                          np->name, np->remote_port);
 564         printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
 565                          np->name, HIPQUAD(np->remote_ip));
 566         printk(KERN_INFO "%s: remote ethernet address %s\n",
 567                          np->name, print_mac(mac, np->remote_mac));
 568 }
 569
 570 int netpoll_parse_options(struct netpoll *np, char *opt)
 571 {
 572         char *cur=opt, *delim;
 573
 574         if (*cur != '@') {
 575                 if ((delim = strchr(cur, '@')) == NULL)
 576                         goto parse_failed;
 577                 *delim = 0;
 578                 np->local_port = simple_strtol(cur, NULL, 10);
 579                 cur = delim;
 580         }
 581         cur++;
 582
 583         if (*cur != '/') {
 584                 if ((delim = strchr(cur, '/')) == NULL)
 585                         goto parse_failed;
 586                 *delim = 0;
 587                 np->local_ip = ntohl(in_aton(cur));
 588                 cur = delim;
 589         }
 590         cur++;
 591
 592         if (*cur != ',') {
 593                 /* parse out dev name */
 594                 if ((delim = strchr(cur, ',')) == NULL)
 595                         goto parse_failed;
 596                 *delim = 0;
 597                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 598                 cur = delim;
 599         }
 600         cur++;
 601
 602         if (*cur != '@') {
 603                 /* dst port */
 604                 if ((delim = strchr(cur, '@')) == NULL)
 605                         goto parse_failed;
 606                 *delim = 0;
 607                 np->remote_port = simple_strtol(cur, NULL, 10);
 608                 cur = delim;
 609         }
 610         cur++;
 611
 612         /* dst ip */
 613         if ((delim = strchr(cur, '/')) == NULL)
 614                 goto parse_failed;
 615         *delim = 0;
 616         np->remote_ip = ntohl(in_aton(cur));
 617         cur = delim + 1;
 618
 619         if (*cur != 0) {
 620                 /* MAC address */
 621                 if ((delim = strchr(cur, ':')) == NULL)
 622                         goto parse_failed;
 623                 *delim = 0;
 624                 np->remote_mac[0] = simple_strtol(cur, NULL, 16);
 625                 cur = delim + 1;
 626                 if ((delim = strchr(cur, ':')) == NULL)
 627                         goto parse_failed;
 628                 *delim = 0;
 629                 np->remote_mac[1] = simple_strtol(cur, NULL, 16);
 630                 cur = delim + 1;
 631                 if ((delim = strchr(cur, ':')) == NULL)
 632                         goto parse_failed;
 633                 *delim = 0;
 634                 np->remote_mac[2] = simple_strtol(cur, NULL, 16);
 635                 cur = delim + 1;
 636                 if ((delim = strchr(cur, ':')) == NULL)
 637                         goto parse_failed;
 638                 *delim = 0;
 639                 np->remote_mac[3] = simple_strtol(cur, NULL, 16);
 640                 cur = delim + 1;
 641                 if ((delim = strchr(cur, ':')) == NULL)
 642                         goto parse_failed;
 643                 *delim = 0;
 644                 np->remote_mac[4] = simple_strtol(cur, NULL, 16);
 645                 cur = delim + 1;
 646                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
 647         }
 648
 649         netpoll_print_options(np);
 650
 651         return 0;
 652
 653  parse_failed:
 654         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
 655                np->name, cur);
 656         return -1;
 657 }
 658
 659 int netpoll_setup(struct netpoll *np)
 660 {
 661         struct net_device *ndev = NULL;
 662         struct in_device *in_dev;
 663         struct netpoll_info *npinfo;
 664         unsigned long flags;
 665         int err;
 666
 667         if (np->dev_name)
 668                 ndev = dev_get_by_name(&init_net, np->dev_name);
 669         if (!ndev) {
 670                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
 671                        np->name, np->dev_name);
 672                 return -ENODEV;
 673         }
 674
 675         np->dev = ndev;
 676         if (!ndev->npinfo) {
 677                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
 678                 if (!npinfo) {
 679                         err = -ENOMEM;
 680                         goto release;
 681                 }
 682
 683                 npinfo->rx_flags = 0;
 684                 npinfo->rx_np = NULL;
 685
 686                 spin_lock_init(&npinfo->rx_lock);
 687                 skb_queue_head_init(&npinfo->arp_tx);
 688                 skb_queue_head_init(&npinfo->txq);
 689                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
 690
 691                 atomic_set(&npinfo->refcnt, 1);
 692         } else {
 693                 npinfo = ndev->npinfo;
 694                 atomic_inc(&npinfo->refcnt);
 695         }
 696
 697         if (!ndev->poll_controller) {
 698                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
 699                        np->name, np->dev_name);
 700                 err = -ENOTSUPP;
 701                 goto release;
 702         }
 703
 704         if (!netif_running(ndev)) {
 705                 unsigned long atmost, atleast;
 706
 707                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
 708                        np->name, np->dev_name);
 709
 710                 rtnl_lock();
 711                 err = dev_open(ndev);
 712                 rtnl_unlock();
 713
 714                 if (err) {
 715                         printk(KERN_ERR "%s: failed to open %s\n",
 716                                np->name, ndev->name);
 717                         goto release;
 718                 }
 719
 720                 atleast = jiffies + HZ/10;
 721                 atmost = jiffies + 4*HZ;
 722                 while (!netif_carrier_ok(ndev)) {
 723                         if (time_after(jiffies, atmost)) {
 724                                 printk(KERN_NOTICE
 725                                        "%s: timeout waiting for carrier\n",
 726                                        np->name);
 727                                 break;
 728                         }
 729                         cond_resched();
 730                 }
 731
 732                 /* If carrier appears to come up instantly, we don't
 733                  * trust it and pause so that we don't pump all our
 734                  * queued console messages into the bitbucket.
 735                  */
 736
 737                 if (time_before(jiffies, atleast)) {
 738                         printk(KERN_NOTICE "%s: carrier detect appears"
 739                                " untrustworthy, waiting 4 seconds\n",
 740                                np->name);
 741                         msleep(4000);
 742                 }
 743         }
 744
 745         if (!np->local_ip) {
 746                 rcu_read_lock();
 747                 in_dev = __in_dev_get_rcu(ndev);
 748
 749                 if (!in_dev || !in_dev->ifa_list) {
 750                         rcu_read_unlock();
 751                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
 752                                np->name, np->dev_name);
 753                         err = -EDESTADDRREQ;
 754                         goto release;
 755                 }
 756
 757                 np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
 758                 rcu_read_unlock();
 759                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 760                        np->name, HIPQUAD(np->local_ip));
 761         }
 762
 763         if (np->rx_hook) {
 764                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 765                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
 766                 npinfo->rx_np = np;
 767                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 768         }
 769
 770         /* fill up the skb queue */
 771         refill_skbs();
 772
 773         /* last thing to do is link it to the net device structure */
 774         ndev->npinfo = npinfo;
 775
 776         /* avoid racing with NAPI reading npinfo */
 777         synchronize_rcu();
 778
 779         return 0;
 780
 781  release:
 782         if (!ndev->npinfo)
 783                 kfree(npinfo);
 784         np->dev = NULL;
 785         dev_put(ndev);
 786         return err;
 787 }
 788
 789 static int __init netpoll_init(void)
 790 {
 791         skb_queue_head_init(&skb_pool);
 792         return 0;
 793 }
 794 core_initcall(netpoll_init);
 795
 796 void netpoll_cleanup(struct netpoll *np)
 797 {
 798         struct netpoll_info *npinfo;
 799         unsigned long flags;
 800
 801         if (np->dev) {
 802                 npinfo = np->dev->npinfo;
 803                 if (npinfo) {
 804                         if (npinfo->rx_np == np) {
 805                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 806                                 npinfo->rx_np = NULL;
 807                                 npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
 808                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 809                         }
 810
 811                         if (atomic_dec_and_test(&npinfo->refcnt)) {
 812                                 skb_queue_purge(&npinfo->arp_tx);
 813                                 skb_queue_purge(&npinfo->txq);
 814                                 cancel_rearming_delayed_work(&npinfo->tx_work);
 815
 816                                 /* clean after last, unfinished work */
 817                                 __skb_queue_purge(&npinfo->txq);
 818                                 kfree(npinfo);
 819                                 np->dev->npinfo = NULL;
 820                         }
 821                 }
 822
 823                 dev_put(np->dev);
 824         }
 825
 826         np->dev = NULL;
 827 }
 828
 829 int netpoll_trap(void)
 830 {
 831         return atomic_read(&trapped);
 832 }
 833
 834 void netpoll_set_trap(int trap)
 835 {
 836         if (trap)
 837                 atomic_inc(&trapped);
 838         else
 839                 atomic_dec(&trapped);
 840 }
 841
 842 EXPORT_SYMBOL(netpoll_set_trap);
 843 EXPORT_SYMBOL(netpoll_trap);
 844 EXPORT_SYMBOL(netpoll_print_options);
 845 EXPORT_SYMBOL(netpoll_parse_options);
 846 EXPORT_SYMBOL(netpoll_setup);
 847 EXPORT_SYMBOL(netpoll_cleanup);
 848 EXPORT_SYMBOL(netpoll_send_udp);
 849 EXPORT_SYMBOL(netpoll_poll);