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