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;
 179
 180         if (!dev || !netif_running(dev))
 181                 return;
 182
 183         ops = dev->netdev_ops;
 184         if (!ops->ndo_poll_controller)
 185                 return;
 186
 187         /* Process pending work on NIC */
 188         ops->ndo_poll_controller(dev);
 189
 190         poll_napi(dev);
 191
 192         service_arp_queue(dev->npinfo);
 193
 194         zap_completion_queue();
 195 }
 196
 197 static void refill_skbs(void)
 198 {
 199         struct sk_buff *skb;
 200         unsigned long flags;
 201
 202         spin_lock_irqsave(&skb_pool.lock, flags);
 203         while (skb_pool.qlen < MAX_SKBS) {
 204                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
 205                 if (!skb)
 206                         break;
 207
 208                 __skb_queue_tail(&skb_pool, skb);
 209         }
 210         spin_unlock_irqrestore(&skb_pool.lock, flags);
 211 }
 212
 213 static void zap_completion_queue(void)
 214 {
 215         unsigned long flags;
 216         struct softnet_data *sd = &get_cpu_var(softnet_data);
 217
 218         if (sd->completion_queue) {
 219                 struct sk_buff *clist;
 220
 221                 local_irq_save(flags);
 222                 clist = sd->completion_queue;
 223                 sd->completion_queue = NULL;
 224                 local_irq_restore(flags);
 225
 226                 while (clist != NULL) {
 227                         struct sk_buff *skb = clist;
 228                         clist = clist->next;
 229                         if (skb->destructor) {
 230                                 atomic_inc(&skb->users);
 231                                 dev_kfree_skb_any(skb); /* put this one back */
 232                         } else {
 233                                 __kfree_skb(skb);
 234                         }
 235                 }
 236         }
 237
 238         put_cpu_var(softnet_data);
 239 }
 240
 241 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
 242 {
 243         int count = 0;
 244         struct sk_buff *skb;
 245
 246         zap_completion_queue();
 247         refill_skbs();
 248 repeat:
 249
 250         skb = alloc_skb(len, GFP_ATOMIC);
 251         if (!skb)
 252                 skb = skb_dequeue(&skb_pool);
 253
 254         if (!skb) {
 255                 if (++count < 10) {
 256                         netpoll_poll(np);
 257                         goto repeat;
 258                 }
 259                 return NULL;
 260         }
 261
 262         atomic_set(&skb->users, 1);
 263         skb_reserve(skb, reserve);
 264         return skb;
 265 }
 266
 267 static int netpoll_owner_active(struct net_device *dev)
 268 {
 269         struct napi_struct *napi;
 270
 271         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 272                 if (napi->poll_owner == smp_processor_id())
 273                         return 1;
 274         }
 275         return 0;
 276 }
 277
 278 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 279 {
 280         int status = NETDEV_TX_BUSY;
 281         unsigned long tries;
 282         struct net_device *dev = np->dev;
 283         const struct net_device_ops *ops = dev->netdev_ops;
 284         struct netpoll_info *npinfo = np->dev->npinfo;
 285
 286         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
 287                 __kfree_skb(skb);
 288                 return;
 289         }
 290
 291         /* don't get messages out of order, and no recursion */
 292         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
 293                 struct netdev_queue *txq;
 294                 unsigned long flags;
 295
 296                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
 297
 298                 local_irq_save(flags);
 299                 /* try until next clock tick */
 300                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
 301                      tries > 0; --tries) {
 302                         if (__netif_tx_trylock(txq)) {
 303                                 if (!netif_tx_queue_stopped(txq))
 304                                         status = ops->ndo_start_xmit(skb, dev);
 305                                 __netif_tx_unlock(txq);
 306
 307                                 if (status == NETDEV_TX_OK)
 308                                         break;
 309
 310                         }
 311
 312                         /* tickle device maybe there is some cleanup */
 313                         netpoll_poll(np);
 314
 315                         udelay(USEC_PER_POLL);
 316                 }
 317                 local_irq_restore(flags);
 318         }
 319
 320         if (status != NETDEV_TX_OK) {
 321                 skb_queue_tail(&npinfo->txq, skb);
 322                 schedule_delayed_work(&npinfo->tx_work,0);
 323         }
 324 }
 325
 326 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 327 {
 328         int total_len, eth_len, ip_len, udp_len;
 329         struct sk_buff *skb;
 330         struct udphdr *udph;
 331         struct iphdr *iph;
 332         struct ethhdr *eth;
 333
 334         udp_len = len + sizeof(*udph);
 335         ip_len = eth_len = udp_len + sizeof(*iph);
 336         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
 337
 338         skb = find_skb(np, total_len, total_len - len);
 339         if (!skb)
 340                 return;
 341
 342         skb_copy_to_linear_data(skb, msg, len);
 343         skb->len += len;
 344
 345         skb_push(skb, sizeof(*udph));
 346         skb_reset_transport_header(skb);
 347         udph = udp_hdr(skb);
 348         udph->source = htons(np->local_port);
 349         udph->dest = htons(np->remote_port);
 350         udph->len = htons(udp_len);
 351         udph->check = 0;
 352         udph->check = csum_tcpudp_magic(np->local_ip,
 353                                         np->remote_ip,
 354                                         udp_len, IPPROTO_UDP,
 355                                         csum_partial(udph, udp_len, 0));
 356         if (udph->check == 0)
 357                 udph->check = CSUM_MANGLED_0;
 358
 359         skb_push(skb, sizeof(*iph));
 360         skb_reset_network_header(skb);
 361         iph = ip_hdr(skb);
 362
 363         /* iph->version = 4; iph->ihl = 5; */
 364         put_unaligned(0x45, (unsigned char *)iph);
 365         iph->tos      = 0;
 366         put_unaligned(htons(ip_len), &(iph->tot_len));
 367         iph->id       = 0;
 368         iph->frag_off = 0;
 369         iph->ttl      = 64;
 370         iph->protocol = IPPROTO_UDP;
 371         iph->check    = 0;
 372         put_unaligned(np->local_ip, &(iph->saddr));
 373         put_unaligned(np->remote_ip, &(iph->daddr));
 374         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 375
 376         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 377         skb_reset_mac_header(skb);
 378         skb->protocol = eth->h_proto = htons(ETH_P_IP);
 379         memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN);
 380         memcpy(eth->h_dest, np->remote_mac, ETH_ALEN);
 381
 382         skb->dev = np->dev;
 383
 384         netpoll_send_skb(np, skb);
 385 }
 386
 387 static void arp_reply(struct sk_buff *skb)
 388 {
 389         struct netpoll_info *npinfo = skb->dev->npinfo;
 390         struct arphdr *arp;
 391         unsigned char *arp_ptr;
 392         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
 393         __be32 sip, tip;
 394         unsigned char *sha;
 395         struct sk_buff *send_skb;
 396         struct netpoll *np = NULL;
 397
 398         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
 399                 np = npinfo->rx_np;
 400         if (!np)
 401                 return;
 402
 403         /* No arp on this interface */
 404         if (skb->dev->flags & IFF_NOARP)
 405                 return;
 406
 407         if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
 408                 return;
 409
 410         skb_reset_network_header(skb);
 411         skb_reset_transport_header(skb);
 412         arp = arp_hdr(skb);
 413
 414         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 415              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 416             arp->ar_pro != htons(ETH_P_IP) ||
 417             arp->ar_op != htons(ARPOP_REQUEST))
 418                 return;
 419
 420         arp_ptr = (unsigned char *)(arp+1);
 421         /* save the location of the src hw addr */
 422         sha = arp_ptr;
 423         arp_ptr += skb->dev->addr_len;
 424         memcpy(&sip, arp_ptr, 4);
 425         arp_ptr += 4;
 426         /* if we actually cared about dst hw addr, it would get copied here */
 427         arp_ptr += skb->dev->addr_len;
 428         memcpy(&tip, arp_ptr, 4);
 429
 430         /* Should we ignore arp? */
 431         if (tip != np->local_ip ||
 432             ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
 433                 return;
 434
 435         size = arp_hdr_len(skb->dev);
 436         send_skb = find_skb(np, size + LL_ALLOCATED_SPACE(np->dev),
 437                             LL_RESERVED_SPACE(np->dev));
 438
 439         if (!send_skb)
 440                 return;
 441
 442         skb_reset_network_header(send_skb);
 443         arp = (struct arphdr *) skb_put(send_skb, size);
 444         send_skb->dev = skb->dev;
 445         send_skb->protocol = htons(ETH_P_ARP);
 446
 447         /* Fill the device header for the ARP frame */
 448         if (dev_hard_header(send_skb, skb->dev, ptype,
 449                             sha, np->dev->dev_addr,
 450                             send_skb->len) < 0) {
 451                 kfree_skb(send_skb);
 452                 return;
 453         }
 454
 455         /*
 456          * Fill out the arp protocol part.
 457          *
 458          * we only support ethernet device type,
 459          * which (according to RFC 1390) should always equal 1 (Ethernet).
 460          */
 461
 462         arp->ar_hrd = htons(np->dev->type);
 463         arp->ar_pro = htons(ETH_P_IP);
 464         arp->ar_hln = np->dev->addr_len;
 465         arp->ar_pln = 4;
 466         arp->ar_op = htons(type);
 467
 468         arp_ptr=(unsigned char *)(arp + 1);
 469         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
 470         arp_ptr += np->dev->addr_len;
 471         memcpy(arp_ptr, &tip, 4);
 472         arp_ptr += 4;
 473         memcpy(arp_ptr, sha, np->dev->addr_len);
 474         arp_ptr += np->dev->addr_len;
 475         memcpy(arp_ptr, &sip, 4);
 476
 477         netpoll_send_skb(np, send_skb);
 478 }
 479
 480 int __netpoll_rx(struct sk_buff *skb)
 481 {
 482         int proto, len, ulen;
 483         struct iphdr *iph;
 484         struct udphdr *uh;
 485         struct netpoll_info *npi = skb->dev->npinfo;
 486         struct netpoll *np = npi->rx_np;
 487
 488         if (!np)
 489                 goto out;
 490         if (skb->dev->type != ARPHRD_ETHER)
 491                 goto out;
 492
 493         /* check if netpoll clients need ARP */
 494         if (skb->protocol == htons(ETH_P_ARP) &&
 495             atomic_read(&trapped)) {
 496                 skb_queue_tail(&npi->arp_tx, skb);
 497                 return 1;
 498         }
 499
 500         proto = ntohs(eth_hdr(skb)->h_proto);
 501         if (proto != ETH_P_IP)
 502                 goto out;
 503         if (skb->pkt_type == PACKET_OTHERHOST)
 504                 goto out;
 505         if (skb_shared(skb))
 506                 goto out;
 507
 508         iph = (struct iphdr *)skb->data;
 509         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 510                 goto out;
 511         if (iph->ihl < 5 || iph->version != 4)
 512                 goto out;
 513         if (!pskb_may_pull(skb, iph->ihl*4))
 514                 goto out;
 515         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
 516                 goto out;
 517
 518         len = ntohs(iph->tot_len);
 519         if (skb->len < len || len < iph->ihl*4)
 520                 goto out;
 521
 522         /*
 523          * Our transport medium may have padded the buffer out.
 524          * Now We trim to the true length of the frame.
 525          */
 526         if (pskb_trim_rcsum(skb, len))
 527                 goto out;
 528
 529         if (iph->protocol != IPPROTO_UDP)
 530                 goto out;
 531
 532         len -= iph->ihl*4;
 533         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
 534         ulen = ntohs(uh->len);
 535
 536         if (ulen != len)
 537                 goto out;
 538         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
 539                 goto out;
 540         if (np->local_ip && np->local_ip != iph->daddr)
 541                 goto out;
 542         if (np->remote_ip && np->remote_ip != iph->saddr)
 543                 goto out;
 544         if (np->local_port && np->local_port != ntohs(uh->dest))
 545                 goto out;
 546
 547         np->rx_hook(np, ntohs(uh->source),
 548                     (char *)(uh+1),
 549                     ulen - sizeof(struct udphdr));
 550
 551         kfree_skb(skb);
 552         return 1;
 553
 554 out:
 555         if (atomic_read(&trapped)) {
 556                 kfree_skb(skb);
 557                 return 1;
 558         }
 559
 560         return 0;
 561 }
 562
 563 void netpoll_print_options(struct netpoll *np)
 564 {
 565         printk(KERN_INFO "%s: local port %d\n",
 566                          np->name, np->local_port);
 567         printk(KERN_INFO "%s: local IP %pI4\n",
 568                          np->name, &np->local_ip);
 569         printk(KERN_INFO "%s: interface %s\n",
 570                          np->name, np->dev_name);
 571         printk(KERN_INFO "%s: remote port %d\n",
 572                          np->name, np->remote_port);
 573         printk(KERN_INFO "%s: remote IP %pI4\n",
 574                          np->name, &np->remote_ip);
 575         printk(KERN_INFO "%s: remote ethernet address %pM\n",
 576                          np->name, np->remote_mac);
 577 }
 578
 579 int netpoll_parse_options(struct netpoll *np, char *opt)
 580 {
 581         char *cur=opt, *delim;
 582
 583         if (*cur != '@') {
 584                 if ((delim = strchr(cur, '@')) == NULL)
 585                         goto parse_failed;
 586                 *delim = 0;
 587                 np->local_port = simple_strtol(cur, NULL, 10);
 588                 cur = delim;
 589         }
 590         cur++;
 591
 592         if (*cur != '/') {
 593                 if ((delim = strchr(cur, '/')) == NULL)
 594                         goto parse_failed;
 595                 *delim = 0;
 596                 np->local_ip = in_aton(cur);
 597                 cur = delim;
 598         }
 599         cur++;
 600
 601         if (*cur != ',') {
 602                 /* parse out dev name */
 603                 if ((delim = strchr(cur, ',')) == NULL)
 604                         goto parse_failed;
 605                 *delim = 0;
 606                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 607                 cur = delim;
 608         }
 609         cur++;
 610
 611         if (*cur != '@') {
 612                 /* dst port */
 613                 if ((delim = strchr(cur, '@')) == NULL)
 614                         goto parse_failed;
 615                 *delim = 0;
 616                 np->remote_port = simple_strtol(cur, NULL, 10);
 617                 cur = delim;
 618         }
 619         cur++;
 620
 621         /* dst ip */
 622         if ((delim = strchr(cur, '/')) == NULL)
 623                 goto parse_failed;
 624         *delim = 0;
 625         np->remote_ip = in_aton(cur);
 626         cur = delim + 1;
 627
 628         if (*cur != 0) {
 629                 /* MAC address */
 630                 if ((delim = strchr(cur, ':')) == NULL)
 631                         goto parse_failed;
 632                 *delim = 0;
 633                 np->remote_mac[0] = simple_strtol(cur, NULL, 16);
 634                 cur = delim + 1;
 635                 if ((delim = strchr(cur, ':')) == NULL)
 636                         goto parse_failed;
 637                 *delim = 0;
 638                 np->remote_mac[1] = simple_strtol(cur, NULL, 16);
 639                 cur = delim + 1;
 640                 if ((delim = strchr(cur, ':')) == NULL)
 641                         goto parse_failed;
 642                 *delim = 0;
 643                 np->remote_mac[2] = simple_strtol(cur, NULL, 16);
 644                 cur = delim + 1;
 645                 if ((delim = strchr(cur, ':')) == NULL)
 646                         goto parse_failed;
 647                 *delim = 0;
 648                 np->remote_mac[3] = simple_strtol(cur, NULL, 16);
 649                 cur = delim + 1;
 650                 if ((delim = strchr(cur, ':')) == NULL)
 651                         goto parse_failed;
 652                 *delim = 0;
 653                 np->remote_mac[4] = simple_strtol(cur, NULL, 16);
 654                 cur = delim + 1;
 655                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
 656         }
 657
 658         netpoll_print_options(np);
 659
 660         return 0;
 661
 662  parse_failed:
 663         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
 664                np->name, cur);
 665         return -1;
 666 }
 667
 668 int netpoll_setup(struct netpoll *np)
 669 {
 670         struct net_device *ndev = NULL;
 671         struct in_device *in_dev;
 672         struct netpoll_info *npinfo;
 673         unsigned long flags;
 674         int err;
 675
 676         if (np->dev_name)
 677                 ndev = dev_get_by_name(&init_net, np->dev_name);
 678         if (!ndev) {
 679                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
 680                        np->name, np->dev_name);
 681                 return -ENODEV;
 682         }
 683
 684         np->dev = ndev;
 685         if (!ndev->npinfo) {
 686                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
 687                 if (!npinfo) {
 688                         err = -ENOMEM;
 689                         goto release;
 690                 }
 691
 692                 npinfo->rx_flags = 0;
 693                 npinfo->rx_np = NULL;
 694
 695                 spin_lock_init(&npinfo->rx_lock);
 696                 skb_queue_head_init(&npinfo->arp_tx);
 697                 skb_queue_head_init(&npinfo->txq);
 698                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
 699
 700                 atomic_set(&npinfo->refcnt, 1);
 701         } else {
 702                 npinfo = ndev->npinfo;
 703                 atomic_inc(&npinfo->refcnt);
 704         }
 705
 706         if (!ndev->netdev_ops->ndo_poll_controller) {
 707                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
 708                        np->name, np->dev_name);
 709                 err = -ENOTSUPP;
 710                 goto release;
 711         }
 712
 713         if (!netif_running(ndev)) {
 714                 unsigned long atmost, atleast;
 715
 716                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
 717                        np->name, np->dev_name);
 718
 719                 rtnl_lock();
 720                 err = dev_open(ndev);
 721                 rtnl_unlock();
 722
 723                 if (err) {
 724                         printk(KERN_ERR "%s: failed to open %s\n",
 725                                np->name, ndev->name);
 726                         goto release;
 727                 }
 728
 729                 atleast = jiffies + HZ/10;
 730                 atmost = jiffies + 4*HZ;
 731                 while (!netif_carrier_ok(ndev)) {
 732                         if (time_after(jiffies, atmost)) {
 733                                 printk(KERN_NOTICE
 734                                        "%s: timeout waiting for carrier\n",
 735                                        np->name);
 736                                 break;
 737                         }
 738                         cond_resched();
 739                 }
 740
 741                 /* If carrier appears to come up instantly, we don't
 742                  * trust it and pause so that we don't pump all our
 743                  * queued console messages into the bitbucket.
 744                  */
 745
 746                 if (time_before(jiffies, atleast)) {
 747                         printk(KERN_NOTICE "%s: carrier detect appears"
 748                                " untrustworthy, waiting 4 seconds\n",
 749                                np->name);
 750                         msleep(4000);
 751                 }
 752         }
 753
 754         if (!np->local_ip) {
 755                 rcu_read_lock();
 756                 in_dev = __in_dev_get_rcu(ndev);
 757
 758                 if (!in_dev || !in_dev->ifa_list) {
 759                         rcu_read_unlock();
 760                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
 761                                np->name, np->dev_name);
 762                         err = -EDESTADDRREQ;
 763                         goto release;
 764                 }
 765
 766                 np->local_ip = in_dev->ifa_list->ifa_local;
 767                 rcu_read_unlock();
 768                 printk(KERN_INFO "%s: local IP %pI4\n", np->name, &np->local_ip);
 769         }
 770
 771         if (np->rx_hook) {
 772                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 773                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
 774                 npinfo->rx_np = np;
 775                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 776         }
 777
 778         /* fill up the skb queue */
 779         refill_skbs();
 780
 781         /* last thing to do is link it to the net device structure */
 782         ndev->npinfo = npinfo;
 783
 784         /* avoid racing with NAPI reading npinfo */
 785         synchronize_rcu();
 786
 787         return 0;
 788
 789  release:
 790         if (!ndev->npinfo)
 791                 kfree(npinfo);
 792         np->dev = NULL;
 793         dev_put(ndev);
 794         return err;
 795 }
 796
 797 static int __init netpoll_init(void)
 798 {
 799         skb_queue_head_init(&skb_pool);
 800         return 0;
 801 }
 802 core_initcall(netpoll_init);
 803
 804 void netpoll_cleanup(struct netpoll *np)
 805 {
 806         struct netpoll_info *npinfo;
 807         unsigned long flags;
 808
 809         if (np->dev) {
 810                 npinfo = np->dev->npinfo;
 811                 if (npinfo) {
 812                         if (npinfo->rx_np == np) {
 813                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 814                                 npinfo->rx_np = NULL;
 815                                 npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
 816                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 817                         }
 818
 819                         if (atomic_dec_and_test(&npinfo->refcnt)) {
 820                                 skb_queue_purge(&npinfo->arp_tx);
 821                                 skb_queue_purge(&npinfo->txq);
 822                                 cancel_rearming_delayed_work(&npinfo->tx_work);
 823
 824                                 /* clean after last, unfinished work */
 825                                 __skb_queue_purge(&npinfo->txq);
 826                                 kfree(npinfo);
 827                                 np->dev->npinfo = NULL;
 828                         }
 829                 }
 830
 831                 dev_put(np->dev);
 832         }
 833
 834         np->dev = NULL;
 835 }
 836
 837 int netpoll_trap(void)
 838 {
 839         return atomic_read(&trapped);
 840 }
 841
 842 void netpoll_set_trap(int trap)
 843 {
 844         if (trap)
 845                 atomic_inc(&trapped);
 846         else
 847                 atomic_dec(&trapped);
 848 }
 849
 850 EXPORT_SYMBOL(netpoll_set_trap);
 851 EXPORT_SYMBOL(netpoll_trap);
 852 EXPORT_SYMBOL(netpoll_print_options);
 853 EXPORT_SYMBOL(netpoll_parse_options);
 854 EXPORT_SYMBOL(netpoll_setup);
 855 EXPORT_SYMBOL(netpoll_cleanup);
 856 EXPORT_SYMBOL(netpoll_send_udp);
 857 EXPORT_SYMBOL(netpoll_poll);