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/smp_lock.h>
  13 #include <linux/netdevice.h>
  14 #include <linux/etherdevice.h>
  15 #include <linux/string.h>
  16 #include <linux/if_arp.h>
  17 #include <linux/inetdevice.h>
  18 #include <linux/inet.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/netpoll.h>
  21 #include <linux/sched.h>
  22 #include <linux/delay.h>
  23 #include <linux/rcupdate.h>
  24 #include <linux/workqueue.h>
  25 #include <net/tcp.h>
  26 #include <net/udp.h>
  27 #include <asm/unaligned.h>
  28
  29 /*
  30  * We maintain a small pool of fully-sized skbs, to make sure the
  31  * message gets out even in extreme OOM situations.
  32  */
  33
  34 #define MAX_UDP_CHUNK 1460
  35 #define MAX_SKBS 32
  36 #define MAX_QUEUE_DEPTH (MAX_SKBS / 2)
  37 #define MAX_RETRIES 20000
  38
  39 static struct sk_buff_head skb_pool;
  40
  41 static atomic_t trapped;
  42
  43 #define NETPOLL_RX_ENABLED  1
  44 #define NETPOLL_RX_DROP     2
  45
  46 #define MAX_SKB_SIZE \
  47                 (MAX_UDP_CHUNK + sizeof(struct udphdr) + \
  48                                 sizeof(struct iphdr) + sizeof(struct ethhdr))
  49
  50 static void zap_completion_queue(void);
  51 static void arp_reply(struct sk_buff *skb);
  52
  53 static void queue_process(void *p)
  54 {
  55         struct netpoll_info *npinfo = p;
  56         struct sk_buff *skb;
  57
  58         while ((skb = skb_dequeue(&npinfo->txq))) {
  59                 struct net_device *dev = skb->dev;
  60
  61                 if (!netif_device_present(dev) || !netif_running(dev)) {
  62                         __kfree_skb(skb);
  63                         continue;
  64                 }
  65
  66                 netif_tx_lock_bh(dev);
  67                 if (netif_queue_stopped(dev) ||
  68                     dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
  69                         skb_queue_head(&npinfo->txq, skb);
  70                         netif_tx_unlock_bh(dev);
  71
  72                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
  73                         return;
  74                 }
  75                 netif_tx_unlock_bh(dev);
  76         }
  77 }
  78
  79 void netpoll_queue(struct sk_buff *skb)
  80 {
  81         struct net_device *dev = skb->dev;
  82         struct netpoll_info *npinfo = dev->npinfo;
  83
  84         if (!npinfo)
  85                 kfree_skb(skb);
  86         else {
  87                 skb_queue_tail(&npinfo->txq, skb);
  88                 schedule_work(&npinfo->tx_work);
  89         }
  90 }
  91
  92 static int checksum_udp(struct sk_buff *skb, struct udphdr *uh,
  93                              unsigned short ulen, u32 saddr, u32 daddr)
  94 {
  95         unsigned int psum;
  96
  97         if (uh->check == 0 || skb->ip_summed == CHECKSUM_UNNECESSARY)
  98                 return 0;
  99
 100         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
 101
 102         if (skb->ip_summed == CHECKSUM_COMPLETE &&
 103             !(u16)csum_fold(csum_add(psum, skb->csum)))
 104                 return 0;
 105
 106         skb->csum = psum;
 107
 108         return __skb_checksum_complete(skb);
 109 }
 110
 111 /*
 112  * Check whether delayed processing was scheduled for our NIC. If so,
 113  * we attempt to grab the poll lock and use ->poll() to pump the card.
 114  * If this fails, either we've recursed in ->poll() or it's already
 115  * running on another CPU.
 116  *
 117  * Note: we don't mask interrupts with this lock because we're using
 118  * trylock here and interrupts are already disabled in the softirq
 119  * case. Further, we test the poll_owner to avoid recursion on UP
 120  * systems where the lock doesn't exist.
 121  *
 122  * In cases where there is bi-directional communications, reading only
 123  * one message at a time can lead to packets being dropped by the
 124  * network adapter, forcing superfluous retries and possibly timeouts.
 125  * Thus, we set our budget to greater than 1.
 126  */
 127 static void poll_napi(struct netpoll *np)
 128 {
 129         struct netpoll_info *npinfo = np->dev->npinfo;
 130         int budget = 16;
 131
 132         if (test_bit(__LINK_STATE_RX_SCHED, &np->dev->state) &&
 133             npinfo->poll_owner != smp_processor_id() &&
 134             spin_trylock(&npinfo->poll_lock)) {
 135                 npinfo->rx_flags |= NETPOLL_RX_DROP;
 136                 atomic_inc(&trapped);
 137
 138                 np->dev->poll(np->dev, &budget);
 139
 140                 atomic_dec(&trapped);
 141                 npinfo->rx_flags &= ~NETPOLL_RX_DROP;
 142                 spin_unlock(&npinfo->poll_lock);
 143         }
 144 }
 145
 146 static void service_arp_queue(struct netpoll_info *npi)
 147 {
 148         struct sk_buff *skb;
 149
 150         if (unlikely(!npi))
 151                 return;
 152
 153         skb = skb_dequeue(&npi->arp_tx);
 154
 155         while (skb != NULL) {
 156                 arp_reply(skb);
 157                 skb = skb_dequeue(&npi->arp_tx);
 158         }
 159         return;
 160 }
 161
 162 void netpoll_poll(struct netpoll *np)
 163 {
 164         if(!np->dev || !netif_running(np->dev) || !np->dev->poll_controller)
 165                 return;
 166
 167         /* Process pending work on NIC */
 168         np->dev->poll_controller(np->dev);
 169         if (np->dev->poll)
 170                 poll_napi(np);
 171
 172         service_arp_queue(np->dev->npinfo);
 173
 174         zap_completion_queue();
 175 }
 176
 177 static void refill_skbs(void)
 178 {
 179         struct sk_buff *skb;
 180         unsigned long flags;
 181
 182         spin_lock_irqsave(&skb_pool.lock, flags);
 183         while (skb_pool.qlen < MAX_SKBS) {
 184                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
 185                 if (!skb)
 186                         break;
 187
 188                 __skb_queue_tail(&skb_pool, skb);
 189         }
 190         spin_unlock_irqrestore(&skb_pool.lock, flags);
 191 }
 192
 193 static void zap_completion_queue(void)
 194 {
 195         unsigned long flags;
 196         struct softnet_data *sd = &get_cpu_var(softnet_data);
 197
 198         if (sd->completion_queue) {
 199                 struct sk_buff *clist;
 200
 201                 local_irq_save(flags);
 202                 clist = sd->completion_queue;
 203                 sd->completion_queue = NULL;
 204                 local_irq_restore(flags);
 205
 206                 while (clist != NULL) {
 207                         struct sk_buff *skb = clist;
 208                         clist = clist->next;
 209                         if(skb->destructor)
 210                                 dev_kfree_skb_any(skb); /* put this one back */
 211                         else
 212                                 __kfree_skb(skb);
 213                 }
 214         }
 215
 216         put_cpu_var(softnet_data);
 217 }
 218
 219 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
 220 {
 221         int count = 0;
 222         struct sk_buff *skb;
 223
 224         zap_completion_queue();
 225         refill_skbs();
 226 repeat:
 227
 228         skb = alloc_skb(len, GFP_ATOMIC);
 229         if (!skb)
 230                 skb = skb_dequeue(&skb_pool);
 231
 232         if(!skb) {
 233                 if (++count < 10) {
 234                         netpoll_poll(np);
 235                         goto repeat;
 236                 }
 237                 return NULL;
 238         }
 239
 240         atomic_set(&skb->users, 1);
 241         skb_reserve(skb, reserve);
 242         return skb;
 243 }
 244
 245 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 246 {
 247         int status;
 248         struct netpoll_info *npinfo;
 249
 250         if (!np || !np->dev || !netif_running(np->dev)) {
 251                 __kfree_skb(skb);
 252                 return;
 253         }
 254
 255         npinfo = np->dev->npinfo;
 256
 257         /* avoid recursion */
 258         if (npinfo->poll_owner == smp_processor_id() ||
 259             np->dev->xmit_lock_owner == smp_processor_id()) {
 260                 if (np->drop)
 261                         np->drop(skb);
 262                 else
 263                         __kfree_skb(skb);
 264                 return;
 265         }
 266
 267         do {
 268                 npinfo->tries--;
 269                 netif_tx_lock(np->dev);
 270
 271                 /*
 272                  * network drivers do not expect to be called if the queue is
 273                  * stopped.
 274                  */
 275                 status = NETDEV_TX_BUSY;
 276                 if (!netif_queue_stopped(np->dev))
 277                         status = np->dev->hard_start_xmit(skb, np->dev);
 278
 279                 netif_tx_unlock(np->dev);
 280
 281                 /* success */
 282                 if(!status) {
 283                         npinfo->tries = MAX_RETRIES; /* reset */
 284                         return;
 285                 }
 286
 287                 /* transmit busy */
 288                 netpoll_poll(np);
 289                 udelay(50);
 290         } while (npinfo->tries > 0);
 291 }
 292
 293 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 294 {
 295         int total_len, eth_len, ip_len, udp_len;
 296         struct sk_buff *skb;
 297         struct udphdr *udph;
 298         struct iphdr *iph;
 299         struct ethhdr *eth;
 300
 301         udp_len = len + sizeof(*udph);
 302         ip_len = eth_len = udp_len + sizeof(*iph);
 303         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
 304
 305         skb = find_skb(np, total_len, total_len - len);
 306         if (!skb)
 307                 return;
 308
 309         memcpy(skb->data, msg, len);
 310         skb->len += len;
 311
 312         skb->h.uh = udph = (struct udphdr *) skb_push(skb, sizeof(*udph));
 313         udph->source = htons(np->local_port);
 314         udph->dest = htons(np->remote_port);
 315         udph->len = htons(udp_len);
 316         udph->check = 0;
 317         udph->check = csum_tcpudp_magic(htonl(np->local_ip),
 318                                         htonl(np->remote_ip),
 319                                         udp_len, IPPROTO_UDP,
 320                                         csum_partial((unsigned char *)udph, udp_len, 0));
 321         if (udph->check == 0)
 322                 udph->check = -1;
 323
 324         skb->nh.iph = iph = (struct iphdr *)skb_push(skb, sizeof(*iph));
 325
 326         /* iph->version = 4; iph->ihl = 5; */
 327         put_unaligned(0x45, (unsigned char *)iph);
 328         iph->tos      = 0;
 329         put_unaligned(htons(ip_len), &(iph->tot_len));
 330         iph->id       = 0;
 331         iph->frag_off = 0;
 332         iph->ttl      = 64;
 333         iph->protocol = IPPROTO_UDP;
 334         iph->check    = 0;
 335         put_unaligned(htonl(np->local_ip), &(iph->saddr));
 336         put_unaligned(htonl(np->remote_ip), &(iph->daddr));
 337         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 338
 339         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 340         skb->mac.raw = skb->data;
 341         skb->protocol = eth->h_proto = htons(ETH_P_IP);
 342         memcpy(eth->h_source, np->local_mac, 6);
 343         memcpy(eth->h_dest, np->remote_mac, 6);
 344
 345         skb->dev = np->dev;
 346
 347         netpoll_send_skb(np, skb);
 348 }
 349
 350 static void arp_reply(struct sk_buff *skb)
 351 {
 352         struct netpoll_info *npinfo = skb->dev->npinfo;
 353         struct arphdr *arp;
 354         unsigned char *arp_ptr;
 355         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
 356         u32 sip, tip;
 357         struct sk_buff *send_skb;
 358         struct netpoll *np = NULL;
 359
 360         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
 361                 np = npinfo->rx_np;
 362         if (!np)
 363                 return;
 364
 365         /* No arp on this interface */
 366         if (skb->dev->flags & IFF_NOARP)
 367                 return;
 368
 369         if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
 370                                  (2 * skb->dev->addr_len) +
 371                                  (2 * sizeof(u32)))))
 372                 return;
 373
 374         skb->h.raw = skb->nh.raw = skb->data;
 375         arp = skb->nh.arph;
 376
 377         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 378              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 379             arp->ar_pro != htons(ETH_P_IP) ||
 380             arp->ar_op != htons(ARPOP_REQUEST))
 381                 return;
 382
 383         arp_ptr = (unsigned char *)(arp+1) + skb->dev->addr_len;
 384         memcpy(&sip, arp_ptr, 4);
 385         arp_ptr += 4 + skb->dev->addr_len;
 386         memcpy(&tip, arp_ptr, 4);
 387
 388         /* Should we ignore arp? */
 389         if (tip != htonl(np->local_ip) || LOOPBACK(tip) || MULTICAST(tip))
 390                 return;
 391
 392         size = sizeof(struct arphdr) + 2 * (skb->dev->addr_len + 4);
 393         send_skb = find_skb(np, size + LL_RESERVED_SPACE(np->dev),
 394                             LL_RESERVED_SPACE(np->dev));
 395
 396         if (!send_skb)
 397                 return;
 398
 399         send_skb->nh.raw = send_skb->data;
 400         arp = (struct arphdr *) skb_put(send_skb, size);
 401         send_skb->dev = skb->dev;
 402         send_skb->protocol = htons(ETH_P_ARP);
 403
 404         /* Fill the device header for the ARP frame */
 405
 406         if (np->dev->hard_header &&
 407             np->dev->hard_header(send_skb, skb->dev, ptype,
 408                                        np->remote_mac, np->local_mac,
 409                                        send_skb->len) < 0) {
 410                 kfree_skb(send_skb);
 411                 return;
 412         }
 413
 414         /*
 415          * Fill out the arp protocol part.
 416          *
 417          * we only support ethernet device type,
 418          * which (according to RFC 1390) should always equal 1 (Ethernet).
 419          */
 420
 421         arp->ar_hrd = htons(np->dev->type);
 422         arp->ar_pro = htons(ETH_P_IP);
 423         arp->ar_hln = np->dev->addr_len;
 424         arp->ar_pln = 4;
 425         arp->ar_op = htons(type);
 426
 427         arp_ptr=(unsigned char *)(arp + 1);
 428         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
 429         arp_ptr += np->dev->addr_len;
 430         memcpy(arp_ptr, &tip, 4);
 431         arp_ptr += 4;
 432         memcpy(arp_ptr, np->remote_mac, np->dev->addr_len);
 433         arp_ptr += np->dev->addr_len;
 434         memcpy(arp_ptr, &sip, 4);
 435
 436         netpoll_send_skb(np, send_skb);
 437 }
 438
 439 int __netpoll_rx(struct sk_buff *skb)
 440 {
 441         int proto, len, ulen;
 442         struct iphdr *iph;
 443         struct udphdr *uh;
 444         struct netpoll_info *npi = skb->dev->npinfo;
 445         struct netpoll *np = npi->rx_np;
 446
 447
 448         if (!np)
 449                 goto out;
 450         if (skb->dev->type != ARPHRD_ETHER)
 451                 goto out;
 452
 453         /* check if netpoll clients need ARP */
 454         if (skb->protocol == __constant_htons(ETH_P_ARP) &&
 455             atomic_read(&trapped)) {
 456                 skb_queue_tail(&npi->arp_tx, skb);
 457                 return 1;
 458         }
 459
 460         proto = ntohs(eth_hdr(skb)->h_proto);
 461         if (proto != ETH_P_IP)
 462                 goto out;
 463         if (skb->pkt_type == PACKET_OTHERHOST)
 464                 goto out;
 465         if (skb_shared(skb))
 466                 goto out;
 467
 468         iph = (struct iphdr *)skb->data;
 469         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 470                 goto out;
 471         if (iph->ihl < 5 || iph->version != 4)
 472                 goto out;
 473         if (!pskb_may_pull(skb, iph->ihl*4))
 474                 goto out;
 475         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
 476                 goto out;
 477
 478         len = ntohs(iph->tot_len);
 479         if (skb->len < len || len < iph->ihl*4)
 480                 goto out;
 481
 482         if (iph->protocol != IPPROTO_UDP)
 483                 goto out;
 484
 485         len -= iph->ihl*4;
 486         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
 487         ulen = ntohs(uh->len);
 488
 489         if (ulen != len)
 490                 goto out;
 491         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
 492                 goto out;
 493         if (np->local_ip && np->local_ip != ntohl(iph->daddr))
 494                 goto out;
 495         if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
 496                 goto out;
 497         if (np->local_port && np->local_port != ntohs(uh->dest))
 498                 goto out;
 499
 500         np->rx_hook(np, ntohs(uh->source),
 501                     (char *)(uh+1),
 502                     ulen - sizeof(struct udphdr));
 503
 504         kfree_skb(skb);
 505         return 1;
 506
 507 out:
 508         if (atomic_read(&trapped)) {
 509                 kfree_skb(skb);
 510                 return 1;
 511         }
 512
 513         return 0;
 514 }
 515
 516 int netpoll_parse_options(struct netpoll *np, char *opt)
 517 {
 518         char *cur=opt, *delim;
 519
 520         if(*cur != '@') {
 521                 if ((delim = strchr(cur, '@')) == NULL)
 522                         goto parse_failed;
 523                 *delim=0;
 524                 np->local_port=simple_strtol(cur, NULL, 10);
 525                 cur=delim;
 526         }
 527         cur++;
 528         printk(KERN_INFO "%s: local port %d\n", np->name, np->local_port);
 529
 530         if(*cur != '/') {
 531                 if ((delim = strchr(cur, '/')) == NULL)
 532                         goto parse_failed;
 533                 *delim=0;
 534                 np->local_ip=ntohl(in_aton(cur));
 535                 cur=delim;
 536
 537                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 538                        np->name, HIPQUAD(np->local_ip));
 539         }
 540         cur++;
 541
 542         if ( *cur != ',') {
 543                 /* parse out dev name */
 544                 if ((delim = strchr(cur, ',')) == NULL)
 545                         goto parse_failed;
 546                 *delim=0;
 547                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 548                 cur=delim;
 549         }
 550         cur++;
 551
 552         printk(KERN_INFO "%s: interface %s\n", np->name, np->dev_name);
 553
 554         if ( *cur != '@' ) {
 555                 /* dst port */
 556                 if ((delim = strchr(cur, '@')) == NULL)
 557                         goto parse_failed;
 558                 *delim=0;
 559                 np->remote_port=simple_strtol(cur, NULL, 10);
 560                 cur=delim;
 561         }
 562         cur++;
 563         printk(KERN_INFO "%s: remote port %d\n", np->name, np->remote_port);
 564
 565         /* dst ip */
 566         if ((delim = strchr(cur, '/')) == NULL)
 567                 goto parse_failed;
 568         *delim=0;
 569         np->remote_ip=ntohl(in_aton(cur));
 570         cur=delim+1;
 571
 572         printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
 573                        np->name, HIPQUAD(np->remote_ip));
 574
 575         if( *cur != 0 )
 576         {
 577                 /* MAC address */
 578                 if ((delim = strchr(cur, ':')) == NULL)
 579                         goto parse_failed;
 580                 *delim=0;
 581                 np->remote_mac[0]=simple_strtol(cur, NULL, 16);
 582                 cur=delim+1;
 583                 if ((delim = strchr(cur, ':')) == NULL)
 584                         goto parse_failed;
 585                 *delim=0;
 586                 np->remote_mac[1]=simple_strtol(cur, NULL, 16);
 587                 cur=delim+1;
 588                 if ((delim = strchr(cur, ':')) == NULL)
 589                         goto parse_failed;
 590                 *delim=0;
 591                 np->remote_mac[2]=simple_strtol(cur, NULL, 16);
 592                 cur=delim+1;
 593                 if ((delim = strchr(cur, ':')) == NULL)
 594                         goto parse_failed;
 595                 *delim=0;
 596                 np->remote_mac[3]=simple_strtol(cur, NULL, 16);
 597                 cur=delim+1;
 598                 if ((delim = strchr(cur, ':')) == NULL)
 599                         goto parse_failed;
 600                 *delim=0;
 601                 np->remote_mac[4]=simple_strtol(cur, NULL, 16);
 602                 cur=delim+1;
 603                 np->remote_mac[5]=simple_strtol(cur, NULL, 16);
 604         }
 605
 606         printk(KERN_INFO "%s: remote ethernet address "
 607                "%02x:%02x:%02x:%02x:%02x:%02x\n",
 608                np->name,
 609                np->remote_mac[0],
 610                np->remote_mac[1],
 611                np->remote_mac[2],
 612                np->remote_mac[3],
 613                np->remote_mac[4],
 614                np->remote_mac[5]);
 615
 616         return 0;
 617
 618  parse_failed:
 619         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
 620                np->name, cur);
 621         return -1;
 622 }
 623
 624 int netpoll_setup(struct netpoll *np)
 625 {
 626         struct net_device *ndev = NULL;
 627         struct in_device *in_dev;
 628         struct netpoll_info *npinfo;
 629         unsigned long flags;
 630         int err;
 631
 632         if (np->dev_name)
 633                 ndev = dev_get_by_name(np->dev_name);
 634         if (!ndev) {
 635                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
 636                        np->name, np->dev_name);
 637                 return -ENODEV;
 638         }
 639
 640         np->dev = ndev;
 641         if (!ndev->npinfo) {
 642                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
 643                 if (!npinfo) {
 644                         err = -ENOMEM;
 645                         goto release;
 646                 }
 647
 648                 npinfo->rx_flags = 0;
 649                 npinfo->rx_np = NULL;
 650                 spin_lock_init(&npinfo->poll_lock);
 651                 npinfo->poll_owner = -1;
 652                 npinfo->tries = MAX_RETRIES;
 653                 spin_lock_init(&npinfo->rx_lock);
 654                 skb_queue_head_init(&npinfo->arp_tx);
 655                 skb_queue_head_init(&npinfo->txq);
 656                 INIT_WORK(&npinfo->tx_work, queue_process, npinfo);
 657
 658                 atomic_set(&npinfo->refcnt, 1);
 659         } else {
 660                 npinfo = ndev->npinfo;
 661                 atomic_inc(&npinfo->refcnt);
 662         }
 663
 664         if (!ndev->poll_controller) {
 665                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
 666                        np->name, np->dev_name);
 667                 err = -ENOTSUPP;
 668                 goto release;
 669         }
 670
 671         if (!netif_running(ndev)) {
 672                 unsigned long atmost, atleast;
 673
 674                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
 675                        np->name, np->dev_name);
 676
 677                 rtnl_lock();
 678                 err = dev_open(ndev);
 679                 rtnl_unlock();
 680
 681                 if (err) {
 682                         printk(KERN_ERR "%s: failed to open %s\n",
 683                                np->name, ndev->name);
 684                         goto release;
 685                 }
 686
 687                 atleast = jiffies + HZ/10;
 688                 atmost = jiffies + 4*HZ;
 689                 while (!netif_carrier_ok(ndev)) {
 690                         if (time_after(jiffies, atmost)) {
 691                                 printk(KERN_NOTICE
 692                                        "%s: timeout waiting for carrier\n",
 693                                        np->name);
 694                                 break;
 695                         }
 696                         cond_resched();
 697                 }
 698
 699                 /* If carrier appears to come up instantly, we don't
 700                  * trust it and pause so that we don't pump all our
 701                  * queued console messages into the bitbucket.
 702                  */
 703
 704                 if (time_before(jiffies, atleast)) {
 705                         printk(KERN_NOTICE "%s: carrier detect appears"
 706                                " untrustworthy, waiting 4 seconds\n",
 707                                np->name);
 708                         msleep(4000);
 709                 }
 710         }
 711
 712         if (is_zero_ether_addr(np->local_mac) && ndev->dev_addr)
 713                 memcpy(np->local_mac, ndev->dev_addr, 6);
 714
 715         if (!np->local_ip) {
 716                 rcu_read_lock();
 717                 in_dev = __in_dev_get_rcu(ndev);
 718
 719                 if (!in_dev || !in_dev->ifa_list) {
 720                         rcu_read_unlock();
 721                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
 722                                np->name, np->dev_name);
 723                         err = -EDESTADDRREQ;
 724                         goto release;
 725                 }
 726
 727                 np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
 728                 rcu_read_unlock();
 729                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 730                        np->name, HIPQUAD(np->local_ip));
 731         }
 732
 733         if (np->rx_hook) {
 734                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 735                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
 736                 npinfo->rx_np = np;
 737                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 738         }
 739
 740         /* fill up the skb queue */
 741         refill_skbs();
 742
 743         /* last thing to do is link it to the net device structure */
 744         ndev->npinfo = npinfo;
 745
 746         /* avoid racing with NAPI reading npinfo */
 747         synchronize_rcu();
 748
 749         return 0;
 750
 751  release:
 752         if (!ndev->npinfo)
 753                 kfree(npinfo);
 754         np->dev = NULL;
 755         dev_put(ndev);
 756         return err;
 757 }
 758
 759 static int __init netpoll_init(void) {
 760         skb_queue_head_init(&skb_pool);
 761         return 0;
 762 }
 763 core_initcall(netpoll_init);
 764
 765 void netpoll_cleanup(struct netpoll *np)
 766 {
 767         struct netpoll_info *npinfo;
 768         unsigned long flags;
 769
 770         if (np->dev) {
 771                 npinfo = np->dev->npinfo;
 772                 if (npinfo) {
 773                         if (npinfo->rx_np == np) {
 774                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 775                                 npinfo->rx_np = NULL;
 776                                 npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
 777                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 778                         }
 779
 780                         np->dev->npinfo = NULL;
 781                         if (atomic_dec_and_test(&npinfo->refcnt)) {
 782                                 skb_queue_purge(&npinfo->arp_tx);
 783                                 skb_queue_purge(&npinfo->txq);
 784                                 cancel_rearming_delayed_work(&npinfo->tx_work);
 785                                 flush_scheduled_work();
 786
 787                                 kfree(npinfo);
 788                         }
 789                 }
 790
 791                 dev_put(np->dev);
 792         }
 793
 794         np->dev = NULL;
 795 }
 796
 797 int netpoll_trap(void)
 798 {
 799         return atomic_read(&trapped);
 800 }
 801
 802 void netpoll_set_trap(int trap)
 803 {
 804         if (trap)
 805                 atomic_inc(&trapped);
 806         else
 807                 atomic_dec(&trapped);
 808 }
 809
 810 EXPORT_SYMBOL(netpoll_set_trap);
 811 EXPORT_SYMBOL(netpoll_trap);
 812 EXPORT_SYMBOL(netpoll_parse_options);
 813 EXPORT_SYMBOL(netpoll_setup);
 814 EXPORT_SYMBOL(netpoll_cleanup);
 815 EXPORT_SYMBOL(netpoll_send_udp);
 816 EXPORT_SYMBOL(netpoll_poll);
 817 EXPORT_SYMBOL(netpoll_queue);