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
  38 static struct sk_buff_head skb_pool;
  39
  40 static atomic_t trapped;
  41
  42 #define USEC_PER_POLL   50
  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(struct work_struct *work)
  54 {
  55         struct netpoll_info *npinfo =
  56                 container_of(work, struct netpoll_info, tx_work.work);
  57         struct sk_buff *skb;
  58
  59         while ((skb = skb_dequeue(&npinfo->txq))) {
  60                 struct net_device *dev = skb->dev;
  61
  62                 if (!netif_device_present(dev) || !netif_running(dev)) {
  63                         __kfree_skb(skb);
  64                         continue;
  65                 }
  66
  67                 netif_tx_lock_bh(dev);
  68                 if (netif_queue_stopped(dev) ||
  69                     dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
  70                         skb_queue_head(&npinfo->txq, skb);
  71                         netif_tx_unlock_bh(dev);
  72
  73                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
  74                         return;
  75                 }
  76         }
  77 }
  78
  79 static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
  80                             unsigned short ulen, __be32 saddr, __be32 daddr)
  81 {
  82         __wsum psum;
  83
  84         if (uh->check == 0 || skb->ip_summed == CHECKSUM_UNNECESSARY)
  85                 return 0;
  86
  87         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
  88
  89         if (skb->ip_summed == CHECKSUM_COMPLETE &&
  90             !csum_fold(csum_add(psum, skb->csum)))
  91                 return 0;
  92
  93         skb->csum = psum;
  94
  95         return __skb_checksum_complete(skb);
  96 }
  97
  98 /*
  99  * Check whether delayed processing was scheduled for our NIC. If so,
 100  * we attempt to grab the poll lock and use ->poll() to pump the card.
 101  * If this fails, either we've recursed in ->poll() or it's already
 102  * running on another CPU.
 103  *
 104  * Note: we don't mask interrupts with this lock because we're using
 105  * trylock here and interrupts are already disabled in the softirq
 106  * case. Further, we test the poll_owner to avoid recursion on UP
 107  * systems where the lock doesn't exist.
 108  *
 109  * In cases where there is bi-directional communications, reading only
 110  * one message at a time can lead to packets being dropped by the
 111  * network adapter, forcing superfluous retries and possibly timeouts.
 112  * Thus, we set our budget to greater than 1.
 113  */
 114 static void poll_napi(struct netpoll *np)
 115 {
 116         struct netpoll_info *npinfo = np->dev->npinfo;
 117         int budget = 16;
 118
 119         if (test_bit(__LINK_STATE_RX_SCHED, &np->dev->state) &&
 120             npinfo->poll_owner != smp_processor_id() &&
 121             spin_trylock(&npinfo->poll_lock)) {
 122                 npinfo->rx_flags |= NETPOLL_RX_DROP;
 123                 atomic_inc(&trapped);
 124
 125                 np->dev->poll(np->dev, &budget);
 126
 127                 atomic_dec(&trapped);
 128                 npinfo->rx_flags &= ~NETPOLL_RX_DROP;
 129                 spin_unlock(&npinfo->poll_lock);
 130         }
 131 }
 132
 133 static void service_arp_queue(struct netpoll_info *npi)
 134 {
 135         struct sk_buff *skb;
 136
 137         if (unlikely(!npi))
 138                 return;
 139
 140         skb = skb_dequeue(&npi->arp_tx);
 141
 142         while (skb != NULL) {
 143                 arp_reply(skb);
 144                 skb = skb_dequeue(&npi->arp_tx);
 145         }
 146 }
 147
 148 void netpoll_poll(struct netpoll *np)
 149 {
 150         if (!np->dev || !netif_running(np->dev) || !np->dev->poll_controller)
 151                 return;
 152
 153         /* Process pending work on NIC */
 154         np->dev->poll_controller(np->dev);
 155         if (np->dev->poll)
 156                 poll_napi(np);
 157
 158         service_arp_queue(np->dev->npinfo);
 159
 160         zap_completion_queue();
 161 }
 162
 163 static void refill_skbs(void)
 164 {
 165         struct sk_buff *skb;
 166         unsigned long flags;
 167
 168         spin_lock_irqsave(&skb_pool.lock, flags);
 169         while (skb_pool.qlen < MAX_SKBS) {
 170                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
 171                 if (!skb)
 172                         break;
 173
 174                 __skb_queue_tail(&skb_pool, skb);
 175         }
 176         spin_unlock_irqrestore(&skb_pool.lock, flags);
 177 }
 178
 179 static void zap_completion_queue(void)
 180 {
 181         unsigned long flags;
 182         struct softnet_data *sd = &get_cpu_var(softnet_data);
 183
 184         if (sd->completion_queue) {
 185                 struct sk_buff *clist;
 186
 187                 local_irq_save(flags);
 188                 clist = sd->completion_queue;
 189                 sd->completion_queue = NULL;
 190                 local_irq_restore(flags);
 191
 192                 while (clist != NULL) {
 193                         struct sk_buff *skb = clist;
 194                         clist = clist->next;
 195                         if (skb->destructor)
 196                                 dev_kfree_skb_any(skb); /* put this one back */
 197                         else
 198                                 __kfree_skb(skb);
 199                 }
 200         }
 201
 202         put_cpu_var(softnet_data);
 203 }
 204
 205 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
 206 {
 207         int count = 0;
 208         struct sk_buff *skb;
 209
 210         zap_completion_queue();
 211         refill_skbs();
 212 repeat:
 213
 214         skb = alloc_skb(len, GFP_ATOMIC);
 215         if (!skb)
 216                 skb = skb_dequeue(&skb_pool);
 217
 218         if (!skb) {
 219                 if (++count < 10) {
 220                         netpoll_poll(np);
 221                         goto repeat;
 222                 }
 223                 return NULL;
 224         }
 225
 226         atomic_set(&skb->users, 1);
 227         skb_reserve(skb, reserve);
 228         return skb;
 229 }
 230
 231 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 232 {
 233         int status = NETDEV_TX_BUSY;
 234         unsigned long tries;
 235         struct net_device *dev = np->dev;
 236         struct netpoll_info *npinfo = np->dev->npinfo;
 237
 238         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
 239                 __kfree_skb(skb);
 240                 return;
 241         }
 242
 243         /* don't get messages out of order, and no recursion */
 244         if (skb_queue_len(&npinfo->txq) == 0 &&
 245                     npinfo->poll_owner != smp_processor_id()) {
 246                 unsigned long flags;
 247
 248                 local_irq_save(flags);
 249                 if (netif_tx_trylock(dev)) {
 250                         /* try until next clock tick */
 251                         for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
 252                                         tries > 0; --tries) {
 253                                 if (!netif_queue_stopped(dev))
 254                                         status = dev->hard_start_xmit(skb, dev);
 255
 256                                 if (status == NETDEV_TX_OK)
 257                                         break;
 258
 259                                 /* tickle device maybe there is some cleanup */
 260                                 netpoll_poll(np);
 261
 262                                 udelay(USEC_PER_POLL);
 263                         }
 264                         netif_tx_unlock(dev);
 265                 }
 266                 local_irq_restore(flags);
 267         }
 268
 269         if (status != NETDEV_TX_OK) {
 270                 skb_queue_tail(&npinfo->txq, skb);
 271                 schedule_delayed_work(&npinfo->tx_work,0);
 272         }
 273 }
 274
 275 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 276 {
 277         int total_len, eth_len, ip_len, udp_len;
 278         struct sk_buff *skb;
 279         struct udphdr *udph;
 280         struct iphdr *iph;
 281         struct ethhdr *eth;
 282
 283         udp_len = len + sizeof(*udph);
 284         ip_len = eth_len = udp_len + sizeof(*iph);
 285         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
 286
 287         skb = find_skb(np, total_len, total_len - len);
 288         if (!skb)
 289                 return;
 290
 291         memcpy(skb->data, msg, len);
 292         skb->len += len;
 293
 294         skb->h.uh = udph = (struct udphdr *) skb_push(skb, sizeof(*udph));
 295         udph->source = htons(np->local_port);
 296         udph->dest = htons(np->remote_port);
 297         udph->len = htons(udp_len);
 298         udph->check = 0;
 299         udph->check = csum_tcpudp_magic(htonl(np->local_ip),
 300                                         htonl(np->remote_ip),
 301                                         udp_len, IPPROTO_UDP,
 302                                         csum_partial((unsigned char *)udph, udp_len, 0));
 303         if (udph->check == 0)
 304                 udph->check = CSUM_MANGLED_0;
 305
 306         skb->nh.iph = iph = (struct iphdr *)skb_push(skb, sizeof(*iph));
 307
 308         /* iph->version = 4; iph->ihl = 5; */
 309         put_unaligned(0x45, (unsigned char *)iph);
 310         iph->tos      = 0;
 311         put_unaligned(htons(ip_len), &(iph->tot_len));
 312         iph->id       = 0;
 313         iph->frag_off = 0;
 314         iph->ttl      = 64;
 315         iph->protocol = IPPROTO_UDP;
 316         iph->check    = 0;
 317         put_unaligned(htonl(np->local_ip), &(iph->saddr));
 318         put_unaligned(htonl(np->remote_ip), &(iph->daddr));
 319         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 320
 321         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 322         skb->mac.raw = skb->data;
 323         skb->protocol = eth->h_proto = htons(ETH_P_IP);
 324         memcpy(eth->h_source, np->local_mac, 6);
 325         memcpy(eth->h_dest, np->remote_mac, 6);
 326
 327         skb->dev = np->dev;
 328
 329         netpoll_send_skb(np, skb);
 330 }
 331
 332 static void arp_reply(struct sk_buff *skb)
 333 {
 334         struct netpoll_info *npinfo = skb->dev->npinfo;
 335         struct arphdr *arp;
 336         unsigned char *arp_ptr;
 337         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
 338         __be32 sip, tip;
 339         unsigned char *sha;
 340         struct sk_buff *send_skb;
 341         struct netpoll *np = NULL;
 342
 343         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
 344                 np = npinfo->rx_np;
 345         if (!np)
 346                 return;
 347
 348         /* No arp on this interface */
 349         if (skb->dev->flags & IFF_NOARP)
 350                 return;
 351
 352         if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
 353                                  (2 * skb->dev->addr_len) +
 354                                  (2 * sizeof(u32)))))
 355                 return;
 356
 357         skb->h.raw = skb->nh.raw = skb->data;
 358         arp = skb->nh.arph;
 359
 360         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 361              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 362             arp->ar_pro != htons(ETH_P_IP) ||
 363             arp->ar_op != htons(ARPOP_REQUEST))
 364                 return;
 365
 366         arp_ptr = (unsigned char *)(arp+1);
 367         /* save the location of the src hw addr */
 368         sha = arp_ptr;
 369         arp_ptr += skb->dev->addr_len;
 370         memcpy(&sip, arp_ptr, 4);
 371         arp_ptr += 4;
 372         /* if we actually cared about dst hw addr, it would get copied here */
 373         arp_ptr += skb->dev->addr_len;
 374         memcpy(&tip, arp_ptr, 4);
 375
 376         /* Should we ignore arp? */
 377         if (tip != htonl(np->local_ip) || LOOPBACK(tip) || MULTICAST(tip))
 378                 return;
 379
 380         size = sizeof(struct arphdr) + 2 * (skb->dev->addr_len + 4);
 381         send_skb = find_skb(np, size + LL_RESERVED_SPACE(np->dev),
 382                             LL_RESERVED_SPACE(np->dev));
 383
 384         if (!send_skb)
 385                 return;
 386
 387         send_skb->nh.raw = send_skb->data;
 388         arp = (struct arphdr *) skb_put(send_skb, size);
 389         send_skb->dev = skb->dev;
 390         send_skb->protocol = htons(ETH_P_ARP);
 391
 392         /* Fill the device header for the ARP frame */
 393
 394         if (np->dev->hard_header &&
 395             np->dev->hard_header(send_skb, skb->dev, ptype,
 396                                  sha, np->local_mac,
 397                                  send_skb->len) < 0) {
 398                 kfree_skb(send_skb);
 399                 return;
 400         }
 401
 402         /*
 403          * Fill out the arp protocol part.
 404          *
 405          * we only support ethernet device type,
 406          * which (according to RFC 1390) should always equal 1 (Ethernet).
 407          */
 408
 409         arp->ar_hrd = htons(np->dev->type);
 410         arp->ar_pro = htons(ETH_P_IP);
 411         arp->ar_hln = np->dev->addr_len;
 412         arp->ar_pln = 4;
 413         arp->ar_op = htons(type);
 414
 415         arp_ptr=(unsigned char *)(arp + 1);
 416         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
 417         arp_ptr += np->dev->addr_len;
 418         memcpy(arp_ptr, &tip, 4);
 419         arp_ptr += 4;
 420         memcpy(arp_ptr, sha, np->dev->addr_len);
 421         arp_ptr += np->dev->addr_len;
 422         memcpy(arp_ptr, &sip, 4);
 423
 424         netpoll_send_skb(np, send_skb);
 425 }
 426
 427 int __netpoll_rx(struct sk_buff *skb)
 428 {
 429         int proto, len, ulen;
 430         struct iphdr *iph;
 431         struct udphdr *uh;
 432         struct netpoll_info *npi = skb->dev->npinfo;
 433         struct netpoll *np = npi->rx_np;
 434
 435         if (!np)
 436                 goto out;
 437         if (skb->dev->type != ARPHRD_ETHER)
 438                 goto out;
 439
 440         /* check if netpoll clients need ARP */
 441         if (skb->protocol == __constant_htons(ETH_P_ARP) &&
 442             atomic_read(&trapped)) {
 443                 skb_queue_tail(&npi->arp_tx, skb);
 444                 return 1;
 445         }
 446
 447         proto = ntohs(eth_hdr(skb)->h_proto);
 448         if (proto != ETH_P_IP)
 449                 goto out;
 450         if (skb->pkt_type == PACKET_OTHERHOST)
 451                 goto out;
 452         if (skb_shared(skb))
 453                 goto out;
 454
 455         iph = (struct iphdr *)skb->data;
 456         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 457                 goto out;
 458         if (iph->ihl < 5 || iph->version != 4)
 459                 goto out;
 460         if (!pskb_may_pull(skb, iph->ihl*4))
 461                 goto out;
 462         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
 463                 goto out;
 464
 465         len = ntohs(iph->tot_len);
 466         if (skb->len < len || len < iph->ihl*4)
 467                 goto out;
 468
 469         if (iph->protocol != IPPROTO_UDP)
 470                 goto out;
 471
 472         len -= iph->ihl*4;
 473         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
 474         ulen = ntohs(uh->len);
 475
 476         if (ulen != len)
 477                 goto out;
 478         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
 479                 goto out;
 480         if (np->local_ip && np->local_ip != ntohl(iph->daddr))
 481                 goto out;
 482         if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
 483                 goto out;
 484         if (np->local_port && np->local_port != ntohs(uh->dest))
 485                 goto out;
 486
 487         np->rx_hook(np, ntohs(uh->source),
 488                     (char *)(uh+1),
 489                     ulen - sizeof(struct udphdr));
 490
 491         kfree_skb(skb);
 492         return 1;
 493
 494 out:
 495         if (atomic_read(&trapped)) {
 496                 kfree_skb(skb);
 497                 return 1;
 498         }
 499
 500         return 0;
 501 }
 502
 503 int netpoll_parse_options(struct netpoll *np, char *opt)
 504 {
 505         char *cur=opt, *delim;
 506
 507         if (*cur != '@') {
 508                 if ((delim = strchr(cur, '@')) == NULL)
 509                         goto parse_failed;
 510                 *delim = 0;
 511                 np->local_port = simple_strtol(cur, NULL, 10);
 512                 cur = delim;
 513         }
 514         cur++;
 515         printk(KERN_INFO "%s: local port %d\n", np->name, np->local_port);
 516
 517         if (*cur != '/') {
 518                 if ((delim = strchr(cur, '/')) == NULL)
 519                         goto parse_failed;
 520                 *delim = 0;
 521                 np->local_ip = ntohl(in_aton(cur));
 522                 cur = delim;
 523
 524                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 525                        np->name, HIPQUAD(np->local_ip));
 526         }
 527         cur++;
 528
 529         if (*cur != ',') {
 530                 /* parse out dev name */
 531                 if ((delim = strchr(cur, ',')) == NULL)
 532                         goto parse_failed;
 533                 *delim = 0;
 534                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 535                 cur = delim;
 536         }
 537         cur++;
 538
 539         printk(KERN_INFO "%s: interface %s\n", np->name, np->dev_name);
 540
 541         if (*cur != '@') {
 542                 /* dst port */
 543                 if ((delim = strchr(cur, '@')) == NULL)
 544                         goto parse_failed;
 545                 *delim = 0;
 546                 np->remote_port = simple_strtol(cur, NULL, 10);
 547                 cur = delim;
 548         }
 549         cur++;
 550         printk(KERN_INFO "%s: remote port %d\n", np->name, np->remote_port);
 551
 552         /* dst ip */
 553         if ((delim = strchr(cur, '/')) == NULL)
 554                 goto parse_failed;
 555         *delim = 0;
 556         np->remote_ip = ntohl(in_aton(cur));
 557         cur = delim + 1;
 558
 559         printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
 560                np->name, HIPQUAD(np->remote_ip));
 561
 562         if (*cur != 0) {
 563                 /* MAC address */
 564                 if ((delim = strchr(cur, ':')) == NULL)
 565                         goto parse_failed;
 566                 *delim = 0;
 567                 np->remote_mac[0] = simple_strtol(cur, NULL, 16);
 568                 cur = delim + 1;
 569                 if ((delim = strchr(cur, ':')) == NULL)
 570                         goto parse_failed;
 571                 *delim = 0;
 572                 np->remote_mac[1] = simple_strtol(cur, NULL, 16);
 573                 cur = delim + 1;
 574                 if ((delim = strchr(cur, ':')) == NULL)
 575                         goto parse_failed;
 576                 *delim = 0;
 577                 np->remote_mac[2] = simple_strtol(cur, NULL, 16);
 578                 cur = delim + 1;
 579                 if ((delim = strchr(cur, ':')) == NULL)
 580                         goto parse_failed;
 581                 *delim = 0;
 582                 np->remote_mac[3] = simple_strtol(cur, NULL, 16);
 583                 cur = delim + 1;
 584                 if ((delim = strchr(cur, ':')) == NULL)
 585                         goto parse_failed;
 586                 *delim = 0;
 587                 np->remote_mac[4] = simple_strtol(cur, NULL, 16);
 588                 cur = delim + 1;
 589                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
 590         }
 591
 592         printk(KERN_INFO "%s: remote ethernet address "
 593                "%02x:%02x:%02x:%02x:%02x:%02x\n",
 594                np->name,
 595                np->remote_mac[0],
 596                np->remote_mac[1],
 597                np->remote_mac[2],
 598                np->remote_mac[3],
 599                np->remote_mac[4],
 600                np->remote_mac[5]);
 601
 602         return 0;
 603
 604  parse_failed:
 605         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
 606                np->name, cur);
 607         return -1;
 608 }
 609
 610 int netpoll_setup(struct netpoll *np)
 611 {
 612         struct net_device *ndev = NULL;
 613         struct in_device *in_dev;
 614         struct netpoll_info *npinfo;
 615         unsigned long flags;
 616         int err;
 617
 618         if (np->dev_name)
 619                 ndev = dev_get_by_name(np->dev_name);
 620         if (!ndev) {
 621                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
 622                        np->name, np->dev_name);
 623                 return -ENODEV;
 624         }
 625
 626         np->dev = ndev;
 627         if (!ndev->npinfo) {
 628                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
 629                 if (!npinfo) {
 630                         err = -ENOMEM;
 631                         goto release;
 632                 }
 633
 634                 npinfo->rx_flags = 0;
 635                 npinfo->rx_np = NULL;
 636                 spin_lock_init(&npinfo->poll_lock);
 637                 npinfo->poll_owner = -1;
 638
 639                 spin_lock_init(&npinfo->rx_lock);
 640                 skb_queue_head_init(&npinfo->arp_tx);
 641                 skb_queue_head_init(&npinfo->txq);
 642                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
 643
 644                 atomic_set(&npinfo->refcnt, 1);
 645         } else {
 646                 npinfo = ndev->npinfo;
 647                 atomic_inc(&npinfo->refcnt);
 648         }
 649
 650         if (!ndev->poll_controller) {
 651                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
 652                        np->name, np->dev_name);
 653                 err = -ENOTSUPP;
 654                 goto release;
 655         }
 656
 657         if (!netif_running(ndev)) {
 658                 unsigned long atmost, atleast;
 659
 660                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
 661                        np->name, np->dev_name);
 662
 663                 rtnl_lock();
 664                 err = dev_open(ndev);
 665                 rtnl_unlock();
 666
 667                 if (err) {
 668                         printk(KERN_ERR "%s: failed to open %s\n",
 669                                np->name, ndev->name);
 670                         goto release;
 671                 }
 672
 673                 atleast = jiffies + HZ/10;
 674                 atmost = jiffies + 4*HZ;
 675                 while (!netif_carrier_ok(ndev)) {
 676                         if (time_after(jiffies, atmost)) {
 677                                 printk(KERN_NOTICE
 678                                        "%s: timeout waiting for carrier\n",
 679                                        np->name);
 680                                 break;
 681                         }
 682                         cond_resched();
 683                 }
 684
 685                 /* If carrier appears to come up instantly, we don't
 686                  * trust it and pause so that we don't pump all our
 687                  * queued console messages into the bitbucket.
 688                  */
 689
 690                 if (time_before(jiffies, atleast)) {
 691                         printk(KERN_NOTICE "%s: carrier detect appears"
 692                                " untrustworthy, waiting 4 seconds\n",
 693                                np->name);
 694                         msleep(4000);
 695                 }
 696         }
 697
 698         if (is_zero_ether_addr(np->local_mac) && ndev->dev_addr)
 699                 memcpy(np->local_mac, ndev->dev_addr, 6);
 700
 701         if (!np->local_ip) {
 702                 rcu_read_lock();
 703                 in_dev = __in_dev_get_rcu(ndev);
 704
 705                 if (!in_dev || !in_dev->ifa_list) {
 706                         rcu_read_unlock();
 707                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
 708                                np->name, np->dev_name);
 709                         err = -EDESTADDRREQ;
 710                         goto release;
 711                 }
 712
 713                 np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
 714                 rcu_read_unlock();
 715                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 716                        np->name, HIPQUAD(np->local_ip));
 717         }
 718
 719         if (np->rx_hook) {
 720                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 721                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
 722                 npinfo->rx_np = np;
 723                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 724         }
 725
 726         /* fill up the skb queue */
 727         refill_skbs();
 728
 729         /* last thing to do is link it to the net device structure */
 730         ndev->npinfo = npinfo;
 731
 732         /* avoid racing with NAPI reading npinfo */
 733         synchronize_rcu();
 734
 735         return 0;
 736
 737  release:
 738         if (!ndev->npinfo)
 739                 kfree(npinfo);
 740         np->dev = NULL;
 741         dev_put(ndev);
 742         return err;
 743 }
 744
 745 static int __init netpoll_init(void)
 746 {
 747         skb_queue_head_init(&skb_pool);
 748         return 0;
 749 }
 750 core_initcall(netpoll_init);
 751
 752 void netpoll_cleanup(struct netpoll *np)
 753 {
 754         struct netpoll_info *npinfo;
 755         unsigned long flags;
 756
 757         if (np->dev) {
 758                 npinfo = np->dev->npinfo;
 759                 if (npinfo) {
 760                         if (npinfo->rx_np == np) {
 761                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 762                                 npinfo->rx_np = NULL;
 763                                 npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
 764                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 765                         }
 766
 767                         np->dev->npinfo = NULL;
 768                         if (atomic_dec_and_test(&npinfo->refcnt)) {
 769                                 skb_queue_purge(&npinfo->arp_tx);
 770                                 skb_queue_purge(&npinfo->txq);
 771                                 cancel_rearming_delayed_work(&npinfo->tx_work);
 772                                 flush_scheduled_work();
 773
 774                                 kfree(npinfo);
 775                         }
 776                 }
 777
 778                 dev_put(np->dev);
 779         }
 780
 781         np->dev = NULL;
 782 }
 783
 784 int netpoll_trap(void)
 785 {
 786         return atomic_read(&trapped);
 787 }
 788
 789 void netpoll_set_trap(int trap)
 790 {
 791         if (trap)
 792                 atomic_inc(&trapped);
 793         else
 794                 atomic_dec(&trapped);
 795 }
 796
 797 EXPORT_SYMBOL(netpoll_set_trap);
 798 EXPORT_SYMBOL(netpoll_trap);
 799 EXPORT_SYMBOL(netpoll_parse_options);
 800 EXPORT_SYMBOL(netpoll_setup);
 801 EXPORT_SYMBOL(netpoll_cleanup);
 802 EXPORT_SYMBOL(netpoll_send_udp);
 803 EXPORT_SYMBOL(netpoll_poll);