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         unsigned long flags;
  59
  60         while ((skb = skb_dequeue(&npinfo->txq))) {
  61                 struct net_device *dev = skb->dev;
  62
  63                 if (!netif_device_present(dev) || !netif_running(dev)) {
  64                         __kfree_skb(skb);
  65                         continue;
  66                 }
  67
  68                 local_irq_save(flags);
  69                 netif_tx_lock(dev);
  70                 if (netif_queue_stopped(dev) ||
  71                     dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
  72                         skb_queue_head(&npinfo->txq, skb);
  73                         netif_tx_unlock(dev);
  74                         local_irq_restore(flags);
  75
  76                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
  77                         return;
  78                 }
  79                 netif_tx_unlock(dev);
  80                 local_irq_restore(flags);
  81         }
  82 }
  83
  84 static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
  85                             unsigned short ulen, __be32 saddr, __be32 daddr)
  86 {
  87         __wsum psum;
  88
  89         if (uh->check == 0 || skb->ip_summed == CHECKSUM_UNNECESSARY)
  90                 return 0;
  91
  92         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
  93
  94         if (skb->ip_summed == CHECKSUM_COMPLETE &&
  95             !csum_fold(csum_add(psum, skb->csum)))
  96                 return 0;
  97
  98         skb->csum = psum;
  99
 100         return __skb_checksum_complete(skb);
 101 }
 102
 103 /*
 104  * Check whether delayed processing was scheduled for our NIC. If so,
 105  * we attempt to grab the poll lock and use ->poll() to pump the card.
 106  * If this fails, either we've recursed in ->poll() or it's already
 107  * running on another CPU.
 108  *
 109  * Note: we don't mask interrupts with this lock because we're using
 110  * trylock here and interrupts are already disabled in the softirq
 111  * case. Further, we test the poll_owner to avoid recursion on UP
 112  * systems where the lock doesn't exist.
 113  *
 114  * In cases where there is bi-directional communications, reading only
 115  * one message at a time can lead to packets being dropped by the
 116  * network adapter, forcing superfluous retries and possibly timeouts.
 117  * Thus, we set our budget to greater than 1.
 118  */
 119 static void poll_napi(struct netpoll *np)
 120 {
 121         struct netpoll_info *npinfo = np->dev->npinfo;
 122         int budget = 16;
 123
 124         if (test_bit(__LINK_STATE_RX_SCHED, &np->dev->state) &&
 125             npinfo->poll_owner != smp_processor_id() &&
 126             spin_trylock(&npinfo->poll_lock)) {
 127                 npinfo->rx_flags |= NETPOLL_RX_DROP;
 128                 atomic_inc(&trapped);
 129
 130                 np->dev->poll(np->dev, &budget);
 131
 132                 atomic_dec(&trapped);
 133                 npinfo->rx_flags &= ~NETPOLL_RX_DROP;
 134                 spin_unlock(&npinfo->poll_lock);
 135         }
 136 }
 137
 138 static void service_arp_queue(struct netpoll_info *npi)
 139 {
 140         struct sk_buff *skb;
 141
 142         if (unlikely(!npi))
 143                 return;
 144
 145         skb = skb_dequeue(&npi->arp_tx);
 146
 147         while (skb != NULL) {
 148                 arp_reply(skb);
 149                 skb = skb_dequeue(&npi->arp_tx);
 150         }
 151 }
 152
 153 void netpoll_poll(struct netpoll *np)
 154 {
 155         if (!np->dev || !netif_running(np->dev) || !np->dev->poll_controller)
 156                 return;
 157
 158         /* Process pending work on NIC */
 159         np->dev->poll_controller(np->dev);
 160         if (np->dev->poll)
 161                 poll_napi(np);
 162
 163         service_arp_queue(np->dev->npinfo);
 164
 165         zap_completion_queue();
 166 }
 167
 168 static void refill_skbs(void)
 169 {
 170         struct sk_buff *skb;
 171         unsigned long flags;
 172
 173         spin_lock_irqsave(&skb_pool.lock, flags);
 174         while (skb_pool.qlen < MAX_SKBS) {
 175                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
 176                 if (!skb)
 177                         break;
 178
 179                 __skb_queue_tail(&skb_pool, skb);
 180         }
 181         spin_unlock_irqrestore(&skb_pool.lock, flags);
 182 }
 183
 184 static void zap_completion_queue(void)
 185 {
 186         unsigned long flags;
 187         struct softnet_data *sd = &get_cpu_var(softnet_data);
 188
 189         if (sd->completion_queue) {
 190                 struct sk_buff *clist;
 191
 192                 local_irq_save(flags);
 193                 clist = sd->completion_queue;
 194                 sd->completion_queue = NULL;
 195                 local_irq_restore(flags);
 196
 197                 while (clist != NULL) {
 198                         struct sk_buff *skb = clist;
 199                         clist = clist->next;
 200                         if (skb->destructor)
 201                                 dev_kfree_skb_any(skb); /* put this one back */
 202                         else
 203                                 __kfree_skb(skb);
 204                 }
 205         }
 206
 207         put_cpu_var(softnet_data);
 208 }
 209
 210 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
 211 {
 212         int count = 0;
 213         struct sk_buff *skb;
 214
 215         zap_completion_queue();
 216         refill_skbs();
 217 repeat:
 218
 219         skb = alloc_skb(len, GFP_ATOMIC);
 220         if (!skb)
 221                 skb = skb_dequeue(&skb_pool);
 222
 223         if (!skb) {
 224                 if (++count < 10) {
 225                         netpoll_poll(np);
 226                         goto repeat;
 227                 }
 228                 return NULL;
 229         }
 230
 231         atomic_set(&skb->users, 1);
 232         skb_reserve(skb, reserve);
 233         return skb;
 234 }
 235
 236 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 237 {
 238         int status = NETDEV_TX_BUSY;
 239         unsigned long tries;
 240         struct net_device *dev = np->dev;
 241         struct netpoll_info *npinfo = np->dev->npinfo;
 242
 243         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
 244                 __kfree_skb(skb);
 245                 return;
 246         }
 247
 248         /* don't get messages out of order, and no recursion */
 249         if (skb_queue_len(&npinfo->txq) == 0 &&
 250                     npinfo->poll_owner != smp_processor_id()) {
 251                 unsigned long flags;
 252
 253                 local_irq_save(flags);
 254                 if (netif_tx_trylock(dev)) {
 255                         /* try until next clock tick */
 256                         for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
 257                                         tries > 0; --tries) {
 258                                 if (!netif_queue_stopped(dev))
 259                                         status = dev->hard_start_xmit(skb, dev);
 260
 261                                 if (status == NETDEV_TX_OK)
 262                                         break;
 263
 264                                 /* tickle device maybe there is some cleanup */
 265                                 netpoll_poll(np);
 266
 267                                 udelay(USEC_PER_POLL);
 268                         }
 269                         netif_tx_unlock(dev);
 270                 }
 271                 local_irq_restore(flags);
 272         }
 273
 274         if (status != NETDEV_TX_OK) {
 275                 skb_queue_tail(&npinfo->txq, skb);
 276                 schedule_delayed_work(&npinfo->tx_work,0);
 277         }
 278 }
 279
 280 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 281 {
 282         int total_len, eth_len, ip_len, udp_len;
 283         struct sk_buff *skb;
 284         struct udphdr *udph;
 285         struct iphdr *iph;
 286         struct ethhdr *eth;
 287
 288         udp_len = len + sizeof(*udph);
 289         ip_len = eth_len = udp_len + sizeof(*iph);
 290         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
 291
 292         skb = find_skb(np, total_len, total_len - len);
 293         if (!skb)
 294                 return;
 295
 296         memcpy(skb->data, msg, len);
 297         skb->len += len;
 298
 299         skb->h.uh = udph = (struct udphdr *) skb_push(skb, sizeof(*udph));
 300         udph->source = htons(np->local_port);
 301         udph->dest = htons(np->remote_port);
 302         udph->len = htons(udp_len);
 303         udph->check = 0;
 304         udph->check = csum_tcpudp_magic(htonl(np->local_ip),
 305                                         htonl(np->remote_ip),
 306                                         udp_len, IPPROTO_UDP,
 307                                         csum_partial((unsigned char *)udph, udp_len, 0));
 308         if (udph->check == 0)
 309                 udph->check = CSUM_MANGLED_0;
 310
 311         skb->nh.iph = iph = (struct iphdr *)skb_push(skb, sizeof(*iph));
 312
 313         /* iph->version = 4; iph->ihl = 5; */
 314         put_unaligned(0x45, (unsigned char *)iph);
 315         iph->tos      = 0;
 316         put_unaligned(htons(ip_len), &(iph->tot_len));
 317         iph->id       = 0;
 318         iph->frag_off = 0;
 319         iph->ttl      = 64;
 320         iph->protocol = IPPROTO_UDP;
 321         iph->check    = 0;
 322         put_unaligned(htonl(np->local_ip), &(iph->saddr));
 323         put_unaligned(htonl(np->remote_ip), &(iph->daddr));
 324         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 325
 326         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 327         skb->mac.raw = skb->data;
 328         skb->protocol = eth->h_proto = htons(ETH_P_IP);
 329         memcpy(eth->h_source, np->local_mac, 6);
 330         memcpy(eth->h_dest, np->remote_mac, 6);
 331
 332         skb->dev = np->dev;
 333
 334         netpoll_send_skb(np, skb);
 335 }
 336
 337 static void arp_reply(struct sk_buff *skb)
 338 {
 339         struct netpoll_info *npinfo = skb->dev->npinfo;
 340         struct arphdr *arp;
 341         unsigned char *arp_ptr;
 342         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
 343         __be32 sip, tip;
 344         unsigned char *sha;
 345         struct sk_buff *send_skb;
 346         struct netpoll *np = NULL;
 347
 348         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
 349                 np = npinfo->rx_np;
 350         if (!np)
 351                 return;
 352
 353         /* No arp on this interface */
 354         if (skb->dev->flags & IFF_NOARP)
 355                 return;
 356
 357         if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
 358                                  (2 * skb->dev->addr_len) +
 359                                  (2 * sizeof(u32)))))
 360                 return;
 361
 362         skb->h.raw = skb->nh.raw = skb->data;
 363         arp = skb->nh.arph;
 364
 365         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 366              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 367             arp->ar_pro != htons(ETH_P_IP) ||
 368             arp->ar_op != htons(ARPOP_REQUEST))
 369                 return;
 370
 371         arp_ptr = (unsigned char *)(arp+1);
 372         /* save the location of the src hw addr */
 373         sha = arp_ptr;
 374         arp_ptr += skb->dev->addr_len;
 375         memcpy(&sip, arp_ptr, 4);
 376         arp_ptr += 4;
 377         /* if we actually cared about dst hw addr, it would get copied here */
 378         arp_ptr += skb->dev->addr_len;
 379         memcpy(&tip, arp_ptr, 4);
 380
 381         /* Should we ignore arp? */
 382         if (tip != htonl(np->local_ip) || LOOPBACK(tip) || MULTICAST(tip))
 383                 return;
 384
 385         size = sizeof(struct arphdr) + 2 * (skb->dev->addr_len + 4);
 386         send_skb = find_skb(np, size + LL_RESERVED_SPACE(np->dev),
 387                             LL_RESERVED_SPACE(np->dev));
 388
 389         if (!send_skb)
 390                 return;
 391
 392         send_skb->nh.raw = send_skb->data;
 393         arp = (struct arphdr *) skb_put(send_skb, size);
 394         send_skb->dev = skb->dev;
 395         send_skb->protocol = htons(ETH_P_ARP);
 396
 397         /* Fill the device header for the ARP frame */
 398
 399         if (np->dev->hard_header &&
 400             np->dev->hard_header(send_skb, skb->dev, ptype,
 401                                  sha, np->local_mac,
 402                                  send_skb->len) < 0) {
 403                 kfree_skb(send_skb);
 404                 return;
 405         }
 406
 407         /*
 408          * Fill out the arp protocol part.
 409          *
 410          * we only support ethernet device type,
 411          * which (according to RFC 1390) should always equal 1 (Ethernet).
 412          */
 413
 414         arp->ar_hrd = htons(np->dev->type);
 415         arp->ar_pro = htons(ETH_P_IP);
 416         arp->ar_hln = np->dev->addr_len;
 417         arp->ar_pln = 4;
 418         arp->ar_op = htons(type);
 419
 420         arp_ptr=(unsigned char *)(arp + 1);
 421         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
 422         arp_ptr += np->dev->addr_len;
 423         memcpy(arp_ptr, &tip, 4);
 424         arp_ptr += 4;
 425         memcpy(arp_ptr, sha, np->dev->addr_len);
 426         arp_ptr += np->dev->addr_len;
 427         memcpy(arp_ptr, &sip, 4);
 428
 429         netpoll_send_skb(np, send_skb);
 430 }
 431
 432 int __netpoll_rx(struct sk_buff *skb)
 433 {
 434         int proto, len, ulen;
 435         struct iphdr *iph;
 436         struct udphdr *uh;
 437         struct netpoll_info *npi = skb->dev->npinfo;
 438         struct netpoll *np = npi->rx_np;
 439
 440         if (!np)
 441                 goto out;
 442         if (skb->dev->type != ARPHRD_ETHER)
 443                 goto out;
 444
 445         /* check if netpoll clients need ARP */
 446         if (skb->protocol == __constant_htons(ETH_P_ARP) &&
 447             atomic_read(&trapped)) {
 448                 skb_queue_tail(&npi->arp_tx, skb);
 449                 return 1;
 450         }
 451
 452         proto = ntohs(eth_hdr(skb)->h_proto);
 453         if (proto != ETH_P_IP)
 454                 goto out;
 455         if (skb->pkt_type == PACKET_OTHERHOST)
 456                 goto out;
 457         if (skb_shared(skb))
 458                 goto out;
 459
 460         iph = (struct iphdr *)skb->data;
 461         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 462                 goto out;
 463         if (iph->ihl < 5 || iph->version != 4)
 464                 goto out;
 465         if (!pskb_may_pull(skb, iph->ihl*4))
 466                 goto out;
 467         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
 468                 goto out;
 469
 470         len = ntohs(iph->tot_len);
 471         if (skb->len < len || len < iph->ihl*4)
 472                 goto out;
 473
 474         /*
 475          * Our transport medium may have padded the buffer out.
 476          * Now We trim to the true length of the frame.
 477          */
 478         if (pskb_trim_rcsum(skb, len))
 479                 goto out;
 480
 481         if (iph->protocol != IPPROTO_UDP)
 482                 goto out;
 483
 484         len -= iph->ihl*4;
 485         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
 486         ulen = ntohs(uh->len);
 487
 488         if (ulen != len)
 489                 goto out;
 490         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
 491                 goto out;
 492         if (np->local_ip && np->local_ip != ntohl(iph->daddr))
 493                 goto out;
 494         if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
 495                 goto out;
 496         if (np->local_port && np->local_port != ntohs(uh->dest))
 497                 goto out;
 498
 499         np->rx_hook(np, ntohs(uh->source),
 500                     (char *)(uh+1),
 501                     ulen - sizeof(struct udphdr));
 502
 503         kfree_skb(skb);
 504         return 1;
 505
 506 out:
 507         if (atomic_read(&trapped)) {
 508                 kfree_skb(skb);
 509                 return 1;
 510         }
 511
 512         return 0;
 513 }
 514
 515 int netpoll_parse_options(struct netpoll *np, char *opt)
 516 {
 517         char *cur=opt, *delim;
 518
 519         if (*cur != '@') {
 520                 if ((delim = strchr(cur, '@')) == NULL)
 521                         goto parse_failed;
 522                 *delim = 0;
 523                 np->local_port = simple_strtol(cur, NULL, 10);
 524                 cur = delim;
 525         }
 526         cur++;
 527         printk(KERN_INFO "%s: local port %d\n", np->name, np->local_port);
 528
 529         if (*cur != '/') {
 530                 if ((delim = strchr(cur, '/')) == NULL)
 531                         goto parse_failed;
 532                 *delim = 0;
 533                 np->local_ip = ntohl(in_aton(cur));
 534                 cur = delim;
 535
 536                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 537                        np->name, HIPQUAD(np->local_ip));
 538         }
 539         cur++;
 540
 541         if (*cur != ',') {
 542                 /* parse out dev name */
 543                 if ((delim = strchr(cur, ',')) == NULL)
 544                         goto parse_failed;
 545                 *delim = 0;
 546                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 547                 cur = delim;
 548         }
 549         cur++;
 550
 551         printk(KERN_INFO "%s: interface %s\n", np->name, np->dev_name);
 552
 553         if (*cur != '@') {
 554                 /* dst port */
 555                 if ((delim = strchr(cur, '@')) == NULL)
 556                         goto parse_failed;
 557                 *delim = 0;
 558                 np->remote_port = simple_strtol(cur, NULL, 10);
 559                 cur = delim;
 560         }
 561         cur++;
 562         printk(KERN_INFO "%s: remote port %d\n", np->name, np->remote_port);
 563
 564         /* dst ip */
 565         if ((delim = strchr(cur, '/')) == NULL)
 566                 goto parse_failed;
 567         *delim = 0;
 568         np->remote_ip = ntohl(in_aton(cur));
 569         cur = delim + 1;
 570
 571         printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
 572                np->name, HIPQUAD(np->remote_ip));
 573
 574         if (*cur != 0) {
 575                 /* MAC address */
 576                 if ((delim = strchr(cur, ':')) == NULL)
 577                         goto parse_failed;
 578                 *delim = 0;
 579                 np->remote_mac[0] = simple_strtol(cur, NULL, 16);
 580                 cur = delim + 1;
 581                 if ((delim = strchr(cur, ':')) == NULL)
 582                         goto parse_failed;
 583                 *delim = 0;
 584                 np->remote_mac[1] = simple_strtol(cur, NULL, 16);
 585                 cur = delim + 1;
 586                 if ((delim = strchr(cur, ':')) == NULL)
 587                         goto parse_failed;
 588                 *delim = 0;
 589                 np->remote_mac[2] = simple_strtol(cur, NULL, 16);
 590                 cur = delim + 1;
 591                 if ((delim = strchr(cur, ':')) == NULL)
 592                         goto parse_failed;
 593                 *delim = 0;
 594                 np->remote_mac[3] = simple_strtol(cur, NULL, 16);
 595                 cur = delim + 1;
 596                 if ((delim = strchr(cur, ':')) == NULL)
 597                         goto parse_failed;
 598                 *delim = 0;
 599                 np->remote_mac[4] = simple_strtol(cur, NULL, 16);
 600                 cur = delim + 1;
 601                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
 602         }
 603
 604         printk(KERN_INFO "%s: remote ethernet address "
 605                "%02x:%02x:%02x:%02x:%02x:%02x\n",
 606                np->name,
 607                np->remote_mac[0],
 608                np->remote_mac[1],
 609                np->remote_mac[2],
 610                np->remote_mac[3],
 611                np->remote_mac[4],
 612                np->remote_mac[5]);
 613
 614         return 0;
 615
 616  parse_failed:
 617         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
 618                np->name, cur);
 619         return -1;
 620 }
 621
 622 int netpoll_setup(struct netpoll *np)
 623 {
 624         struct net_device *ndev = NULL;
 625         struct in_device *in_dev;
 626         struct netpoll_info *npinfo;
 627         unsigned long flags;
 628         int err;
 629
 630         if (np->dev_name)
 631                 ndev = dev_get_by_name(np->dev_name);
 632         if (!ndev) {
 633                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
 634                        np->name, np->dev_name);
 635                 return -ENODEV;
 636         }
 637
 638         np->dev = ndev;
 639         if (!ndev->npinfo) {
 640                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
 641                 if (!npinfo) {
 642                         err = -ENOMEM;
 643                         goto release;
 644                 }
 645
 646                 npinfo->rx_flags = 0;
 647                 npinfo->rx_np = NULL;
 648                 spin_lock_init(&npinfo->poll_lock);
 649                 npinfo->poll_owner = -1;
 650
 651                 spin_lock_init(&npinfo->rx_lock);
 652                 skb_queue_head_init(&npinfo->arp_tx);
 653                 skb_queue_head_init(&npinfo->txq);
 654                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
 655
 656                 atomic_set(&npinfo->refcnt, 1);
 657         } else {
 658                 npinfo = ndev->npinfo;
 659                 atomic_inc(&npinfo->refcnt);
 660         }
 661
 662         if (!ndev->poll_controller) {
 663                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
 664                        np->name, np->dev_name);
 665                 err = -ENOTSUPP;
 666                 goto release;
 667         }
 668
 669         if (!netif_running(ndev)) {
 670                 unsigned long atmost, atleast;
 671
 672                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
 673                        np->name, np->dev_name);
 674
 675                 rtnl_lock();
 676                 err = dev_open(ndev);
 677                 rtnl_unlock();
 678
 679                 if (err) {
 680                         printk(KERN_ERR "%s: failed to open %s\n",
 681                                np->name, ndev->name);
 682                         goto release;
 683                 }
 684
 685                 atleast = jiffies + HZ/10;
 686                 atmost = jiffies + 4*HZ;
 687                 while (!netif_carrier_ok(ndev)) {
 688                         if (time_after(jiffies, atmost)) {
 689                                 printk(KERN_NOTICE
 690                                        "%s: timeout waiting for carrier\n",
 691                                        np->name);
 692                                 break;
 693                         }
 694                         cond_resched();
 695                 }
 696
 697                 /* If carrier appears to come up instantly, we don't
 698                  * trust it and pause so that we don't pump all our
 699                  * queued console messages into the bitbucket.
 700                  */
 701
 702                 if (time_before(jiffies, atleast)) {
 703                         printk(KERN_NOTICE "%s: carrier detect appears"
 704                                " untrustworthy, waiting 4 seconds\n",
 705                                np->name);
 706                         msleep(4000);
 707                 }
 708         }
 709
 710         if (is_zero_ether_addr(np->local_mac) && ndev->dev_addr)
 711                 memcpy(np->local_mac, ndev->dev_addr, 6);
 712
 713         if (!np->local_ip) {
 714                 rcu_read_lock();
 715                 in_dev = __in_dev_get_rcu(ndev);
 716
 717                 if (!in_dev || !in_dev->ifa_list) {
 718                         rcu_read_unlock();
 719                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
 720                                np->name, np->dev_name);
 721                         err = -EDESTADDRREQ;
 722                         goto release;
 723                 }
 724
 725                 np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
 726                 rcu_read_unlock();
 727                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 728                        np->name, HIPQUAD(np->local_ip));
 729         }
 730
 731         if (np->rx_hook) {
 732                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 733                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
 734                 npinfo->rx_np = np;
 735                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 736         }
 737
 738         /* fill up the skb queue */
 739         refill_skbs();
 740
 741         /* last thing to do is link it to the net device structure */
 742         ndev->npinfo = npinfo;
 743
 744         /* avoid racing with NAPI reading npinfo */
 745         synchronize_rcu();
 746
 747         return 0;
 748
 749  release:
 750         if (!ndev->npinfo)
 751                 kfree(npinfo);
 752         np->dev = NULL;
 753         dev_put(ndev);
 754         return err;
 755 }
 756
 757 static int __init netpoll_init(void)
 758 {
 759         skb_queue_head_init(&skb_pool);
 760         return 0;
 761 }
 762 core_initcall(netpoll_init);
 763
 764 void netpoll_cleanup(struct netpoll *np)
 765 {
 766         struct netpoll_info *npinfo;
 767         unsigned long flags;
 768
 769         if (np->dev) {
 770                 npinfo = np->dev->npinfo;
 771                 if (npinfo) {
 772                         if (npinfo->rx_np == np) {
 773                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 774                                 npinfo->rx_np = NULL;
 775                                 npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
 776                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 777                         }
 778
 779                         np->dev->npinfo = NULL;
 780                         if (atomic_dec_and_test(&npinfo->refcnt)) {
 781                                 skb_queue_purge(&npinfo->arp_tx);
 782                                 skb_queue_purge(&npinfo->txq);
 783                                 cancel_rearming_delayed_work(&npinfo->tx_work);
 784                                 flush_scheduled_work();
 785
 786                                 kfree(npinfo);
 787                         }
 788                 }
 789
 790                 dev_put(np->dev);
 791         }
 792
 793         np->dev = NULL;
 794 }
 795
 796 int netpoll_trap(void)
 797 {
 798         return atomic_read(&trapped);
 799 }
 800
 801 void netpoll_set_trap(int trap)
 802 {
 803         if (trap)
 804                 atomic_inc(&trapped);
 805         else
 806                 atomic_dec(&trapped);
 807 }
 808
 809 EXPORT_SYMBOL(netpoll_set_trap);
 810 EXPORT_SYMBOL(netpoll_trap);
 811 EXPORT_SYMBOL(netpoll_parse_options);
 812 EXPORT_SYMBOL(netpoll_setup);
 813 EXPORT_SYMBOL(netpoll_cleanup);
 814 EXPORT_SYMBOL(netpoll_send_udp);
 815 EXPORT_SYMBOL(netpoll_poll);