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
  62                 if (!netif_device_present(dev) || !netif_running(dev)) {
  63                         __kfree_skb(skb);
  64                         continue;
  65                 }
  66
  67                 local_irq_save(flags);
  68                 netif_tx_lock(dev);
  69                 if (netif_queue_stopped(dev) ||
  70                     dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
  71                         skb_queue_head(&npinfo->txq, skb);
  72                         netif_tx_unlock(dev);
  73                         local_irq_restore(flags);
  74
  75                         if (atomic_read(&npinfo->refcnt))
  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_csum_unnecessary(skb))
  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                 /* try until next clock tick */
 255                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
 256                      tries > 0; --tries) {
 257                         if (netif_tx_trylock(dev)) {
 258                                 if (!netif_queue_stopped(dev))
 259                                         status = dev->hard_start_xmit(skb, dev);
 260                                 netif_tx_unlock(dev);
 261
 262                                 if (status == NETDEV_TX_OK)
 263                                         break;
 264
 265                         }
 266
 267                         /* tickle device maybe there is some cleanup */
 268                         netpoll_poll(np);
 269
 270                         udelay(USEC_PER_POLL);
 271                 }
 272                 local_irq_restore(flags);
 273         }
 274
 275         if (status != NETDEV_TX_OK) {
 276                 skb_queue_tail(&npinfo->txq, skb);
 277                 schedule_delayed_work(&npinfo->tx_work,0);
 278         }
 279 }
 280
 281 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 282 {
 283         int total_len, eth_len, ip_len, udp_len;
 284         struct sk_buff *skb;
 285         struct udphdr *udph;
 286         struct iphdr *iph;
 287         struct ethhdr *eth;
 288
 289         udp_len = len + sizeof(*udph);
 290         ip_len = eth_len = udp_len + sizeof(*iph);
 291         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
 292
 293         skb = find_skb(np, total_len, total_len - len);
 294         if (!skb)
 295                 return;
 296
 297         skb_copy_to_linear_data(skb, msg, len);
 298         skb->len += len;
 299
 300         skb_push(skb, sizeof(*udph));
 301         skb_reset_transport_header(skb);
 302         udph = udp_hdr(skb);
 303         udph->source = htons(np->local_port);
 304         udph->dest = htons(np->remote_port);
 305         udph->len = htons(udp_len);
 306         udph->check = 0;
 307         udph->check = csum_tcpudp_magic(htonl(np->local_ip),
 308                                         htonl(np->remote_ip),
 309                                         udp_len, IPPROTO_UDP,
 310                                         csum_partial((unsigned char *)udph, udp_len, 0));
 311         if (udph->check == 0)
 312                 udph->check = CSUM_MANGLED_0;
 313
 314         skb_push(skb, sizeof(*iph));
 315         skb_reset_network_header(skb);
 316         iph = ip_hdr(skb);
 317
 318         /* iph->version = 4; iph->ihl = 5; */
 319         put_unaligned(0x45, (unsigned char *)iph);
 320         iph->tos      = 0;
 321         put_unaligned(htons(ip_len), &(iph->tot_len));
 322         iph->id       = 0;
 323         iph->frag_off = 0;
 324         iph->ttl      = 64;
 325         iph->protocol = IPPROTO_UDP;
 326         iph->check    = 0;
 327         put_unaligned(htonl(np->local_ip), &(iph->saddr));
 328         put_unaligned(htonl(np->remote_ip), &(iph->daddr));
 329         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 330
 331         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 332         skb_reset_mac_header(skb);
 333         skb->protocol = eth->h_proto = htons(ETH_P_IP);
 334         memcpy(eth->h_source, np->local_mac, 6);
 335         memcpy(eth->h_dest, np->remote_mac, 6);
 336
 337         skb->dev = np->dev;
 338
 339         netpoll_send_skb(np, skb);
 340 }
 341
 342 static void arp_reply(struct sk_buff *skb)
 343 {
 344         struct netpoll_info *npinfo = skb->dev->npinfo;
 345         struct arphdr *arp;
 346         unsigned char *arp_ptr;
 347         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
 348         __be32 sip, tip;
 349         unsigned char *sha;
 350         struct sk_buff *send_skb;
 351         struct netpoll *np = NULL;
 352
 353         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
 354                 np = npinfo->rx_np;
 355         if (!np)
 356                 return;
 357
 358         /* No arp on this interface */
 359         if (skb->dev->flags & IFF_NOARP)
 360                 return;
 361
 362         if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
 363                                  (2 * skb->dev->addr_len) +
 364                                  (2 * sizeof(u32)))))
 365                 return;
 366
 367         skb_reset_network_header(skb);
 368         skb_reset_transport_header(skb);
 369         arp = arp_hdr(skb);
 370
 371         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 372              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 373             arp->ar_pro != htons(ETH_P_IP) ||
 374             arp->ar_op != htons(ARPOP_REQUEST))
 375                 return;
 376
 377         arp_ptr = (unsigned char *)(arp+1);
 378         /* save the location of the src hw addr */
 379         sha = arp_ptr;
 380         arp_ptr += skb->dev->addr_len;
 381         memcpy(&sip, arp_ptr, 4);
 382         arp_ptr += 4;
 383         /* if we actually cared about dst hw addr, it would get copied here */
 384         arp_ptr += skb->dev->addr_len;
 385         memcpy(&tip, arp_ptr, 4);
 386
 387         /* Should we ignore arp? */
 388         if (tip != htonl(np->local_ip) || LOOPBACK(tip) || MULTICAST(tip))
 389                 return;
 390
 391         size = sizeof(struct arphdr) + 2 * (skb->dev->addr_len + 4);
 392         send_skb = find_skb(np, size + LL_RESERVED_SPACE(np->dev),
 393                             LL_RESERVED_SPACE(np->dev));
 394
 395         if (!send_skb)
 396                 return;
 397
 398         skb_reset_network_header(send_skb);
 399         arp = (struct arphdr *) skb_put(send_skb, size);
 400         send_skb->dev = skb->dev;
 401         send_skb->protocol = htons(ETH_P_ARP);
 402
 403         /* Fill the device header for the ARP frame */
 404
 405         if (np->dev->hard_header &&
 406             np->dev->hard_header(send_skb, skb->dev, ptype,
 407                                  sha, np->local_mac,
 408                                  send_skb->len) < 0) {
 409                 kfree_skb(send_skb);
 410                 return;
 411         }
 412
 413         /*
 414          * Fill out the arp protocol part.
 415          *
 416          * we only support ethernet device type,
 417          * which (according to RFC 1390) should always equal 1 (Ethernet).
 418          */
 419
 420         arp->ar_hrd = htons(np->dev->type);
 421         arp->ar_pro = htons(ETH_P_IP);
 422         arp->ar_hln = np->dev->addr_len;
 423         arp->ar_pln = 4;
 424         arp->ar_op = htons(type);
 425
 426         arp_ptr=(unsigned char *)(arp + 1);
 427         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
 428         arp_ptr += np->dev->addr_len;
 429         memcpy(arp_ptr, &tip, 4);
 430         arp_ptr += 4;
 431         memcpy(arp_ptr, sha, np->dev->addr_len);
 432         arp_ptr += np->dev->addr_len;
 433         memcpy(arp_ptr, &sip, 4);
 434
 435         netpoll_send_skb(np, send_skb);
 436 }
 437
 438 int __netpoll_rx(struct sk_buff *skb)
 439 {
 440         int proto, len, ulen;
 441         struct iphdr *iph;
 442         struct udphdr *uh;
 443         struct netpoll_info *npi = skb->dev->npinfo;
 444         struct netpoll *np = npi->rx_np;
 445
 446         if (!np)
 447                 goto out;
 448         if (skb->dev->type != ARPHRD_ETHER)
 449                 goto out;
 450
 451         /* check if netpoll clients need ARP */
 452         if (skb->protocol == htons(ETH_P_ARP) &&
 453             atomic_read(&trapped)) {
 454                 skb_queue_tail(&npi->arp_tx, skb);
 455                 return 1;
 456         }
 457
 458         proto = ntohs(eth_hdr(skb)->h_proto);
 459         if (proto != ETH_P_IP)
 460                 goto out;
 461         if (skb->pkt_type == PACKET_OTHERHOST)
 462                 goto out;
 463         if (skb_shared(skb))
 464                 goto out;
 465
 466         iph = (struct iphdr *)skb->data;
 467         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 468                 goto out;
 469         if (iph->ihl < 5 || iph->version != 4)
 470                 goto out;
 471         if (!pskb_may_pull(skb, iph->ihl*4))
 472                 goto out;
 473         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
 474                 goto out;
 475
 476         len = ntohs(iph->tot_len);
 477         if (skb->len < len || len < iph->ihl*4)
 478                 goto out;
 479
 480         /*
 481          * Our transport medium may have padded the buffer out.
 482          * Now We trim to the true length of the frame.
 483          */
 484         if (pskb_trim_rcsum(skb, len))
 485                 goto out;
 486
 487         if (iph->protocol != IPPROTO_UDP)
 488                 goto out;
 489
 490         len -= iph->ihl*4;
 491         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
 492         ulen = ntohs(uh->len);
 493
 494         if (ulen != len)
 495                 goto out;
 496         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
 497                 goto out;
 498         if (np->local_ip && np->local_ip != ntohl(iph->daddr))
 499                 goto out;
 500         if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
 501                 goto out;
 502         if (np->local_port && np->local_port != ntohs(uh->dest))
 503                 goto out;
 504
 505         np->rx_hook(np, ntohs(uh->source),
 506                     (char *)(uh+1),
 507                     ulen - sizeof(struct udphdr));
 508
 509         kfree_skb(skb);
 510         return 1;
 511
 512 out:
 513         if (atomic_read(&trapped)) {
 514                 kfree_skb(skb);
 515                 return 1;
 516         }
 517
 518         return 0;
 519 }
 520
 521 int netpoll_parse_options(struct netpoll *np, char *opt)
 522 {
 523         char *cur=opt, *delim;
 524
 525         if (*cur != '@') {
 526                 if ((delim = strchr(cur, '@')) == NULL)
 527                         goto parse_failed;
 528                 *delim = 0;
 529                 np->local_port = simple_strtol(cur, NULL, 10);
 530                 cur = delim;
 531         }
 532         cur++;
 533         printk(KERN_INFO "%s: local port %d\n", np->name, np->local_port);
 534
 535         if (*cur != '/') {
 536                 if ((delim = strchr(cur, '/')) == NULL)
 537                         goto parse_failed;
 538                 *delim = 0;
 539                 np->local_ip = ntohl(in_aton(cur));
 540                 cur = delim;
 541
 542                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 543                        np->name, HIPQUAD(np->local_ip));
 544         }
 545         cur++;
 546
 547         if (*cur != ',') {
 548                 /* parse out dev name */
 549                 if ((delim = strchr(cur, ',')) == NULL)
 550                         goto parse_failed;
 551                 *delim = 0;
 552                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 553                 cur = delim;
 554         }
 555         cur++;
 556
 557         printk(KERN_INFO "%s: interface %s\n", np->name, np->dev_name);
 558
 559         if (*cur != '@') {
 560                 /* dst port */
 561                 if ((delim = strchr(cur, '@')) == NULL)
 562                         goto parse_failed;
 563                 *delim = 0;
 564                 np->remote_port = simple_strtol(cur, NULL, 10);
 565                 cur = delim;
 566         }
 567         cur++;
 568         printk(KERN_INFO "%s: remote port %d\n", np->name, np->remote_port);
 569
 570         /* dst ip */
 571         if ((delim = strchr(cur, '/')) == NULL)
 572                 goto parse_failed;
 573         *delim = 0;
 574         np->remote_ip = ntohl(in_aton(cur));
 575         cur = delim + 1;
 576
 577         printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
 578                np->name, HIPQUAD(np->remote_ip));
 579
 580         if (*cur != 0) {
 581                 /* MAC address */
 582                 if ((delim = strchr(cur, ':')) == NULL)
 583                         goto parse_failed;
 584                 *delim = 0;
 585                 np->remote_mac[0] = simple_strtol(cur, NULL, 16);
 586                 cur = delim + 1;
 587                 if ((delim = strchr(cur, ':')) == NULL)
 588                         goto parse_failed;
 589                 *delim = 0;
 590                 np->remote_mac[1] = simple_strtol(cur, NULL, 16);
 591                 cur = delim + 1;
 592                 if ((delim = strchr(cur, ':')) == NULL)
 593                         goto parse_failed;
 594                 *delim = 0;
 595                 np->remote_mac[2] = simple_strtol(cur, NULL, 16);
 596                 cur = delim + 1;
 597                 if ((delim = strchr(cur, ':')) == NULL)
 598                         goto parse_failed;
 599                 *delim = 0;
 600                 np->remote_mac[3] = simple_strtol(cur, NULL, 16);
 601                 cur = delim + 1;
 602                 if ((delim = strchr(cur, ':')) == NULL)
 603                         goto parse_failed;
 604                 *delim = 0;
 605                 np->remote_mac[4] = simple_strtol(cur, NULL, 16);
 606                 cur = delim + 1;
 607                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
 608         }
 609
 610         printk(KERN_INFO "%s: remote ethernet address "
 611                "%02x:%02x:%02x:%02x:%02x:%02x\n",
 612                np->name,
 613                np->remote_mac[0],
 614                np->remote_mac[1],
 615                np->remote_mac[2],
 616                np->remote_mac[3],
 617                np->remote_mac[4],
 618                np->remote_mac[5]);
 619
 620         return 0;
 621
 622  parse_failed:
 623         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
 624                np->name, cur);
 625         return -1;
 626 }
 627
 628 int netpoll_setup(struct netpoll *np)
 629 {
 630         struct net_device *ndev = NULL;
 631         struct in_device *in_dev;
 632         struct netpoll_info *npinfo;
 633         unsigned long flags;
 634         int err;
 635
 636         if (np->dev_name)
 637                 ndev = dev_get_by_name(np->dev_name);
 638         if (!ndev) {
 639                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
 640                        np->name, np->dev_name);
 641                 return -ENODEV;
 642         }
 643
 644         np->dev = ndev;
 645         if (!ndev->npinfo) {
 646                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
 647                 if (!npinfo) {
 648                         err = -ENOMEM;
 649                         goto release;
 650                 }
 651
 652                 npinfo->rx_flags = 0;
 653                 npinfo->rx_np = NULL;
 654                 spin_lock_init(&npinfo->poll_lock);
 655                 npinfo->poll_owner = -1;
 656
 657                 spin_lock_init(&npinfo->rx_lock);
 658                 skb_queue_head_init(&npinfo->arp_tx);
 659                 skb_queue_head_init(&npinfo->txq);
 660                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
 661
 662                 atomic_set(&npinfo->refcnt, 1);
 663         } else {
 664                 npinfo = ndev->npinfo;
 665                 atomic_inc(&npinfo->refcnt);
 666         }
 667
 668         if (!ndev->poll_controller) {
 669                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
 670                        np->name, np->dev_name);
 671                 err = -ENOTSUPP;
 672                 goto release;
 673         }
 674
 675         if (!netif_running(ndev)) {
 676                 unsigned long atmost, atleast;
 677
 678                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
 679                        np->name, np->dev_name);
 680
 681                 rtnl_lock();
 682                 err = dev_open(ndev);
 683                 rtnl_unlock();
 684
 685                 if (err) {
 686                         printk(KERN_ERR "%s: failed to open %s\n",
 687                                np->name, ndev->name);
 688                         goto release;
 689                 }
 690
 691                 atleast = jiffies + HZ/10;
 692                 atmost = jiffies + 4*HZ;
 693                 while (!netif_carrier_ok(ndev)) {
 694                         if (time_after(jiffies, atmost)) {
 695                                 printk(KERN_NOTICE
 696                                        "%s: timeout waiting for carrier\n",
 697                                        np->name);
 698                                 break;
 699                         }
 700                         cond_resched();
 701                 }
 702
 703                 /* If carrier appears to come up instantly, we don't
 704                  * trust it and pause so that we don't pump all our
 705                  * queued console messages into the bitbucket.
 706                  */
 707
 708                 if (time_before(jiffies, atleast)) {
 709                         printk(KERN_NOTICE "%s: carrier detect appears"
 710                                " untrustworthy, waiting 4 seconds\n",
 711                                np->name);
 712                         msleep(4000);
 713                 }
 714         }
 715
 716         if (is_zero_ether_addr(np->local_mac) && ndev->dev_addr)
 717                 memcpy(np->local_mac, ndev->dev_addr, 6);
 718
 719         if (!np->local_ip) {
 720                 rcu_read_lock();
 721                 in_dev = __in_dev_get_rcu(ndev);
 722
 723                 if (!in_dev || !in_dev->ifa_list) {
 724                         rcu_read_unlock();
 725                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
 726                                np->name, np->dev_name);
 727                         err = -EDESTADDRREQ;
 728                         goto release;
 729                 }
 730
 731                 np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
 732                 rcu_read_unlock();
 733                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 734                        np->name, HIPQUAD(np->local_ip));
 735         }
 736
 737         if (np->rx_hook) {
 738                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 739                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
 740                 npinfo->rx_np = np;
 741                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 742         }
 743
 744         /* fill up the skb queue */
 745         refill_skbs();
 746
 747         /* last thing to do is link it to the net device structure */
 748         ndev->npinfo = npinfo;
 749
 750         /* avoid racing with NAPI reading npinfo */
 751         synchronize_rcu();
 752
 753         return 0;
 754
 755  release:
 756         if (!ndev->npinfo)
 757                 kfree(npinfo);
 758         np->dev = NULL;
 759         dev_put(ndev);
 760         return err;
 761 }
 762
 763 static int __init netpoll_init(void)
 764 {
 765         skb_queue_head_init(&skb_pool);
 766         return 0;
 767 }
 768 core_initcall(netpoll_init);
 769
 770 void netpoll_cleanup(struct netpoll *np)
 771 {
 772         struct netpoll_info *npinfo;
 773         unsigned long flags;
 774
 775         if (np->dev) {
 776                 npinfo = np->dev->npinfo;
 777                 if (npinfo) {
 778                         if (npinfo->rx_np == np) {
 779                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 780                                 npinfo->rx_np = NULL;
 781                                 npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
 782                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 783                         }
 784
 785                         np->dev->npinfo = NULL;
 786                         if (atomic_dec_and_test(&npinfo->refcnt)) {
 787                                 skb_queue_purge(&npinfo->arp_tx);
 788                                 skb_queue_purge(&npinfo->txq);
 789                                 cancel_delayed_work(&npinfo->tx_work);
 790                                 flush_scheduled_work();
 791
 792                                 /* clean after last, unfinished work */
 793                                 if (!skb_queue_empty(&npinfo->txq)) {
 794                                         struct sk_buff *skb;
 795                                         skb = __skb_dequeue(&npinfo->txq);
 796                                         kfree_skb(skb);
 797                                 }
 798                                 kfree(npinfo);
 799                         }
 800                 }
 801
 802                 dev_put(np->dev);
 803         }
 804
 805         np->dev = NULL;
 806 }
 807
 808 int netpoll_trap(void)
 809 {
 810         return atomic_read(&trapped);
 811 }
 812
 813 void netpoll_set_trap(int trap)
 814 {
 815         if (trap)
 816                 atomic_inc(&trapped);
 817         else
 818                 atomic_dec(&trapped);
 819 }
 820
 821 EXPORT_SYMBOL(netpoll_set_trap);
 822 EXPORT_SYMBOL(netpoll_trap);
 823 EXPORT_SYMBOL(netpoll_parse_options);
 824 EXPORT_SYMBOL(netpoll_setup);
 825 EXPORT_SYMBOL(netpoll_cleanup);
 826 EXPORT_SYMBOL(netpoll_send_udp);
 827 EXPORT_SYMBOL(netpoll_poll);