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 DEFINE_SPINLOCK(skb_list_lock);
  40 static int nr_skbs;
  41 static struct sk_buff *skbs;
  42
  43 static DEFINE_SPINLOCK(queue_lock);
  44 static int queue_depth;
  45 static struct sk_buff *queue_head, *queue_tail;
  46
  47 static atomic_t trapped;
  48
  49 #define NETPOLL_RX_ENABLED  1
  50 #define NETPOLL_RX_DROP     2
  51
  52 #define MAX_SKB_SIZE \
  53                 (MAX_UDP_CHUNK + sizeof(struct udphdr) + \
  54                                 sizeof(struct iphdr) + sizeof(struct ethhdr))
  55
  56 static void zap_completion_queue(void);
  57
  58 static void queue_process(void *p)
  59 {
  60         unsigned long flags;
  61         struct sk_buff *skb;
  62
  63         while (queue_head) {
  64                 spin_lock_irqsave(&queue_lock, flags);
  65
  66                 skb = queue_head;
  67                 queue_head = skb->next;
  68                 if (skb == queue_tail)
  69                         queue_head = NULL;
  70
  71                 queue_depth--;
  72
  73                 spin_unlock_irqrestore(&queue_lock, flags);
  74
  75                 dev_queue_xmit(skb);
  76         }
  77 }
  78
  79 static DECLARE_WORK(send_queue, queue_process, NULL);
  80
  81 void netpoll_queue(struct sk_buff *skb)
  82 {
  83         unsigned long flags;
  84
  85         if (queue_depth == MAX_QUEUE_DEPTH) {
  86                 __kfree_skb(skb);
  87                 return;
  88         }
  89
  90         spin_lock_irqsave(&queue_lock, flags);
  91         if (!queue_head)
  92                 queue_head = skb;
  93         else
  94                 queue_tail->next = skb;
  95         queue_tail = skb;
  96         queue_depth++;
  97         spin_unlock_irqrestore(&queue_lock, flags);
  98
  99         schedule_work(&send_queue);
 100 }
 101
 102 static int checksum_udp(struct sk_buff *skb, struct udphdr *uh,
 103                              unsigned short ulen, u32 saddr, u32 daddr)
 104 {
 105         unsigned int psum;
 106
 107         if (uh->check == 0 || skb->ip_summed == CHECKSUM_UNNECESSARY)
 108                 return 0;
 109
 110         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
 111
 112         if (skb->ip_summed == CHECKSUM_HW &&
 113             !(u16)csum_fold(csum_add(psum, skb->csum)))
 114                 return 0;
 115
 116         skb->csum = psum;
 117
 118         return __skb_checksum_complete(skb);
 119 }
 120
 121 /*
 122  * Check whether delayed processing was scheduled for our NIC. If so,
 123  * we attempt to grab the poll lock and use ->poll() to pump the card.
 124  * If this fails, either we've recursed in ->poll() or it's already
 125  * running on another CPU.
 126  *
 127  * Note: we don't mask interrupts with this lock because we're using
 128  * trylock here and interrupts are already disabled in the softirq
 129  * case. Further, we test the poll_owner to avoid recursion on UP
 130  * systems where the lock doesn't exist.
 131  *
 132  * In cases where there is bi-directional communications, reading only
 133  * one message at a time can lead to packets being dropped by the
 134  * network adapter, forcing superfluous retries and possibly timeouts.
 135  * Thus, we set our budget to greater than 1.
 136  */
 137 static void poll_napi(struct netpoll *np)
 138 {
 139         struct netpoll_info *npinfo = np->dev->npinfo;
 140         int budget = 16;
 141
 142         if (test_bit(__LINK_STATE_RX_SCHED, &np->dev->state) &&
 143             npinfo->poll_owner != smp_processor_id() &&
 144             spin_trylock(&npinfo->poll_lock)) {
 145                 npinfo->rx_flags |= NETPOLL_RX_DROP;
 146                 atomic_inc(&trapped);
 147
 148                 np->dev->poll(np->dev, &budget);
 149
 150                 atomic_dec(&trapped);
 151                 npinfo->rx_flags &= ~NETPOLL_RX_DROP;
 152                 spin_unlock(&npinfo->poll_lock);
 153         }
 154 }
 155
 156 void netpoll_poll(struct netpoll *np)
 157 {
 158         if(!np->dev || !netif_running(np->dev) || !np->dev->poll_controller)
 159                 return;
 160
 161         /* Process pending work on NIC */
 162         np->dev->poll_controller(np->dev);
 163         if (np->dev->poll)
 164                 poll_napi(np);
 165
 166         zap_completion_queue();
 167 }
 168
 169 static void refill_skbs(void)
 170 {
 171         struct sk_buff *skb;
 172         unsigned long flags;
 173
 174         spin_lock_irqsave(&skb_list_lock, flags);
 175         while (nr_skbs < MAX_SKBS) {
 176                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
 177                 if (!skb)
 178                         break;
 179
 180                 skb->next = skbs;
 181                 skbs = skb;
 182                 nr_skbs++;
 183         }
 184         spin_unlock_irqrestore(&skb_list_lock, flags);
 185 }
 186
 187 static void zap_completion_queue(void)
 188 {
 189         unsigned long flags;
 190         struct softnet_data *sd = &get_cpu_var(softnet_data);
 191
 192         if (sd->completion_queue) {
 193                 struct sk_buff *clist;
 194
 195                 local_irq_save(flags);
 196                 clist = sd->completion_queue;
 197                 sd->completion_queue = NULL;
 198                 local_irq_restore(flags);
 199
 200                 while (clist != NULL) {
 201                         struct sk_buff *skb = clist;
 202                         clist = clist->next;
 203                         if(skb->destructor)
 204                                 dev_kfree_skb_any(skb); /* put this one back */
 205                         else
 206                                 __kfree_skb(skb);
 207                 }
 208         }
 209
 210         put_cpu_var(softnet_data);
 211 }
 212
 213 static struct sk_buff * find_skb(struct netpoll *np, int len, int reserve)
 214 {
 215         int once = 1, count = 0;
 216         unsigned long flags;
 217         struct sk_buff *skb = NULL;
 218
 219         zap_completion_queue();
 220 repeat:
 221         if (nr_skbs < MAX_SKBS)
 222                 refill_skbs();
 223
 224         skb = alloc_skb(len, GFP_ATOMIC);
 225
 226         if (!skb) {
 227                 spin_lock_irqsave(&skb_list_lock, flags);
 228                 skb = skbs;
 229                 if (skb) {
 230                         skbs = skb->next;
 231                         skb->next = NULL;
 232                         nr_skbs--;
 233                 }
 234                 spin_unlock_irqrestore(&skb_list_lock, flags);
 235         }
 236
 237         if(!skb) {
 238                 count++;
 239                 if (once && (count == 1000000)) {
 240                         printk("out of netpoll skbs!\n");
 241                         once = 0;
 242                 }
 243                 netpoll_poll(np);
 244                 goto repeat;
 245         }
 246
 247         atomic_set(&skb->users, 1);
 248         skb_reserve(skb, reserve);
 249         return skb;
 250 }
 251
 252 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 253 {
 254         int status;
 255         struct netpoll_info *npinfo;
 256
 257         if (!np || !np->dev || !netif_running(np->dev)) {
 258                 __kfree_skb(skb);
 259                 return;
 260         }
 261
 262         npinfo = np->dev->npinfo;
 263
 264         /* avoid recursion */
 265         if (npinfo->poll_owner == smp_processor_id() ||
 266             np->dev->xmit_lock_owner == smp_processor_id()) {
 267                 if (np->drop)
 268                         np->drop(skb);
 269                 else
 270                         __kfree_skb(skb);
 271                 return;
 272         }
 273
 274         do {
 275                 npinfo->tries--;
 276                 netif_tx_lock(np->dev);
 277
 278                 /*
 279                  * network drivers do not expect to be called if the queue is
 280                  * stopped.
 281                  */
 282                 if (netif_queue_stopped(np->dev)) {
 283                         netif_tx_unlock(np->dev);
 284                         netpoll_poll(np);
 285                         udelay(50);
 286                         continue;
 287                 }
 288
 289                 status = np->dev->hard_start_xmit(skb, np->dev);
 290                 netif_tx_unlock(np->dev);
 291
 292                 /* success */
 293                 if(!status) {
 294                         npinfo->tries = MAX_RETRIES; /* reset */
 295                         return;
 296                 }
 297
 298                 /* transmit busy */
 299                 netpoll_poll(np);
 300                 udelay(50);
 301         } while (npinfo->tries > 0);
 302 }
 303
 304 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 305 {
 306         int total_len, eth_len, ip_len, udp_len;
 307         struct sk_buff *skb;
 308         struct udphdr *udph;
 309         struct iphdr *iph;
 310         struct ethhdr *eth;
 311
 312         udp_len = len + sizeof(*udph);
 313         ip_len = eth_len = udp_len + sizeof(*iph);
 314         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
 315
 316         skb = find_skb(np, total_len, total_len - len);
 317         if (!skb)
 318                 return;
 319
 320         memcpy(skb->data, msg, len);
 321         skb->len += len;
 322
 323         udph = (struct udphdr *) skb_push(skb, sizeof(*udph));
 324         udph->source = htons(np->local_port);
 325         udph->dest = htons(np->remote_port);
 326         udph->len = htons(udp_len);
 327         udph->check = 0;
 328
 329         iph = (struct iphdr *)skb_push(skb, sizeof(*iph));
 330
 331         /* iph->version = 4; iph->ihl = 5; */
 332         put_unaligned(0x45, (unsigned char *)iph);
 333         iph->tos      = 0;
 334         put_unaligned(htons(ip_len), &(iph->tot_len));
 335         iph->id       = 0;
 336         iph->frag_off = 0;
 337         iph->ttl      = 64;
 338         iph->protocol = IPPROTO_UDP;
 339         iph->check    = 0;
 340         put_unaligned(htonl(np->local_ip), &(iph->saddr));
 341         put_unaligned(htonl(np->remote_ip), &(iph->daddr));
 342         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 343
 344         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 345
 346         eth->h_proto = htons(ETH_P_IP);
 347         memcpy(eth->h_source, np->local_mac, 6);
 348         memcpy(eth->h_dest, np->remote_mac, 6);
 349
 350         skb->dev = np->dev;
 351
 352         netpoll_send_skb(np, skb);
 353 }
 354
 355 static void arp_reply(struct sk_buff *skb)
 356 {
 357         struct netpoll_info *npinfo = skb->dev->npinfo;
 358         struct arphdr *arp;
 359         unsigned char *arp_ptr;
 360         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
 361         u32 sip, tip;
 362         struct sk_buff *send_skb;
 363         struct netpoll *np = NULL;
 364
 365         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
 366                 np = npinfo->rx_np;
 367         if (!np)
 368                 return;
 369
 370         /* No arp on this interface */
 371         if (skb->dev->flags & IFF_NOARP)
 372                 return;
 373
 374         if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
 375                                  (2 * skb->dev->addr_len) +
 376                                  (2 * sizeof(u32)))))
 377                 return;
 378
 379         skb->h.raw = skb->nh.raw = skb->data;
 380         arp = skb->nh.arph;
 381
 382         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 383              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 384             arp->ar_pro != htons(ETH_P_IP) ||
 385             arp->ar_op != htons(ARPOP_REQUEST))
 386                 return;
 387
 388         arp_ptr = (unsigned char *)(arp+1) + skb->dev->addr_len;
 389         memcpy(&sip, arp_ptr, 4);
 390         arp_ptr += 4 + skb->dev->addr_len;
 391         memcpy(&tip, arp_ptr, 4);
 392
 393         /* Should we ignore arp? */
 394         if (tip != htonl(np->local_ip) || LOOPBACK(tip) || MULTICAST(tip))
 395                 return;
 396
 397         size = sizeof(struct arphdr) + 2 * (skb->dev->addr_len + 4);
 398         send_skb = find_skb(np, size + LL_RESERVED_SPACE(np->dev),
 399                             LL_RESERVED_SPACE(np->dev));
 400
 401         if (!send_skb)
 402                 return;
 403
 404         send_skb->nh.raw = send_skb->data;
 405         arp = (struct arphdr *) skb_put(send_skb, size);
 406         send_skb->dev = skb->dev;
 407         send_skb->protocol = htons(ETH_P_ARP);
 408
 409         /* Fill the device header for the ARP frame */
 410
 411         if (np->dev->hard_header &&
 412             np->dev->hard_header(send_skb, skb->dev, ptype,
 413                                        np->remote_mac, np->local_mac,
 414                                        send_skb->len) < 0) {
 415                 kfree_skb(send_skb);
 416                 return;
 417         }
 418
 419         /*
 420          * Fill out the arp protocol part.
 421          *
 422          * we only support ethernet device type,
 423          * which (according to RFC 1390) should always equal 1 (Ethernet).
 424          */
 425
 426         arp->ar_hrd = htons(np->dev->type);
 427         arp->ar_pro = htons(ETH_P_IP);
 428         arp->ar_hln = np->dev->addr_len;
 429         arp->ar_pln = 4;
 430         arp->ar_op = htons(type);
 431
 432         arp_ptr=(unsigned char *)(arp + 1);
 433         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
 434         arp_ptr += np->dev->addr_len;
 435         memcpy(arp_ptr, &tip, 4);
 436         arp_ptr += 4;
 437         memcpy(arp_ptr, np->remote_mac, np->dev->addr_len);
 438         arp_ptr += np->dev->addr_len;
 439         memcpy(arp_ptr, &sip, 4);
 440
 441         netpoll_send_skb(np, send_skb);
 442 }
 443
 444 int __netpoll_rx(struct sk_buff *skb)
 445 {
 446         int proto, len, ulen;
 447         struct iphdr *iph;
 448         struct udphdr *uh;
 449         struct netpoll *np = skb->dev->npinfo->rx_np;
 450
 451         if (!np)
 452                 goto out;
 453         if (skb->dev->type != ARPHRD_ETHER)
 454                 goto out;
 455
 456         /* check if netpoll clients need ARP */
 457         if (skb->protocol == __constant_htons(ETH_P_ARP) &&
 458             atomic_read(&trapped)) {
 459                 arp_reply(skb);
 460                 return 1;
 461         }
 462
 463         proto = ntohs(eth_hdr(skb)->h_proto);
 464         if (proto != ETH_P_IP)
 465                 goto out;
 466         if (skb->pkt_type == PACKET_OTHERHOST)
 467                 goto out;
 468         if (skb_shared(skb))
 469                 goto out;
 470
 471         iph = (struct iphdr *)skb->data;
 472         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 473                 goto out;
 474         if (iph->ihl < 5 || iph->version != 4)
 475                 goto out;
 476         if (!pskb_may_pull(skb, iph->ihl*4))
 477                 goto out;
 478         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
 479                 goto out;
 480
 481         len = ntohs(iph->tot_len);
 482         if (skb->len < len || len < iph->ihl*4)
 483                 goto out;
 484
 485         if (iph->protocol != IPPROTO_UDP)
 486                 goto out;
 487
 488         len -= iph->ihl*4;
 489         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
 490         ulen = ntohs(uh->len);
 491
 492         if (ulen != len)
 493                 goto out;
 494         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
 495                 goto out;
 496         if (np->local_ip && np->local_ip != ntohl(iph->daddr))
 497                 goto out;
 498         if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
 499                 goto out;
 500         if (np->local_port && np->local_port != ntohs(uh->dest))
 501                 goto out;
 502
 503         np->rx_hook(np, ntohs(uh->source),
 504                     (char *)(uh+1),
 505                     ulen - sizeof(struct udphdr));
 506
 507         kfree_skb(skb);
 508         return 1;
 509
 510 out:
 511         if (atomic_read(&trapped)) {
 512                 kfree_skb(skb);
 513                 return 1;
 514         }
 515
 516         return 0;
 517 }
 518
 519 int netpoll_parse_options(struct netpoll *np, char *opt)
 520 {
 521         char *cur=opt, *delim;
 522
 523         if(*cur != '@') {
 524                 if ((delim = strchr(cur, '@')) == NULL)
 525                         goto parse_failed;
 526                 *delim=0;
 527                 np->local_port=simple_strtol(cur, NULL, 10);
 528                 cur=delim;
 529         }
 530         cur++;
 531         printk(KERN_INFO "%s: local port %d\n", np->name, np->local_port);
 532
 533         if(*cur != '/') {
 534                 if ((delim = strchr(cur, '/')) == NULL)
 535                         goto parse_failed;
 536                 *delim=0;
 537                 np->local_ip=ntohl(in_aton(cur));
 538                 cur=delim;
 539
 540                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 541                        np->name, HIPQUAD(np->local_ip));
 542         }
 543         cur++;
 544
 545         if ( *cur != ',') {
 546                 /* parse out dev name */
 547                 if ((delim = strchr(cur, ',')) == NULL)
 548                         goto parse_failed;
 549                 *delim=0;
 550                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 551                 cur=delim;
 552         }
 553         cur++;
 554
 555         printk(KERN_INFO "%s: interface %s\n", np->name, np->dev_name);
 556
 557         if ( *cur != '@' ) {
 558                 /* dst port */
 559                 if ((delim = strchr(cur, '@')) == NULL)
 560                         goto parse_failed;
 561                 *delim=0;
 562                 np->remote_port=simple_strtol(cur, NULL, 10);
 563                 cur=delim;
 564         }
 565         cur++;
 566         printk(KERN_INFO "%s: remote port %d\n", np->name, np->remote_port);
 567
 568         /* dst ip */
 569         if ((delim = strchr(cur, '/')) == NULL)
 570                 goto parse_failed;
 571         *delim=0;
 572         np->remote_ip=ntohl(in_aton(cur));
 573         cur=delim+1;
 574
 575         printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
 576                        np->name, HIPQUAD(np->remote_ip));
 577
 578         if( *cur != 0 )
 579         {
 580                 /* MAC address */
 581                 if ((delim = strchr(cur, ':')) == NULL)
 582                         goto parse_failed;
 583                 *delim=0;
 584                 np->remote_mac[0]=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[1]=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[2]=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[3]=simple_strtol(cur, NULL, 16);
 600                 cur=delim+1;
 601                 if ((delim = strchr(cur, ':')) == NULL)
 602                         goto parse_failed;
 603                 *delim=0;
 604                 np->remote_mac[4]=simple_strtol(cur, NULL, 16);
 605                 cur=delim+1;
 606                 np->remote_mac[5]=simple_strtol(cur, NULL, 16);
 607         }
 608
 609         printk(KERN_INFO "%s: remote ethernet address "
 610                "%02x:%02x:%02x:%02x:%02x:%02x\n",
 611                np->name,
 612                np->remote_mac[0],
 613                np->remote_mac[1],
 614                np->remote_mac[2],
 615                np->remote_mac[3],
 616                np->remote_mac[4],
 617                np->remote_mac[5]);
 618
 619         return 0;
 620
 621  parse_failed:
 622         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
 623                np->name, cur);
 624         return -1;
 625 }
 626
 627 int netpoll_setup(struct netpoll *np)
 628 {
 629         struct net_device *ndev = NULL;
 630         struct in_device *in_dev;
 631         struct netpoll_info *npinfo;
 632         unsigned long flags;
 633
 634         if (np->dev_name)
 635                 ndev = dev_get_by_name(np->dev_name);
 636         if (!ndev) {
 637                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
 638                        np->name, np->dev_name);
 639                 return -1;
 640         }
 641
 642         np->dev = ndev;
 643         if (!ndev->npinfo) {
 644                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
 645                 if (!npinfo)
 646                         goto release;
 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         } else
 655                 npinfo = ndev->npinfo;
 656
 657         if (!ndev->poll_controller) {
 658                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
 659                        np->name, np->dev_name);
 660                 goto release;
 661         }
 662
 663         if (!netif_running(ndev)) {
 664                 unsigned long atmost, atleast;
 665
 666                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
 667                        np->name, np->dev_name);
 668
 669                 rtnl_lock();
 670                 if (dev_change_flags(ndev, ndev->flags | IFF_UP) < 0) {
 671                         printk(KERN_ERR "%s: failed to open %s\n",
 672                                np->name, np->dev_name);
 673                         rtnl_unlock();
 674                         goto release;
 675                 }
 676                 rtnl_unlock();
 677
 678                 atleast = jiffies + HZ/10;
 679                 atmost = jiffies + 4*HZ;
 680                 while (!netif_carrier_ok(ndev)) {
 681                         if (time_after(jiffies, atmost)) {
 682                                 printk(KERN_NOTICE
 683                                        "%s: timeout waiting for carrier\n",
 684                                        np->name);
 685                                 break;
 686                         }
 687                         cond_resched();
 688                 }
 689
 690                 /* If carrier appears to come up instantly, we don't
 691                  * trust it and pause so that we don't pump all our
 692                  * queued console messages into the bitbucket.
 693                  */
 694
 695                 if (time_before(jiffies, atleast)) {
 696                         printk(KERN_NOTICE "%s: carrier detect appears"
 697                                " untrustworthy, waiting 4 seconds\n",
 698                                np->name);
 699                         msleep(4000);
 700                 }
 701         }
 702
 703         if (is_zero_ether_addr(np->local_mac) && ndev->dev_addr)
 704                 memcpy(np->local_mac, ndev->dev_addr, 6);
 705
 706         if (!np->local_ip) {
 707                 rcu_read_lock();
 708                 in_dev = __in_dev_get_rcu(ndev);
 709
 710                 if (!in_dev || !in_dev->ifa_list) {
 711                         rcu_read_unlock();
 712                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
 713                                np->name, np->dev_name);
 714                         goto release;
 715                 }
 716
 717                 np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
 718                 rcu_read_unlock();
 719                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
 720                        np->name, HIPQUAD(np->local_ip));
 721         }
 722
 723         if (np->rx_hook) {
 724                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 725                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
 726                 npinfo->rx_np = np;
 727                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 728         }
 729
 730         /* fill up the skb queue */
 731         refill_skbs();
 732
 733         /* last thing to do is link it to the net device structure */
 734         ndev->npinfo = npinfo;
 735
 736         /* avoid racing with NAPI reading npinfo */
 737         synchronize_rcu();
 738
 739         return 0;
 740
 741  release:
 742         if (!ndev->npinfo)
 743                 kfree(npinfo);
 744         np->dev = NULL;
 745         dev_put(ndev);
 746         return -1;
 747 }
 748
 749 void netpoll_cleanup(struct netpoll *np)
 750 {
 751         struct netpoll_info *npinfo;
 752         unsigned long flags;
 753
 754         if (np->dev) {
 755                 npinfo = np->dev->npinfo;
 756                 if (npinfo && npinfo->rx_np == np) {
 757                         spin_lock_irqsave(&npinfo->rx_lock, flags);
 758                         npinfo->rx_np = NULL;
 759                         npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
 760                         spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 761                 }
 762                 dev_put(np->dev);
 763         }
 764
 765         np->dev = NULL;
 766 }
 767
 768 int netpoll_trap(void)
 769 {
 770         return atomic_read(&trapped);
 771 }
 772
 773 void netpoll_set_trap(int trap)
 774 {
 775         if (trap)
 776                 atomic_inc(&trapped);
 777         else
 778                 atomic_dec(&trapped);
 779 }
 780
 781 EXPORT_SYMBOL(netpoll_set_trap);
 782 EXPORT_SYMBOL(netpoll_trap);
 783 EXPORT_SYMBOL(netpoll_parse_options);
 784 EXPORT_SYMBOL(netpoll_setup);
 785 EXPORT_SYMBOL(netpoll_cleanup);
 786 EXPORT_SYMBOL(netpoll_send_udp);
 787 EXPORT_SYMBOL(netpoll_poll);
 788 EXPORT_SYMBOL(netpoll_queue);