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 #include <trace/napi.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                 const struct net_device_ops *ops = dev->netdev_ops;
  63                 struct netdev_queue *txq;
  64
  65                 if (!netif_device_present(dev) || !netif_running(dev)) {
  66                         __kfree_skb(skb);
  67                         continue;
  68                 }
  69
  70                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
  71
  72                 local_irq_save(flags);
  73                 __netif_tx_lock(txq, smp_processor_id());
  74                 if (netif_tx_queue_stopped(txq) ||
  75                     netif_tx_queue_frozen(txq) ||
  76                     ops->ndo_start_xmit(skb, dev) != NETDEV_TX_OK) {
  77                         skb_queue_head(&npinfo->txq, skb);
  78                         __netif_tx_unlock(txq);
  79                         local_irq_restore(flags);
  80
  81                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
  82                         return;
  83                 }
  84                 __netif_tx_unlock(txq);
  85                 local_irq_restore(flags);
  86         }
  87 }
  88
  89 static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
  90                             unsigned short ulen, __be32 saddr, __be32 daddr)
  91 {
  92         __wsum psum;
  93
  94         if (uh->check == 0 || skb_csum_unnecessary(skb))
  95                 return 0;
  96
  97         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
  98
  99         if (skb->ip_summed == CHECKSUM_COMPLETE &&
 100             !csum_fold(csum_add(psum, skb->csum)))
 101                 return 0;
 102
 103         skb->csum = psum;
 104
 105         return __skb_checksum_complete(skb);
 106 }
 107
 108 /*
 109  * Check whether delayed processing was scheduled for our NIC. If so,
 110  * we attempt to grab the poll lock and use ->poll() to pump the card.
 111  * If this fails, either we've recursed in ->poll() or it's already
 112  * running on another CPU.
 113  *
 114  * Note: we don't mask interrupts with this lock because we're using
 115  * trylock here and interrupts are already disabled in the softirq
 116  * case. Further, we test the poll_owner to avoid recursion on UP
 117  * systems where the lock doesn't exist.
 118  *
 119  * In cases where there is bi-directional communications, reading only
 120  * one message at a time can lead to packets being dropped by the
 121  * network adapter, forcing superfluous retries and possibly timeouts.
 122  * Thus, we set our budget to greater than 1.
 123  */
 124 static int poll_one_napi(struct netpoll_info *npinfo,
 125                          struct napi_struct *napi, int budget)
 126 {
 127         int work;
 128
 129         /* net_rx_action's ->poll() invocations and our's are
 130          * synchronized by this test which is only made while
 131          * holding the napi->poll_lock.
 132          */
 133         if (!test_bit(NAPI_STATE_SCHED, &napi->state))
 134                 return budget;
 135
 136         npinfo->rx_flags |= NETPOLL_RX_DROP;
 137         atomic_inc(&trapped);
 138         set_bit(NAPI_STATE_NPSVC, &napi->state);
 139
 140         work = napi->poll(napi, budget);
 141         trace_napi_poll(napi->dev);
 142
 143         clear_bit(NAPI_STATE_NPSVC, &napi->state);
 144         atomic_dec(&trapped);
 145         npinfo->rx_flags &= ~NETPOLL_RX_DROP;
 146
 147         return budget - work;
 148 }
 149
 150 static void poll_napi(struct net_device *dev)
 151 {
 152         struct napi_struct *napi;
 153         int budget = 16;
 154
 155         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 156                 if (napi->poll_owner != smp_processor_id() &&
 157                     spin_trylock(&napi->poll_lock)) {
 158                         budget = poll_one_napi(dev->npinfo, napi, budget);
 159                         spin_unlock(&napi->poll_lock);
 160
 161                         if (!budget)
 162                                 break;
 163                 }
 164         }
 165 }
 166
 167 static void service_arp_queue(struct netpoll_info *npi)
 168 {
 169         if (npi) {
 170                 struct sk_buff *skb;
 171
 172                 while ((skb = skb_dequeue(&npi->arp_tx)))
 173                         arp_reply(skb);
 174         }
 175 }
 176
 177 void netpoll_poll(struct netpoll *np)
 178 {
 179         struct net_device *dev = np->dev;
 180         const struct net_device_ops *ops;
 181
 182         if (!dev || !netif_running(dev))
 183                 return;
 184
 185         ops = dev->netdev_ops;
 186         if (!ops->ndo_poll_controller)
 187                 return;
 188
 189         /* Process pending work on NIC */
 190         ops->ndo_poll_controller(dev);
 191
 192         poll_napi(dev);
 193
 194         service_arp_queue(dev->npinfo);
 195
 196         zap_completion_queue();
 197 }
 198
 199 static void refill_skbs(void)
 200 {
 201         struct sk_buff *skb;
 202         unsigned long flags;
 203
 204         spin_lock_irqsave(&skb_pool.lock, flags);
 205         while (skb_pool.qlen < MAX_SKBS) {
 206                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
 207                 if (!skb)
 208                         break;
 209
 210                 __skb_queue_tail(&skb_pool, skb);
 211         }
 212         spin_unlock_irqrestore(&skb_pool.lock, flags);
 213 }
 214
 215 static void zap_completion_queue(void)
 216 {
 217         unsigned long flags;
 218         struct softnet_data *sd = &get_cpu_var(softnet_data);
 219
 220         if (sd->completion_queue) {
 221                 struct sk_buff *clist;
 222
 223                 local_irq_save(flags);
 224                 clist = sd->completion_queue;
 225                 sd->completion_queue = NULL;
 226                 local_irq_restore(flags);
 227
 228                 while (clist != NULL) {
 229                         struct sk_buff *skb = clist;
 230                         clist = clist->next;
 231                         if (skb->destructor) {
 232                                 atomic_inc(&skb->users);
 233                                 dev_kfree_skb_any(skb); /* put this one back */
 234                         } else {
 235                                 __kfree_skb(skb);
 236                         }
 237                 }
 238         }
 239
 240         put_cpu_var(softnet_data);
 241 }
 242
 243 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
 244 {
 245         int count = 0;
 246         struct sk_buff *skb;
 247
 248         zap_completion_queue();
 249         refill_skbs();
 250 repeat:
 251
 252         skb = alloc_skb(len, GFP_ATOMIC);
 253         if (!skb)
 254                 skb = skb_dequeue(&skb_pool);
 255
 256         if (!skb) {
 257                 if (++count < 10) {
 258                         netpoll_poll(np);
 259                         goto repeat;
 260                 }
 261                 return NULL;
 262         }
 263
 264         atomic_set(&skb->users, 1);
 265         skb_reserve(skb, reserve);
 266         return skb;
 267 }
 268
 269 static int netpoll_owner_active(struct net_device *dev)
 270 {
 271         struct napi_struct *napi;
 272
 273         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 274                 if (napi->poll_owner == smp_processor_id())
 275                         return 1;
 276         }
 277         return 0;
 278 }
 279
 280 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 281 {
 282         int status = NETDEV_TX_BUSY;
 283         unsigned long tries;
 284         struct net_device *dev = np->dev;
 285         const struct net_device_ops *ops = dev->netdev_ops;
 286         struct netpoll_info *npinfo = np->dev->npinfo;
 287
 288         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
 289                 __kfree_skb(skb);
 290                 return;
 291         }
 292
 293         /* don't get messages out of order, and no recursion */
 294         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
 295                 struct netdev_queue *txq;
 296                 unsigned long flags;
 297
 298                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
 299
 300                 local_irq_save(flags);
 301                 /* try until next clock tick */
 302                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
 303                      tries > 0; --tries) {
 304                         if (__netif_tx_trylock(txq)) {
 305                                 if (!netif_tx_queue_stopped(txq))
 306                                         status = ops->ndo_start_xmit(skb, dev);
 307                                 __netif_tx_unlock(txq);
 308
 309                                 if (status == NETDEV_TX_OK)
 310                                         break;
 311
 312                         }
 313
 314                         /* tickle device maybe there is some cleanup */
 315                         netpoll_poll(np);
 316
 317                         udelay(USEC_PER_POLL);
 318                 }
 319                 local_irq_restore(flags);
 320         }
 321
 322         if (status != NETDEV_TX_OK) {
 323                 skb_queue_tail(&npinfo->txq, skb);
 324                 schedule_delayed_work(&npinfo->tx_work,0);
 325         }
 326 }
 327
 328 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 329 {
 330         int total_len, eth_len, ip_len, udp_len;
 331         struct sk_buff *skb;
 332         struct udphdr *udph;
 333         struct iphdr *iph;
 334         struct ethhdr *eth;
 335
 336         udp_len = len + sizeof(*udph);
 337         ip_len = eth_len = udp_len + sizeof(*iph);
 338         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
 339
 340         skb = find_skb(np, total_len, total_len - len);
 341         if (!skb)
 342                 return;
 343
 344         skb_copy_to_linear_data(skb, msg, len);
 345         skb->len += len;
 346
 347         skb_push(skb, sizeof(*udph));
 348         skb_reset_transport_header(skb);
 349         udph = udp_hdr(skb);
 350         udph->source = htons(np->local_port);
 351         udph->dest = htons(np->remote_port);
 352         udph->len = htons(udp_len);
 353         udph->check = 0;
 354         udph->check = csum_tcpudp_magic(np->local_ip,
 355                                         np->remote_ip,
 356                                         udp_len, IPPROTO_UDP,
 357                                         csum_partial(udph, udp_len, 0));
 358         if (udph->check == 0)
 359                 udph->check = CSUM_MANGLED_0;
 360
 361         skb_push(skb, sizeof(*iph));
 362         skb_reset_network_header(skb);
 363         iph = ip_hdr(skb);
 364
 365         /* iph->version = 4; iph->ihl = 5; */
 366         put_unaligned(0x45, (unsigned char *)iph);
 367         iph->tos      = 0;
 368         put_unaligned(htons(ip_len), &(iph->tot_len));
 369         iph->id       = 0;
 370         iph->frag_off = 0;
 371         iph->ttl      = 64;
 372         iph->protocol = IPPROTO_UDP;
 373         iph->check    = 0;
 374         put_unaligned(np->local_ip, &(iph->saddr));
 375         put_unaligned(np->remote_ip, &(iph->daddr));
 376         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 377
 378         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
 379         skb_reset_mac_header(skb);
 380         skb->protocol = eth->h_proto = htons(ETH_P_IP);
 381         memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN);
 382         memcpy(eth->h_dest, np->remote_mac, ETH_ALEN);
 383
 384         skb->dev = np->dev;
 385
 386         netpoll_send_skb(np, skb);
 387 }
 388
 389 static void arp_reply(struct sk_buff *skb)
 390 {
 391         struct netpoll_info *npinfo = skb->dev->npinfo;
 392         struct arphdr *arp;
 393         unsigned char *arp_ptr;
 394         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
 395         __be32 sip, tip;
 396         unsigned char *sha;
 397         struct sk_buff *send_skb;
 398         struct netpoll *np = NULL;
 399
 400         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
 401                 np = npinfo->rx_np;
 402         if (!np)
 403                 return;
 404
 405         /* No arp on this interface */
 406         if (skb->dev->flags & IFF_NOARP)
 407                 return;
 408
 409         if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
 410                 return;
 411
 412         skb_reset_network_header(skb);
 413         skb_reset_transport_header(skb);
 414         arp = arp_hdr(skb);
 415
 416         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
 417              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
 418             arp->ar_pro != htons(ETH_P_IP) ||
 419             arp->ar_op != htons(ARPOP_REQUEST))
 420                 return;
 421
 422         arp_ptr = (unsigned char *)(arp+1);
 423         /* save the location of the src hw addr */
 424         sha = arp_ptr;
 425         arp_ptr += skb->dev->addr_len;
 426         memcpy(&sip, arp_ptr, 4);
 427         arp_ptr += 4;
 428         /* if we actually cared about dst hw addr, it would get copied here */
 429         arp_ptr += skb->dev->addr_len;
 430         memcpy(&tip, arp_ptr, 4);
 431
 432         /* Should we ignore arp? */
 433         if (tip != np->local_ip ||
 434             ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
 435                 return;
 436
 437         size = arp_hdr_len(skb->dev);
 438         send_skb = find_skb(np, size + LL_ALLOCATED_SPACE(np->dev),
 439                             LL_RESERVED_SPACE(np->dev));
 440
 441         if (!send_skb)
 442                 return;
 443
 444         skb_reset_network_header(send_skb);
 445         arp = (struct arphdr *) skb_put(send_skb, size);
 446         send_skb->dev = skb->dev;
 447         send_skb->protocol = htons(ETH_P_ARP);
 448
 449         /* Fill the device header for the ARP frame */
 450         if (dev_hard_header(send_skb, skb->dev, ptype,
 451                             sha, np->dev->dev_addr,
 452                             send_skb->len) < 0) {
 453                 kfree_skb(send_skb);
 454                 return;
 455         }
 456
 457         /*
 458          * Fill out the arp protocol part.
 459          *
 460          * we only support ethernet device type,
 461          * which (according to RFC 1390) should always equal 1 (Ethernet).
 462          */
 463
 464         arp->ar_hrd = htons(np->dev->type);
 465         arp->ar_pro = htons(ETH_P_IP);
 466         arp->ar_hln = np->dev->addr_len;
 467         arp->ar_pln = 4;
 468         arp->ar_op = htons(type);
 469
 470         arp_ptr=(unsigned char *)(arp + 1);
 471         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
 472         arp_ptr += np->dev->addr_len;
 473         memcpy(arp_ptr, &tip, 4);
 474         arp_ptr += 4;
 475         memcpy(arp_ptr, sha, np->dev->addr_len);
 476         arp_ptr += np->dev->addr_len;
 477         memcpy(arp_ptr, &sip, 4);
 478
 479         netpoll_send_skb(np, send_skb);
 480 }
 481
 482 int __netpoll_rx(struct sk_buff *skb)
 483 {
 484         int proto, len, ulen;
 485         struct iphdr *iph;
 486         struct udphdr *uh;
 487         struct netpoll_info *npi = skb->dev->npinfo;
 488         struct netpoll *np = npi->rx_np;
 489
 490         if (!np)
 491                 goto out;
 492         if (skb->dev->type != ARPHRD_ETHER)
 493                 goto out;
 494
 495         /* check if netpoll clients need ARP */
 496         if (skb->protocol == htons(ETH_P_ARP) &&
 497             atomic_read(&trapped)) {
 498                 skb_queue_tail(&npi->arp_tx, skb);
 499                 return 1;
 500         }
 501
 502         proto = ntohs(eth_hdr(skb)->h_proto);
 503         if (proto != ETH_P_IP)
 504                 goto out;
 505         if (skb->pkt_type == PACKET_OTHERHOST)
 506                 goto out;
 507         if (skb_shared(skb))
 508                 goto out;
 509
 510         iph = (struct iphdr *)skb->data;
 511         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 512                 goto out;
 513         if (iph->ihl < 5 || iph->version != 4)
 514                 goto out;
 515         if (!pskb_may_pull(skb, iph->ihl*4))
 516                 goto out;
 517         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
 518                 goto out;
 519
 520         len = ntohs(iph->tot_len);
 521         if (skb->len < len || len < iph->ihl*4)
 522                 goto out;
 523
 524         /*
 525          * Our transport medium may have padded the buffer out.
 526          * Now We trim to the true length of the frame.
 527          */
 528         if (pskb_trim_rcsum(skb, len))
 529                 goto out;
 530
 531         if (iph->protocol != IPPROTO_UDP)
 532                 goto out;
 533
 534         len -= iph->ihl*4;
 535         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
 536         ulen = ntohs(uh->len);
 537
 538         if (ulen != len)
 539                 goto out;
 540         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
 541                 goto out;
 542         if (np->local_ip && np->local_ip != iph->daddr)
 543                 goto out;
 544         if (np->remote_ip && np->remote_ip != iph->saddr)
 545                 goto out;
 546         if (np->local_port && np->local_port != ntohs(uh->dest))
 547                 goto out;
 548
 549         np->rx_hook(np, ntohs(uh->source),
 550                     (char *)(uh+1),
 551                     ulen - sizeof(struct udphdr));
 552
 553         kfree_skb(skb);
 554         return 1;
 555
 556 out:
 557         if (atomic_read(&trapped)) {
 558                 kfree_skb(skb);
 559                 return 1;
 560         }
 561
 562         return 0;
 563 }
 564
 565 void netpoll_print_options(struct netpoll *np)
 566 {
 567         printk(KERN_INFO "%s: local port %d\n",
 568                          np->name, np->local_port);
 569         printk(KERN_INFO "%s: local IP %pI4\n",
 570                          np->name, &np->local_ip);
 571         printk(KERN_INFO "%s: interface %s\n",
 572                          np->name, np->dev_name);
 573         printk(KERN_INFO "%s: remote port %d\n",
 574                          np->name, np->remote_port);
 575         printk(KERN_INFO "%s: remote IP %pI4\n",
 576                          np->name, &np->remote_ip);
 577         printk(KERN_INFO "%s: remote ethernet address %pM\n",
 578                          np->name, np->remote_mac);
 579 }
 580
 581 int netpoll_parse_options(struct netpoll *np, char *opt)
 582 {
 583         char *cur=opt, *delim;
 584
 585         if (*cur != '@') {
 586                 if ((delim = strchr(cur, '@')) == NULL)
 587                         goto parse_failed;
 588                 *delim = 0;
 589                 np->local_port = simple_strtol(cur, NULL, 10);
 590                 cur = delim;
 591         }
 592         cur++;
 593
 594         if (*cur != '/') {
 595                 if ((delim = strchr(cur, '/')) == NULL)
 596                         goto parse_failed;
 597                 *delim = 0;
 598                 np->local_ip = in_aton(cur);
 599                 cur = delim;
 600         }
 601         cur++;
 602
 603         if (*cur != ',') {
 604                 /* parse out dev name */
 605                 if ((delim = strchr(cur, ',')) == NULL)
 606                         goto parse_failed;
 607                 *delim = 0;
 608                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 609                 cur = delim;
 610         }
 611         cur++;
 612
 613         if (*cur != '@') {
 614                 /* dst port */
 615                 if ((delim = strchr(cur, '@')) == NULL)
 616                         goto parse_failed;
 617                 *delim = 0;
 618                 np->remote_port = simple_strtol(cur, NULL, 10);
 619                 cur = delim;
 620         }
 621         cur++;
 622
 623         /* dst ip */
 624         if ((delim = strchr(cur, '/')) == NULL)
 625                 goto parse_failed;
 626         *delim = 0;
 627         np->remote_ip = in_aton(cur);
 628         cur = delim + 1;
 629
 630         if (*cur != 0) {
 631                 /* MAC address */
 632                 if ((delim = strchr(cur, ':')) == NULL)
 633                         goto parse_failed;
 634                 *delim = 0;
 635                 np->remote_mac[0] = simple_strtol(cur, NULL, 16);
 636                 cur = delim + 1;
 637                 if ((delim = strchr(cur, ':')) == NULL)
 638                         goto parse_failed;
 639                 *delim = 0;
 640                 np->remote_mac[1] = simple_strtol(cur, NULL, 16);
 641                 cur = delim + 1;
 642                 if ((delim = strchr(cur, ':')) == NULL)
 643                         goto parse_failed;
 644                 *delim = 0;
 645                 np->remote_mac[2] = simple_strtol(cur, NULL, 16);
 646                 cur = delim + 1;
 647                 if ((delim = strchr(cur, ':')) == NULL)
 648                         goto parse_failed;
 649                 *delim = 0;
 650                 np->remote_mac[3] = simple_strtol(cur, NULL, 16);
 651                 cur = delim + 1;
 652                 if ((delim = strchr(cur, ':')) == NULL)
 653                         goto parse_failed;
 654                 *delim = 0;
 655                 np->remote_mac[4] = simple_strtol(cur, NULL, 16);
 656                 cur = delim + 1;
 657                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
 658         }
 659
 660         netpoll_print_options(np);
 661
 662         return 0;
 663
 664  parse_failed:
 665         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
 666                np->name, cur);
 667         return -1;
 668 }
 669
 670 int netpoll_setup(struct netpoll *np)
 671 {
 672         struct net_device *ndev = NULL;
 673         struct in_device *in_dev;
 674         struct netpoll_info *npinfo;
 675         unsigned long flags;
 676         int err;
 677
 678         if (np->dev_name)
 679                 ndev = dev_get_by_name(&init_net, np->dev_name);
 680         if (!ndev) {
 681                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
 682                        np->name, np->dev_name);
 683                 return -ENODEV;
 684         }
 685
 686         np->dev = ndev;
 687         if (!ndev->npinfo) {
 688                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
 689                 if (!npinfo) {
 690                         err = -ENOMEM;
 691                         goto release;
 692                 }
 693
 694                 npinfo->rx_flags = 0;
 695                 npinfo->rx_np = NULL;
 696
 697                 spin_lock_init(&npinfo->rx_lock);
 698                 skb_queue_head_init(&npinfo->arp_tx);
 699                 skb_queue_head_init(&npinfo->txq);
 700                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
 701
 702                 atomic_set(&npinfo->refcnt, 1);
 703         } else {
 704                 npinfo = ndev->npinfo;
 705                 atomic_inc(&npinfo->refcnt);
 706         }
 707
 708         if (!ndev->netdev_ops->ndo_poll_controller) {
 709                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
 710                        np->name, np->dev_name);
 711                 err = -ENOTSUPP;
 712                 goto release;
 713         }
 714
 715         if (!netif_running(ndev)) {
 716                 unsigned long atmost, atleast;
 717
 718                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
 719                        np->name, np->dev_name);
 720
 721                 rtnl_lock();
 722                 err = dev_open(ndev);
 723                 rtnl_unlock();
 724
 725                 if (err) {
 726                         printk(KERN_ERR "%s: failed to open %s\n",
 727                                np->name, ndev->name);
 728                         goto release;
 729                 }
 730
 731                 atleast = jiffies + HZ/10;
 732                 atmost = jiffies + 4*HZ;
 733                 while (!netif_carrier_ok(ndev)) {
 734                         if (time_after(jiffies, atmost)) {
 735                                 printk(KERN_NOTICE
 736                                        "%s: timeout waiting for carrier\n",
 737                                        np->name);
 738                                 break;
 739                         }
 740                         cond_resched();
 741                 }
 742
 743                 /* If carrier appears to come up instantly, we don't
 744                  * trust it and pause so that we don't pump all our
 745                  * queued console messages into the bitbucket.
 746                  */
 747
 748                 if (time_before(jiffies, atleast)) {
 749                         printk(KERN_NOTICE "%s: carrier detect appears"
 750                                " untrustworthy, waiting 4 seconds\n",
 751                                np->name);
 752                         msleep(4000);
 753                 }
 754         }
 755
 756         if (!np->local_ip) {
 757                 rcu_read_lock();
 758                 in_dev = __in_dev_get_rcu(ndev);
 759
 760                 if (!in_dev || !in_dev->ifa_list) {
 761                         rcu_read_unlock();
 762                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
 763                                np->name, np->dev_name);
 764                         err = -EDESTADDRREQ;
 765                         goto release;
 766                 }
 767
 768                 np->local_ip = in_dev->ifa_list->ifa_local;
 769                 rcu_read_unlock();
 770                 printk(KERN_INFO "%s: local IP %pI4\n", np->name, &np->local_ip);
 771         }
 772
 773         if (np->rx_hook) {
 774                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 775                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
 776                 npinfo->rx_np = np;
 777                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 778         }
 779
 780         /* fill up the skb queue */
 781         refill_skbs();
 782
 783         /* last thing to do is link it to the net device structure */
 784         ndev->npinfo = npinfo;
 785
 786         /* avoid racing with NAPI reading npinfo */
 787         synchronize_rcu();
 788
 789         return 0;
 790
 791  release:
 792         if (!ndev->npinfo)
 793                 kfree(npinfo);
 794         np->dev = NULL;
 795         dev_put(ndev);
 796         return err;
 797 }
 798
 799 static int __init netpoll_init(void)
 800 {
 801         skb_queue_head_init(&skb_pool);
 802         return 0;
 803 }
 804 core_initcall(netpoll_init);
 805
 806 void netpoll_cleanup(struct netpoll *np)
 807 {
 808         struct netpoll_info *npinfo;
 809         unsigned long flags;
 810
 811         if (np->dev) {
 812                 npinfo = np->dev->npinfo;
 813                 if (npinfo) {
 814                         if (npinfo->rx_np == np) {
 815                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
 816                                 npinfo->rx_np = NULL;
 817                                 npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
 818                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 819                         }
 820
 821                         if (atomic_dec_and_test(&npinfo->refcnt)) {
 822                                 skb_queue_purge(&npinfo->arp_tx);
 823                                 skb_queue_purge(&npinfo->txq);
 824                                 cancel_rearming_delayed_work(&npinfo->tx_work);
 825
 826                                 /* clean after last, unfinished work */
 827                                 __skb_queue_purge(&npinfo->txq);
 828                                 kfree(npinfo);
 829                                 np->dev->npinfo = NULL;
 830                         }
 831                 }
 832
 833                 dev_put(np->dev);
 834         }
 835
 836         np->dev = NULL;
 837 }
 838
 839 int netpoll_trap(void)
 840 {
 841         return atomic_read(&trapped);
 842 }
 843
 844 void netpoll_set_trap(int trap)
 845 {
 846         if (trap)
 847                 atomic_inc(&trapped);
 848         else
 849                 atomic_dec(&trapped);
 850 }
 851
 852 EXPORT_SYMBOL(netpoll_set_trap);
 853 EXPORT_SYMBOL(netpoll_trap);
 854 EXPORT_SYMBOL(netpoll_print_options);
 855 EXPORT_SYMBOL(netpoll_parse_options);
 856 EXPORT_SYMBOL(netpoll_setup);
 857 EXPORT_SYMBOL(netpoll_cleanup);
 858 EXPORT_SYMBOL(netpoll_send_udp);
 859 EXPORT_SYMBOL(netpoll_poll);