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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/moduleparam.h>
  15 #include <linux/kernel.h>
  16 #include <linux/netdevice.h>
  17 #include <linux/etherdevice.h>
  18 #include <linux/string.h>
  19 #include <linux/if_arp.h>
  20 #include <linux/inetdevice.h>
  21 #include <linux/inet.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/netpoll.h>
  24 #include <linux/sched.h>
  25 #include <linux/delay.h>
  26 #include <linux/rcupdate.h>
  27 #include <linux/workqueue.h>
  28 #include <linux/slab.h>
  29 #include <linux/export.h>
  30 #include <linux/if_vlan.h>
  31 #include <net/tcp.h>
  32 #include <net/udp.h>
  33 #include <net/addrconf.h>
  34 #include <net/ndisc.h>
  35 #include <net/ip6_checksum.h>
  36 #include <asm/unaligned.h>
  37 #include <trace/events/napi.h>
  38
  39 /*
  40  * We maintain a small pool of fully-sized skbs, to make sure the
  41  * message gets out even in extreme OOM situations.
  42  */
  43
  44 #define MAX_UDP_CHUNK 1460
  45 #define MAX_SKBS 32
  46
  47 static struct sk_buff_head skb_pool;
  48
  49 DEFINE_STATIC_SRCU(netpoll_srcu);
  50
  51 #define USEC_PER_POLL   50
  52
  53 #define MAX_SKB_SIZE                                                    \
  54         (sizeof(struct ethhdr) +                                        \
  55          sizeof(struct iphdr) +                                         \
  56          sizeof(struct udphdr) +                                        \
  57          MAX_UDP_CHUNK)
  58
  59 static void zap_completion_queue(void);
  60 static void netpoll_async_cleanup(struct work_struct *work);
  61
  62 static unsigned int carrier_timeout = 4;
  63 module_param(carrier_timeout, uint, 0644);
  64
  65 #define np_info(np, fmt, ...)                           \
  66         pr_info("%s: " fmt, np->name, ##__VA_ARGS__)
  67 #define np_err(np, fmt, ...)                            \
  68         pr_err("%s: " fmt, np->name, ##__VA_ARGS__)
  69 #define np_notice(np, fmt, ...)                         \
  70         pr_notice("%s: " fmt, np->name, ##__VA_ARGS__)
  71
  72 static int netpoll_start_xmit(struct sk_buff *skb, struct net_device *dev,
  73                               struct netdev_queue *txq)
  74 {
  75         int status = NETDEV_TX_OK;
  76         netdev_features_t features;
  77
  78         features = netif_skb_features(skb);
  79
  80         if (skb_vlan_tag_present(skb) &&
  81             !vlan_hw_offload_capable(features, skb->vlan_proto)) {
  82                 skb = __vlan_hwaccel_push_inside(skb);
  83                 if (unlikely(!skb)) {
  84                         /* This is actually a packet drop, but we
  85                          * don't want the code that calls this
  86                          * function to try and operate on a NULL skb.
  87                          */
  88                         goto out;
  89                 }
  90         }
  91
  92         status = netdev_start_xmit(skb, dev, txq, false);
  93
  94 out:
  95         return status;
  96 }
  97
  98 static void queue_process(struct work_struct *work)
  99 {
 100         struct netpoll_info *npinfo =
 101                 container_of(work, struct netpoll_info, tx_work.work);
 102         struct sk_buff *skb;
 103         unsigned long flags;
 104
 105         while ((skb = skb_dequeue(&npinfo->txq))) {
 106                 struct net_device *dev = skb->dev;
 107                 struct netdev_queue *txq;
 108                 unsigned int q_index;
 109
 110                 if (!netif_device_present(dev) || !netif_running(dev)) {
 111                         kfree_skb(skb);
 112                         continue;
 113                 }
 114
 115                 local_irq_save(flags);
 116                 /* check if skb->queue_mapping is still valid */
 117                 q_index = skb_get_queue_mapping(skb);
 118                 if (unlikely(q_index >= dev->real_num_tx_queues)) {
 119                         q_index = q_index % dev->real_num_tx_queues;
 120                         skb_set_queue_mapping(skb, q_index);
 121                 }
 122                 txq = netdev_get_tx_queue(dev, q_index);
 123                 HARD_TX_LOCK(dev, txq, smp_processor_id());
 124                 if (netif_xmit_frozen_or_stopped(txq) ||
 125                     netpoll_start_xmit(skb, dev, txq) != NETDEV_TX_OK) {
 126                         skb_queue_head(&npinfo->txq, skb);
 127                         HARD_TX_UNLOCK(dev, txq);
 128                         local_irq_restore(flags);
 129
 130                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
 131                         return;
 132                 }
 133                 HARD_TX_UNLOCK(dev, txq);
 134                 local_irq_restore(flags);
 135         }
 136 }
 137
 138 /*
 139  * Check whether delayed processing was scheduled for our NIC. If so,
 140  * we attempt to grab the poll lock and use ->poll() to pump the card.
 141  * If this fails, either we've recursed in ->poll() or it's already
 142  * running on another CPU.
 143  *
 144  * Note: we don't mask interrupts with this lock because we're using
 145  * trylock here and interrupts are already disabled in the softirq
 146  * case. Further, we test the poll_owner to avoid recursion on UP
 147  * systems where the lock doesn't exist.
 148  */
 149 static void poll_one_napi(struct napi_struct *napi)
 150 {
 151         int work = 0;
 152
 153         /* net_rx_action's ->poll() invocations and our's are
 154          * synchronized by this test which is only made while
 155          * holding the napi->poll_lock.
 156          */
 157         if (!test_bit(NAPI_STATE_SCHED, &napi->state))
 158                 return;
 159
 160         /* If we set this bit but see that it has already been set,
 161          * that indicates that napi has been disabled and we need
 162          * to abort this operation
 163          */
 164         if (test_and_set_bit(NAPI_STATE_NPSVC, &napi->state))
 165                 return;
 166
 167         /* We explicilty pass the polling call a budget of 0 to
 168          * indicate that we are clearing the Tx path only.
 169          */
 170         work = napi->poll(napi, 0);
 171         WARN_ONCE(work, "%pF exceeded budget in poll\n", napi->poll);
 172         trace_napi_poll(napi, work, 0);
 173
 174         clear_bit(NAPI_STATE_NPSVC, &napi->state);
 175 }
 176
 177 static void poll_napi(struct net_device *dev)
 178 {
 179         struct napi_struct *napi;
 180         int cpu = smp_processor_id();
 181
 182         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 183                 if (cmpxchg(&napi->poll_owner, -1, cpu) == -1) {
 184                         poll_one_napi(napi);
 185                         smp_store_release(&napi->poll_owner, -1);
 186                 }
 187         }
 188 }
 189
 190 static void netpoll_poll_dev(struct net_device *dev)
 191 {
 192         const struct net_device_ops *ops;
 193         struct netpoll_info *ni = rcu_dereference_bh(dev->npinfo);
 194
 195         /* Don't do any rx activity if the dev_lock mutex is held
 196          * the dev_open/close paths use this to block netpoll activity
 197          * while changing device state
 198          */
 199         if (down_trylock(&ni->dev_lock))
 200                 return;
 201
 202         if (!netif_running(dev)) {
 203                 up(&ni->dev_lock);
 204                 return;
 205         }
 206
 207         ops = dev->netdev_ops;
 208         if (!ops->ndo_poll_controller) {
 209                 up(&ni->dev_lock);
 210                 return;
 211         }
 212
 213         /* Process pending work on NIC */
 214         ops->ndo_poll_controller(dev);
 215
 216         poll_napi(dev);
 217
 218         up(&ni->dev_lock);
 219
 220         zap_completion_queue();
 221 }
 222
 223 void netpoll_poll_disable(struct net_device *dev)
 224 {
 225         struct netpoll_info *ni;
 226         int idx;
 227         might_sleep();
 228         idx = srcu_read_lock(&netpoll_srcu);
 229         ni = srcu_dereference(dev->npinfo, &netpoll_srcu);
 230         if (ni)
 231                 down(&ni->dev_lock);
 232         srcu_read_unlock(&netpoll_srcu, idx);
 233 }
 234 EXPORT_SYMBOL(netpoll_poll_disable);
 235
 236 void netpoll_poll_enable(struct net_device *dev)
 237 {
 238         struct netpoll_info *ni;
 239         rcu_read_lock();
 240         ni = rcu_dereference(dev->npinfo);
 241         if (ni)
 242                 up(&ni->dev_lock);
 243         rcu_read_unlock();
 244 }
 245 EXPORT_SYMBOL(netpoll_poll_enable);
 246
 247 static void refill_skbs(void)
 248 {
 249         struct sk_buff *skb;
 250         unsigned long flags;
 251
 252         spin_lock_irqsave(&skb_pool.lock, flags);
 253         while (skb_pool.qlen < MAX_SKBS) {
 254                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
 255                 if (!skb)
 256                         break;
 257
 258                 __skb_queue_tail(&skb_pool, skb);
 259         }
 260         spin_unlock_irqrestore(&skb_pool.lock, flags);
 261 }
 262
 263 static void zap_completion_queue(void)
 264 {
 265         unsigned long flags;
 266         struct softnet_data *sd = &get_cpu_var(softnet_data);
 267
 268         if (sd->completion_queue) {
 269                 struct sk_buff *clist;
 270
 271                 local_irq_save(flags);
 272                 clist = sd->completion_queue;
 273                 sd->completion_queue = NULL;
 274                 local_irq_restore(flags);
 275
 276                 while (clist != NULL) {
 277                         struct sk_buff *skb = clist;
 278                         clist = clist->next;
 279                         if (!skb_irq_freeable(skb)) {
 280                                 refcount_set(&skb->users, 1);
 281                                 dev_kfree_skb_any(skb); /* put this one back */
 282                         } else {
 283                                 __kfree_skb(skb);
 284                         }
 285                 }
 286         }
 287
 288         put_cpu_var(softnet_data);
 289 }
 290
 291 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
 292 {
 293         int count = 0;
 294         struct sk_buff *skb;
 295
 296         zap_completion_queue();
 297         refill_skbs();
 298 repeat:
 299
 300         skb = alloc_skb(len, GFP_ATOMIC);
 301         if (!skb)
 302                 skb = skb_dequeue(&skb_pool);
 303
 304         if (!skb) {
 305                 if (++count < 10) {
 306                         netpoll_poll_dev(np->dev);
 307                         goto repeat;
 308                 }
 309                 return NULL;
 310         }
 311
 312         refcount_set(&skb->users, 1);
 313         skb_reserve(skb, reserve);
 314         return skb;
 315 }
 316
 317 static int netpoll_owner_active(struct net_device *dev)
 318 {
 319         struct napi_struct *napi;
 320
 321         list_for_each_entry(napi, &dev->napi_list, dev_list) {
 322                 if (napi->poll_owner == smp_processor_id())
 323                         return 1;
 324         }
 325         return 0;
 326 }
 327
 328 /* call with IRQ disabled */
 329 void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
 330                              struct net_device *dev)
 331 {
 332         int status = NETDEV_TX_BUSY;
 333         unsigned long tries;
 334         /* It is up to the caller to keep npinfo alive. */
 335         struct netpoll_info *npinfo;
 336
 337         WARN_ON_ONCE(!irqs_disabled());
 338
 339         npinfo = rcu_dereference_bh(np->dev->npinfo);
 340         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
 341                 dev_kfree_skb_irq(skb);
 342                 return;
 343         }
 344
 345         /* don't get messages out of order, and no recursion */
 346         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
 347                 struct netdev_queue *txq;
 348
 349                 txq = netdev_pick_tx(dev, skb, NULL);
 350
 351                 /* try until next clock tick */
 352                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
 353                      tries > 0; --tries) {
 354                         if (HARD_TX_TRYLOCK(dev, txq)) {
 355                                 if (!netif_xmit_stopped(txq))
 356                                         status = netpoll_start_xmit(skb, dev, txq);
 357
 358                                 HARD_TX_UNLOCK(dev, txq);
 359
 360                                 if (status == NETDEV_TX_OK)
 361                                         break;
 362
 363                         }
 364
 365                         /* tickle device maybe there is some cleanup */
 366                         netpoll_poll_dev(np->dev);
 367
 368                         udelay(USEC_PER_POLL);
 369                 }
 370
 371                 WARN_ONCE(!irqs_disabled(),
 372                         "netpoll_send_skb_on_dev(): %s enabled interrupts in poll (%pF)\n",
 373                         dev->name, dev->netdev_ops->ndo_start_xmit);
 374
 375         }
 376
 377         if (status != NETDEV_TX_OK) {
 378                 skb_queue_tail(&npinfo->txq, skb);
 379                 schedule_delayed_work(&npinfo->tx_work,0);
 380         }
 381 }
 382 EXPORT_SYMBOL(netpoll_send_skb_on_dev);
 383
 384 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 385 {
 386         int total_len, ip_len, udp_len;
 387         struct sk_buff *skb;
 388         struct udphdr *udph;
 389         struct iphdr *iph;
 390         struct ethhdr *eth;
 391         static atomic_t ip_ident;
 392         struct ipv6hdr *ip6h;
 393
 394         WARN_ON_ONCE(!irqs_disabled());
 395
 396         udp_len = len + sizeof(*udph);
 397         if (np->ipv6)
 398                 ip_len = udp_len + sizeof(*ip6h);
 399         else
 400                 ip_len = udp_len + sizeof(*iph);
 401
 402         total_len = ip_len + LL_RESERVED_SPACE(np->dev);
 403
 404         skb = find_skb(np, total_len + np->dev->needed_tailroom,
 405                        total_len - len);
 406         if (!skb)
 407                 return;
 408
 409         skb_copy_to_linear_data(skb, msg, len);
 410         skb_put(skb, len);
 411
 412         skb_push(skb, sizeof(*udph));
 413         skb_reset_transport_header(skb);
 414         udph = udp_hdr(skb);
 415         udph->source = htons(np->local_port);
 416         udph->dest = htons(np->remote_port);
 417         udph->len = htons(udp_len);
 418
 419         if (np->ipv6) {
 420                 udph->check = 0;
 421                 udph->check = csum_ipv6_magic(&np->local_ip.in6,
 422                                               &np->remote_ip.in6,
 423                                               udp_len, IPPROTO_UDP,
 424                                               csum_partial(udph, udp_len, 0));
 425                 if (udph->check == 0)
 426                         udph->check = CSUM_MANGLED_0;
 427
 428                 skb_push(skb, sizeof(*ip6h));
 429                 skb_reset_network_header(skb);
 430                 ip6h = ipv6_hdr(skb);
 431
 432                 /* ip6h->version = 6; ip6h->priority = 0; */
 433                 put_unaligned(0x60, (unsigned char *)ip6h);
 434                 ip6h->flow_lbl[0] = 0;
 435                 ip6h->flow_lbl[1] = 0;
 436                 ip6h->flow_lbl[2] = 0;
 437
 438                 ip6h->payload_len = htons(sizeof(struct udphdr) + len);
 439                 ip6h->nexthdr = IPPROTO_UDP;
 440                 ip6h->hop_limit = 32;
 441                 ip6h->saddr = np->local_ip.in6;
 442                 ip6h->daddr = np->remote_ip.in6;
 443
 444                 eth = skb_push(skb, ETH_HLEN);
 445                 skb_reset_mac_header(skb);
 446                 skb->protocol = eth->h_proto = htons(ETH_P_IPV6);
 447         } else {
 448                 udph->check = 0;
 449                 udph->check = csum_tcpudp_magic(np->local_ip.ip,
 450                                                 np->remote_ip.ip,
 451                                                 udp_len, IPPROTO_UDP,
 452                                                 csum_partial(udph, udp_len, 0));
 453                 if (udph->check == 0)
 454                         udph->check = CSUM_MANGLED_0;
 455
 456                 skb_push(skb, sizeof(*iph));
 457                 skb_reset_network_header(skb);
 458                 iph = ip_hdr(skb);
 459
 460                 /* iph->version = 4; iph->ihl = 5; */
 461                 put_unaligned(0x45, (unsigned char *)iph);
 462                 iph->tos      = 0;
 463                 put_unaligned(htons(ip_len), &(iph->tot_len));
 464                 iph->id       = htons(atomic_inc_return(&ip_ident));
 465                 iph->frag_off = 0;
 466                 iph->ttl      = 64;
 467                 iph->protocol = IPPROTO_UDP;
 468                 iph->check    = 0;
 469                 put_unaligned(np->local_ip.ip, &(iph->saddr));
 470                 put_unaligned(np->remote_ip.ip, &(iph->daddr));
 471                 iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 472
 473                 eth = skb_push(skb, ETH_HLEN);
 474                 skb_reset_mac_header(skb);
 475                 skb->protocol = eth->h_proto = htons(ETH_P_IP);
 476         }
 477
 478         ether_addr_copy(eth->h_source, np->dev->dev_addr);
 479         ether_addr_copy(eth->h_dest, np->remote_mac);
 480
 481         skb->dev = np->dev;
 482
 483         netpoll_send_skb(np, skb);
 484 }
 485 EXPORT_SYMBOL(netpoll_send_udp);
 486
 487 void netpoll_print_options(struct netpoll *np)
 488 {
 489         np_info(np, "local port %d\n", np->local_port);
 490         if (np->ipv6)
 491                 np_info(np, "local IPv6 address %pI6c\n", &np->local_ip.in6);
 492         else
 493                 np_info(np, "local IPv4 address %pI4\n", &np->local_ip.ip);
 494         np_info(np, "interface '%s'\n", np->dev_name);
 495         np_info(np, "remote port %d\n", np->remote_port);
 496         if (np->ipv6)
 497                 np_info(np, "remote IPv6 address %pI6c\n", &np->remote_ip.in6);
 498         else
 499                 np_info(np, "remote IPv4 address %pI4\n", &np->remote_ip.ip);
 500         np_info(np, "remote ethernet address %pM\n", np->remote_mac);
 501 }
 502 EXPORT_SYMBOL(netpoll_print_options);
 503
 504 static int netpoll_parse_ip_addr(const char *str, union inet_addr *addr)
 505 {
 506         const char *end;
 507
 508         if (!strchr(str, ':') &&
 509             in4_pton(str, -1, (void *)addr, -1, &end) > 0) {
 510                 if (!*end)
 511                         return 0;
 512         }
 513         if (in6_pton(str, -1, addr->in6.s6_addr, -1, &end) > 0) {
 514 #if IS_ENABLED(CONFIG_IPV6)
 515                 if (!*end)
 516                         return 1;
 517 #else
 518                 return -1;
 519 #endif
 520         }
 521         return -1;
 522 }
 523
 524 int netpoll_parse_options(struct netpoll *np, char *opt)
 525 {
 526         char *cur=opt, *delim;
 527         int ipv6;
 528         bool ipversion_set = false;
 529
 530         if (*cur != '@') {
 531                 if ((delim = strchr(cur, '@')) == NULL)
 532                         goto parse_failed;
 533                 *delim = 0;
 534                 if (kstrtou16(cur, 10, &np->local_port))
 535                         goto parse_failed;
 536                 cur = delim;
 537         }
 538         cur++;
 539
 540         if (*cur != '/') {
 541                 ipversion_set = true;
 542                 if ((delim = strchr(cur, '/')) == NULL)
 543                         goto parse_failed;
 544                 *delim = 0;
 545                 ipv6 = netpoll_parse_ip_addr(cur, &np->local_ip);
 546                 if (ipv6 < 0)
 547                         goto parse_failed;
 548                 else
 549                         np->ipv6 = (bool)ipv6;
 550                 cur = delim;
 551         }
 552         cur++;
 553
 554         if (*cur != ',') {
 555                 /* parse out dev name */
 556                 if ((delim = strchr(cur, ',')) == NULL)
 557                         goto parse_failed;
 558                 *delim = 0;
 559                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
 560                 cur = delim;
 561         }
 562         cur++;
 563
 564         if (*cur != '@') {
 565                 /* dst port */
 566                 if ((delim = strchr(cur, '@')) == NULL)
 567                         goto parse_failed;
 568                 *delim = 0;
 569                 if (*cur == ' ' || *cur == '\t')
 570                         np_info(np, "warning: whitespace is not allowed\n");
 571                 if (kstrtou16(cur, 10, &np->remote_port))
 572                         goto parse_failed;
 573                 cur = delim;
 574         }
 575         cur++;
 576
 577         /* dst ip */
 578         if ((delim = strchr(cur, '/')) == NULL)
 579                 goto parse_failed;
 580         *delim = 0;
 581         ipv6 = netpoll_parse_ip_addr(cur, &np->remote_ip);
 582         if (ipv6 < 0)
 583                 goto parse_failed;
 584         else if (ipversion_set && np->ipv6 != (bool)ipv6)
 585                 goto parse_failed;
 586         else
 587                 np->ipv6 = (bool)ipv6;
 588         cur = delim + 1;
 589
 590         if (*cur != 0) {
 591                 /* MAC address */
 592                 if (!mac_pton(cur, np->remote_mac))
 593                         goto parse_failed;
 594         }
 595
 596         netpoll_print_options(np);
 597
 598         return 0;
 599
 600  parse_failed:
 601         np_info(np, "couldn't parse config at '%s'!\n", cur);
 602         return -1;
 603 }
 604 EXPORT_SYMBOL(netpoll_parse_options);
 605
 606 int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
 607 {
 608         struct netpoll_info *npinfo;
 609         const struct net_device_ops *ops;
 610         int err;
 611
 612         np->dev = ndev;
 613         strlcpy(np->dev_name, ndev->name, IFNAMSIZ);
 614         INIT_WORK(&np->cleanup_work, netpoll_async_cleanup);
 615
 616         if ((ndev->priv_flags & IFF_DISABLE_NETPOLL) ||
 617             !ndev->netdev_ops->ndo_poll_controller) {
 618                 np_err(np, "%s doesn't support polling, aborting\n",
 619                        np->dev_name);
 620                 err = -ENOTSUPP;
 621                 goto out;
 622         }
 623
 624         if (!ndev->npinfo) {
 625                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
 626                 if (!npinfo) {
 627                         err = -ENOMEM;
 628                         goto out;
 629                 }
 630
 631                 sema_init(&npinfo->dev_lock, 1);
 632                 skb_queue_head_init(&npinfo->txq);
 633                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
 634
 635                 refcount_set(&npinfo->refcnt, 1);
 636
 637                 ops = np->dev->netdev_ops;
 638                 if (ops->ndo_netpoll_setup) {
 639                         err = ops->ndo_netpoll_setup(ndev, npinfo);
 640                         if (err)
 641                                 goto free_npinfo;
 642                 }
 643         } else {
 644                 npinfo = rtnl_dereference(ndev->npinfo);
 645                 refcount_inc(&npinfo->refcnt);
 646         }
 647
 648         npinfo->netpoll = np;
 649
 650         /* last thing to do is link it to the net device structure */
 651         rcu_assign_pointer(ndev->npinfo, npinfo);
 652
 653         return 0;
 654
 655 free_npinfo:
 656         kfree(npinfo);
 657 out:
 658         return err;
 659 }
 660 EXPORT_SYMBOL_GPL(__netpoll_setup);
 661
 662 int netpoll_setup(struct netpoll *np)
 663 {
 664         struct net_device *ndev = NULL;
 665         struct in_device *in_dev;
 666         int err;
 667
 668         rtnl_lock();
 669         if (np->dev_name[0]) {
 670                 struct net *net = current->nsproxy->net_ns;
 671                 ndev = __dev_get_by_name(net, np->dev_name);
 672         }
 673         if (!ndev) {
 674                 np_err(np, "%s doesn't exist, aborting\n", np->dev_name);
 675                 err = -ENODEV;
 676                 goto unlock;
 677         }
 678         dev_hold(ndev);
 679
 680         if (netdev_master_upper_dev_get(ndev)) {
 681                 np_err(np, "%s is a slave device, aborting\n", np->dev_name);
 682                 err = -EBUSY;
 683                 goto put;
 684         }
 685
 686         if (!netif_running(ndev)) {
 687                 unsigned long atmost, atleast;
 688
 689                 np_info(np, "device %s not up yet, forcing it\n", np->dev_name);
 690
 691                 err = dev_open(ndev);
 692
 693                 if (err) {
 694                         np_err(np, "failed to open %s\n", ndev->name);
 695                         goto put;
 696                 }
 697
 698                 rtnl_unlock();
 699                 atleast = jiffies + HZ/10;
 700                 atmost = jiffies + carrier_timeout * HZ;
 701                 while (!netif_carrier_ok(ndev)) {
 702                         if (time_after(jiffies, atmost)) {
 703                                 np_notice(np, "timeout waiting for carrier\n");
 704                                 break;
 705                         }
 706                         msleep(1);
 707                 }
 708
 709                 /* If carrier appears to come up instantly, we don't
 710                  * trust it and pause so that we don't pump all our
 711                  * queued console messages into the bitbucket.
 712                  */
 713
 714                 if (time_before(jiffies, atleast)) {
 715                         np_notice(np, "carrier detect appears untrustworthy, waiting 4 seconds\n");
 716                         msleep(4000);
 717                 }
 718                 rtnl_lock();
 719         }
 720
 721         if (!np->local_ip.ip) {
 722                 if (!np->ipv6) {
 723                         in_dev = __in_dev_get_rtnl(ndev);
 724
 725                         if (!in_dev || !in_dev->ifa_list) {
 726                                 np_err(np, "no IP address for %s, aborting\n",
 727                                        np->dev_name);
 728                                 err = -EDESTADDRREQ;
 729                                 goto put;
 730                         }
 731
 732                         np->local_ip.ip = in_dev->ifa_list->ifa_local;
 733                         np_info(np, "local IP %pI4\n", &np->local_ip.ip);
 734                 } else {
 735 #if IS_ENABLED(CONFIG_IPV6)
 736                         struct inet6_dev *idev;
 737
 738                         err = -EDESTADDRREQ;
 739                         idev = __in6_dev_get(ndev);
 740                         if (idev) {
 741                                 struct inet6_ifaddr *ifp;
 742
 743                                 read_lock_bh(&idev->lock);
 744                                 list_for_each_entry(ifp, &idev->addr_list, if_list) {
 745                                         if (ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL)
 746                                                 continue;
 747                                         np->local_ip.in6 = ifp->addr;
 748                                         err = 0;
 749                                         break;
 750                                 }
 751                                 read_unlock_bh(&idev->lock);
 752                         }
 753                         if (err) {
 754                                 np_err(np, "no IPv6 address for %s, aborting\n",
 755                                        np->dev_name);
 756                                 goto put;
 757                         } else
 758                                 np_info(np, "local IPv6 %pI6c\n", &np->local_ip.in6);
 759 #else
 760                         np_err(np, "IPv6 is not supported %s, aborting\n",
 761                                np->dev_name);
 762                         err = -EINVAL;
 763                         goto put;
 764 #endif
 765                 }
 766         }
 767
 768         /* fill up the skb queue */
 769         refill_skbs();
 770
 771         err = __netpoll_setup(np, ndev);
 772         if (err)
 773                 goto put;
 774
 775         rtnl_unlock();
 776         return 0;
 777
 778 put:
 779         dev_put(ndev);
 780 unlock:
 781         rtnl_unlock();
 782         return err;
 783 }
 784 EXPORT_SYMBOL(netpoll_setup);
 785
 786 static int __init netpoll_init(void)
 787 {
 788         skb_queue_head_init(&skb_pool);
 789         return 0;
 790 }
 791 core_initcall(netpoll_init);
 792
 793 static void rcu_cleanup_netpoll_info(struct rcu_head *rcu_head)
 794 {
 795         struct netpoll_info *npinfo =
 796                         container_of(rcu_head, struct netpoll_info, rcu);
 797
 798         skb_queue_purge(&npinfo->txq);
 799
 800         /* we can't call cancel_delayed_work_sync here, as we are in softirq */
 801         cancel_delayed_work(&npinfo->tx_work);
 802
 803         /* clean after last, unfinished work */
 804         __skb_queue_purge(&npinfo->txq);
 805         /* now cancel it again */
 806         cancel_delayed_work(&npinfo->tx_work);
 807         kfree(npinfo);
 808 }
 809
 810 void __netpoll_cleanup(struct netpoll *np)
 811 {
 812         struct netpoll_info *npinfo;
 813
 814         /* rtnl_dereference would be preferable here but
 815          * rcu_cleanup_netpoll path can put us in here safely without
 816          * holding the rtnl, so plain rcu_dereference it is
 817          */
 818         npinfo = rtnl_dereference(np->dev->npinfo);
 819         if (!npinfo)
 820                 return;
 821
 822         synchronize_srcu(&netpoll_srcu);
 823
 824         if (refcount_dec_and_test(&npinfo->refcnt)) {
 825                 const struct net_device_ops *ops;
 826
 827                 ops = np->dev->netdev_ops;
 828                 if (ops->ndo_netpoll_cleanup)
 829                         ops->ndo_netpoll_cleanup(np->dev);
 830
 831                 RCU_INIT_POINTER(np->dev->npinfo, NULL);
 832                 call_rcu_bh(&npinfo->rcu, rcu_cleanup_netpoll_info);
 833         } else
 834                 RCU_INIT_POINTER(np->dev->npinfo, NULL);
 835 }
 836 EXPORT_SYMBOL_GPL(__netpoll_cleanup);
 837
 838 static void netpoll_async_cleanup(struct work_struct *work)
 839 {
 840         struct netpoll *np = container_of(work, struct netpoll, cleanup_work);
 841
 842         rtnl_lock();
 843         __netpoll_cleanup(np);
 844         rtnl_unlock();
 845         kfree(np);
 846 }
 847
 848 void __netpoll_free_async(struct netpoll *np)
 849 {
 850         schedule_work(&np->cleanup_work);
 851 }
 852 EXPORT_SYMBOL_GPL(__netpoll_free_async);
 853
 854 void netpoll_cleanup(struct netpoll *np)
 855 {
 856         rtnl_lock();
 857         if (!np->dev)
 858                 goto out;
 859         __netpoll_cleanup(np);
 860         dev_put(np->dev);
 861         np->dev = NULL;
 862 out:
 863         rtnl_unlock();
 864 }
 865 EXPORT_SYMBOL(netpoll_cleanup);