drivers/net/netconsole.c

   1 /*
   2  *  linux/drivers/net/netconsole.c
   3  *
   4  *  Copyright (C) 2001  Ingo Molnar <mingo@redhat.com>
   5  *
   6  *  This file contains the implementation of an IRQ-safe, crash-safe
   7  *  kernel console implementation that outputs kernel messages to the
   8  *  network.
   9  *
  10  * Modification history:
  11  *
  12  * 2001-09-17    started by Ingo Molnar.
  13  * 2003-08-11    2.6 port by Matt Mackall
  14  *               simplified options
  15  *               generic card hooks
  16  *               works non-modular
  17  * 2003-09-07    rewritten with netpoll api
  18  */
  19
  20 /****************************************************************
  21  *      This program is free software; you can redistribute it and/or modify
  22  *      it under the terms of the GNU General Public License as published by
  23  *      the Free Software Foundation; either version 2, or (at your option)
  24  *      any later version.
  25  *
  26  *      This program is distributed in the hope that it will be useful,
  27  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  28  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  29  *      GNU General Public License for more details.
  30  *
  31  *      You should have received a copy of the GNU General Public License
  32  *      along with this program; if not, write to the Free Software
  33  *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  34  *
  35  ****************************************************************/
  36
  37 #include <linux/mm.h>
  38 #include <linux/init.h>
  39 #include <linux/module.h>
  40 #include <linux/slab.h>
  41 #include <linux/console.h>
  42 #include <linux/moduleparam.h>
  43 #include <linux/string.h>
  44 #include <linux/netpoll.h>
  45 #include <linux/inet.h>
  46 #include <linux/configfs.h>
  47
  48 MODULE_AUTHOR("Maintainer: Matt Mackall <mpm@selenic.com>");
  49 MODULE_DESCRIPTION("Console driver for network interfaces");
  50 MODULE_LICENSE("GPL");
  51
  52 #define MAX_PARAM_LENGTH        256
  53 #define MAX_PRINT_CHUNK         1000
  54
  55 static char config[MAX_PARAM_LENGTH];
  56 module_param_string(netconsole, config, MAX_PARAM_LENGTH, 0);
  57 MODULE_PARM_DESC(netconsole, " netconsole=[src-port]@[src-ip]/[dev],[tgt-port]@<tgt-ip>/[tgt-macaddr]");
  58
  59 static bool oops_only = false;
  60 module_param(oops_only, bool, 0600);
  61 MODULE_PARM_DESC(oops_only, "Only log oops messages");
  62
  63 #ifndef MODULE
  64 static int __init option_setup(char *opt)
  65 {
  66         strlcpy(config, opt, MAX_PARAM_LENGTH);
  67         return 1;
  68 }
  69 __setup("netconsole=", option_setup);
  70 #endif  /* MODULE */
  71
  72 /* Linked list of all configured targets */
  73 static LIST_HEAD(target_list);
  74
  75 /* This needs to be a spinlock because write_msg() cannot sleep */
  76 static DEFINE_SPINLOCK(target_list_lock);
  77
  78 /**
  79  * struct netconsole_target - Represents a configured netconsole target.
  80  * @list:       Links this target into the target_list.
  81  * @item:       Links us into the configfs subsystem hierarchy.
  82  * @enabled:    On / off knob to enable / disable target.
  83  *              Visible from userspace (read-write).
  84  *              We maintain a strict 1:1 correspondence between this and
  85  *              whether the corresponding netpoll is active or inactive.
  86  *              Also, other parameters of a target may be modified at
  87  *              runtime only when it is disabled (enabled == 0).
  88  * @np:         The netpoll structure for this target.
  89  *              Contains the other userspace visible parameters:
  90  *              dev_name        (read-write)
  91  *              local_port      (read-write)
  92  *              remote_port     (read-write)
  93  *              local_ip        (read-write)
  94  *              remote_ip       (read-write)
  95  *              local_mac       (read-only)
  96  *              remote_mac      (read-write)
  97  */
  98 struct netconsole_target {
  99         struct list_head        list;
 100 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
 101         struct config_item      item;
 102 #endif
 103         int                     enabled;
 104         struct netpoll          np;
 105 };
 106
 107 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
 108
 109 static struct configfs_subsystem netconsole_subsys;
 110
 111 static int __init dynamic_netconsole_init(void)
 112 {
 113         config_group_init(&netconsole_subsys.su_group);
 114         mutex_init(&netconsole_subsys.su_mutex);
 115         return configfs_register_subsystem(&netconsole_subsys);
 116 }
 117
 118 static void __exit dynamic_netconsole_exit(void)
 119 {
 120         configfs_unregister_subsystem(&netconsole_subsys);
 121 }
 122
 123 /*
 124  * Targets that were created by parsing the boot/module option string
 125  * do not exist in the configfs hierarchy (and have NULL names) and will
 126  * never go away, so make these a no-op for them.
 127  */
 128 static void netconsole_target_get(struct netconsole_target *nt)
 129 {
 130         if (config_item_name(&nt->item))
 131                 config_item_get(&nt->item);
 132 }
 133
 134 static void netconsole_target_put(struct netconsole_target *nt)
 135 {
 136         if (config_item_name(&nt->item))
 137                 config_item_put(&nt->item);
 138 }
 139
 140 #else   /* !CONFIG_NETCONSOLE_DYNAMIC */
 141
 142 static int __init dynamic_netconsole_init(void)
 143 {
 144         return 0;
 145 }
 146
 147 static void __exit dynamic_netconsole_exit(void)
 148 {
 149 }
 150
 151 /*
 152  * No danger of targets going away from under us when dynamic
 153  * reconfigurability is off.
 154  */
 155 static void netconsole_target_get(struct netconsole_target *nt)
 156 {
 157 }
 158
 159 static void netconsole_target_put(struct netconsole_target *nt)
 160 {
 161 }
 162
 163 #endif  /* CONFIG_NETCONSOLE_DYNAMIC */
 164
 165 /* Allocate new target (from boot/module param) and setup netpoll for it */
 166 static struct netconsole_target *alloc_param_target(char *target_config)
 167 {
 168         int err = -ENOMEM;
 169         struct netconsole_target *nt;
 170
 171         /*
 172          * Allocate and initialize with defaults.
 173          * Note that these targets get their config_item fields zeroed-out.
 174          */
 175         nt = kzalloc(sizeof(*nt), GFP_KERNEL);
 176         if (!nt)
 177                 goto fail;
 178
 179         nt->np.name = "netconsole";
 180         strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
 181         nt->np.local_port = 6665;
 182         nt->np.remote_port = 6666;
 183         memset(nt->np.remote_mac, 0xff, ETH_ALEN);
 184
 185         /* Parse parameters and setup netpoll */
 186         err = netpoll_parse_options(&nt->np, target_config);
 187         if (err)
 188                 goto fail;
 189
 190         err = netpoll_setup(&nt->np);
 191         if (err)
 192                 goto fail;
 193
 194         nt->enabled = 1;
 195
 196         return nt;
 197
 198 fail:
 199         kfree(nt);
 200         return ERR_PTR(err);
 201 }
 202
 203 /* Cleanup netpoll for given target (from boot/module param) and free it */
 204 static void free_param_target(struct netconsole_target *nt)
 205 {
 206         netpoll_cleanup(&nt->np);
 207         kfree(nt);
 208 }
 209
 210 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
 211
 212 /*
 213  * Our subsystem hierarchy is:
 214  *
 215  * /sys/kernel/config/netconsole/
 216  *                              |
 217  *                              <target>/
 218  *                              |       enabled
 219  *                              |       dev_name
 220  *                              |       local_port
 221  *                              |       remote_port
 222  *                              |       local_ip
 223  *                              |       remote_ip
 224  *                              |       local_mac
 225  *                              |       remote_mac
 226  *                              |
 227  *                              <target>/...
 228  */
 229
 230 struct netconsole_target_attr {
 231         struct configfs_attribute       attr;
 232         ssize_t                         (*show)(struct netconsole_target *nt,
 233                                                 char *buf);
 234         ssize_t                         (*store)(struct netconsole_target *nt,
 235                                                  const char *buf,
 236                                                  size_t count);
 237 };
 238
 239 static struct netconsole_target *to_target(struct config_item *item)
 240 {
 241         return item ?
 242                 container_of(item, struct netconsole_target, item) :
 243                 NULL;
 244 }
 245
 246 /*
 247  * Attribute operations for netconsole_target.
 248  */
 249
 250 static ssize_t show_enabled(struct netconsole_target *nt, char *buf)
 251 {
 252         return snprintf(buf, PAGE_SIZE, "%d\n", nt->enabled);
 253 }
 254
 255 static ssize_t show_dev_name(struct netconsole_target *nt, char *buf)
 256 {
 257         return snprintf(buf, PAGE_SIZE, "%s\n", nt->np.dev_name);
 258 }
 259
 260 static ssize_t show_local_port(struct netconsole_target *nt, char *buf)
 261 {
 262         return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.local_port);
 263 }
 264
 265 static ssize_t show_remote_port(struct netconsole_target *nt, char *buf)
 266 {
 267         return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.remote_port);
 268 }
 269
 270 static ssize_t show_local_ip(struct netconsole_target *nt, char *buf)
 271 {
 272         return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.local_ip);
 273 }
 274
 275 static ssize_t show_remote_ip(struct netconsole_target *nt, char *buf)
 276 {
 277         return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.remote_ip);
 278 }
 279
 280 static ssize_t show_local_mac(struct netconsole_target *nt, char *buf)
 281 {
 282         struct net_device *dev = nt->np.dev;
 283         static const u8 bcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 284
 285         return snprintf(buf, PAGE_SIZE, "%pM\n", dev ? dev->dev_addr : bcast);
 286 }
 287
 288 static ssize_t show_remote_mac(struct netconsole_target *nt, char *buf)
 289 {
 290         return snprintf(buf, PAGE_SIZE, "%pM\n", nt->np.remote_mac);
 291 }
 292
 293 /*
 294  * This one is special -- targets created through the configfs interface
 295  * are not enabled (and the corresponding netpoll activated) by default.
 296  * The user is expected to set the desired parameters first (which
 297  * would enable him to dynamically add new netpoll targets for new
 298  * network interfaces as and when they come up).
 299  */
 300 static ssize_t store_enabled(struct netconsole_target *nt,
 301                              const char *buf,
 302                              size_t count)
 303 {
 304         int enabled;
 305         int err;
 306
 307         err = kstrtoint(buf, 10, &enabled);
 308         if (err < 0)
 309                 return err;
 310         if (enabled < 0 || enabled > 1)
 311                 return -EINVAL;
 312         if (enabled == nt->enabled) {
 313                 printk(KERN_INFO "netconsole: network logging has already %s\n",
 314                                 nt->enabled ? "started" : "stopped");
 315                 return -EINVAL;
 316         }
 317
 318         if (enabled) {  /* 1 */
 319
 320                 /*
 321                  * Skip netpoll_parse_options() -- all the attributes are
 322                  * already configured via configfs. Just print them out.
 323                  */
 324                 netpoll_print_options(&nt->np);
 325
 326                 err = netpoll_setup(&nt->np);
 327                 if (err)
 328                         return err;
 329
 330                 printk(KERN_INFO "netconsole: network logging started\n");
 331
 332         } else {        /* 0 */
 333                 netpoll_cleanup(&nt->np);
 334         }
 335
 336         nt->enabled = enabled;
 337
 338         return strnlen(buf, count);
 339 }
 340
 341 static ssize_t store_dev_name(struct netconsole_target *nt,
 342                               const char *buf,
 343                               size_t count)
 344 {
 345         size_t len;
 346
 347         if (nt->enabled) {
 348                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 349                                 "disable to update parameters\n",
 350                                 config_item_name(&nt->item));
 351                 return -EINVAL;
 352         }
 353
 354         strlcpy(nt->np.dev_name, buf, IFNAMSIZ);
 355
 356         /* Get rid of possible trailing newline from echo(1) */
 357         len = strnlen(nt->np.dev_name, IFNAMSIZ);
 358         if (nt->np.dev_name[len - 1] == '\n')
 359                 nt->np.dev_name[len - 1] = '\0';
 360
 361         return strnlen(buf, count);
 362 }
 363
 364 static ssize_t store_local_port(struct netconsole_target *nt,
 365                                 const char *buf,
 366                                 size_t count)
 367 {
 368         int rv;
 369
 370         if (nt->enabled) {
 371                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 372                                 "disable to update parameters\n",
 373                                 config_item_name(&nt->item));
 374                 return -EINVAL;
 375         }
 376
 377         rv = kstrtou16(buf, 10, &nt->np.local_port);
 378         if (rv < 0)
 379                 return rv;
 380         return strnlen(buf, count);
 381 }
 382
 383 static ssize_t store_remote_port(struct netconsole_target *nt,
 384                                  const char *buf,
 385                                  size_t count)
 386 {
 387         int rv;
 388
 389         if (nt->enabled) {
 390                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 391                                 "disable to update parameters\n",
 392                                 config_item_name(&nt->item));
 393                 return -EINVAL;
 394         }
 395
 396         rv = kstrtou16(buf, 10, &nt->np.remote_port);
 397         if (rv < 0)
 398                 return rv;
 399         return strnlen(buf, count);
 400 }
 401
 402 static ssize_t store_local_ip(struct netconsole_target *nt,
 403                               const char *buf,
 404                               size_t count)
 405 {
 406         if (nt->enabled) {
 407                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 408                                 "disable to update parameters\n",
 409                                 config_item_name(&nt->item));
 410                 return -EINVAL;
 411         }
 412
 413         nt->np.local_ip = in_aton(buf);
 414
 415         return strnlen(buf, count);
 416 }
 417
 418 static ssize_t store_remote_ip(struct netconsole_target *nt,
 419                                const char *buf,
 420                                size_t count)
 421 {
 422         if (nt->enabled) {
 423                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 424                                 "disable to update parameters\n",
 425                                 config_item_name(&nt->item));
 426                 return -EINVAL;
 427         }
 428
 429         nt->np.remote_ip = in_aton(buf);
 430
 431         return strnlen(buf, count);
 432 }
 433
 434 static ssize_t store_remote_mac(struct netconsole_target *nt,
 435                                 const char *buf,
 436                                 size_t count)
 437 {
 438         u8 remote_mac[ETH_ALEN];
 439
 440         if (nt->enabled) {
 441                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 442                                 "disable to update parameters\n",
 443                                 config_item_name(&nt->item));
 444                 return -EINVAL;
 445         }
 446
 447         if (!mac_pton(buf, remote_mac))
 448                 return -EINVAL;
 449         if (buf[3 * ETH_ALEN - 1] && buf[3 * ETH_ALEN - 1] != '\n')
 450                 return -EINVAL;
 451         memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
 452
 453         return strnlen(buf, count);
 454 }
 455
 456 /*
 457  * Attribute definitions for netconsole_target.
 458  */
 459
 460 #define NETCONSOLE_TARGET_ATTR_RO(_name)                                \
 461 static struct netconsole_target_attr netconsole_target_##_name =        \
 462         __CONFIGFS_ATTR(_name, S_IRUGO, show_##_name, NULL)
 463
 464 #define NETCONSOLE_TARGET_ATTR_RW(_name)                                \
 465 static struct netconsole_target_attr netconsole_target_##_name =        \
 466         __CONFIGFS_ATTR(_name, S_IRUGO | S_IWUSR, show_##_name, store_##_name)
 467
 468 NETCONSOLE_TARGET_ATTR_RW(enabled);
 469 NETCONSOLE_TARGET_ATTR_RW(dev_name);
 470 NETCONSOLE_TARGET_ATTR_RW(local_port);
 471 NETCONSOLE_TARGET_ATTR_RW(remote_port);
 472 NETCONSOLE_TARGET_ATTR_RW(local_ip);
 473 NETCONSOLE_TARGET_ATTR_RW(remote_ip);
 474 NETCONSOLE_TARGET_ATTR_RO(local_mac);
 475 NETCONSOLE_TARGET_ATTR_RW(remote_mac);
 476
 477 static struct configfs_attribute *netconsole_target_attrs[] = {
 478         &netconsole_target_enabled.attr,
 479         &netconsole_target_dev_name.attr,
 480         &netconsole_target_local_port.attr,
 481         &netconsole_target_remote_port.attr,
 482         &netconsole_target_local_ip.attr,
 483         &netconsole_target_remote_ip.attr,
 484         &netconsole_target_local_mac.attr,
 485         &netconsole_target_remote_mac.attr,
 486         NULL,
 487 };
 488
 489 /*
 490  * Item operations and type for netconsole_target.
 491  */
 492
 493 static void netconsole_target_release(struct config_item *item)
 494 {
 495         kfree(to_target(item));
 496 }
 497
 498 static ssize_t netconsole_target_attr_show(struct config_item *item,
 499                                            struct configfs_attribute *attr,
 500                                            char *buf)
 501 {
 502         ssize_t ret = -EINVAL;
 503         struct netconsole_target *nt = to_target(item);
 504         struct netconsole_target_attr *na =
 505                 container_of(attr, struct netconsole_target_attr, attr);
 506
 507         if (na->show)
 508                 ret = na->show(nt, buf);
 509
 510         return ret;
 511 }
 512
 513 static ssize_t netconsole_target_attr_store(struct config_item *item,
 514                                             struct configfs_attribute *attr,
 515                                             const char *buf,
 516                                             size_t count)
 517 {
 518         ssize_t ret = -EINVAL;
 519         struct netconsole_target *nt = to_target(item);
 520         struct netconsole_target_attr *na =
 521                 container_of(attr, struct netconsole_target_attr, attr);
 522
 523         if (na->store)
 524                 ret = na->store(nt, buf, count);
 525
 526         return ret;
 527 }
 528
 529 static struct configfs_item_operations netconsole_target_item_ops = {
 530         .release                = netconsole_target_release,
 531         .show_attribute         = netconsole_target_attr_show,
 532         .store_attribute        = netconsole_target_attr_store,
 533 };
 534
 535 static struct config_item_type netconsole_target_type = {
 536         .ct_attrs               = netconsole_target_attrs,
 537         .ct_item_ops            = &netconsole_target_item_ops,
 538         .ct_owner               = THIS_MODULE,
 539 };
 540
 541 /*
 542  * Group operations and type for netconsole_subsys.
 543  */
 544
 545 static struct config_item *make_netconsole_target(struct config_group *group,
 546                                                   const char *name)
 547 {
 548         unsigned long flags;
 549         struct netconsole_target *nt;
 550
 551         /*
 552          * Allocate and initialize with defaults.
 553          * Target is disabled at creation (enabled == 0).
 554          */
 555         nt = kzalloc(sizeof(*nt), GFP_KERNEL);
 556         if (!nt)
 557                 return ERR_PTR(-ENOMEM);
 558
 559         nt->np.name = "netconsole";
 560         strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
 561         nt->np.local_port = 6665;
 562         nt->np.remote_port = 6666;
 563         memset(nt->np.remote_mac, 0xff, ETH_ALEN);
 564
 565         /* Initialize the config_item member */
 566         config_item_init_type_name(&nt->item, name, &netconsole_target_type);
 567
 568         /* Adding, but it is disabled */
 569         spin_lock_irqsave(&target_list_lock, flags);
 570         list_add(&nt->list, &target_list);
 571         spin_unlock_irqrestore(&target_list_lock, flags);
 572
 573         return &nt->item;
 574 }
 575
 576 static void drop_netconsole_target(struct config_group *group,
 577                                    struct config_item *item)
 578 {
 579         unsigned long flags;
 580         struct netconsole_target *nt = to_target(item);
 581
 582         spin_lock_irqsave(&target_list_lock, flags);
 583         list_del(&nt->list);
 584         spin_unlock_irqrestore(&target_list_lock, flags);
 585
 586         /*
 587          * The target may have never been enabled, or was manually disabled
 588          * before being removed so netpoll may have already been cleaned up.
 589          */
 590         if (nt->enabled)
 591                 netpoll_cleanup(&nt->np);
 592
 593         config_item_put(&nt->item);
 594 }
 595
 596 static struct configfs_group_operations netconsole_subsys_group_ops = {
 597         .make_item      = make_netconsole_target,
 598         .drop_item      = drop_netconsole_target,
 599 };
 600
 601 static struct config_item_type netconsole_subsys_type = {
 602         .ct_group_ops   = &netconsole_subsys_group_ops,
 603         .ct_owner       = THIS_MODULE,
 604 };
 605
 606 /* The netconsole configfs subsystem */
 607 static struct configfs_subsystem netconsole_subsys = {
 608         .su_group       = {
 609                 .cg_item        = {
 610                         .ci_namebuf     = "netconsole",
 611                         .ci_type        = &netconsole_subsys_type,
 612                 },
 613         },
 614 };
 615
 616 #endif  /* CONFIG_NETCONSOLE_DYNAMIC */
 617
 618 /* Handle network interface device notifications */
 619 static int netconsole_netdev_event(struct notifier_block *this,
 620                                    unsigned long event,
 621                                    void *ptr)
 622 {
 623         unsigned long flags;
 624         struct netconsole_target *nt;
 625         struct net_device *dev = ptr;
 626         bool stopped = false;
 627
 628         if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER ||
 629               event == NETDEV_RELEASE || event == NETDEV_JOIN))
 630                 goto done;
 631
 632         spin_lock_irqsave(&target_list_lock, flags);
 633         list_for_each_entry(nt, &target_list, list) {
 634                 netconsole_target_get(nt);
 635                 if (nt->np.dev == dev) {
 636                         switch (event) {
 637                         case NETDEV_CHANGENAME:
 638                                 strlcpy(nt->np.dev_name, dev->name, IFNAMSIZ);
 639                                 break;
 640                         case NETDEV_RELEASE:
 641                         case NETDEV_JOIN:
 642                         case NETDEV_UNREGISTER:
 643                                 /*
 644                                  * rtnl_lock already held
 645                                  */
 646                                 if (nt->np.dev) {
 647                                         __netpoll_cleanup(&nt->np);
 648                                         dev_put(nt->np.dev);
 649                                         nt->np.dev = NULL;
 650                                 }
 651                                 nt->enabled = 0;
 652                                 stopped = true;
 653                                 break;
 654                         }
 655                 }
 656                 netconsole_target_put(nt);
 657         }
 658         spin_unlock_irqrestore(&target_list_lock, flags);
 659         if (stopped) {
 660                 printk(KERN_INFO "netconsole: network logging stopped on "
 661                        "interface %s as it ", dev->name);
 662                 switch (event) {
 663                 case NETDEV_UNREGISTER:
 664                         printk(KERN_CONT "unregistered\n");
 665                         break;
 666                 case NETDEV_RELEASE:
 667                         printk(KERN_CONT "released slaves\n");
 668                         break;
 669                 case NETDEV_JOIN:
 670                         printk(KERN_CONT "is joining a master device\n");
 671                         break;
 672                 }
 673         }
 674
 675 done:
 676         return NOTIFY_DONE;
 677 }
 678
 679 static struct notifier_block netconsole_netdev_notifier = {
 680         .notifier_call  = netconsole_netdev_event,
 681 };
 682
 683 static void write_msg(struct console *con, const char *msg, unsigned int len)
 684 {
 685         int frag, left;
 686         unsigned long flags;
 687         struct netconsole_target *nt;
 688         const char *tmp;
 689
 690         if (oops_only && !oops_in_progress)
 691                 return;
 692         /* Avoid taking lock and disabling interrupts unnecessarily */
 693         if (list_empty(&target_list))
 694                 return;
 695
 696         spin_lock_irqsave(&target_list_lock, flags);
 697         list_for_each_entry(nt, &target_list, list) {
 698                 netconsole_target_get(nt);
 699                 if (nt->enabled && netif_running(nt->np.dev)) {
 700                         /*
 701                          * We nest this inside the for-each-target loop above
 702                          * so that we're able to get as much logging out to
 703                          * at least one target if we die inside here, instead
 704                          * of unnecessarily keeping all targets in lock-step.
 705                          */
 706                         tmp = msg;
 707                         for (left = len; left;) {
 708                                 frag = min(left, MAX_PRINT_CHUNK);
 709                                 netpoll_send_udp(&nt->np, tmp, frag);
 710                                 tmp += frag;
 711                                 left -= frag;
 712                         }
 713                 }
 714                 netconsole_target_put(nt);
 715         }
 716         spin_unlock_irqrestore(&target_list_lock, flags);
 717 }
 718
 719 static struct console netconsole = {
 720         .name   = "netcon",
 721         .flags  = CON_ENABLED,
 722         .write  = write_msg,
 723 };
 724
 725 static int __init init_netconsole(void)
 726 {
 727         int err;
 728         struct netconsole_target *nt, *tmp;
 729         unsigned long flags;
 730         char *target_config;
 731         char *input = config;
 732
 733         if (strnlen(input, MAX_PARAM_LENGTH)) {
 734                 while ((target_config = strsep(&input, ";"))) {
 735                         nt = alloc_param_target(target_config);
 736                         if (IS_ERR(nt)) {
 737                                 err = PTR_ERR(nt);
 738                                 goto fail;
 739                         }
 740                         /* Dump existing printks when we register */
 741                         netconsole.flags |= CON_PRINTBUFFER;
 742
 743                         spin_lock_irqsave(&target_list_lock, flags);
 744                         list_add(&nt->list, &target_list);
 745                         spin_unlock_irqrestore(&target_list_lock, flags);
 746                 }
 747         }
 748
 749         err = register_netdevice_notifier(&netconsole_netdev_notifier);
 750         if (err)
 751                 goto fail;
 752
 753         err = dynamic_netconsole_init();
 754         if (err)
 755                 goto undonotifier;
 756
 757         register_console(&netconsole);
 758         printk(KERN_INFO "netconsole: network logging started\n");
 759
 760         return err;
 761
 762 undonotifier:
 763         unregister_netdevice_notifier(&netconsole_netdev_notifier);
 764
 765 fail:
 766         printk(KERN_ERR "netconsole: cleaning up\n");
 767
 768         /*
 769          * Remove all targets and destroy them (only targets created
 770          * from the boot/module option exist here). Skipping the list
 771          * lock is safe here, and netpoll_cleanup() will sleep.
 772          */
 773         list_for_each_entry_safe(nt, tmp, &target_list, list) {
 774                 list_del(&nt->list);
 775                 free_param_target(nt);
 776         }
 777
 778         return err;
 779 }
 780
 781 static void __exit cleanup_netconsole(void)
 782 {
 783         struct netconsole_target *nt, *tmp;
 784
 785         unregister_console(&netconsole);
 786         dynamic_netconsole_exit();
 787         unregister_netdevice_notifier(&netconsole_netdev_notifier);
 788
 789         /*
 790          * Targets created via configfs pin references on our module
 791          * and would first be rmdir(2)'ed from userspace. We reach
 792          * here only when they are already destroyed, and only those
 793          * created from the boot/module option are left, so remove and
 794          * destroy them. Skipping the list lock is safe here, and
 795          * netpoll_cleanup() will sleep.
 796          */
 797         list_for_each_entry_safe(nt, tmp, &target_list, list) {
 798                 list_del(&nt->list);
 799                 free_param_target(nt);
 800         }
 801 }
 802
 803 /*
 804  * Use late_initcall to ensure netconsole is
 805  * initialized after network device driver if built-in.
 806  *
 807  * late_initcall() and module_init() are identical if built as module.
 808  */
 809 late_initcall(init_netconsole);
 810 module_exit(cleanup_netconsole);