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 #ifndef MODULE
  60 static int __init option_setup(char *opt)
  61 {
  62         strlcpy(config, opt, MAX_PARAM_LENGTH);
  63         return 1;
  64 }
  65 __setup("netconsole=", option_setup);
  66 #endif  /* MODULE */
  67
  68 /* Linked list of all configured targets */
  69 static LIST_HEAD(target_list);
  70
  71 /* This needs to be a spinlock because write_msg() cannot sleep */
  72 static DEFINE_SPINLOCK(target_list_lock);
  73
  74 /**
  75  * struct netconsole_target - Represents a configured netconsole target.
  76  * @list:       Links this target into the target_list.
  77  * @item:       Links us into the configfs subsystem hierarchy.
  78  * @enabled:    On / off knob to enable / disable target.
  79  *              Visible from userspace (read-write).
  80  *              We maintain a strict 1:1 correspondence between this and
  81  *              whether the corresponding netpoll is active or inactive.
  82  *              Also, other parameters of a target may be modified at
  83  *              runtime only when it is disabled (enabled == 0).
  84  * @np:         The netpoll structure for this target.
  85  *              Contains the other userspace visible parameters:
  86  *              dev_name        (read-write)
  87  *              local_port      (read-write)
  88  *              remote_port     (read-write)
  89  *              local_ip        (read-write)
  90  *              remote_ip       (read-write)
  91  *              local_mac       (read-only)
  92  *              remote_mac      (read-write)
  93  */
  94 struct netconsole_target {
  95         struct list_head        list;
  96 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
  97         struct config_item      item;
  98 #endif
  99         int                     enabled;
 100         struct netpoll          np;
 101 };
 102
 103 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
 104
 105 static struct configfs_subsystem netconsole_subsys;
 106
 107 static int __init dynamic_netconsole_init(void)
 108 {
 109         config_group_init(&netconsole_subsys.su_group);
 110         mutex_init(&netconsole_subsys.su_mutex);
 111         return configfs_register_subsystem(&netconsole_subsys);
 112 }
 113
 114 static void __exit dynamic_netconsole_exit(void)
 115 {
 116         configfs_unregister_subsystem(&netconsole_subsys);
 117 }
 118
 119 /*
 120  * Targets that were created by parsing the boot/module option string
 121  * do not exist in the configfs hierarchy (and have NULL names) and will
 122  * never go away, so make these a no-op for them.
 123  */
 124 static void netconsole_target_get(struct netconsole_target *nt)
 125 {
 126         if (config_item_name(&nt->item))
 127                 config_item_get(&nt->item);
 128 }
 129
 130 static void netconsole_target_put(struct netconsole_target *nt)
 131 {
 132         if (config_item_name(&nt->item))
 133                 config_item_put(&nt->item);
 134 }
 135
 136 #else   /* !CONFIG_NETCONSOLE_DYNAMIC */
 137
 138 static int __init dynamic_netconsole_init(void)
 139 {
 140         return 0;
 141 }
 142
 143 static void __exit dynamic_netconsole_exit(void)
 144 {
 145 }
 146
 147 /*
 148  * No danger of targets going away from under us when dynamic
 149  * reconfigurability is off.
 150  */
 151 static void netconsole_target_get(struct netconsole_target *nt)
 152 {
 153 }
 154
 155 static void netconsole_target_put(struct netconsole_target *nt)
 156 {
 157 }
 158
 159 #endif  /* CONFIG_NETCONSOLE_DYNAMIC */
 160
 161 /* Allocate new target (from boot/module param) and setup netpoll for it */
 162 static struct netconsole_target *alloc_param_target(char *target_config)
 163 {
 164         int err = -ENOMEM;
 165         struct netconsole_target *nt;
 166
 167         /*
 168          * Allocate and initialize with defaults.
 169          * Note that these targets get their config_item fields zeroed-out.
 170          */
 171         nt = kzalloc(sizeof(*nt), GFP_KERNEL);
 172         if (!nt)
 173                 goto fail;
 174
 175         nt->np.name = "netconsole";
 176         strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
 177         nt->np.local_port = 6665;
 178         nt->np.remote_port = 6666;
 179         memset(nt->np.remote_mac, 0xff, ETH_ALEN);
 180
 181         /* Parse parameters and setup netpoll */
 182         err = netpoll_parse_options(&nt->np, target_config);
 183         if (err)
 184                 goto fail;
 185
 186         err = netpoll_setup(&nt->np);
 187         if (err)
 188                 goto fail;
 189
 190         nt->enabled = 1;
 191
 192         return nt;
 193
 194 fail:
 195         kfree(nt);
 196         return ERR_PTR(err);
 197 }
 198
 199 /* Cleanup netpoll for given target (from boot/module param) and free it */
 200 static void free_param_target(struct netconsole_target *nt)
 201 {
 202         netpoll_cleanup(&nt->np);
 203         kfree(nt);
 204 }
 205
 206 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
 207
 208 /*
 209  * Our subsystem hierarchy is:
 210  *
 211  * /sys/kernel/config/netconsole/
 212  *                              |
 213  *                              <target>/
 214  *                              |       enabled
 215  *                              |       dev_name
 216  *                              |       local_port
 217  *                              |       remote_port
 218  *                              |       local_ip
 219  *                              |       remote_ip
 220  *                              |       local_mac
 221  *                              |       remote_mac
 222  *                              |
 223  *                              <target>/...
 224  */
 225
 226 struct netconsole_target_attr {
 227         struct configfs_attribute       attr;
 228         ssize_t                         (*show)(struct netconsole_target *nt,
 229                                                 char *buf);
 230         ssize_t                         (*store)(struct netconsole_target *nt,
 231                                                  const char *buf,
 232                                                  size_t count);
 233 };
 234
 235 static struct netconsole_target *to_target(struct config_item *item)
 236 {
 237         return item ?
 238                 container_of(item, struct netconsole_target, item) :
 239                 NULL;
 240 }
 241
 242 /*
 243  * Attribute operations for netconsole_target.
 244  */
 245
 246 static ssize_t show_enabled(struct netconsole_target *nt, char *buf)
 247 {
 248         return snprintf(buf, PAGE_SIZE, "%d\n", nt->enabled);
 249 }
 250
 251 static ssize_t show_dev_name(struct netconsole_target *nt, char *buf)
 252 {
 253         return snprintf(buf, PAGE_SIZE, "%s\n", nt->np.dev_name);
 254 }
 255
 256 static ssize_t show_local_port(struct netconsole_target *nt, char *buf)
 257 {
 258         return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.local_port);
 259 }
 260
 261 static ssize_t show_remote_port(struct netconsole_target *nt, char *buf)
 262 {
 263         return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.remote_port);
 264 }
 265
 266 static ssize_t show_local_ip(struct netconsole_target *nt, char *buf)
 267 {
 268         return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.local_ip);
 269 }
 270
 271 static ssize_t show_remote_ip(struct netconsole_target *nt, char *buf)
 272 {
 273         return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.remote_ip);
 274 }
 275
 276 static ssize_t show_local_mac(struct netconsole_target *nt, char *buf)
 277 {
 278         struct net_device *dev = nt->np.dev;
 279         static const u8 bcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 280
 281         return snprintf(buf, PAGE_SIZE, "%pM\n", dev ? dev->dev_addr : bcast);
 282 }
 283
 284 static ssize_t show_remote_mac(struct netconsole_target *nt, char *buf)
 285 {
 286         return snprintf(buf, PAGE_SIZE, "%pM\n", nt->np.remote_mac);
 287 }
 288
 289 /*
 290  * This one is special -- targets created through the configfs interface
 291  * are not enabled (and the corresponding netpoll activated) by default.
 292  * The user is expected to set the desired parameters first (which
 293  * would enable him to dynamically add new netpoll targets for new
 294  * network interfaces as and when they come up).
 295  */
 296 static ssize_t store_enabled(struct netconsole_target *nt,
 297                              const char *buf,
 298                              size_t count)
 299 {
 300         int enabled;
 301         int err;
 302
 303         err = kstrtoint(buf, 10, &enabled);
 304         if (err < 0)
 305                 return err;
 306         if (enabled < 0 || enabled > 1)
 307                 return -EINVAL;
 308         if (enabled == nt->enabled) {
 309                 printk(KERN_INFO "netconsole: network logging has already %s\n",
 310                                 nt->enabled ? "started" : "stopped");
 311                 return -EINVAL;
 312         }
 313
 314         if (enabled) {  /* 1 */
 315
 316                 /*
 317                  * Skip netpoll_parse_options() -- all the attributes are
 318                  * already configured via configfs. Just print them out.
 319                  */
 320                 netpoll_print_options(&nt->np);
 321
 322                 err = netpoll_setup(&nt->np);
 323                 if (err)
 324                         return err;
 325
 326                 printk(KERN_INFO "netconsole: network logging started\n");
 327
 328         } else {        /* 0 */
 329                 netpoll_cleanup(&nt->np);
 330         }
 331
 332         nt->enabled = enabled;
 333
 334         return strnlen(buf, count);
 335 }
 336
 337 static ssize_t store_dev_name(struct netconsole_target *nt,
 338                               const char *buf,
 339                               size_t count)
 340 {
 341         size_t len;
 342
 343         if (nt->enabled) {
 344                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 345                                 "disable to update parameters\n",
 346                                 config_item_name(&nt->item));
 347                 return -EINVAL;
 348         }
 349
 350         strlcpy(nt->np.dev_name, buf, IFNAMSIZ);
 351
 352         /* Get rid of possible trailing newline from echo(1) */
 353         len = strnlen(nt->np.dev_name, IFNAMSIZ);
 354         if (nt->np.dev_name[len - 1] == '\n')
 355                 nt->np.dev_name[len - 1] = '\0';
 356
 357         return strnlen(buf, count);
 358 }
 359
 360 static ssize_t store_local_port(struct netconsole_target *nt,
 361                                 const char *buf,
 362                                 size_t count)
 363 {
 364         int rv;
 365
 366         if (nt->enabled) {
 367                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 368                                 "disable to update parameters\n",
 369                                 config_item_name(&nt->item));
 370                 return -EINVAL;
 371         }
 372
 373         rv = kstrtou16(buf, 10, &nt->np.local_port);
 374         if (rv < 0)
 375                 return rv;
 376         return strnlen(buf, count);
 377 }
 378
 379 static ssize_t store_remote_port(struct netconsole_target *nt,
 380                                  const char *buf,
 381                                  size_t count)
 382 {
 383         int rv;
 384
 385         if (nt->enabled) {
 386                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 387                                 "disable to update parameters\n",
 388                                 config_item_name(&nt->item));
 389                 return -EINVAL;
 390         }
 391
 392         rv = kstrtou16(buf, 10, &nt->np.remote_port);
 393         if (rv < 0)
 394                 return rv;
 395         return strnlen(buf, count);
 396 }
 397
 398 static ssize_t store_local_ip(struct netconsole_target *nt,
 399                               const char *buf,
 400                               size_t count)
 401 {
 402         if (nt->enabled) {
 403                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 404                                 "disable to update parameters\n",
 405                                 config_item_name(&nt->item));
 406                 return -EINVAL;
 407         }
 408
 409         nt->np.local_ip = in_aton(buf);
 410
 411         return strnlen(buf, count);
 412 }
 413
 414 static ssize_t store_remote_ip(struct netconsole_target *nt,
 415                                const char *buf,
 416                                size_t count)
 417 {
 418         if (nt->enabled) {
 419                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 420                                 "disable to update parameters\n",
 421                                 config_item_name(&nt->item));
 422                 return -EINVAL;
 423         }
 424
 425         nt->np.remote_ip = in_aton(buf);
 426
 427         return strnlen(buf, count);
 428 }
 429
 430 static ssize_t store_remote_mac(struct netconsole_target *nt,
 431                                 const char *buf,
 432                                 size_t count)
 433 {
 434         u8 remote_mac[ETH_ALEN];
 435
 436         if (nt->enabled) {
 437                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 438                                 "disable to update parameters\n",
 439                                 config_item_name(&nt->item));
 440                 return -EINVAL;
 441         }
 442
 443         if (!mac_pton(buf, remote_mac))
 444                 return -EINVAL;
 445         if (buf[3 * ETH_ALEN - 1] && buf[3 * ETH_ALEN - 1] != '\n')
 446                 return -EINVAL;
 447         memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
 448
 449         return strnlen(buf, count);
 450 }
 451
 452 /*
 453  * Attribute definitions for netconsole_target.
 454  */
 455
 456 #define NETCONSOLE_TARGET_ATTR_RO(_name)                                \
 457 static struct netconsole_target_attr netconsole_target_##_name =        \
 458         __CONFIGFS_ATTR(_name, S_IRUGO, show_##_name, NULL)
 459
 460 #define NETCONSOLE_TARGET_ATTR_RW(_name)                                \
 461 static struct netconsole_target_attr netconsole_target_##_name =        \
 462         __CONFIGFS_ATTR(_name, S_IRUGO | S_IWUSR, show_##_name, store_##_name)
 463
 464 NETCONSOLE_TARGET_ATTR_RW(enabled);
 465 NETCONSOLE_TARGET_ATTR_RW(dev_name);
 466 NETCONSOLE_TARGET_ATTR_RW(local_port);
 467 NETCONSOLE_TARGET_ATTR_RW(remote_port);
 468 NETCONSOLE_TARGET_ATTR_RW(local_ip);
 469 NETCONSOLE_TARGET_ATTR_RW(remote_ip);
 470 NETCONSOLE_TARGET_ATTR_RO(local_mac);
 471 NETCONSOLE_TARGET_ATTR_RW(remote_mac);
 472
 473 static struct configfs_attribute *netconsole_target_attrs[] = {
 474         &netconsole_target_enabled.attr,
 475         &netconsole_target_dev_name.attr,
 476         &netconsole_target_local_port.attr,
 477         &netconsole_target_remote_port.attr,
 478         &netconsole_target_local_ip.attr,
 479         &netconsole_target_remote_ip.attr,
 480         &netconsole_target_local_mac.attr,
 481         &netconsole_target_remote_mac.attr,
 482         NULL,
 483 };
 484
 485 /*
 486  * Item operations and type for netconsole_target.
 487  */
 488
 489 static void netconsole_target_release(struct config_item *item)
 490 {
 491         kfree(to_target(item));
 492 }
 493
 494 static ssize_t netconsole_target_attr_show(struct config_item *item,
 495                                            struct configfs_attribute *attr,
 496                                            char *buf)
 497 {
 498         ssize_t ret = -EINVAL;
 499         struct netconsole_target *nt = to_target(item);
 500         struct netconsole_target_attr *na =
 501                 container_of(attr, struct netconsole_target_attr, attr);
 502
 503         if (na->show)
 504                 ret = na->show(nt, buf);
 505
 506         return ret;
 507 }
 508
 509 static ssize_t netconsole_target_attr_store(struct config_item *item,
 510                                             struct configfs_attribute *attr,
 511                                             const char *buf,
 512                                             size_t count)
 513 {
 514         ssize_t ret = -EINVAL;
 515         struct netconsole_target *nt = to_target(item);
 516         struct netconsole_target_attr *na =
 517                 container_of(attr, struct netconsole_target_attr, attr);
 518
 519         if (na->store)
 520                 ret = na->store(nt, buf, count);
 521
 522         return ret;
 523 }
 524
 525 static struct configfs_item_operations netconsole_target_item_ops = {
 526         .release                = netconsole_target_release,
 527         .show_attribute         = netconsole_target_attr_show,
 528         .store_attribute        = netconsole_target_attr_store,
 529 };
 530
 531 static struct config_item_type netconsole_target_type = {
 532         .ct_attrs               = netconsole_target_attrs,
 533         .ct_item_ops            = &netconsole_target_item_ops,
 534         .ct_owner               = THIS_MODULE,
 535 };
 536
 537 /*
 538  * Group operations and type for netconsole_subsys.
 539  */
 540
 541 static struct config_item *make_netconsole_target(struct config_group *group,
 542                                                   const char *name)
 543 {
 544         unsigned long flags;
 545         struct netconsole_target *nt;
 546
 547         /*
 548          * Allocate and initialize with defaults.
 549          * Target is disabled at creation (enabled == 0).
 550          */
 551         nt = kzalloc(sizeof(*nt), GFP_KERNEL);
 552         if (!nt)
 553                 return ERR_PTR(-ENOMEM);
 554
 555         nt->np.name = "netconsole";
 556         strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
 557         nt->np.local_port = 6665;
 558         nt->np.remote_port = 6666;
 559         memset(nt->np.remote_mac, 0xff, ETH_ALEN);
 560
 561         /* Initialize the config_item member */
 562         config_item_init_type_name(&nt->item, name, &netconsole_target_type);
 563
 564         /* Adding, but it is disabled */
 565         spin_lock_irqsave(&target_list_lock, flags);
 566         list_add(&nt->list, &target_list);
 567         spin_unlock_irqrestore(&target_list_lock, flags);
 568
 569         return &nt->item;
 570 }
 571
 572 static void drop_netconsole_target(struct config_group *group,
 573                                    struct config_item *item)
 574 {
 575         unsigned long flags;
 576         struct netconsole_target *nt = to_target(item);
 577
 578         spin_lock_irqsave(&target_list_lock, flags);
 579         list_del(&nt->list);
 580         spin_unlock_irqrestore(&target_list_lock, flags);
 581
 582         /*
 583          * The target may have never been enabled, or was manually disabled
 584          * before being removed so netpoll may have already been cleaned up.
 585          */
 586         if (nt->enabled)
 587                 netpoll_cleanup(&nt->np);
 588
 589         config_item_put(&nt->item);
 590 }
 591
 592 static struct configfs_group_operations netconsole_subsys_group_ops = {
 593         .make_item      = make_netconsole_target,
 594         .drop_item      = drop_netconsole_target,
 595 };
 596
 597 static struct config_item_type netconsole_subsys_type = {
 598         .ct_group_ops   = &netconsole_subsys_group_ops,
 599         .ct_owner       = THIS_MODULE,
 600 };
 601
 602 /* The netconsole configfs subsystem */
 603 static struct configfs_subsystem netconsole_subsys = {
 604         .su_group       = {
 605                 .cg_item        = {
 606                         .ci_namebuf     = "netconsole",
 607                         .ci_type        = &netconsole_subsys_type,
 608                 },
 609         },
 610 };
 611
 612 #endif  /* CONFIG_NETCONSOLE_DYNAMIC */
 613
 614 /* Handle network interface device notifications */
 615 static int netconsole_netdev_event(struct notifier_block *this,
 616                                    unsigned long event,
 617                                    void *ptr)
 618 {
 619         unsigned long flags;
 620         struct netconsole_target *nt;
 621         struct net_device *dev = ptr;
 622         bool stopped = false;
 623
 624         if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER ||
 625               event == NETDEV_RELEASE || event == NETDEV_JOIN))
 626                 goto done;
 627
 628         spin_lock_irqsave(&target_list_lock, flags);
 629         list_for_each_entry(nt, &target_list, list) {
 630                 netconsole_target_get(nt);
 631                 if (nt->np.dev == dev) {
 632                         switch (event) {
 633                         case NETDEV_CHANGENAME:
 634                                 strlcpy(nt->np.dev_name, dev->name, IFNAMSIZ);
 635                                 break;
 636                         case NETDEV_RELEASE:
 637                         case NETDEV_JOIN:
 638                         case NETDEV_UNREGISTER:
 639                                 /*
 640                                  * rtnl_lock already held
 641                                  */
 642                                 if (nt->np.dev) {
 643                                         spin_unlock_irqrestore(
 644                                                               &target_list_lock,
 645                                                               flags);
 646                                         __netpoll_cleanup(&nt->np);
 647                                         spin_lock_irqsave(&target_list_lock,
 648                                                           flags);
 649                                         dev_put(nt->np.dev);
 650                                         nt->np.dev = NULL;
 651                                         netconsole_target_put(nt);
 652                                 }
 653                                 nt->enabled = 0;
 654                                 stopped = true;
 655                                 break;
 656                         }
 657                 }
 658                 netconsole_target_put(nt);
 659         }
 660         spin_unlock_irqrestore(&target_list_lock, flags);
 661         if (stopped) {
 662                 printk(KERN_INFO "netconsole: network logging stopped on "
 663                        "interface %s as it ", dev->name);
 664                 switch (event) {
 665                 case NETDEV_UNREGISTER:
 666                         printk(KERN_CONT "unregistered\n");
 667                         break;
 668                 case NETDEV_RELEASE:
 669                         printk(KERN_CONT "released slaves\n");
 670                         break;
 671                 case NETDEV_JOIN:
 672                         printk(KERN_CONT "is joining a master device\n");
 673                         break;
 674                 }
 675         }
 676
 677 done:
 678         return NOTIFY_DONE;
 679 }
 680
 681 static struct notifier_block netconsole_netdev_notifier = {
 682         .notifier_call  = netconsole_netdev_event,
 683 };
 684
 685 static void write_msg(struct console *con, const char *msg, unsigned int len)
 686 {
 687         int frag, left;
 688         unsigned long flags;
 689         struct netconsole_target *nt;
 690         const char *tmp;
 691
 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);