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/console.h>
  41 #include <linux/moduleparam.h>
  42 #include <linux/string.h>
  43 #include <linux/netpoll.h>
  44 #include <linux/inet.h>
  45 #include <linux/configfs.h>
  46
  47 MODULE_AUTHOR("Maintainer: Matt Mackall <mpm@selenic.com>");
  48 MODULE_DESCRIPTION("Console driver for network interfaces");
  49 MODULE_LICENSE("GPL");
  50
  51 #define MAX_PARAM_LENGTH        256
  52 #define MAX_PRINT_CHUNK         1000
  53
  54 static char config[MAX_PARAM_LENGTH];
  55 module_param_string(netconsole, config, MAX_PARAM_LENGTH, 0);
  56 MODULE_PARM_DESC(netconsole, " netconsole=[src-port]@[src-ip]/[dev],[tgt-port]@<tgt-ip>/[tgt-macaddr]");
  57
  58 #ifndef MODULE
  59 static int __init option_setup(char *opt)
  60 {
  61         strlcpy(config, opt, MAX_PARAM_LENGTH);
  62         return 1;
  63 }
  64 __setup("netconsole=", option_setup);
  65 #endif  /* MODULE */
  66
  67 /* Linked list of all configured targets */
  68 static LIST_HEAD(target_list);
  69
  70 /* This needs to be a spinlock because write_msg() cannot sleep */
  71 static DEFINE_SPINLOCK(target_list_lock);
  72
  73 /**
  74  * struct netconsole_target - Represents a configured netconsole target.
  75  * @list:       Links this target into the target_list.
  76  * @item:       Links us into the configfs subsystem hierarchy.
  77  * @enabled:    On / off knob to enable / disable target.
  78  *              Visible from userspace (read-write).
  79  *              We maintain a strict 1:1 correspondence between this and
  80  *              whether the corresponding netpoll is active or inactive.
  81  *              Also, other parameters of a target may be modified at
  82  *              runtime only when it is disabled (enabled == 0).
  83  * @np:         The netpoll structure for this target.
  84  *              Contains the other userspace visible parameters:
  85  *              dev_name        (read-write)
  86  *              local_port      (read-write)
  87  *              remote_port     (read-write)
  88  *              local_ip        (read-write)
  89  *              remote_ip       (read-write)
  90  *              local_mac       (read-only)
  91  *              remote_mac      (read-write)
  92  */
  93 struct netconsole_target {
  94         struct list_head        list;
  95 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
  96         struct config_item      item;
  97 #endif
  98         int                     enabled;
  99         struct netpoll          np;
 100 };
 101
 102 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
 103
 104 static struct configfs_subsystem netconsole_subsys;
 105
 106 static int __init dynamic_netconsole_init(void)
 107 {
 108         config_group_init(&netconsole_subsys.su_group);
 109         mutex_init(&netconsole_subsys.su_mutex);
 110         return configfs_register_subsystem(&netconsole_subsys);
 111 }
 112
 113 static void __exit dynamic_netconsole_exit(void)
 114 {
 115         configfs_unregister_subsystem(&netconsole_subsys);
 116 }
 117
 118 /*
 119  * Targets that were created by parsing the boot/module option string
 120  * do not exist in the configfs hierarchy (and have NULL names) and will
 121  * never go away, so make these a no-op for them.
 122  */
 123 static void netconsole_target_get(struct netconsole_target *nt)
 124 {
 125         if (config_item_name(&nt->item))
 126                 config_item_get(&nt->item);
 127 }
 128
 129 static void netconsole_target_put(struct netconsole_target *nt)
 130 {
 131         if (config_item_name(&nt->item))
 132                 config_item_put(&nt->item);
 133 }
 134
 135 #else   /* !CONFIG_NETCONSOLE_DYNAMIC */
 136
 137 static int __init dynamic_netconsole_init(void)
 138 {
 139         return 0;
 140 }
 141
 142 static void __exit dynamic_netconsole_exit(void)
 143 {
 144 }
 145
 146 /*
 147  * No danger of targets going away from under us when dynamic
 148  * reconfigurability is off.
 149  */
 150 static void netconsole_target_get(struct netconsole_target *nt)
 151 {
 152 }
 153
 154 static void netconsole_target_put(struct netconsole_target *nt)
 155 {
 156 }
 157
 158 #endif  /* CONFIG_NETCONSOLE_DYNAMIC */
 159
 160 /* Allocate new target (from boot/module param) and setup netpoll for it */
 161 static struct netconsole_target *alloc_param_target(char *target_config)
 162 {
 163         int err = -ENOMEM;
 164         struct netconsole_target *nt;
 165
 166         /*
 167          * Allocate and initialize with defaults.
 168          * Note that these targets get their config_item fields zeroed-out.
 169          */
 170         nt = kzalloc(sizeof(*nt), GFP_KERNEL);
 171         if (!nt) {
 172                 printk(KERN_ERR "netconsole: failed to allocate memory\n");
 173                 goto fail;
 174         }
 175
 176         nt->np.name = "netconsole";
 177         strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
 178         nt->np.local_port = 6665;
 179         nt->np.remote_port = 6666;
 180         memset(nt->np.remote_mac, 0xff, ETH_ALEN);
 181
 182         /* Parse parameters and setup netpoll */
 183         err = netpoll_parse_options(&nt->np, target_config);
 184         if (err)
 185                 goto fail;
 186
 187         err = netpoll_setup(&nt->np);
 188         if (err)
 189                 goto fail;
 190
 191         nt->enabled = 1;
 192
 193         return nt;
 194
 195 fail:
 196         kfree(nt);
 197         return ERR_PTR(err);
 198 }
 199
 200 /* Cleanup netpoll for given target (from boot/module param) and free it */
 201 static void free_param_target(struct netconsole_target *nt)
 202 {
 203         netpoll_cleanup(&nt->np);
 204         kfree(nt);
 205 }
 206
 207 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
 208
 209 /*
 210  * Our subsystem hierarchy is:
 211  *
 212  * /sys/kernel/config/netconsole/
 213  *                              |
 214  *                              <target>/
 215  *                              |       enabled
 216  *                              |       dev_name
 217  *                              |       local_port
 218  *                              |       remote_port
 219  *                              |       local_ip
 220  *                              |       remote_ip
 221  *                              |       local_mac
 222  *                              |       remote_mac
 223  *                              |
 224  *                              <target>/...
 225  */
 226
 227 struct netconsole_target_attr {
 228         struct configfs_attribute       attr;
 229         ssize_t                         (*show)(struct netconsole_target *nt,
 230                                                 char *buf);
 231         ssize_t                         (*store)(struct netconsole_target *nt,
 232                                                  const char *buf,
 233                                                  size_t count);
 234 };
 235
 236 static struct netconsole_target *to_target(struct config_item *item)
 237 {
 238         return item ?
 239                 container_of(item, struct netconsole_target, item) :
 240                 NULL;
 241 }
 242
 243 /*
 244  * Wrapper over simple_strtol (base 10) with sanity and range checking.
 245  * We return (signed) long only because we may want to return errors.
 246  * Do not use this to convert numbers that are allowed to be negative.
 247  */
 248 static long strtol10_check_range(const char *cp, long min, long max)
 249 {
 250         long ret;
 251         char *p = (char *) cp;
 252
 253         WARN_ON(min < 0);
 254         WARN_ON(max < min);
 255
 256         ret = simple_strtol(p, &p, 10);
 257
 258         if (*p && (*p != '\n')) {
 259                 printk(KERN_ERR "netconsole: invalid input\n");
 260                 return -EINVAL;
 261         }
 262         if ((ret < min) || (ret > max)) {
 263                 printk(KERN_ERR "netconsole: input %ld must be between "
 264                                 "%ld and %ld\n", ret, min, max);
 265                 return -EINVAL;
 266         }
 267
 268         return ret;
 269 }
 270
 271 /*
 272  * Attribute operations for netconsole_target.
 273  */
 274
 275 static ssize_t show_enabled(struct netconsole_target *nt, char *buf)
 276 {
 277         return snprintf(buf, PAGE_SIZE, "%d\n", nt->enabled);
 278 }
 279
 280 static ssize_t show_dev_name(struct netconsole_target *nt, char *buf)
 281 {
 282         return snprintf(buf, PAGE_SIZE, "%s\n", nt->np.dev_name);
 283 }
 284
 285 static ssize_t show_local_port(struct netconsole_target *nt, char *buf)
 286 {
 287         return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.local_port);
 288 }
 289
 290 static ssize_t show_remote_port(struct netconsole_target *nt, char *buf)
 291 {
 292         return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.remote_port);
 293 }
 294
 295 static ssize_t show_local_ip(struct netconsole_target *nt, char *buf)
 296 {
 297         return snprintf(buf, PAGE_SIZE, "%d.%d.%d.%d\n",
 298                         HIPQUAD(nt->np.local_ip));
 299 }
 300
 301 static ssize_t show_remote_ip(struct netconsole_target *nt, char *buf)
 302 {
 303         return snprintf(buf, PAGE_SIZE, "%d.%d.%d.%d\n",
 304                         HIPQUAD(nt->np.remote_ip));
 305 }
 306
 307 static ssize_t show_local_mac(struct netconsole_target *nt, char *buf)
 308 {
 309         struct net_device *dev = nt->np.dev;
 310         static const u8 bcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 311
 312         return snprintf(buf, PAGE_SIZE, "%pM\n", dev ? dev->dev_addr : bcast);
 313 }
 314
 315 static ssize_t show_remote_mac(struct netconsole_target *nt, char *buf)
 316 {
 317         return snprintf(buf, PAGE_SIZE, "%pM\n", nt->np.remote_mac);
 318 }
 319
 320 /*
 321  * This one is special -- targets created through the configfs interface
 322  * are not enabled (and the corresponding netpoll activated) by default.
 323  * The user is expected to set the desired parameters first (which
 324  * would enable him to dynamically add new netpoll targets for new
 325  * network interfaces as and when they come up).
 326  */
 327 static ssize_t store_enabled(struct netconsole_target *nt,
 328                              const char *buf,
 329                              size_t count)
 330 {
 331         int err;
 332         long enabled;
 333
 334         enabled = strtol10_check_range(buf, 0, 1);
 335         if (enabled < 0)
 336                 return enabled;
 337
 338         if (enabled) {  /* 1 */
 339
 340                 /*
 341                  * Skip netpoll_parse_options() -- all the attributes are
 342                  * already configured via configfs. Just print them out.
 343                  */
 344                 netpoll_print_options(&nt->np);
 345
 346                 err = netpoll_setup(&nt->np);
 347                 if (err)
 348                         return err;
 349
 350                 printk(KERN_INFO "netconsole: network logging started\n");
 351
 352         } else {        /* 0 */
 353                 netpoll_cleanup(&nt->np);
 354         }
 355
 356         nt->enabled = enabled;
 357
 358         return strnlen(buf, count);
 359 }
 360
 361 static ssize_t store_dev_name(struct netconsole_target *nt,
 362                               const char *buf,
 363                               size_t count)
 364 {
 365         size_t len;
 366
 367         if (nt->enabled) {
 368                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 369                                 "disable to update parameters\n",
 370                                 config_item_name(&nt->item));
 371                 return -EINVAL;
 372         }
 373
 374         strlcpy(nt->np.dev_name, buf, IFNAMSIZ);
 375
 376         /* Get rid of possible trailing newline from echo(1) */
 377         len = strnlen(nt->np.dev_name, IFNAMSIZ);
 378         if (nt->np.dev_name[len - 1] == '\n')
 379                 nt->np.dev_name[len - 1] = '\0';
 380
 381         return strnlen(buf, count);
 382 }
 383
 384 static ssize_t store_local_port(struct netconsole_target *nt,
 385                                 const char *buf,
 386                                 size_t count)
 387 {
 388         long local_port;
 389 #define __U16_MAX       ((__u16) ~0U)
 390
 391         if (nt->enabled) {
 392                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 393                                 "disable to update parameters\n",
 394                                 config_item_name(&nt->item));
 395                 return -EINVAL;
 396         }
 397
 398         local_port = strtol10_check_range(buf, 0, __U16_MAX);
 399         if (local_port < 0)
 400                 return local_port;
 401
 402         nt->np.local_port = local_port;
 403
 404         return strnlen(buf, count);
 405 }
 406
 407 static ssize_t store_remote_port(struct netconsole_target *nt,
 408                                  const char *buf,
 409                                  size_t count)
 410 {
 411         long remote_port;
 412 #define __U16_MAX       ((__u16) ~0U)
 413
 414         if (nt->enabled) {
 415                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 416                                 "disable to update parameters\n",
 417                                 config_item_name(&nt->item));
 418                 return -EINVAL;
 419         }
 420
 421         remote_port = strtol10_check_range(buf, 0, __U16_MAX);
 422         if (remote_port < 0)
 423                 return remote_port;
 424
 425         nt->np.remote_port = remote_port;
 426
 427         return strnlen(buf, count);
 428 }
 429
 430 static ssize_t store_local_ip(struct netconsole_target *nt,
 431                               const char *buf,
 432                               size_t count)
 433 {
 434         if (nt->enabled) {
 435                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 436                                 "disable to update parameters\n",
 437                                 config_item_name(&nt->item));
 438                 return -EINVAL;
 439         }
 440
 441         nt->np.local_ip = ntohl(in_aton(buf));
 442
 443         return strnlen(buf, count);
 444 }
 445
 446 static ssize_t store_remote_ip(struct netconsole_target *nt,
 447                                const char *buf,
 448                                size_t count)
 449 {
 450         if (nt->enabled) {
 451                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 452                                 "disable to update parameters\n",
 453                                 config_item_name(&nt->item));
 454                 return -EINVAL;
 455         }
 456
 457         nt->np.remote_ip = ntohl(in_aton(buf));
 458
 459         return strnlen(buf, count);
 460 }
 461
 462 static ssize_t store_remote_mac(struct netconsole_target *nt,
 463                                 const char *buf,
 464                                 size_t count)
 465 {
 466         u8 remote_mac[ETH_ALEN];
 467         char *p = (char *) buf;
 468         int i;
 469
 470         if (nt->enabled) {
 471                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 472                                 "disable to update parameters\n",
 473                                 config_item_name(&nt->item));
 474                 return -EINVAL;
 475         }
 476
 477         for (i = 0; i < ETH_ALEN - 1; i++) {
 478                 remote_mac[i] = simple_strtoul(p, &p, 16);
 479                 if (*p != ':')
 480                         goto invalid;
 481                 p++;
 482         }
 483         remote_mac[ETH_ALEN - 1] = simple_strtoul(p, &p, 16);
 484         if (*p && (*p != '\n'))
 485                 goto invalid;
 486
 487         memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
 488
 489         return strnlen(buf, count);
 490
 491 invalid:
 492         printk(KERN_ERR "netconsole: invalid input\n");
 493         return -EINVAL;
 494 }
 495
 496 /*
 497  * Attribute definitions for netconsole_target.
 498  */
 499
 500 #define NETCONSOLE_TARGET_ATTR_RO(_name)                                \
 501 static struct netconsole_target_attr netconsole_target_##_name =        \
 502         __CONFIGFS_ATTR(_name, S_IRUGO, show_##_name, NULL)
 503
 504 #define NETCONSOLE_TARGET_ATTR_RW(_name)                                \
 505 static struct netconsole_target_attr netconsole_target_##_name =        \
 506         __CONFIGFS_ATTR(_name, S_IRUGO | S_IWUSR, show_##_name, store_##_name)
 507
 508 NETCONSOLE_TARGET_ATTR_RW(enabled);
 509 NETCONSOLE_TARGET_ATTR_RW(dev_name);
 510 NETCONSOLE_TARGET_ATTR_RW(local_port);
 511 NETCONSOLE_TARGET_ATTR_RW(remote_port);
 512 NETCONSOLE_TARGET_ATTR_RW(local_ip);
 513 NETCONSOLE_TARGET_ATTR_RW(remote_ip);
 514 NETCONSOLE_TARGET_ATTR_RO(local_mac);
 515 NETCONSOLE_TARGET_ATTR_RW(remote_mac);
 516
 517 static struct configfs_attribute *netconsole_target_attrs[] = {
 518         &netconsole_target_enabled.attr,
 519         &netconsole_target_dev_name.attr,
 520         &netconsole_target_local_port.attr,
 521         &netconsole_target_remote_port.attr,
 522         &netconsole_target_local_ip.attr,
 523         &netconsole_target_remote_ip.attr,
 524         &netconsole_target_local_mac.attr,
 525         &netconsole_target_remote_mac.attr,
 526         NULL,
 527 };
 528
 529 /*
 530  * Item operations and type for netconsole_target.
 531  */
 532
 533 static void netconsole_target_release(struct config_item *item)
 534 {
 535         kfree(to_target(item));
 536 }
 537
 538 static ssize_t netconsole_target_attr_show(struct config_item *item,
 539                                            struct configfs_attribute *attr,
 540                                            char *buf)
 541 {
 542         ssize_t ret = -EINVAL;
 543         struct netconsole_target *nt = to_target(item);
 544         struct netconsole_target_attr *na =
 545                 container_of(attr, struct netconsole_target_attr, attr);
 546
 547         if (na->show)
 548                 ret = na->show(nt, buf);
 549
 550         return ret;
 551 }
 552
 553 static ssize_t netconsole_target_attr_store(struct config_item *item,
 554                                             struct configfs_attribute *attr,
 555                                             const char *buf,
 556                                             size_t count)
 557 {
 558         ssize_t ret = -EINVAL;
 559         struct netconsole_target *nt = to_target(item);
 560         struct netconsole_target_attr *na =
 561                 container_of(attr, struct netconsole_target_attr, attr);
 562
 563         if (na->store)
 564                 ret = na->store(nt, buf, count);
 565
 566         return ret;
 567 }
 568
 569 static struct configfs_item_operations netconsole_target_item_ops = {
 570         .release                = netconsole_target_release,
 571         .show_attribute         = netconsole_target_attr_show,
 572         .store_attribute        = netconsole_target_attr_store,
 573 };
 574
 575 static struct config_item_type netconsole_target_type = {
 576         .ct_attrs               = netconsole_target_attrs,
 577         .ct_item_ops            = &netconsole_target_item_ops,
 578         .ct_owner               = THIS_MODULE,
 579 };
 580
 581 /*
 582  * Group operations and type for netconsole_subsys.
 583  */
 584
 585 static struct config_item *make_netconsole_target(struct config_group *group,
 586                                                   const char *name)
 587 {
 588         unsigned long flags;
 589         struct netconsole_target *nt;
 590
 591         /*
 592          * Allocate and initialize with defaults.
 593          * Target is disabled at creation (enabled == 0).
 594          */
 595         nt = kzalloc(sizeof(*nt), GFP_KERNEL);
 596         if (!nt) {
 597                 printk(KERN_ERR "netconsole: failed to allocate memory\n");
 598                 return ERR_PTR(-ENOMEM);
 599         }
 600
 601         nt->np.name = "netconsole";
 602         strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
 603         nt->np.local_port = 6665;
 604         nt->np.remote_port = 6666;
 605         memset(nt->np.remote_mac, 0xff, ETH_ALEN);
 606
 607         /* Initialize the config_item member */
 608         config_item_init_type_name(&nt->item, name, &netconsole_target_type);
 609
 610         /* Adding, but it is disabled */
 611         spin_lock_irqsave(&target_list_lock, flags);
 612         list_add(&nt->list, &target_list);
 613         spin_unlock_irqrestore(&target_list_lock, flags);
 614
 615         return &nt->item;
 616 }
 617
 618 static void drop_netconsole_target(struct config_group *group,
 619                                    struct config_item *item)
 620 {
 621         unsigned long flags;
 622         struct netconsole_target *nt = to_target(item);
 623
 624         spin_lock_irqsave(&target_list_lock, flags);
 625         list_del(&nt->list);
 626         spin_unlock_irqrestore(&target_list_lock, flags);
 627
 628         /*
 629          * The target may have never been enabled, or was manually disabled
 630          * before being removed so netpoll may have already been cleaned up.
 631          */
 632         if (nt->enabled)
 633                 netpoll_cleanup(&nt->np);
 634
 635         config_item_put(&nt->item);
 636 }
 637
 638 static struct configfs_group_operations netconsole_subsys_group_ops = {
 639         .make_item      = make_netconsole_target,
 640         .drop_item      = drop_netconsole_target,
 641 };
 642
 643 static struct config_item_type netconsole_subsys_type = {
 644         .ct_group_ops   = &netconsole_subsys_group_ops,
 645         .ct_owner       = THIS_MODULE,
 646 };
 647
 648 /* The netconsole configfs subsystem */
 649 static struct configfs_subsystem netconsole_subsys = {
 650         .su_group       = {
 651                 .cg_item        = {
 652                         .ci_namebuf     = "netconsole",
 653                         .ci_type        = &netconsole_subsys_type,
 654                 },
 655         },
 656 };
 657
 658 #endif  /* CONFIG_NETCONSOLE_DYNAMIC */
 659
 660 /* Handle network interface device notifications */
 661 static int netconsole_netdev_event(struct notifier_block *this,
 662                                    unsigned long event,
 663                                    void *ptr)
 664 {
 665         unsigned long flags;
 666         struct netconsole_target *nt;
 667         struct net_device *dev = ptr;
 668
 669         if (!(event == NETDEV_CHANGENAME))
 670                 goto done;
 671
 672         spin_lock_irqsave(&target_list_lock, flags);
 673         list_for_each_entry(nt, &target_list, list) {
 674                 netconsole_target_get(nt);
 675                 if (nt->np.dev == dev) {
 676                         switch (event) {
 677                         case NETDEV_CHANGENAME:
 678                                 strlcpy(nt->np.dev_name, dev->name, IFNAMSIZ);
 679                                 break;
 680                         }
 681                 }
 682                 netconsole_target_put(nt);
 683         }
 684         spin_unlock_irqrestore(&target_list_lock, flags);
 685
 686 done:
 687         return NOTIFY_DONE;
 688 }
 689
 690 static struct notifier_block netconsole_netdev_notifier = {
 691         .notifier_call  = netconsole_netdev_event,
 692 };
 693
 694 static void write_msg(struct console *con, const char *msg, unsigned int len)
 695 {
 696         int frag, left;
 697         unsigned long flags;
 698         struct netconsole_target *nt;
 699         const char *tmp;
 700
 701         /* Avoid taking lock and disabling interrupts unnecessarily */
 702         if (list_empty(&target_list))
 703                 return;
 704
 705         spin_lock_irqsave(&target_list_lock, flags);
 706         list_for_each_entry(nt, &target_list, list) {
 707                 netconsole_target_get(nt);
 708                 if (nt->enabled && netif_running(nt->np.dev)) {
 709                         /*
 710                          * We nest this inside the for-each-target loop above
 711                          * so that we're able to get as much logging out to
 712                          * at least one target if we die inside here, instead
 713                          * of unnecessarily keeping all targets in lock-step.
 714                          */
 715                         tmp = msg;
 716                         for (left = len; left;) {
 717                                 frag = min(left, MAX_PRINT_CHUNK);
 718                                 netpoll_send_udp(&nt->np, tmp, frag);
 719                                 tmp += frag;
 720                                 left -= frag;
 721                         }
 722                 }
 723                 netconsole_target_put(nt);
 724         }
 725         spin_unlock_irqrestore(&target_list_lock, flags);
 726 }
 727
 728 static struct console netconsole = {
 729         .name   = "netcon",
 730         .flags  = CON_ENABLED,
 731         .write  = write_msg,
 732 };
 733
 734 static int __init init_netconsole(void)
 735 {
 736         int err;
 737         struct netconsole_target *nt, *tmp;
 738         unsigned long flags;
 739         char *target_config;
 740         char *input = config;
 741
 742         if (strnlen(input, MAX_PARAM_LENGTH)) {
 743                 while ((target_config = strsep(&input, ";"))) {
 744                         nt = alloc_param_target(target_config);
 745                         if (IS_ERR(nt)) {
 746                                 err = PTR_ERR(nt);
 747                                 goto fail;
 748                         }
 749                         /* Dump existing printks when we register */
 750                         netconsole.flags |= CON_PRINTBUFFER;
 751
 752                         spin_lock_irqsave(&target_list_lock, flags);
 753                         list_add(&nt->list, &target_list);
 754                         spin_unlock_irqrestore(&target_list_lock, flags);
 755                 }
 756         }
 757
 758         err = register_netdevice_notifier(&netconsole_netdev_notifier);
 759         if (err)
 760                 goto fail;
 761
 762         err = dynamic_netconsole_init();
 763         if (err)
 764                 goto undonotifier;
 765
 766         register_console(&netconsole);
 767         printk(KERN_INFO "netconsole: network logging started\n");
 768
 769         return err;
 770
 771 undonotifier:
 772         unregister_netdevice_notifier(&netconsole_netdev_notifier);
 773
 774 fail:
 775         printk(KERN_ERR "netconsole: cleaning up\n");
 776
 777         /*
 778          * Remove all targets and destroy them (only targets created
 779          * from the boot/module option exist here). Skipping the list
 780          * lock is safe here, and netpoll_cleanup() will sleep.
 781          */
 782         list_for_each_entry_safe(nt, tmp, &target_list, list) {
 783                 list_del(&nt->list);
 784                 free_param_target(nt);
 785         }
 786
 787         return err;
 788 }
 789
 790 static void __exit cleanup_netconsole(void)
 791 {
 792         struct netconsole_target *nt, *tmp;
 793
 794         unregister_console(&netconsole);
 795         dynamic_netconsole_exit();
 796         unregister_netdevice_notifier(&netconsole_netdev_notifier);
 797
 798         /*
 799          * Targets created via configfs pin references on our module
 800          * and would first be rmdir(2)'ed from userspace. We reach
 801          * here only when they are already destroyed, and only those
 802          * created from the boot/module option are left, so remove and
 803          * destroy them. Skipping the list lock is safe here, and
 804          * netpoll_cleanup() will sleep.
 805          */
 806         list_for_each_entry_safe(nt, tmp, &target_list, list) {
 807                 list_del(&nt->list);
 808                 free_param_target(nt);
 809         }
 810 }
 811
 812 module_init(init_netconsole);
 813 module_exit(cleanup_netconsole);