linux/drivers/net/netconsole.c
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   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
  48MODULE_AUTHOR("Maintainer: Matt Mackall <mpm@selenic.com>");
  49MODULE_DESCRIPTION("Console driver for network interfaces");
  50MODULE_LICENSE("GPL");
  51
  52#define MAX_PARAM_LENGTH        256
  53#define MAX_PRINT_CHUNK         1000
  54
  55static char config[MAX_PARAM_LENGTH];
  56module_param_string(netconsole, config, MAX_PARAM_LENGTH, 0);
  57MODULE_PARM_DESC(netconsole, " netconsole=[src-port]@[src-ip]/[dev],[tgt-port]@<tgt-ip>/[tgt-macaddr]");
  58
  59static bool oops_only = false;
  60module_param(oops_only, bool, 0600);
  61MODULE_PARM_DESC(oops_only, "Only log oops messages");
  62
  63#ifndef MODULE
  64static 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 */
  73static LIST_HEAD(target_list);
  74
  75/* This needs to be a spinlock because write_msg() cannot sleep */
  76static 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 */
  98struct 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
 109static struct configfs_subsystem netconsole_subsys;
 110
 111static 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
 118static 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 */
 128static void netconsole_target_get(struct netconsole_target *nt)
 129{
 130        if (config_item_name(&nt->item))
 131                config_item_get(&nt->item);
 132}
 133
 134static 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
 142static int __init dynamic_netconsole_init(void)
 143{
 144        return 0;
 145}
 146
 147static 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 */
 155static void netconsole_target_get(struct netconsole_target *nt)
 156{
 157}
 158
 159static 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 */
 166static 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
 198fail:
 199        kfree(nt);
 200        return ERR_PTR(err);
 201}
 202
 203/* Cleanup netpoll for given target (from boot/module param) and free it */
 204static 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
 230struct 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
 239static 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
 250static ssize_t show_enabled(struct netconsole_target *nt, char *buf)
 251{
 252        return snprintf(buf, PAGE_SIZE, "%d\n", nt->enabled);
 253}
 254
 255static 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
 260static 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
 265static 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
 270static ssize_t show_local_ip(struct netconsole_target *nt, char *buf)
 271{
 272        if (nt->np.ipv6)
 273                return snprintf(buf, PAGE_SIZE, "%pI6c\n", &nt->np.local_ip.in6);
 274        else
 275                return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.local_ip);
 276}
 277
 278static ssize_t show_remote_ip(struct netconsole_target *nt, char *buf)
 279{
 280        if (nt->np.ipv6)
 281                return snprintf(buf, PAGE_SIZE, "%pI6c\n", &nt->np.remote_ip.in6);
 282        else
 283                return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.remote_ip);
 284}
 285
 286static ssize_t show_local_mac(struct netconsole_target *nt, char *buf)
 287{
 288        struct net_device *dev = nt->np.dev;
 289        static const u8 bcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 290
 291        return snprintf(buf, PAGE_SIZE, "%pM\n", dev ? dev->dev_addr : bcast);
 292}
 293
 294static ssize_t show_remote_mac(struct netconsole_target *nt, char *buf)
 295{
 296        return snprintf(buf, PAGE_SIZE, "%pM\n", nt->np.remote_mac);
 297}
 298
 299/*
 300 * This one is special -- targets created through the configfs interface
 301 * are not enabled (and the corresponding netpoll activated) by default.
 302 * The user is expected to set the desired parameters first (which
 303 * would enable him to dynamically add new netpoll targets for new
 304 * network interfaces as and when they come up).
 305 */
 306static ssize_t store_enabled(struct netconsole_target *nt,
 307                             const char *buf,
 308                             size_t count)
 309{
 310        int enabled;
 311        int err;
 312
 313        err = kstrtoint(buf, 10, &enabled);
 314        if (err < 0)
 315                return err;
 316        if (enabled < 0 || enabled > 1)
 317                return -EINVAL;
 318        if (enabled == nt->enabled) {
 319                printk(KERN_INFO "netconsole: network logging has already %s\n",
 320                                nt->enabled ? "started" : "stopped");
 321                return -EINVAL;
 322        }
 323
 324        if (enabled) {  /* 1 */
 325
 326                /*
 327                 * Skip netpoll_parse_options() -- all the attributes are
 328                 * already configured via configfs. Just print them out.
 329                 */
 330                netpoll_print_options(&nt->np);
 331
 332                err = netpoll_setup(&nt->np);
 333                if (err)
 334                        return err;
 335
 336                printk(KERN_INFO "netconsole: network logging started\n");
 337
 338        } else {        /* 0 */
 339                netpoll_cleanup(&nt->np);
 340        }
 341
 342        nt->enabled = enabled;
 343
 344        return strnlen(buf, count);
 345}
 346
 347static ssize_t store_dev_name(struct netconsole_target *nt,
 348                              const char *buf,
 349                              size_t count)
 350{
 351        size_t len;
 352
 353        if (nt->enabled) {
 354                printk(KERN_ERR "netconsole: target (%s) is enabled, "
 355                                "disable to update parameters\n",
 356                                config_item_name(&nt->item));
 357                return -EINVAL;
 358        }
 359
 360        strlcpy(nt->np.dev_name, buf, IFNAMSIZ);
 361
 362        /* Get rid of possible trailing newline from echo(1) */
 363        len = strnlen(nt->np.dev_name, IFNAMSIZ);
 364        if (nt->np.dev_name[len - 1] == '\n')
 365                nt->np.dev_name[len - 1] = '\0';
 366
 367        return strnlen(buf, count);
 368}
 369
 370static ssize_t store_local_port(struct netconsole_target *nt,
 371                                const char *buf,
 372                                size_t count)
 373{
 374        int rv;
 375
 376        if (nt->enabled) {
 377                printk(KERN_ERR "netconsole: target (%s) is enabled, "
 378                                "disable to update parameters\n",
 379                                config_item_name(&nt->item));
 380                return -EINVAL;
 381        }
 382
 383        rv = kstrtou16(buf, 10, &nt->np.local_port);
 384        if (rv < 0)
 385                return rv;
 386        return strnlen(buf, count);
 387}
 388
 389static ssize_t store_remote_port(struct netconsole_target *nt,
 390                                 const char *buf,
 391                                 size_t count)
 392{
 393        int rv;
 394
 395        if (nt->enabled) {
 396                printk(KERN_ERR "netconsole: target (%s) is enabled, "
 397                                "disable to update parameters\n",
 398                                config_item_name(&nt->item));
 399                return -EINVAL;
 400        }
 401
 402        rv = kstrtou16(buf, 10, &nt->np.remote_port);
 403        if (rv < 0)
 404                return rv;
 405        return strnlen(buf, count);
 406}
 407
 408static ssize_t store_local_ip(struct netconsole_target *nt,
 409                              const char *buf,
 410                              size_t count)
 411{
 412        if (nt->enabled) {
 413                printk(KERN_ERR "netconsole: target (%s) is enabled, "
 414                                "disable to update parameters\n",
 415                                config_item_name(&nt->item));
 416                return -EINVAL;
 417        }
 418
 419        if (strnchr(buf, count, ':')) {
 420                const char *end;
 421                if (in6_pton(buf, count, nt->np.local_ip.in6.s6_addr, -1, &end) > 0) {
 422                        if (*end && *end != '\n') {
 423                                printk(KERN_ERR "netconsole: invalid IPv6 address at: <%c>\n", *end);
 424                                return -EINVAL;
 425                        }
 426                        nt->np.ipv6 = true;
 427                } else
 428                        return -EINVAL;
 429        } else {
 430                if (!nt->np.ipv6) {
 431                        nt->np.local_ip.ip = in_aton(buf);
 432                } else
 433                        return -EINVAL;
 434        }
 435
 436        return strnlen(buf, count);
 437}
 438
 439static ssize_t store_remote_ip(struct netconsole_target *nt,
 440                               const char *buf,
 441                               size_t count)
 442{
 443        if (nt->enabled) {
 444                printk(KERN_ERR "netconsole: target (%s) is enabled, "
 445                                "disable to update parameters\n",
 446                                config_item_name(&nt->item));
 447                return -EINVAL;
 448        }
 449
 450        if (strnchr(buf, count, ':')) {
 451                const char *end;
 452                if (in6_pton(buf, count, nt->np.remote_ip.in6.s6_addr, -1, &end) > 0) {
 453                        if (*end && *end != '\n') {
 454                                printk(KERN_ERR "netconsole: invalid IPv6 address at: <%c>\n", *end);
 455                                return -EINVAL;
 456                        }
 457                        nt->np.ipv6 = true;
 458                } else
 459                        return -EINVAL;
 460        } else {
 461                if (!nt->np.ipv6) {
 462                        nt->np.remote_ip.ip = in_aton(buf);
 463                } else
 464                        return -EINVAL;
 465        }
 466
 467        return strnlen(buf, count);
 468}
 469
 470static ssize_t store_remote_mac(struct netconsole_target *nt,
 471                                const char *buf,
 472                                size_t count)
 473{
 474        u8 remote_mac[ETH_ALEN];
 475
 476        if (nt->enabled) {
 477                printk(KERN_ERR "netconsole: target (%s) is enabled, "
 478                                "disable to update parameters\n",
 479                                config_item_name(&nt->item));
 480                return -EINVAL;
 481        }
 482
 483        if (!mac_pton(buf, remote_mac))
 484                return -EINVAL;
 485        if (buf[3 * ETH_ALEN - 1] && buf[3 * ETH_ALEN - 1] != '\n')
 486                return -EINVAL;
 487        memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
 488
 489        return strnlen(buf, count);
 490}
 491
 492/*
 493 * Attribute definitions for netconsole_target.
 494 */
 495
 496#define NETCONSOLE_TARGET_ATTR_RO(_name)                                \
 497static struct netconsole_target_attr netconsole_target_##_name =        \
 498        __CONFIGFS_ATTR(_name, S_IRUGO, show_##_name, NULL)
 499
 500#define NETCONSOLE_TARGET_ATTR_RW(_name)                                \
 501static struct netconsole_target_attr netconsole_target_##_name =        \
 502        __CONFIGFS_ATTR(_name, S_IRUGO | S_IWUSR, show_##_name, store_##_name)
 503
 504NETCONSOLE_TARGET_ATTR_RW(enabled);
 505NETCONSOLE_TARGET_ATTR_RW(dev_name);
 506NETCONSOLE_TARGET_ATTR_RW(local_port);
 507NETCONSOLE_TARGET_ATTR_RW(remote_port);
 508NETCONSOLE_TARGET_ATTR_RW(local_ip);
 509NETCONSOLE_TARGET_ATTR_RW(remote_ip);
 510NETCONSOLE_TARGET_ATTR_RO(local_mac);
 511NETCONSOLE_TARGET_ATTR_RW(remote_mac);
 512
 513static struct configfs_attribute *netconsole_target_attrs[] = {
 514        &netconsole_target_enabled.attr,
 515        &netconsole_target_dev_name.attr,
 516        &netconsole_target_local_port.attr,
 517        &netconsole_target_remote_port.attr,
 518        &netconsole_target_local_ip.attr,
 519        &netconsole_target_remote_ip.attr,
 520        &netconsole_target_local_mac.attr,
 521        &netconsole_target_remote_mac.attr,
 522        NULL,
 523};
 524
 525/*
 526 * Item operations and type for netconsole_target.
 527 */
 528
 529static void netconsole_target_release(struct config_item *item)
 530{
 531        kfree(to_target(item));
 532}
 533
 534static ssize_t netconsole_target_attr_show(struct config_item *item,
 535                                           struct configfs_attribute *attr,
 536                                           char *buf)
 537{
 538        ssize_t ret = -EINVAL;
 539        struct netconsole_target *nt = to_target(item);
 540        struct netconsole_target_attr *na =
 541                container_of(attr, struct netconsole_target_attr, attr);
 542
 543        if (na->show)
 544                ret = na->show(nt, buf);
 545
 546        return ret;
 547}
 548
 549static ssize_t netconsole_target_attr_store(struct config_item *item,
 550                                            struct configfs_attribute *attr,
 551                                            const char *buf,
 552                                            size_t count)
 553{
 554        ssize_t ret = -EINVAL;
 555        struct netconsole_target *nt = to_target(item);
 556        struct netconsole_target_attr *na =
 557                container_of(attr, struct netconsole_target_attr, attr);
 558
 559        if (na->store)
 560                ret = na->store(nt, buf, count);
 561
 562        return ret;
 563}
 564
 565static struct configfs_item_operations netconsole_target_item_ops = {
 566        .release                = netconsole_target_release,
 567        .show_attribute         = netconsole_target_attr_show,
 568        .store_attribute        = netconsole_target_attr_store,
 569};
 570
 571static struct config_item_type netconsole_target_type = {
 572        .ct_attrs               = netconsole_target_attrs,
 573        .ct_item_ops            = &netconsole_target_item_ops,
 574        .ct_owner               = THIS_MODULE,
 575};
 576
 577/*
 578 * Group operations and type for netconsole_subsys.
 579 */
 580
 581static struct config_item *make_netconsole_target(struct config_group *group,
 582                                                  const char *name)
 583{
 584        unsigned long flags;
 585        struct netconsole_target *nt;
 586
 587        /*
 588         * Allocate and initialize with defaults.
 589         * Target is disabled at creation (enabled == 0).
 590         */
 591        nt = kzalloc(sizeof(*nt), GFP_KERNEL);
 592        if (!nt)
 593                return ERR_PTR(-ENOMEM);
 594
 595        nt->np.name = "netconsole";
 596        strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
 597        nt->np.local_port = 6665;
 598        nt->np.remote_port = 6666;
 599        memset(nt->np.remote_mac, 0xff, ETH_ALEN);
 600
 601        /* Initialize the config_item member */
 602        config_item_init_type_name(&nt->item, name, &netconsole_target_type);
 603
 604        /* Adding, but it is disabled */
 605        spin_lock_irqsave(&target_list_lock, flags);
 606        list_add(&nt->list, &target_list);
 607        spin_unlock_irqrestore(&target_list_lock, flags);
 608
 609        return &nt->item;
 610}
 611
 612static void drop_netconsole_target(struct config_group *group,
 613                                   struct config_item *item)
 614{
 615        unsigned long flags;
 616        struct netconsole_target *nt = to_target(item);
 617
 618        spin_lock_irqsave(&target_list_lock, flags);
 619        list_del(&nt->list);
 620        spin_unlock_irqrestore(&target_list_lock, flags);
 621
 622        /*
 623         * The target may have never been enabled, or was manually disabled
 624         * before being removed so netpoll may have already been cleaned up.
 625         */
 626        if (nt->enabled)
 627                netpoll_cleanup(&nt->np);
 628
 629        config_item_put(&nt->item);
 630}
 631
 632static struct configfs_group_operations netconsole_subsys_group_ops = {
 633        .make_item      = make_netconsole_target,
 634        .drop_item      = drop_netconsole_target,
 635};
 636
 637static struct config_item_type netconsole_subsys_type = {
 638        .ct_group_ops   = &netconsole_subsys_group_ops,
 639        .ct_owner       = THIS_MODULE,
 640};
 641
 642/* The netconsole configfs subsystem */
 643static struct configfs_subsystem netconsole_subsys = {
 644        .su_group       = {
 645                .cg_item        = {
 646                        .ci_namebuf     = "netconsole",
 647                        .ci_type        = &netconsole_subsys_type,
 648                },
 649        },
 650};
 651
 652#endif  /* CONFIG_NETCONSOLE_DYNAMIC */
 653
 654/* Handle network interface device notifications */
 655static int netconsole_netdev_event(struct notifier_block *this,
 656                                   unsigned long event,
 657                                   void *ptr)
 658{
 659        unsigned long flags;
 660        struct netconsole_target *nt;
 661        struct net_device *dev = ptr;
 662        bool stopped = false;
 663
 664        if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER ||
 665              event == NETDEV_RELEASE || event == NETDEV_JOIN))
 666                goto done;
 667
 668        spin_lock_irqsave(&target_list_lock, flags);
 669restart:
 670        list_for_each_entry(nt, &target_list, list) {
 671                netconsole_target_get(nt);
 672                if (nt->np.dev == dev) {
 673                        switch (event) {
 674                        case NETDEV_CHANGENAME:
 675                                strlcpy(nt->np.dev_name, dev->name, IFNAMSIZ);
 676                                break;
 677                        case NETDEV_RELEASE:
 678                        case NETDEV_JOIN:
 679                        case NETDEV_UNREGISTER:
 680                                /*
 681                                 * rtnl_lock already held
 682                                 * we might sleep in __netpoll_cleanup()
 683                                 */
 684                                spin_unlock_irqrestore(&target_list_lock, flags);
 685                                __netpoll_cleanup(&nt->np);
 686                                spin_lock_irqsave(&target_list_lock, flags);
 687                                dev_put(nt->np.dev);
 688                                nt->np.dev = NULL;
 689                                nt->enabled = 0;
 690                                stopped = true;
 691                                netconsole_target_put(nt);
 692                                goto restart;
 693                        }
 694                }
 695                netconsole_target_put(nt);
 696        }
 697        spin_unlock_irqrestore(&target_list_lock, flags);
 698        if (stopped) {
 699                printk(KERN_INFO "netconsole: network logging stopped on "
 700                       "interface %s as it ", dev->name);
 701                switch (event) {
 702                case NETDEV_UNREGISTER:
 703                        printk(KERN_CONT "unregistered\n");
 704                        break;
 705                case NETDEV_RELEASE:
 706                        printk(KERN_CONT "released slaves\n");
 707                        break;
 708                case NETDEV_JOIN:
 709                        printk(KERN_CONT "is joining a master device\n");
 710                        break;
 711                }
 712        }
 713
 714done:
 715        return NOTIFY_DONE;
 716}
 717
 718static struct notifier_block netconsole_netdev_notifier = {
 719        .notifier_call  = netconsole_netdev_event,
 720};
 721
 722static void write_msg(struct console *con, const char *msg, unsigned int len)
 723{
 724        int frag, left;
 725        unsigned long flags;
 726        struct netconsole_target *nt;
 727        const char *tmp;
 728
 729        if (oops_only && !oops_in_progress)
 730                return;
 731        /* Avoid taking lock and disabling interrupts unnecessarily */
 732        if (list_empty(&target_list))
 733                return;
 734
 735        spin_lock_irqsave(&target_list_lock, flags);
 736        list_for_each_entry(nt, &target_list, list) {
 737                netconsole_target_get(nt);
 738                if (nt->enabled && netif_running(nt->np.dev)) {
 739                        /*
 740                         * We nest this inside the for-each-target loop above
 741                         * so that we're able to get as much logging out to
 742                         * at least one target if we die inside here, instead
 743                         * of unnecessarily keeping all targets in lock-step.
 744                         */
 745                        tmp = msg;
 746                        for (left = len; left;) {
 747                                frag = min(left, MAX_PRINT_CHUNK);
 748                                netpoll_send_udp(&nt->np, tmp, frag);
 749                                tmp += frag;
 750                                left -= frag;
 751                        }
 752                }
 753                netconsole_target_put(nt);
 754        }
 755        spin_unlock_irqrestore(&target_list_lock, flags);
 756}
 757
 758static struct console netconsole = {
 759        .name   = "netcon",
 760        .flags  = CON_ENABLED,
 761        .write  = write_msg,
 762};
 763
 764static int __init init_netconsole(void)
 765{
 766        int err;
 767        struct netconsole_target *nt, *tmp;
 768        unsigned long flags;
 769        char *target_config;
 770        char *input = config;
 771
 772        if (strnlen(input, MAX_PARAM_LENGTH)) {
 773                while ((target_config = strsep(&input, ";"))) {
 774                        nt = alloc_param_target(target_config);
 775                        if (IS_ERR(nt)) {
 776                                err = PTR_ERR(nt);
 777                                goto fail;
 778                        }
 779                        /* Dump existing printks when we register */
 780                        netconsole.flags |= CON_PRINTBUFFER;
 781
 782                        spin_lock_irqsave(&target_list_lock, flags);
 783                        list_add(&nt->list, &target_list);
 784                        spin_unlock_irqrestore(&target_list_lock, flags);
 785                }
 786        }
 787
 788        err = register_netdevice_notifier(&netconsole_netdev_notifier);
 789        if (err)
 790                goto fail;
 791
 792        err = dynamic_netconsole_init();
 793        if (err)
 794                goto undonotifier;
 795
 796        register_console(&netconsole);
 797        printk(KERN_INFO "netconsole: network logging started\n");
 798
 799        return err;
 800
 801undonotifier:
 802        unregister_netdevice_notifier(&netconsole_netdev_notifier);
 803
 804fail:
 805        printk(KERN_ERR "netconsole: cleaning up\n");
 806
 807        /*
 808         * Remove all targets and destroy them (only targets created
 809         * from the boot/module option exist here). Skipping the list
 810         * lock is safe here, and netpoll_cleanup() will sleep.
 811         */
 812        list_for_each_entry_safe(nt, tmp, &target_list, list) {
 813                list_del(&nt->list);
 814                free_param_target(nt);
 815        }
 816
 817        return err;
 818}
 819
 820static void __exit cleanup_netconsole(void)
 821{
 822        struct netconsole_target *nt, *tmp;
 823
 824        unregister_console(&netconsole);
 825        dynamic_netconsole_exit();
 826        unregister_netdevice_notifier(&netconsole_netdev_notifier);
 827
 828        /*
 829         * Targets created via configfs pin references on our module
 830         * and would first be rmdir(2)'ed from userspace. We reach
 831         * here only when they are already destroyed, and only those
 832         * created from the boot/module option are left, so remove and
 833         * destroy them. Skipping the list lock is safe here, and
 834         * netpoll_cleanup() will sleep.
 835         */
 836        list_for_each_entry_safe(nt, tmp, &target_list, list) {
 837                list_del(&nt->list);
 838                free_param_target(nt);
 839        }
 840}
 841
 842/*
 843 * Use late_initcall to ensure netconsole is
 844 * initialized after network device driver if built-in.
 845 *
 846 * late_initcall() and module_init() are identical if built as module.
 847 */
 848late_initcall(init_netconsole);
 849module_exit(cleanup_netconsole);
 850
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