Initial import

1 files changed, 860 insertions, 0 deletions

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
new file mode 100644
index 000000000..abf634548
--- /dev/null
+++ b/drivers/net/netconsole.c
@@ -0,0 +1,860 @@
+/*
+ *  linux/drivers/net/netconsole.c
+ *
+ *  Copyright (C) 2001  Ingo Molnar <mingo@redhat.com>
+ *
+ *  This file contains the implementation of an IRQ-safe, crash-safe
+ *  kernel console implementation that outputs kernel messages to the
+ *  network.
+ *
+ * Modification history:
+ *
+ * 2001-09-17    started by Ingo Molnar.
+ * 2003-08-11    2.6 port by Matt Mackall
+ *               simplified options
+ *               generic card hooks
+ *               works non-modular
+ * 2003-09-07    rewritten with netpoll api
+ */
+
+/****************************************************************
+ *      This program is free software; you can redistribute it and/or modify
+ *      it under the terms of the GNU General Public License as published by
+ *      the Free Software Foundation; either version 2, or (at your option)
+ *      any later version.
+ *
+ *      This program is distributed in the hope that it will be useful,
+ *      but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *      GNU General Public License for more details.
+ *
+ *      You should have received a copy of the GNU General Public License
+ *      along with this program; if not, write to the Free Software
+ *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ ****************************************************************/
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/console.h>
+#include <linux/moduleparam.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/netpoll.h>
+#include <linux/inet.h>
+#include <linux/configfs.h>
+#include <linux/etherdevice.h>
+
+MODULE_AUTHOR("Maintainer: Matt Mackall <mpm@selenic.com>");
+MODULE_DESCRIPTION("Console driver for network interfaces");
+MODULE_LICENSE("GPL");
+
+#define MAX_PARAM_LENGTH	256
+#define MAX_PRINT_CHUNK		1000
+
+static char config[MAX_PARAM_LENGTH];
+module_param_string(netconsole, config, MAX_PARAM_LENGTH, 0);
+MODULE_PARM_DESC(netconsole, " netconsole=[src-port]@[src-ip]/[dev],[tgt-port]@<tgt-ip>/[tgt-macaddr]");
+
+static bool oops_only = false;
+module_param(oops_only, bool, 0600);
+MODULE_PARM_DESC(oops_only, "Only log oops messages");
+
+#ifndef	MODULE
+static int __init option_setup(char *opt)
+{
+	strlcpy(config, opt, MAX_PARAM_LENGTH);
+	return 1;
+}
+__setup("netconsole=", option_setup);
+#endif	/* MODULE */
+
+/* Linked list of all configured targets */
+static LIST_HEAD(target_list);
+
+/* This needs to be a spinlock because write_msg() cannot sleep */
+static DEFINE_SPINLOCK(target_list_lock);
+
+/**
+ * struct netconsole_target - Represents a configured netconsole target.
+ * @list:	Links this target into the target_list.
+ * @item:	Links us into the configfs subsystem hierarchy.
+ * @enabled:	On / off knob to enable / disable target.
+ *		Visible from userspace (read-write).
+ *		We maintain a strict 1:1 correspondence between this and
+ *		whether the corresponding netpoll is active or inactive.
+ *		Also, other parameters of a target may be modified at
+ *		runtime only when it is disabled (enabled == 0).
+ * @np:		The netpoll structure for this target.
+ *		Contains the other userspace visible parameters:
+ *		dev_name	(read-write)
+ *		local_port	(read-write)
+ *		remote_port	(read-write)
+ *		local_ip	(read-write)
+ *		remote_ip	(read-write)
+ *		local_mac	(read-only)
+ *		remote_mac	(read-write)
+ */
+struct netconsole_target {
+	struct list_head	list;
+#ifdef	CONFIG_NETCONSOLE_DYNAMIC
+	struct config_item	item;
+#endif
+	int			enabled;
+	struct mutex		mutex;
+	struct netpoll		np;
+};
+
+#ifdef	CONFIG_NETCONSOLE_DYNAMIC
+
+static struct configfs_subsystem netconsole_subsys;
+
+static int __init dynamic_netconsole_init(void)
+{
+	config_group_init(&netconsole_subsys.su_group);
+	mutex_init(&netconsole_subsys.su_mutex);
+	return configfs_register_subsystem(&netconsole_subsys);
+}
+
+static void __exit dynamic_netconsole_exit(void)
+{
+	configfs_unregister_subsystem(&netconsole_subsys);
+}
+
+/*
+ * Targets that were created by parsing the boot/module option string
+ * do not exist in the configfs hierarchy (and have NULL names) and will
+ * never go away, so make these a no-op for them.
+ */
+static void netconsole_target_get(struct netconsole_target *nt)
+{
+	if (config_item_name(&nt->item))
+		config_item_get(&nt->item);
+}
+
+static void netconsole_target_put(struct netconsole_target *nt)
+{
+	if (config_item_name(&nt->item))
+		config_item_put(&nt->item);
+}
+
+#else	/* !CONFIG_NETCONSOLE_DYNAMIC */
+
+static int __init dynamic_netconsole_init(void)
+{
+	return 0;
+}
+
+static void __exit dynamic_netconsole_exit(void)
+{
+}
+
+/*
+ * No danger of targets going away from under us when dynamic
+ * reconfigurability is off.
+ */
+static void netconsole_target_get(struct netconsole_target *nt)
+{
+}
+
+static void netconsole_target_put(struct netconsole_target *nt)
+{
+}
+
+#endif	/* CONFIG_NETCONSOLE_DYNAMIC */
+
+/* Allocate new target (from boot/module param) and setup netpoll for it */
+static struct netconsole_target *alloc_param_target(char *target_config)
+{
+	int err = -ENOMEM;
+	struct netconsole_target *nt;
+
+	/*
+	 * Allocate and initialize with defaults.
+	 * Note that these targets get their config_item fields zeroed-out.
+	 */
+	nt = kzalloc(sizeof(*nt), GFP_KERNEL);
+	if (!nt)
+		goto fail;
+
+	nt->np.name = "netconsole";
+	strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
+	nt->np.local_port = 6665;
+	nt->np.remote_port = 6666;
+	mutex_init(&nt->mutex);
+	eth_broadcast_addr(nt->np.remote_mac);
+
+	/* Parse parameters and setup netpoll */
+	err = netpoll_parse_options(&nt->np, target_config);
+	if (err)
+		goto fail;
+
+	err = netpoll_setup(&nt->np);
+	if (err)
+		goto fail;
+
+	nt->enabled = 1;
+
+	return nt;
+
+fail:
+	kfree(nt);
+	return ERR_PTR(err);
+}
+
+/* Cleanup netpoll for given target (from boot/module param) and free it */
+static void free_param_target(struct netconsole_target *nt)
+{
+	netpoll_cleanup(&nt->np);
+	kfree(nt);
+}
+
+#ifdef	CONFIG_NETCONSOLE_DYNAMIC
+
+/*
+ * Our subsystem hierarchy is:
+ *
+ * /sys/kernel/config/netconsole/
+ *				|
+ *				<target>/
+ *				|	enabled
+ *				|	dev_name
+ *				|	local_port
+ *				|	remote_port
+ *				|	local_ip
+ *				|	remote_ip
+ *				|	local_mac
+ *				|	remote_mac
+ *				|
+ *				<target>/...
+ */
+
+struct netconsole_target_attr {
+	struct configfs_attribute	attr;
+	ssize_t				(*show)(struct netconsole_target *nt,
+						char *buf);
+	ssize_t				(*store)(struct netconsole_target *nt,
+						 const char *buf,
+						 size_t count);
+};
+
+static struct netconsole_target *to_target(struct config_item *item)
+{
+	return item ?
+		container_of(item, struct netconsole_target, item) :
+		NULL;
+}
+
+/*
+ * Attribute operations for netconsole_target.
+ */
+
+static ssize_t show_enabled(struct netconsole_target *nt, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%d\n", nt->enabled);
+}
+
+static ssize_t show_dev_name(struct netconsole_target *nt, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%s\n", nt->np.dev_name);
+}
+
+static ssize_t show_local_port(struct netconsole_target *nt, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.local_port);
+}
+
+static ssize_t show_remote_port(struct netconsole_target *nt, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.remote_port);
+}
+
+static ssize_t show_local_ip(struct netconsole_target *nt, char *buf)
+{
+	if (nt->np.ipv6)
+		return snprintf(buf, PAGE_SIZE, "%pI6c\n", &nt->np.local_ip.in6);
+	else
+		return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.local_ip);
+}
+
+static ssize_t show_remote_ip(struct netconsole_target *nt, char *buf)
+{
+	if (nt->np.ipv6)
+		return snprintf(buf, PAGE_SIZE, "%pI6c\n", &nt->np.remote_ip.in6);
+	else
+		return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.remote_ip);
+}
+
+static ssize_t show_local_mac(struct netconsole_target *nt, char *buf)
+{
+	struct net_device *dev = nt->np.dev;
+	static const u8 bcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
+
+	return snprintf(buf, PAGE_SIZE, "%pM\n", dev ? dev->dev_addr : bcast);
+}
+
+static ssize_t show_remote_mac(struct netconsole_target *nt, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%pM\n", nt->np.remote_mac);
+}
+
+/*
+ * This one is special -- targets created through the configfs interface
+ * are not enabled (and the corresponding netpoll activated) by default.
+ * The user is expected to set the desired parameters first (which
+ * would enable him to dynamically add new netpoll targets for new
+ * network interfaces as and when they come up).
+ */
+static ssize_t store_enabled(struct netconsole_target *nt,
+			     const char *buf,
+			     size_t count)
+{
+	unsigned long flags;
+	int enabled;
+	int err;
+
+	err = kstrtoint(buf, 10, &enabled);
+	if (err < 0)
+		return err;
+	if (enabled < 0 || enabled > 1)
+		return -EINVAL;
+	if (enabled == nt->enabled) {
+		pr_info("network logging has already %s\n",
+			nt->enabled ? "started" : "stopped");
+		return -EINVAL;
+	}
+
+	if (enabled) {	/* 1 */
+		/*
+		 * Skip netpoll_parse_options() -- all the attributes are
+		 * already configured via configfs. Just print them out.
+		 */
+		netpoll_print_options(&nt->np);
+
+		err = netpoll_setup(&nt->np);
+		if (err)
+			return err;
+
+		pr_info("netconsole: network logging started\n");
+	} else {	/* 0 */
+		/* We need to disable the netconsole before cleaning it up
+		 * otherwise we might end up in write_msg() with
+		 * nt->np.dev == NULL and nt->enabled == 1
+		 */
+		spin_lock_irqsave(&target_list_lock, flags);
+		nt->enabled = 0;
+		spin_unlock_irqrestore(&target_list_lock, flags);
+		netpoll_cleanup(&nt->np);
+	}
+
+	nt->enabled = enabled;
+
+	return strnlen(buf, count);
+}
+
+static ssize_t store_dev_name(struct netconsole_target *nt,
+			      const char *buf,
+			      size_t count)
+{
+	size_t len;
+
+	if (nt->enabled) {
+		pr_err("target (%s) is enabled, disable to update parameters\n",
+		       config_item_name(&nt->item));
+		return -EINVAL;
+	}
+
+	strlcpy(nt->np.dev_name, buf, IFNAMSIZ);
+
+	/* Get rid of possible trailing newline from echo(1) */
+	len = strnlen(nt->np.dev_name, IFNAMSIZ);
+	if (nt->np.dev_name[len - 1] == '\n')
+		nt->np.dev_name[len - 1] = '\0';
+
+	return strnlen(buf, count);
+}
+
+static ssize_t store_local_port(struct netconsole_target *nt,
+				const char *buf,
+				size_t count)
+{
+	int rv;
+
+	if (nt->enabled) {
+		pr_err("target (%s) is enabled, disable to update parameters\n",
+		       config_item_name(&nt->item));
+		return -EINVAL;
+	}
+
+	rv = kstrtou16(buf, 10, &nt->np.local_port);
+	if (rv < 0)
+		return rv;
+	return strnlen(buf, count);
+}
+
+static ssize_t store_remote_port(struct netconsole_target *nt,
+				 const char *buf,
+				 size_t count)
+{
+	int rv;
+
+	if (nt->enabled) {
+		pr_err("target (%s) is enabled, disable to update parameters\n",
+		       config_item_name(&nt->item));
+		return -EINVAL;
+	}
+
+	rv = kstrtou16(buf, 10, &nt->np.remote_port);
+	if (rv < 0)
+		return rv;
+	return strnlen(buf, count);
+}
+
+static ssize_t store_local_ip(struct netconsole_target *nt,
+			      const char *buf,
+			      size_t count)
+{
+	if (nt->enabled) {
+		pr_err("target (%s) is enabled, disable to update parameters\n",
+		       config_item_name(&nt->item));
+		return -EINVAL;
+	}
+
+	if (strnchr(buf, count, ':')) {
+		const char *end;
+		if (in6_pton(buf, count, nt->np.local_ip.in6.s6_addr, -1, &end) > 0) {
+			if (*end && *end != '\n') {
+				pr_err("invalid IPv6 address at: <%c>\n", *end);
+				return -EINVAL;
+			}
+			nt->np.ipv6 = true;
+		} else
+			return -EINVAL;
+	} else {
+		if (!nt->np.ipv6) {
+			nt->np.local_ip.ip = in_aton(buf);
+		} else
+			return -EINVAL;
+	}
+
+	return strnlen(buf, count);
+}
+
+static ssize_t store_remote_ip(struct netconsole_target *nt,
+			       const char *buf,
+			       size_t count)
+{
+	if (nt->enabled) {
+		pr_err("target (%s) is enabled, disable to update parameters\n",
+		       config_item_name(&nt->item));
+		return -EINVAL;
+	}
+
+	if (strnchr(buf, count, ':')) {
+		const char *end;
+		if (in6_pton(buf, count, nt->np.remote_ip.in6.s6_addr, -1, &end) > 0) {
+			if (*end && *end != '\n') {
+				pr_err("invalid IPv6 address at: <%c>\n", *end);
+				return -EINVAL;
+			}
+			nt->np.ipv6 = true;
+		} else
+			return -EINVAL;
+	} else {
+		if (!nt->np.ipv6) {
+			nt->np.remote_ip.ip = in_aton(buf);
+		} else
+			return -EINVAL;
+	}
+
+	return strnlen(buf, count);
+}
+
+static ssize_t store_remote_mac(struct netconsole_target *nt,
+				const char *buf,
+				size_t count)
+{
+	u8 remote_mac[ETH_ALEN];
+
+	if (nt->enabled) {
+		pr_err("target (%s) is enabled, disable to update parameters\n",
+		       config_item_name(&nt->item));
+		return -EINVAL;
+	}
+
+	if (!mac_pton(buf, remote_mac))
+		return -EINVAL;
+	if (buf[3 * ETH_ALEN - 1] && buf[3 * ETH_ALEN - 1] != '\n')
+		return -EINVAL;
+	memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
+
+	return strnlen(buf, count);
+}
+
+/*
+ * Attribute definitions for netconsole_target.
+ */
+
+#define NETCONSOLE_TARGET_ATTR_RO(_name)				\
+static struct netconsole_target_attr netconsole_target_##_name =	\
+	__CONFIGFS_ATTR(_name, S_IRUGO, show_##_name, NULL)
+
+#define NETCONSOLE_TARGET_ATTR_RW(_name)				\
+static struct netconsole_target_attr netconsole_target_##_name =	\
+	__CONFIGFS_ATTR(_name, S_IRUGO | S_IWUSR, show_##_name, store_##_name)
+
+NETCONSOLE_TARGET_ATTR_RW(enabled);
+NETCONSOLE_TARGET_ATTR_RW(dev_name);
+NETCONSOLE_TARGET_ATTR_RW(local_port);
+NETCONSOLE_TARGET_ATTR_RW(remote_port);
+NETCONSOLE_TARGET_ATTR_RW(local_ip);
+NETCONSOLE_TARGET_ATTR_RW(remote_ip);
+NETCONSOLE_TARGET_ATTR_RO(local_mac);
+NETCONSOLE_TARGET_ATTR_RW(remote_mac);
+
+static struct configfs_attribute *netconsole_target_attrs[] = {
+	&netconsole_target_enabled.attr,
+	&netconsole_target_dev_name.attr,
+	&netconsole_target_local_port.attr,
+	&netconsole_target_remote_port.attr,
+	&netconsole_target_local_ip.attr,
+	&netconsole_target_remote_ip.attr,
+	&netconsole_target_local_mac.attr,
+	&netconsole_target_remote_mac.attr,
+	NULL,
+};
+
+/*
+ * Item operations and type for netconsole_target.
+ */
+
+static void netconsole_target_release(struct config_item *item)
+{
+	kfree(to_target(item));
+}
+
+static ssize_t netconsole_target_attr_show(struct config_item *item,
+					   struct configfs_attribute *attr,
+					   char *buf)
+{
+	ssize_t ret = -EINVAL;
+	struct netconsole_target *nt = to_target(item);
+	struct netconsole_target_attr *na =
+		container_of(attr, struct netconsole_target_attr, attr);
+
+	if (na->show)
+		ret = na->show(nt, buf);
+
+	return ret;
+}
+
+static ssize_t netconsole_target_attr_store(struct config_item *item,
+					    struct configfs_attribute *attr,
+					    const char *buf,
+					    size_t count)
+{
+	ssize_t ret = -EINVAL;
+	struct netconsole_target *nt = to_target(item);
+	struct netconsole_target_attr *na =
+		container_of(attr, struct netconsole_target_attr, attr);
+
+	mutex_lock(&nt->mutex);
+	if (na->store)
+		ret = na->store(nt, buf, count);
+	mutex_unlock(&nt->mutex);
+
+	return ret;
+}
+
+static struct configfs_item_operations netconsole_target_item_ops = {
+	.release		= netconsole_target_release,
+	.show_attribute		= netconsole_target_attr_show,
+	.store_attribute	= netconsole_target_attr_store,
+};
+
+static struct config_item_type netconsole_target_type = {
+	.ct_attrs		= netconsole_target_attrs,
+	.ct_item_ops		= &netconsole_target_item_ops,
+	.ct_owner		= THIS_MODULE,
+};
+
+/*
+ * Group operations and type for netconsole_subsys.
+ */
+
+static struct config_item *make_netconsole_target(struct config_group *group,
+						  const char *name)
+{
+	unsigned long flags;
+	struct netconsole_target *nt;
+
+	/*
+	 * Allocate and initialize with defaults.
+	 * Target is disabled at creation (enabled == 0).
+	 */
+	nt = kzalloc(sizeof(*nt), GFP_KERNEL);
+	if (!nt)
+		return ERR_PTR(-ENOMEM);
+
+	nt->np.name = "netconsole";
+	strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
+	nt->np.local_port = 6665;
+	nt->np.remote_port = 6666;
+	mutex_init(&nt->mutex);
+	eth_broadcast_addr(nt->np.remote_mac);
+
+	/* Initialize the config_item member */
+	config_item_init_type_name(&nt->item, name, &netconsole_target_type);
+
+	/* Adding, but it is disabled */
+	spin_lock_irqsave(&target_list_lock, flags);
+	list_add(&nt->list, &target_list);
+	spin_unlock_irqrestore(&target_list_lock, flags);
+
+	return &nt->item;
+}
+
+static void drop_netconsole_target(struct config_group *group,
+				   struct config_item *item)
+{
+	unsigned long flags;
+	struct netconsole_target *nt = to_target(item);
+
+	spin_lock_irqsave(&target_list_lock, flags);
+	list_del(&nt->list);
+	spin_unlock_irqrestore(&target_list_lock, flags);
+
+	/*
+	 * The target may have never been enabled, or was manually disabled
+	 * before being removed so netpoll may have already been cleaned up.
+	 */
+	if (nt->enabled)
+		netpoll_cleanup(&nt->np);
+
+	config_item_put(&nt->item);
+}
+
+static struct configfs_group_operations netconsole_subsys_group_ops = {
+	.make_item	= make_netconsole_target,
+	.drop_item	= drop_netconsole_target,
+};
+
+static struct config_item_type netconsole_subsys_type = {
+	.ct_group_ops	= &netconsole_subsys_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+/* The netconsole configfs subsystem */
+static struct configfs_subsystem netconsole_subsys = {
+	.su_group	= {
+		.cg_item	= {
+			.ci_namebuf	= "netconsole",
+			.ci_type	= &netconsole_subsys_type,
+		},
+	},
+};
+
+#endif	/* CONFIG_NETCONSOLE_DYNAMIC */
+
+/* Handle network interface device notifications */
+static int netconsole_netdev_event(struct notifier_block *this,
+				   unsigned long event, void *ptr)
+{
+	unsigned long flags;
+	struct netconsole_target *nt;
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	bool stopped = false;
+
+	if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER ||
+	      event == NETDEV_RELEASE || event == NETDEV_JOIN))
+		goto done;
+
+	spin_lock_irqsave(&target_list_lock, flags);
+restart:
+	list_for_each_entry(nt, &target_list, list) {
+		netconsole_target_get(nt);
+		if (nt->np.dev == dev) {
+			switch (event) {
+			case NETDEV_CHANGENAME:
+				strlcpy(nt->np.dev_name, dev->name, IFNAMSIZ);
+				break;
+			case NETDEV_RELEASE:
+			case NETDEV_JOIN:
+			case NETDEV_UNREGISTER:
+				/* rtnl_lock already held
+				 * we might sleep in __netpoll_cleanup()
+				 */
+				spin_unlock_irqrestore(&target_list_lock, flags);
+
+				__netpoll_cleanup(&nt->np);
+
+				spin_lock_irqsave(&target_list_lock, flags);
+				dev_put(nt->np.dev);
+				nt->np.dev = NULL;
+				nt->enabled = 0;
+				stopped = true;
+				netconsole_target_put(nt);
+				goto restart;
+			}
+		}
+		netconsole_target_put(nt);
+	}
+	spin_unlock_irqrestore(&target_list_lock, flags);
+	if (stopped) {
+		const char *msg = "had an event";
+		switch (event) {
+		case NETDEV_UNREGISTER:
+			msg = "unregistered";
+			break;
+		case NETDEV_RELEASE:
+			msg = "released slaves";
+			break;
+		case NETDEV_JOIN:
+			msg = "is joining a master device";
+			break;
+		}
+		pr_info("network logging stopped on interface %s as it %s\n",
+			dev->name, msg);
+	}
+
+done:
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block netconsole_netdev_notifier = {
+	.notifier_call  = netconsole_netdev_event,
+};
+
+static void write_msg(struct console *con, const char *msg, unsigned int len,
+                      unsigned int loglevel)
+{
+	int frag, left;
+	unsigned long flags;
+	struct netconsole_target *nt;
+	const char *tmp;
+
+	if (oops_only && !oops_in_progress)
+		return;
+	/* Avoid taking lock and disabling interrupts unnecessarily */
+	if (list_empty(&target_list))
+		return;
+
+	spin_lock_irqsave(&target_list_lock, flags);
+	list_for_each_entry(nt, &target_list, list) {
+		netconsole_target_get(nt);
+		if (nt->enabled && netif_running(nt->np.dev)) {
+			/*
+			 * We nest this inside the for-each-target loop above
+			 * so that we're able to get as much logging out to
+			 * at least one target if we die inside here, instead
+			 * of unnecessarily keeping all targets in lock-step.
+			 */
+			tmp = msg;
+			for (left = len; left;) {
+				frag = min(left, MAX_PRINT_CHUNK);
+				netpoll_send_udp(&nt->np, tmp, frag);
+				tmp += frag;
+				left -= frag;
+			}
+		}
+		netconsole_target_put(nt);
+	}
+	spin_unlock_irqrestore(&target_list_lock, flags);
+}
+
+static struct console netconsole = {
+	.name	= "netcon",
+	.flags	= CON_ENABLED,
+	.write	= write_msg,
+};
+
+static int __init init_netconsole(void)
+{
+	int err;
+	struct netconsole_target *nt, *tmp;
+	unsigned long flags;
+	char *target_config;
+	char *input = config;
+
+	if (strnlen(input, MAX_PARAM_LENGTH)) {
+		while ((target_config = strsep(&input, ";"))) {
+			nt = alloc_param_target(target_config);
+			if (IS_ERR(nt)) {
+				err = PTR_ERR(nt);
+				goto fail;
+			}
+			/* Dump existing printks when we register */
+			netconsole.flags |= CON_PRINTBUFFER;
+
+			spin_lock_irqsave(&target_list_lock, flags);
+			list_add(&nt->list, &target_list);
+			spin_unlock_irqrestore(&target_list_lock, flags);
+		}
+	}
+
+	err = register_netdevice_notifier(&netconsole_netdev_notifier);
+	if (err)
+		goto fail;
+
+	err = dynamic_netconsole_init();
+	if (err)
+		goto undonotifier;
+
+	register_console(&netconsole);
+	pr_info("network logging started\n");
+
+	return err;
+
+undonotifier:
+	unregister_netdevice_notifier(&netconsole_netdev_notifier);
+
+fail:
+	pr_err("cleaning up\n");
+
+	/*
+	 * Remove all targets and destroy them (only targets created
+	 * from the boot/module option exist here). Skipping the list
+	 * lock is safe here, and netpoll_cleanup() will sleep.
+	 */
+	list_for_each_entry_safe(nt, tmp, &target_list, list) {
+		list_del(&nt->list);
+		free_param_target(nt);
+	}
+
+	return err;
+}
+
+static void __exit cleanup_netconsole(void)
+{
+	struct netconsole_target *nt, *tmp;
+
+	unregister_console(&netconsole);
+	dynamic_netconsole_exit();
+	unregister_netdevice_notifier(&netconsole_netdev_notifier);
+
+	/*
+	 * Targets created via configfs pin references on our module
+	 * and would first be rmdir(2)'ed from userspace. We reach
+	 * here only when they are already destroyed, and only those
+	 * created from the boot/module option are left, so remove and
+	 * destroy them. Skipping the list lock is safe here, and
+	 * netpoll_cleanup() will sleep.
+	 */
+	list_for_each_entry_safe(nt, tmp, &target_list, list) {
+		list_del(&nt->list);
+		free_param_target(nt);
+	}
+}
+
+/*
+ * Use late_initcall to ensure netconsole is
+ * initialized after network device driver if built-in.
+ *
+ * late_initcall() and module_init() are identical if built as module.
+ */
+late_initcall(init_netconsole);
+module_exit(cleanup_netconsole);