5 files changed, 683 insertions, 45 deletions

diff --git a/Documentation/networking/netconsole.txt b/Documentation/networking/netconsole.txt
index 1aaa7383e41d..3c2f2b328638 100644
--- a/Documentation/networking/netconsole.txt
+++ b/Documentation/networking/netconsole.txt
@@ -3,6 +3,10 @@ started by Ingo Molnar <mingo@redhat.com>, 2001.09.17
 2.6 port and netpoll api by Matt Mackall <mpm@selenic.com>, Sep 9 2003
 
 Please send bug reports to Matt Mackall <mpm@selenic.com>
+and Satyam Sharma <satyam.sharma@gmail.com>
+
+Introduction:
+=============
 
 This module logs kernel printk messages over UDP allowing debugging of
 problem where disk logging fails and serial consoles are impractical.
@@ -13,6 +17,9 @@ the specified interface as soon as possible. While this doesn't allow
 capture of early kernel panics, it does capture most of the boot
 process.
 
+Sender and receiver configuration:
+==================================
+
 It takes a string configuration parameter "netconsole" in the
 following format:
 
@@ -46,6 +53,67 @@ address.
 
 The remote host can run either 'netcat -u -l -p <port>' or syslogd.
 
+Dynamic reconfiguration:
+========================
+
+Dynamic reconfigurability is a useful addition to netconsole that enables
+remote logging targets to be dynamically added, removed, or have their
+parameters reconfigured at runtime from a configfs-based userspace interface.
+[ Note that the parameters of netconsole targets that were specified/created
+from the boot/module option are not exposed via this interface, and hence
+cannot be modified dynamically. ]
+
+To include this feature, select CONFIG_NETCONSOLE_DYNAMIC when building the
+netconsole module (or kernel, if netconsole is built-in).
+
+Some examples follow (where configfs is mounted at the /sys/kernel/config
+mountpoint).
+
+To add a remote logging target (target names can be arbitrary):
+
+ cd /sys/kernel/config/netconsole/
+ mkdir target1
+
+Note that newly created targets have default parameter values (as mentioned
+above) and are disabled by default -- they must first be enabled by writing
+"1" to the "enabled" attribute (usually after setting parameters accordingly)
+as described below.
+
+To remove a target:
+
+ rmdir /sys/kernel/config/netconsole/othertarget/
+
+The interface exposes these parameters of a netconsole target to userspace:
+
+        enabled         Is this target currently enabled?       (read-write)
+        dev_name        Local network interface name            (read-write)
+        local_port      Source UDP port to use                  (read-write)
+        remote_port     Remote agent's UDP port                 (read-write)
+        local_ip        Source IP address to use                (read-write)
+        remote_ip       Remote agent's IP address               (read-write)
+        local_mac       Local interface's MAC address           (read-only)
+        remote_mac      Remote agent's MAC address              (read-write)
+
+The "enabled" attribute is also used to control whether the parameters of
+a target can be updated or not -- you can modify the parameters of only
+disabled targets (i.e. if "enabled" is 0).
+
+To update a target's parameters:
+
+ cat enabled                            # check if enabled is 1
+ echo 0 > enabled                       # disable the target (if required)
+ echo eth2 > dev_name                   # set local interface
+ echo 10.0.0.4 > remote_ip              # update some parameter
+ echo cb:a9:87:65:43:21 > remote_mac    # update more parameters
+ echo 1 > enabled                       # enable target again
+
+You can also update the local interface dynamically. This is especially
+useful if you want to use interfaces that have newly come up (and may not
+have existed when netconsole was loaded / initialized).
+
+Miscellaneous notes:
+====================
+
 WARNING: the default target ethernet setting uses the broadcast
 ethernet address to send packets, which can cause increased load on
 other systems on the same ethernet segment.
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 40ff9a5269a2..10ed28ef3566 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -3082,6 +3082,16 @@ config NETCONSOLE
         If you want to log kernel messages over the network, enable this.
         See <file:Documentation/networking/netconsole.txt> for details.
 
+config NETCONSOLE_DYNAMIC
+        bool "Dynamic reconfiguration of logging targets (EXPERIMENTAL)"
+        depends on NETCONSOLE && SYSFS && EXPERIMENTAL
+        select CONFIGFS_FS
+        help
+          This option enables the ability to dynamically reconfigure target
+          parameters (interface, IP addresses, port numbers, MAC addresses)
+          at runtime through a userspace interface exported using configfs.
+          See <file:Documentation/networking/netconsole.txt> for details.
+
 config NETPOLL
         def_bool NETCONSOLE
 
diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 458c4d674a9e..69ef1eb03bea 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -41,6 +41,8 @@
 #include <linux/moduleparam.h>
 #include <linux/string.h>
 #include <linux/netpoll.h>
+#include <linux/inet.h>
+#include <linux/configfs.h>
 
 MODULE_AUTHOR("Maintainer: Matt Mackall <mpm@selenic.com>");
 MODULE_DESCRIPTION("Console driver for network interfaces");
@@ -71,20 +73,100 @@ 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 netpoll          np;
 };
 
-/* Allocate new target and setup netpoll for it */
-static struct netconsole_target *alloc_target(char *target_config)
+#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 */
+        /*
+         * Allocate and initialize with defaults.
+         * Note that these targets get their config_item fields zeroed-out.
+         */
         nt = kzalloc(sizeof(*nt), GFP_KERNEL);
         if (!nt) {
                 printk(KERN_ERR "netconsole: failed to allocate memory\n");
@@ -106,6 +188,8 @@ static struct netconsole_target *alloc_target(char *target_config)
         if (err)
                 goto fail;
 
+        nt->enabled = 1;
+
         return nt;
 
 fail:
@@ -113,13 +197,469 @@ fail:
         return ERR_PTR(err);
 }
 
-/* Cleanup netpoll for given target and free it */
-static void free_target(struct netconsole_target *nt)
+/* 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;
+}
+
+/*
+ * Wrapper over simple_strtol (base 10) with sanity and range checking.
+ * We return (signed) long only because we may want to return errors.
+ * Do not use this to convert numbers that are allowed to be negative.
+ */
+static long strtol10_check_range(const char *cp, long min, long max)
+{
+        long ret;
+        char *p = (char *) cp;
+
+        WARN_ON(min < 0);
+        WARN_ON(max < min);
+
+        ret = simple_strtol(p, &p, 10);
+
+        if (*p && (*p != '\n')) {
+                printk(KERN_ERR "netconsole: invalid input\n");
+                return -EINVAL;
+        }
+        if ((ret < min) || (ret > max)) {
+                printk(KERN_ERR "netconsole: input %ld must be between "
+                                "%ld and %ld\n", ret, min, max);
+                return -EINVAL;
+        }
+
+        return ret;
+}
+
+/*
+ * 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)
+{
+        return snprintf(buf, PAGE_SIZE, "%d.%d.%d.%d\n",
+                        HIPQUAD(nt->np.local_ip));
+}
+
+static ssize_t show_remote_ip(struct netconsole_target *nt, char *buf)
+{
+        return snprintf(buf, PAGE_SIZE, "%d.%d.%d.%d\n",
+                        HIPQUAD(nt->np.remote_ip));
+}
+
+static ssize_t show_local_mac(struct netconsole_target *nt, char *buf)
+{
+        return snprintf(buf, PAGE_SIZE, "%02x:%02x:%02x:%02x:%02x:%02x\n",
+                        nt->np.local_mac[0], nt->np.local_mac[1],
+                        nt->np.local_mac[2], nt->np.local_mac[3],
+                        nt->np.local_mac[4], nt->np.local_mac[5]);
+}
+
+static ssize_t show_remote_mac(struct netconsole_target *nt, char *buf)
+{
+        return snprintf(buf, PAGE_SIZE, "%02x:%02x:%02x:%02x:%02x:%02x\n",
+                        nt->np.remote_mac[0], nt->np.remote_mac[1],
+                        nt->np.remote_mac[2], nt->np.remote_mac[3],
+                        nt->np.remote_mac[4], nt->np.remote_mac[5]);
+}
+
+/*
+ * 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)
+{
+        int err;
+        long enabled;
+
+        enabled = strtol10_check_range(buf, 0, 1);
+        if (enabled < 0)
+                return enabled;
+
+        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;
+
+                printk(KERN_INFO "netconsole: network logging started\n");
+
+        } else {        /* 0 */
+                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) {
+                printk(KERN_ERR "netconsole: 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)
+{
+        long local_port;
+#define __U16_MAX       ((__u16) ~0U)
+
+        if (nt->enabled) {
+                printk(KERN_ERR "netconsole: target (%s) is enabled, "
+                                "disable to update parameters\n",
+                                config_item_name(&nt->item));
+                return -EINVAL;
+        }
+
+        local_port = strtol10_check_range(buf, 0, __U16_MAX);
+        if (local_port < 0)
+                return local_port;
+
+        nt->np.local_port = local_port;
+
+        return strnlen(buf, count);
+}
+
+static ssize_t store_remote_port(struct netconsole_target *nt,
+                                 const char *buf,
+                                 size_t count)
+{
+        long remote_port;
+#define __U16_MAX       ((__u16) ~0U)
+
+        if (nt->enabled) {
+                printk(KERN_ERR "netconsole: target (%s) is enabled, "
+                                "disable to update parameters\n",
+                                config_item_name(&nt->item));
+                return -EINVAL;
+        }
+
+        remote_port = strtol10_check_range(buf, 0, __U16_MAX);
+        if (remote_port < 0)
+                return remote_port;
+
+        nt->np.remote_port = remote_port;
+
+        return strnlen(buf, count);
+}
+
+static ssize_t store_local_ip(struct netconsole_target *nt,
+                              const char *buf,
+                              size_t count)
+{
+        if (nt->enabled) {
+                printk(KERN_ERR "netconsole: target (%s) is enabled, "
+                                "disable to update parameters\n",
+                                config_item_name(&nt->item));
+                return -EINVAL;
+        }
+
+        nt->np.local_ip = ntohl(in_aton(buf));
+
+        return strnlen(buf, count);
+}
+
+static ssize_t store_remote_ip(struct netconsole_target *nt,
+                               const char *buf,
+                               size_t count)
+{
+        if (nt->enabled) {
+                printk(KERN_ERR "netconsole: target (%s) is enabled, "
+                                "disable to update parameters\n",
+                                config_item_name(&nt->item));
+                return -EINVAL;
+        }
+
+        nt->np.remote_ip = ntohl(in_aton(buf));
+
+        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];
+        char *p = (char *) buf;
+        int i;
+
+        if (nt->enabled) {
+                printk(KERN_ERR "netconsole: target (%s) is enabled, "
+                                "disable to update parameters\n",
+                                config_item_name(&nt->item));
+                return -EINVAL;
+        }
+
+        for (i = 0; i < ETH_ALEN - 1; i++) {
+                remote_mac[i] = simple_strtoul(p, &p, 16);
+                if (*p != ':')
+                        goto invalid;
+                p++;
+        }
+        remote_mac[ETH_ALEN - 1] = simple_strtoul(p, &p, 16);
+        if (*p && (*p != '\n'))
+                goto invalid;
+
+        memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
+
+        return strnlen(buf, count);
+
+invalid:
+        printk(KERN_ERR "netconsole: invalid input\n");
+        return -EINVAL;
+}
+
+/*
+ * 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);
+
+        if (na->store)
+                ret = na->store(nt, buf, count);
+
+        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) {
+                printk(KERN_ERR "netconsole: failed to allocate memory\n");
+                return NULL;
+        }
+
+        nt->np.name = "netconsole";
+        strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
+        nt->np.local_port = 6665;
+        nt->np.remote_port = 6666;
+        memset(nt->np.remote_mac, 0xff, ETH_ALEN);
+
+        /* 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,
@@ -134,6 +674,7 @@ static int netconsole_netdev_event(struct notifier_block *this,
 
         spin_lock_irqsave(&target_list_lock, flags);
         list_for_each_entry(nt, &target_list, list) {
+                netconsole_target_get(nt);
                 if (nt->np.dev == dev) {
                         switch (event) {
                         case NETDEV_CHANGEADDR:
@@ -145,6 +686,7 @@ static int netconsole_netdev_event(struct notifier_block *this,
                                 break;
                         }
                 }
+                netconsole_target_put(nt);
         }
         spin_unlock_irqrestore(&target_list_lock, flags);
 
@@ -169,7 +711,8 @@ static void write_msg(struct console *con, const char *msg, unsigned int len)
 
         spin_lock_irqsave(&target_list_lock, flags);
         list_for_each_entry(nt, &target_list, list) {
-                if (netif_running(nt->np.dev)) {
+                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
@@ -184,6 +727,7 @@ static void write_msg(struct console *con, const char *msg, unsigned int len)
                                 left -= frag;
                         }
                 }
+                netconsole_target_put(nt);
         }
         spin_unlock_irqrestore(&target_list_lock, flags);
 }
@@ -196,48 +740,52 @@ static struct console netconsole = {
 
 static int __init init_netconsole(void)
 {
-        int err = 0;
+        int err;
         struct netconsole_target *nt, *tmp;
         unsigned long flags;
         char *target_config;
         char *input = config;
 
-        if (!strnlen(input, MAX_PARAM_LENGTH)) {
-                printk(KERN_INFO "netconsole: not configured, aborting\n");
-                goto out;
-        }
-
-        while ((target_config = strsep(&input, ";"))) {
-                nt = alloc_target(target_config);
-                if (IS_ERR(nt)) {
-                        err = PTR_ERR(nt);
-                        goto fail;
+        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;
+                        }
+                        spin_lock_irqsave(&target_list_lock, flags);
+                        list_add(&nt->list, &target_list);
+                        spin_unlock_irqrestore(&target_list_lock, flags);
                 }
-                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);
         printk(KERN_INFO "netconsole: network logging started\n");
 
-out:
         return err;
 
+undonotifier:
+        unregister_netdevice_notifier(&netconsole_netdev_notifier);
+
 fail:
         printk(KERN_ERR "netconsole: cleaning up\n");
 
         /*
-         * Remove all targets and destroy them. Skipping the list
+         * 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_target(nt);
+                free_param_target(nt);
         }
 
         return err;
@@ -248,15 +796,20 @@ static void __exit cleanup_netconsole(void)
         struct netconsole_target *nt, *tmp;
 
         unregister_console(&netconsole);
+        dynamic_netconsole_exit();
         unregister_netdevice_notifier(&netconsole_netdev_notifier);
 
         /*
-         * Remove all targets and destroy them. Skipping the list
-         * lock is safe here, and netpoll_cleanup() will sleep.
+         * 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_target(nt);
+                free_param_target(nt);
         }
 }
 
diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index 08dcc39ec18d..20250d963d72 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -35,6 +35,7 @@ struct netpoll_info {
 
 void netpoll_poll(struct netpoll *np);
 void netpoll_send_udp(struct netpoll *np, const char *msg, int len);
+void netpoll_print_options(struct netpoll *np);
 int netpoll_parse_options(struct netpoll *np, char *opt);
 int netpoll_setup(struct netpoll *np);
 int netpoll_trap(void);
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index abe6e3a4cc44..0952f936b292 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -532,6 +532,29 @@ out:
         return 0;
 }
 
+void netpoll_print_options(struct netpoll *np)
+{
+        printk(KERN_INFO "%s: local port %d\n",
+                         np->name, np->local_port);
+        printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
+                         np->name, HIPQUAD(np->local_ip));
+        printk(KERN_INFO "%s: interface %s\n",
+                         np->name, np->dev_name);
+        printk(KERN_INFO "%s: remote port %d\n",
+                         np->name, np->remote_port);
+        printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
+                         np->name, HIPQUAD(np->remote_ip));
+        printk(KERN_INFO "%s: remote ethernet address "
+                         "%02x:%02x:%02x:%02x:%02x:%02x\n",
+                         np->name,
+                         np->remote_mac[0],
+                         np->remote_mac[1],
+                         np->remote_mac[2],
+                         np->remote_mac[3],
+                         np->remote_mac[4],
+                         np->remote_mac[5]);
+}
+
 int netpoll_parse_options(struct netpoll *np, char *opt)
 {
         char *cur=opt, *delim;
@@ -544,7 +567,6 @@ int netpoll_parse_options(struct netpoll *np, char *opt)
                 cur = delim;
         }
         cur++;
-        printk(KERN_INFO "%s: local port %d\n", np->name, np->local_port);
 
         if (*cur != '/') {
                 if ((delim = strchr(cur, '/')) == NULL)
@@ -552,9 +574,6 @@ int netpoll_parse_options(struct netpoll *np, char *opt)
                 *delim = 0;
                 np->local_ip = ntohl(in_aton(cur));
                 cur = delim;
-
-                printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
-                       np->name, HIPQUAD(np->local_ip));
         }
         cur++;
 
@@ -568,8 +587,6 @@ int netpoll_parse_options(struct netpoll *np, char *opt)
         }
         cur++;
 
-        printk(KERN_INFO "%s: interface %s\n", np->name, np->dev_name);
-
         if (*cur != '@') {
                 /* dst port */
                 if ((delim = strchr(cur, '@')) == NULL)
@@ -579,7 +596,6 @@ int netpoll_parse_options(struct netpoll *np, char *opt)
                 cur = delim;
         }
         cur++;
-        printk(KERN_INFO "%s: remote port %d\n", np->name, np->remote_port);
 
         /* dst ip */
         if ((delim = strchr(cur, '/')) == NULL)
@@ -588,9 +604,6 @@ int netpoll_parse_options(struct netpoll *np, char *opt)
         np->remote_ip = ntohl(in_aton(cur));
         cur = delim + 1;
 
-        printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
-               np->name, HIPQUAD(np->remote_ip));
-
         if (*cur != 0) {
                 /* MAC address */
                 if ((delim = strchr(cur, ':')) == NULL)
@@ -621,15 +634,7 @@ int netpoll_parse_options(struct netpoll *np, char *opt)
                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
         }
 
-        printk(KERN_INFO "%s: remote ethernet address "
-               "%02x:%02x:%02x:%02x:%02x:%02x\n",
-               np->name,
-               np->remote_mac[0],
-               np->remote_mac[1],
-               np->remote_mac[2],
-               np->remote_mac[3],
-               np->remote_mac[4],
-               np->remote_mac[5]);
+        netpoll_print_options(np);
 
         return 0;
 
@@ -831,6 +836,7 @@ void netpoll_set_trap(int trap)
 
 EXPORT_SYMBOL(netpoll_set_trap);
 EXPORT_SYMBOL(netpoll_trap);
+EXPORT_SYMBOL(netpoll_print_options);
 EXPORT_SYMBOL(netpoll_parse_options);
 EXPORT_SYMBOL(netpoll_setup);
 EXPORT_SYMBOL(netpoll_cleanup);