aufs: ioctl, from aufs2.2-3.0

[zen-stable.git] / net / 802 / garp.c

/*
 *      IEEE 802.1D Generic Attribute Registration Protocol (GARP)
 *
 *      Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      version 2 as published by the Free Software Foundation.
 */
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <linux/llc.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <net/llc.h>
#include <net/llc_pdu.h>
#include <net/garp.h>
#include <asm/unaligned.h>

static unsigned int garp_join_time __read_mostly = 200;
module_param(garp_join_time, uint, 0644);
MODULE_PARM_DESC(garp_join_time, "Join time in ms (default 200ms)");
MODULE_LICENSE("GPL");

static const struct garp_state_trans {
        u8      state;
        u8      action;
} garp_applicant_state_table[GARP_APPLICANT_MAX + 1][GARP_EVENT_MAX + 1] = {
        [GARP_APPLICANT_VA] = {
                [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_AA,
                                                    .action = GARP_ACTION_S_JOIN_IN },
                [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_AA },
                [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VA },
                [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VA },
                [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VA },
                [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
                [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_LA },
        },
        [GARP_APPLICANT_AA] = {
                [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_QA,
                                                    .action = GARP_ACTION_S_JOIN_IN },
                [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QA },
                [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VA },
                [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VA },
                [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VA },
                [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
                [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_LA },
        },
        [GARP_APPLICANT_QA] = {
                [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
                [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QA },
                [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VA },
                [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VA },
                [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
                [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_LA },
        },
        [GARP_APPLICANT_LA] = {
                [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_VO,
                                                    .action = GARP_ACTION_S_LEAVE_EMPTY },
                [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_LA },
                [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_LA },
                [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_LA },
                [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_VA },
                [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
        },
        [GARP_APPLICANT_VP] = {
                [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_AA,
                                                    .action = GARP_ACTION_S_JOIN_IN },
                [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_AP },
                [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
                [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_VO },
        },
        [GARP_APPLICANT_AP] = {
                [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_QA,
                                                    .action = GARP_ACTION_S_JOIN_IN },
                [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QP },
                [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
                [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_AO },
        },
        [GARP_APPLICANT_QP] = {
                [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
                [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QP },
                [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
                [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_QO },
        },
        [GARP_APPLICANT_VO] = {
                [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
                [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_AO },
                [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_VP },
                [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
        },
        [GARP_APPLICANT_AO] = {
                [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
                [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QO },
                [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_AP },
                [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
        },
        [GARP_APPLICANT_QO] = {
                [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
                [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QO },
                [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
                [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_QP },
                [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
        },
};

static int garp_attr_cmp(const struct garp_attr *attr,
                         const void *data, u8 len, u8 type)
{
        if (attr->type != type)
                return attr->type - type;
        if (attr->dlen != len)
                return attr->dlen - len;
        return memcmp(attr->data, data, len);
}

static struct garp_attr *garp_attr_lookup(const struct garp_applicant *app,
                                          const void *data, u8 len, u8 type)
{
        struct rb_node *parent = app->gid.rb_node;
        struct garp_attr *attr;
        int d;

        while (parent) {
                attr = rb_entry(parent, struct garp_attr, node);
                d = garp_attr_cmp(attr, data, len, type);
                if (d < 0)
                        parent = parent->rb_left;
                else if (d > 0)
                        parent = parent->rb_right;
                else
                        return attr;
        }
        return NULL;
}

static void garp_attr_insert(struct garp_applicant *app, struct garp_attr *new)
{
        struct rb_node *parent = NULL, **p = &app->gid.rb_node;
        struct garp_attr *attr;
        int d;

        while (*p) {
                parent = *p;
                attr = rb_entry(parent, struct garp_attr, node);
                d = garp_attr_cmp(attr, new->data, new->dlen, new->type);
                if (d < 0)
                        p = &parent->rb_left;
                else if (d > 0)
                        p = &parent->rb_right;
        }
        rb_link_node(&new->node, parent, p);
        rb_insert_color(&new->node, &app->gid);
}

static struct garp_attr *garp_attr_create(struct garp_applicant *app,
                                          const void *data, u8 len, u8 type)
{
        struct garp_attr *attr;

        attr = kmalloc(sizeof(*attr) + len, GFP_ATOMIC);
        if (!attr)
                return attr;
        attr->state = GARP_APPLICANT_VO;
        attr->type  = type;
        attr->dlen  = len;
        memcpy(attr->data, data, len);
        garp_attr_insert(app, attr);
        return attr;
}

static void garp_attr_destroy(struct garp_applicant *app, struct garp_attr *attr)
{
        rb_erase(&attr->node, &app->gid);
        kfree(attr);
}

static int garp_pdu_init(struct garp_applicant *app)
{
        struct sk_buff *skb;
        struct garp_pdu_hdr *gp;

#define LLC_RESERVE     sizeof(struct llc_pdu_un)
        skb = alloc_skb(app->dev->mtu + LL_RESERVED_SPACE(app->dev),
                        GFP_ATOMIC);
        if (!skb)
                return -ENOMEM;

        skb->dev = app->dev;
        skb->protocol = htons(ETH_P_802_2);
        skb_reserve(skb, LL_RESERVED_SPACE(app->dev) + LLC_RESERVE);

        gp = (struct garp_pdu_hdr *)__skb_put(skb, sizeof(*gp));
        put_unaligned(htons(GARP_PROTOCOL_ID), &gp->protocol);

        app->pdu = skb;
        return 0;
}

static int garp_pdu_append_end_mark(struct garp_applicant *app)
{
        if (skb_tailroom(app->pdu) < sizeof(u8))
                return -1;
        *(u8 *)__skb_put(app->pdu, sizeof(u8)) = GARP_END_MARK;
        return 0;
}

static void garp_pdu_queue(struct garp_applicant *app)
{
        if (!app->pdu)
                return;

        garp_pdu_append_end_mark(app);
        garp_pdu_append_end_mark(app);

        llc_pdu_header_init(app->pdu, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
                            LLC_SAP_BSPAN, LLC_PDU_CMD);
        llc_pdu_init_as_ui_cmd(app->pdu);
        llc_mac_hdr_init(app->pdu, app->dev->dev_addr,
                         app->app->proto.group_address);

        skb_queue_tail(&app->queue, app->pdu);
        app->pdu = NULL;
}

static void garp_queue_xmit(struct garp_applicant *app)
{
        struct sk_buff *skb;

        while ((skb = skb_dequeue(&app->queue)))
                dev_queue_xmit(skb);
}

static int garp_pdu_append_msg(struct garp_applicant *app, u8 attrtype)
{
        struct garp_msg_hdr *gm;

        if (skb_tailroom(app->pdu) < sizeof(*gm))
                return -1;
        gm = (struct garp_msg_hdr *)__skb_put(app->pdu, sizeof(*gm));
        gm->attrtype = attrtype;
        garp_cb(app->pdu)->cur_type = attrtype;
        return 0;
}

static int garp_pdu_append_attr(struct garp_applicant *app,
                                const struct garp_attr *attr,
                                enum garp_attr_event event)
{
        struct garp_attr_hdr *ga;
        unsigned int len;
        int err;
again:
        if (!app->pdu) {
                err = garp_pdu_init(app);
                if (err < 0)
                        return err;
        }

        if (garp_cb(app->pdu)->cur_type != attr->type) {
                if (garp_cb(app->pdu)->cur_type &&
                    garp_pdu_append_end_mark(app) < 0)
                        goto queue;
                if (garp_pdu_append_msg(app, attr->type) < 0)
                        goto queue;
        }

        len = sizeof(*ga) + attr->dlen;
        if (skb_tailroom(app->pdu) < len)
                goto queue;
        ga = (struct garp_attr_hdr *)__skb_put(app->pdu, len);
        ga->len   = len;
        ga->event = event;
        memcpy(ga->data, attr->data, attr->dlen);
        return 0;

queue:
        garp_pdu_queue(app);
        goto again;
}

static void garp_attr_event(struct garp_applicant *app,
                            struct garp_attr *attr, enum garp_event event)
{
        enum garp_applicant_state state;

        state = garp_applicant_state_table[attr->state][event].state;
        if (state == GARP_APPLICANT_INVALID)
                return;

        switch (garp_applicant_state_table[attr->state][event].action) {
        case GARP_ACTION_NONE:
                break;
        case GARP_ACTION_S_JOIN_IN:
                /* When appending the attribute fails, don't update state in
                 * order to retry on next TRANSMIT_PDU event. */
                if (garp_pdu_append_attr(app, attr, GARP_JOIN_IN) < 0)
                        return;
                break;
        case GARP_ACTION_S_LEAVE_EMPTY:
                garp_pdu_append_attr(app, attr, GARP_LEAVE_EMPTY);
                /* As a pure applicant, sending a leave message implies that
                 * the attribute was unregistered and can be destroyed. */
                garp_attr_destroy(app, attr);
                return;
        default:
                WARN_ON(1);
        }

        attr->state = state;
}

int garp_request_join(const struct net_device *dev,
                      const struct garp_application *appl,
                      const void *data, u8 len, u8 type)
{
        struct garp_port *port = rtnl_dereference(dev->garp_port);
        struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
        struct garp_attr *attr;

        spin_lock_bh(&app->lock);
        attr = garp_attr_create(app, data, len, type);
        if (!attr) {
                spin_unlock_bh(&app->lock);
                return -ENOMEM;
        }
        garp_attr_event(app, attr, GARP_EVENT_REQ_JOIN);
        spin_unlock_bh(&app->lock);
        return 0;
}
EXPORT_SYMBOL_GPL(garp_request_join);

void garp_request_leave(const struct net_device *dev,
                        const struct garp_application *appl,
                        const void *data, u8 len, u8 type)
{
        struct garp_port *port = rtnl_dereference(dev->garp_port);
        struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);
        struct garp_attr *attr;

        spin_lock_bh(&app->lock);
        attr = garp_attr_lookup(app, data, len, type);
        if (!attr) {
                spin_unlock_bh(&app->lock);
                return;
        }
        garp_attr_event(app, attr, GARP_EVENT_REQ_LEAVE);
        spin_unlock_bh(&app->lock);
}
EXPORT_SYMBOL_GPL(garp_request_leave);

static void garp_gid_event(struct garp_applicant *app, enum garp_event event)
{
        struct rb_node *node, *next;
        struct garp_attr *attr;

        for (node = rb_first(&app->gid);
             next = node ? rb_next(node) : NULL, node != NULL;
             node = next) {
                attr = rb_entry(node, struct garp_attr, node);
                garp_attr_event(app, attr, event);
        }
}

static void garp_join_timer_arm(struct garp_applicant *app)
{
        unsigned long delay;

        delay = (u64)msecs_to_jiffies(garp_join_time) * net_random() >> 32;
        mod_timer(&app->join_timer, jiffies + delay);
}

static void garp_join_timer(unsigned long data)
{
        struct garp_applicant *app = (struct garp_applicant *)data;

        spin_lock(&app->lock);
        garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
        garp_pdu_queue(app);
        spin_unlock(&app->lock);

        garp_queue_xmit(app);
        garp_join_timer_arm(app);
}

static int garp_pdu_parse_end_mark(struct sk_buff *skb)
{
        if (!pskb_may_pull(skb, sizeof(u8)))
                return -1;
        if (*skb->data == GARP_END_MARK) {
                skb_pull(skb, sizeof(u8));
                return -1;
        }
        return 0;
}

static int garp_pdu_parse_attr(struct garp_applicant *app, struct sk_buff *skb,
                               u8 attrtype)
{
        const struct garp_attr_hdr *ga;
        struct garp_attr *attr;
        enum garp_event event;
        unsigned int dlen;

        if (!pskb_may_pull(skb, sizeof(*ga)))
                return -1;
        ga = (struct garp_attr_hdr *)skb->data;
        if (ga->len < sizeof(*ga))
                return -1;

        if (!pskb_may_pull(skb, ga->len))
                return -1;
        skb_pull(skb, ga->len);
        dlen = sizeof(*ga) - ga->len;

        if (attrtype > app->app->maxattr)
                return 0;

        switch (ga->event) {
        case GARP_LEAVE_ALL:
                if (dlen != 0)
                        return -1;
                garp_gid_event(app, GARP_EVENT_R_LEAVE_EMPTY);
                return 0;
        case GARP_JOIN_EMPTY:
                event = GARP_EVENT_R_JOIN_EMPTY;
                break;
        case GARP_JOIN_IN:
                event = GARP_EVENT_R_JOIN_IN;
                break;
        case GARP_LEAVE_EMPTY:
                event = GARP_EVENT_R_LEAVE_EMPTY;
                break;
        case GARP_EMPTY:
                event = GARP_EVENT_R_EMPTY;
                break;
        default:
                return 0;
        }

        if (dlen == 0)
                return -1;
        attr = garp_attr_lookup(app, ga->data, dlen, attrtype);
        if (attr == NULL)
                return 0;
        garp_attr_event(app, attr, event);
        return 0;
}

static int garp_pdu_parse_msg(struct garp_applicant *app, struct sk_buff *skb)
{
        const struct garp_msg_hdr *gm;

        if (!pskb_may_pull(skb, sizeof(*gm)))
                return -1;
        gm = (struct garp_msg_hdr *)skb->data;
        if (gm->attrtype == 0)
                return -1;
        skb_pull(skb, sizeof(*gm));

        while (skb->len > 0) {
                if (garp_pdu_parse_attr(app, skb, gm->attrtype) < 0)
                        return -1;
                if (garp_pdu_parse_end_mark(skb) < 0)
                        break;
        }
        return 0;
}

static void garp_pdu_rcv(const struct stp_proto *proto, struct sk_buff *skb,
                         struct net_device *dev)
{
        struct garp_application *appl = proto->data;
        struct garp_port *port;
        struct garp_applicant *app;
        const struct garp_pdu_hdr *gp;

        port = rcu_dereference(dev->garp_port);
        if (!port)
                goto err;
        app = rcu_dereference(port->applicants[appl->type]);
        if (!app)
                goto err;

        if (!pskb_may_pull(skb, sizeof(*gp)))
                goto err;
        gp = (struct garp_pdu_hdr *)skb->data;
        if (get_unaligned(&gp->protocol) != htons(GARP_PROTOCOL_ID))
                goto err;
        skb_pull(skb, sizeof(*gp));

        spin_lock(&app->lock);
        while (skb->len > 0) {
                if (garp_pdu_parse_msg(app, skb) < 0)
                        break;
                if (garp_pdu_parse_end_mark(skb) < 0)
                        break;
        }
        spin_unlock(&app->lock);
err:
        kfree_skb(skb);
}

static int garp_init_port(struct net_device *dev)
{
        struct garp_port *port;

        port = kzalloc(sizeof(*port), GFP_KERNEL);
        if (!port)
                return -ENOMEM;
        rcu_assign_pointer(dev->garp_port, port);
        return 0;
}

static void garp_release_port(struct net_device *dev)
{
        struct garp_port *port = rtnl_dereference(dev->garp_port);
        unsigned int i;

        for (i = 0; i <= GARP_APPLICATION_MAX; i++) {
                if (rtnl_dereference(port->applicants[i]))
                        return;
        }
        RCU_INIT_POINTER(dev->garp_port, NULL);
        kfree_rcu(port, rcu);
}

int garp_init_applicant(struct net_device *dev, struct garp_application *appl)
{
        struct garp_applicant *app;
        int err;

        ASSERT_RTNL();

        if (!rtnl_dereference(dev->garp_port)) {
                err = garp_init_port(dev);
                if (err < 0)
                        goto err1;
        }

        err = -ENOMEM;
        app = kzalloc(sizeof(*app), GFP_KERNEL);
        if (!app)
                goto err2;

        err = dev_mc_add(dev, appl->proto.group_address);
        if (err < 0)
                goto err3;

        app->dev = dev;
        app->app = appl;
        app->gid = RB_ROOT;
        spin_lock_init(&app->lock);
        skb_queue_head_init(&app->queue);
        rcu_assign_pointer(dev->garp_port->applicants[appl->type], app);
        setup_timer(&app->join_timer, garp_join_timer, (unsigned long)app);
        garp_join_timer_arm(app);
        return 0;

err3:
        kfree(app);
err2:
        garp_release_port(dev);
err1:
        return err;
}
EXPORT_SYMBOL_GPL(garp_init_applicant);

void garp_uninit_applicant(struct net_device *dev, struct garp_application *appl)
{
        struct garp_port *port = rtnl_dereference(dev->garp_port);
        struct garp_applicant *app = rtnl_dereference(port->applicants[appl->type]);

        ASSERT_RTNL();

        RCU_INIT_POINTER(port->applicants[appl->type], NULL);

        /* Delete timer and generate a final TRANSMIT_PDU event to flush out
         * all pending messages before the applicant is gone. */
        del_timer_sync(&app->join_timer);
        garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
        garp_pdu_queue(app);
        garp_queue_xmit(app);

        dev_mc_del(dev, appl->proto.group_address);
        kfree_rcu(app, rcu);
        garp_release_port(dev);
}
EXPORT_SYMBOL_GPL(garp_uninit_applicant);

int garp_register_application(struct garp_application *appl)
{
        appl->proto.rcv = garp_pdu_rcv;
        appl->proto.data = appl;
        return stp_proto_register(&appl->proto);
}
EXPORT_SYMBOL_GPL(garp_register_application);

void garp_unregister_application(struct garp_application *appl)
{
        stp_proto_unregister(&appl->proto);
}
EXPORT_SYMBOL_GPL(garp_unregister_application);