mlock: fix race when munlocking pages in do_wp_page()

[linux/fpc-iii.git] / net / batman-adv / send.c

/*
 * Copyright (C) 2007-2010 B.A.T.M.A.N. contributors:
 *
 * Marek Lindner, Simon Wunderlich
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 *
 */

#include "main.h"
#include "send.h"
#include "routing.h"
#include "translation-table.h"
#include "soft-interface.h"
#include "hard-interface.h"
#include "types.h"
#include "vis.h"
#include "aggregation.h"
#include "gateway_common.h"
#include "originator.h"

static void send_outstanding_bcast_packet(struct work_struct *work);

/* apply hop penalty for a normal link */
static uint8_t hop_penalty(const uint8_t tq, struct bat_priv *bat_priv)
{
        int hop_penalty = atomic_read(&bat_priv->hop_penalty);
        return (tq * (TQ_MAX_VALUE - hop_penalty)) / (TQ_MAX_VALUE);
}

/* when do we schedule our own packet to be sent */
static unsigned long own_send_time(struct bat_priv *bat_priv)
{
        return jiffies + msecs_to_jiffies(
                   atomic_read(&bat_priv->orig_interval) -
                   JITTER + (random32() % 2*JITTER));
}

/* when do we schedule a forwarded packet to be sent */
static unsigned long forward_send_time(struct bat_priv *bat_priv)
{
        return jiffies + msecs_to_jiffies(random32() % (JITTER/2));
}

/* send out an already prepared packet to the given address via the
 * specified batman interface */
int send_skb_packet(struct sk_buff *skb,
                                struct batman_if *batman_if,
                                uint8_t *dst_addr)
{
        struct ethhdr *ethhdr;

        if (batman_if->if_status != IF_ACTIVE)
                goto send_skb_err;

        if (unlikely(!batman_if->net_dev))
                goto send_skb_err;

        if (!(batman_if->net_dev->flags & IFF_UP)) {
                pr_warning("Interface %s is not up - can't send packet via "
                           "that interface!\n", batman_if->net_dev->name);
                goto send_skb_err;
        }

        /* push to the ethernet header. */
        if (my_skb_head_push(skb, sizeof(struct ethhdr)) < 0)
                goto send_skb_err;

        skb_reset_mac_header(skb);

        ethhdr = (struct ethhdr *) skb_mac_header(skb);
        memcpy(ethhdr->h_source, batman_if->net_dev->dev_addr, ETH_ALEN);
        memcpy(ethhdr->h_dest, dst_addr, ETH_ALEN);
        ethhdr->h_proto = __constant_htons(ETH_P_BATMAN);

        skb_set_network_header(skb, ETH_HLEN);
        skb->priority = TC_PRIO_CONTROL;
        skb->protocol = __constant_htons(ETH_P_BATMAN);

        skb->dev = batman_if->net_dev;

        /* dev_queue_xmit() returns a negative result on error.  However on
         * congestion and traffic shaping, it drops and returns NET_XMIT_DROP
         * (which is > 0). This will not be treated as an error. */

        return dev_queue_xmit(skb);
send_skb_err:
        kfree_skb(skb);
        return NET_XMIT_DROP;
}

/* Send a packet to a given interface */
static void send_packet_to_if(struct forw_packet *forw_packet,
                              struct batman_if *batman_if)
{
        struct bat_priv *bat_priv = netdev_priv(batman_if->soft_iface);
        char *fwd_str;
        uint8_t packet_num;
        int16_t buff_pos;
        struct batman_packet *batman_packet;
        struct sk_buff *skb;

        if (batman_if->if_status != IF_ACTIVE)
                return;

        packet_num = 0;
        buff_pos = 0;
        batman_packet = (struct batman_packet *)forw_packet->skb->data;

        /* adjust all flags and log packets */
        while (aggregated_packet(buff_pos,
                                 forw_packet->packet_len,
                                 batman_packet->num_hna)) {

                /* we might have aggregated direct link packets with an
                 * ordinary base packet */
                if ((forw_packet->direct_link_flags & (1 << packet_num)) &&
                    (forw_packet->if_incoming == batman_if))
                        batman_packet->flags |= DIRECTLINK;
                else
                        batman_packet->flags &= ~DIRECTLINK;

                fwd_str = (packet_num > 0 ? "Forwarding" : (forw_packet->own ?
                                                            "Sending own" :
                                                            "Forwarding"));
                bat_dbg(DBG_BATMAN, bat_priv,
                        "%s %spacket (originator %pM, seqno %d, TQ %d, TTL %d,"
                        " IDF %s) on interface %s [%pM]\n",
                        fwd_str, (packet_num > 0 ? "aggregated " : ""),
                        batman_packet->orig, ntohl(batman_packet->seqno),
                        batman_packet->tq, batman_packet->ttl,
                        (batman_packet->flags & DIRECTLINK ?
                         "on" : "off"),
                        batman_if->net_dev->name, batman_if->net_dev->dev_addr);

                buff_pos += sizeof(struct batman_packet) +
                        (batman_packet->num_hna * ETH_ALEN);
                packet_num++;
                batman_packet = (struct batman_packet *)
                        (forw_packet->skb->data + buff_pos);
        }

        /* create clone because function is called more than once */
        skb = skb_clone(forw_packet->skb, GFP_ATOMIC);
        if (skb)
                send_skb_packet(skb, batman_if, broadcast_addr);
}

/* send a batman packet */
static void send_packet(struct forw_packet *forw_packet)
{
        struct batman_if *batman_if;
        struct net_device *soft_iface;
        struct bat_priv *bat_priv;
        struct batman_packet *batman_packet =
                (struct batman_packet *)(forw_packet->skb->data);
        unsigned char directlink = (batman_packet->flags & DIRECTLINK ? 1 : 0);

        if (!forw_packet->if_incoming) {
                pr_err("Error - can't forward packet: incoming iface not "
                       "specified\n");
                return;
        }

        soft_iface = forw_packet->if_incoming->soft_iface;
        bat_priv = netdev_priv(soft_iface);

        if (forw_packet->if_incoming->if_status != IF_ACTIVE)
                return;

        /* multihomed peer assumed */
        /* non-primary OGMs are only broadcasted on their interface */
        if ((directlink && (batman_packet->ttl == 1)) ||
            (forw_packet->own && (forw_packet->if_incoming->if_num > 0))) {

                /* FIXME: what about aggregated packets ? */
                bat_dbg(DBG_BATMAN, bat_priv,
                        "%s packet (originator %pM, seqno %d, TTL %d) "
                        "on interface %s [%pM]\n",
                        (forw_packet->own ? "Sending own" : "Forwarding"),
                        batman_packet->orig, ntohl(batman_packet->seqno),
                        batman_packet->ttl,
                        forw_packet->if_incoming->net_dev->name,
                        forw_packet->if_incoming->net_dev->dev_addr);

                /* skb is only used once and than forw_packet is free'd */
                send_skb_packet(forw_packet->skb, forw_packet->if_incoming,
                                broadcast_addr);
                forw_packet->skb = NULL;

                return;
        }

        /* broadcast on every interface */
        rcu_read_lock();
        list_for_each_entry_rcu(batman_if, &if_list, list) {
                if (batman_if->soft_iface != soft_iface)
                        continue;

                send_packet_to_if(forw_packet, batman_if);
        }
        rcu_read_unlock();
}

static void rebuild_batman_packet(struct bat_priv *bat_priv,
                                  struct batman_if *batman_if)
{
        int new_len;
        unsigned char *new_buff;
        struct batman_packet *batman_packet;

        new_len = sizeof(struct batman_packet) +
                        (bat_priv->num_local_hna * ETH_ALEN);
        new_buff = kmalloc(new_len, GFP_ATOMIC);

        /* keep old buffer if kmalloc should fail */
        if (new_buff) {
                memcpy(new_buff, batman_if->packet_buff,
                       sizeof(struct batman_packet));
                batman_packet = (struct batman_packet *)new_buff;

                batman_packet->num_hna = hna_local_fill_buffer(bat_priv,
                                new_buff + sizeof(struct batman_packet),
                                new_len - sizeof(struct batman_packet));

                kfree(batman_if->packet_buff);
                batman_if->packet_buff = new_buff;
                batman_if->packet_len = new_len;
        }
}

void schedule_own_packet(struct batman_if *batman_if)
{
        struct bat_priv *bat_priv = netdev_priv(batman_if->soft_iface);
        unsigned long send_time;
        struct batman_packet *batman_packet;
        int vis_server;

        if ((batman_if->if_status == IF_NOT_IN_USE) ||
            (batman_if->if_status == IF_TO_BE_REMOVED))
                return;

        vis_server = atomic_read(&bat_priv->vis_mode);

        /**
         * the interface gets activated here to avoid race conditions between
         * the moment of activating the interface in
         * hardif_activate_interface() where the originator mac is set and
         * outdated packets (especially uninitialized mac addresses) in the
         * packet queue
         */
        if (batman_if->if_status == IF_TO_BE_ACTIVATED)
                batman_if->if_status = IF_ACTIVE;

        /* if local hna has changed and interface is a primary interface */
        if ((atomic_read(&bat_priv->hna_local_changed)) &&
            (batman_if == bat_priv->primary_if))
                rebuild_batman_packet(bat_priv, batman_if);

        /**
         * NOTE: packet_buff might just have been re-allocated in
         * rebuild_batman_packet()
         */
        batman_packet = (struct batman_packet *)batman_if->packet_buff;

        /* change sequence number to network order */
        batman_packet->seqno =
                htonl((uint32_t)atomic_read(&batman_if->seqno));

        if (vis_server == VIS_TYPE_SERVER_SYNC)
                batman_packet->flags |= VIS_SERVER;
        else
                batman_packet->flags &= ~VIS_SERVER;

        if ((batman_if == bat_priv->primary_if) &&
            (atomic_read(&bat_priv->gw_mode) == GW_MODE_SERVER))
                batman_packet->gw_flags =
                                (uint8_t)atomic_read(&bat_priv->gw_bandwidth);
        else
                batman_packet->gw_flags = 0;

        atomic_inc(&batman_if->seqno);

        slide_own_bcast_window(batman_if);
        send_time = own_send_time(bat_priv);
        add_bat_packet_to_list(bat_priv,
                               batman_if->packet_buff,
                               batman_if->packet_len,
                               batman_if, 1, send_time);
}

void schedule_forward_packet(struct orig_node *orig_node,
                             struct ethhdr *ethhdr,
                             struct batman_packet *batman_packet,
                             uint8_t directlink, int hna_buff_len,
                             struct batman_if *if_incoming)
{
        struct bat_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        unsigned char in_tq, in_ttl, tq_avg = 0;
        unsigned long send_time;

        if (batman_packet->ttl <= 1) {
                bat_dbg(DBG_BATMAN, bat_priv, "ttl exceeded\n");
                return;
        }

        in_tq = batman_packet->tq;
        in_ttl = batman_packet->ttl;

        batman_packet->ttl--;
        memcpy(batman_packet->prev_sender, ethhdr->h_source, ETH_ALEN);

        /* rebroadcast tq of our best ranking neighbor to ensure the rebroadcast
         * of our best tq value */
        if ((orig_node->router) && (orig_node->router->tq_avg != 0)) {

                /* rebroadcast ogm of best ranking neighbor as is */
                if (!compare_orig(orig_node->router->addr, ethhdr->h_source)) {
                        batman_packet->tq = orig_node->router->tq_avg;

                        if (orig_node->router->last_ttl)
                                batman_packet->ttl = orig_node->router->last_ttl
                                                        - 1;
                }

                tq_avg = orig_node->router->tq_avg;
        }

        /* apply hop penalty */
        batman_packet->tq = hop_penalty(batman_packet->tq, bat_priv);

        bat_dbg(DBG_BATMAN, bat_priv,
                "Forwarding packet: tq_orig: %i, tq_avg: %i, "
                "tq_forw: %i, ttl_orig: %i, ttl_forw: %i\n",
                in_tq, tq_avg, batman_packet->tq, in_ttl - 1,
                batman_packet->ttl);

        batman_packet->seqno = htonl(batman_packet->seqno);

        /* switch of primaries first hop flag when forwarding */
        batman_packet->flags &= ~PRIMARIES_FIRST_HOP;
        if (directlink)
                batman_packet->flags |= DIRECTLINK;
        else
                batman_packet->flags &= ~DIRECTLINK;

        send_time = forward_send_time(bat_priv);
        add_bat_packet_to_list(bat_priv,
                               (unsigned char *)batman_packet,
                               sizeof(struct batman_packet) + hna_buff_len,
                               if_incoming, 0, send_time);
}

static void forw_packet_free(struct forw_packet *forw_packet)
{
        if (forw_packet->skb)
                kfree_skb(forw_packet->skb);
        kfree(forw_packet);
}

static void _add_bcast_packet_to_list(struct bat_priv *bat_priv,
                                      struct forw_packet *forw_packet,
                                      unsigned long send_time)
{
        INIT_HLIST_NODE(&forw_packet->list);

        /* add new packet to packet list */
        spin_lock_bh(&bat_priv->forw_bcast_list_lock);
        hlist_add_head(&forw_packet->list, &bat_priv->forw_bcast_list);
        spin_unlock_bh(&bat_priv->forw_bcast_list_lock);

        /* start timer for this packet */
        INIT_DELAYED_WORK(&forw_packet->delayed_work,
                          send_outstanding_bcast_packet);
        queue_delayed_work(bat_event_workqueue, &forw_packet->delayed_work,
                           send_time);
}

#define atomic_dec_not_zero(v)          atomic_add_unless((v), -1, 0)
/* add a broadcast packet to the queue and setup timers. broadcast packets
 * are sent multiple times to increase probability for beeing received.
 *
 * This function returns NETDEV_TX_OK on success and NETDEV_TX_BUSY on
 * errors.
 *
 * The skb is not consumed, so the caller should make sure that the
 * skb is freed. */
int add_bcast_packet_to_list(struct bat_priv *bat_priv, struct sk_buff *skb)
{
        struct forw_packet *forw_packet;
        struct bcast_packet *bcast_packet;

        if (!atomic_dec_not_zero(&bat_priv->bcast_queue_left)) {
                bat_dbg(DBG_BATMAN, bat_priv, "bcast packet queue full\n");
                goto out;
        }

        if (!bat_priv->primary_if)
                goto out;

        forw_packet = kmalloc(sizeof(struct forw_packet), GFP_ATOMIC);

        if (!forw_packet)
                goto out_and_inc;

        skb = skb_copy(skb, GFP_ATOMIC);
        if (!skb)
                goto packet_free;

        /* as we have a copy now, it is safe to decrease the TTL */
        bcast_packet = (struct bcast_packet *)skb->data;
        bcast_packet->ttl--;

        skb_reset_mac_header(skb);

        forw_packet->skb = skb;
        forw_packet->if_incoming = bat_priv->primary_if;

        /* how often did we send the bcast packet ? */
        forw_packet->num_packets = 0;

        _add_bcast_packet_to_list(bat_priv, forw_packet, 1);
        return NETDEV_TX_OK;

packet_free:
        kfree(forw_packet);
out_and_inc:
        atomic_inc(&bat_priv->bcast_queue_left);
out:
        return NETDEV_TX_BUSY;
}

static void send_outstanding_bcast_packet(struct work_struct *work)
{
        struct batman_if *batman_if;
        struct delayed_work *delayed_work =
                container_of(work, struct delayed_work, work);
        struct forw_packet *forw_packet =
                container_of(delayed_work, struct forw_packet, delayed_work);
        struct sk_buff *skb1;
        struct net_device *soft_iface = forw_packet->if_incoming->soft_iface;
        struct bat_priv *bat_priv = netdev_priv(soft_iface);

        spin_lock_bh(&bat_priv->forw_bcast_list_lock);
        hlist_del(&forw_packet->list);
        spin_unlock_bh(&bat_priv->forw_bcast_list_lock);

        if (atomic_read(&bat_priv->mesh_state) == MESH_DEACTIVATING)
                goto out;

        /* rebroadcast packet */
        rcu_read_lock();
        list_for_each_entry_rcu(batman_if, &if_list, list) {
                if (batman_if->soft_iface != soft_iface)
                        continue;

                /* send a copy of the saved skb */
                skb1 = skb_clone(forw_packet->skb, GFP_ATOMIC);
                if (skb1)
                        send_skb_packet(skb1, batman_if, broadcast_addr);
        }
        rcu_read_unlock();

        forw_packet->num_packets++;

        /* if we still have some more bcasts to send */
        if (forw_packet->num_packets < 3) {
                _add_bcast_packet_to_list(bat_priv, forw_packet,
                                          ((5 * HZ) / 1000));
                return;
        }

out:
        forw_packet_free(forw_packet);
        atomic_inc(&bat_priv->bcast_queue_left);
}

void send_outstanding_bat_packet(struct work_struct *work)
{
        struct delayed_work *delayed_work =
                container_of(work, struct delayed_work, work);
        struct forw_packet *forw_packet =
                container_of(delayed_work, struct forw_packet, delayed_work);
        struct bat_priv *bat_priv;

        bat_priv = netdev_priv(forw_packet->if_incoming->soft_iface);
        spin_lock_bh(&bat_priv->forw_bat_list_lock);
        hlist_del(&forw_packet->list);
        spin_unlock_bh(&bat_priv->forw_bat_list_lock);

        if (atomic_read(&bat_priv->mesh_state) == MESH_DEACTIVATING)
                goto out;

        send_packet(forw_packet);

        /**
         * we have to have at least one packet in the queue
         * to determine the queues wake up time unless we are
         * shutting down
         */
        if (forw_packet->own)
                schedule_own_packet(forw_packet->if_incoming);

out:
        /* don't count own packet */
        if (!forw_packet->own)
                atomic_inc(&bat_priv->batman_queue_left);

        forw_packet_free(forw_packet);
}

void purge_outstanding_packets(struct bat_priv *bat_priv,
                               struct batman_if *batman_if)
{
        struct forw_packet *forw_packet;
        struct hlist_node *tmp_node, *safe_tmp_node;

        if (batman_if)
                bat_dbg(DBG_BATMAN, bat_priv,
                        "purge_outstanding_packets(): %s\n",
                        batman_if->net_dev->name);
        else
                bat_dbg(DBG_BATMAN, bat_priv,
                        "purge_outstanding_packets()\n");

        /* free bcast list */
        spin_lock_bh(&bat_priv->forw_bcast_list_lock);
        hlist_for_each_entry_safe(forw_packet, tmp_node, safe_tmp_node,
                                  &bat_priv->forw_bcast_list, list) {

                /**
                 * if purge_outstanding_packets() was called with an argmument
                 * we delete only packets belonging to the given interface
                 */
                if ((batman_if) &&
                    (forw_packet->if_incoming != batman_if))
                        continue;

                spin_unlock_bh(&bat_priv->forw_bcast_list_lock);

                /**
                 * send_outstanding_bcast_packet() will lock the list to
                 * delete the item from the list
                 */
                cancel_delayed_work_sync(&forw_packet->delayed_work);
                spin_lock_bh(&bat_priv->forw_bcast_list_lock);
        }
        spin_unlock_bh(&bat_priv->forw_bcast_list_lock);

        /* free batman packet list */
        spin_lock_bh(&bat_priv->forw_bat_list_lock);
        hlist_for_each_entry_safe(forw_packet, tmp_node, safe_tmp_node,
                                  &bat_priv->forw_bat_list, list) {

                /**
                 * if purge_outstanding_packets() was called with an argmument
                 * we delete only packets belonging to the given interface
                 */
                if ((batman_if) &&
                    (forw_packet->if_incoming != batman_if))
                        continue;

                spin_unlock_bh(&bat_priv->forw_bat_list_lock);

                /**
                 * send_outstanding_bat_packet() will lock the list to
                 * delete the item from the list
                 */
                cancel_delayed_work_sync(&forw_packet->delayed_work);
                spin_lock_bh(&bat_priv->forw_bat_list_lock);
        }
        spin_unlock_bh(&bat_priv->forw_bat_list_lock);
}