/*
* Copyright (c) 2008 open80211s Ltd.
* Author: Luis Carlos Cobo <luisca@cozybit.com>
*
* 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/etherdevice.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/random.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "mesh.h"
/* There will be initially 2^INIT_PATHS_SIZE_ORDER buckets */
#define INIT_PATHS_SIZE_ORDER 2
/* Keep the mean chain length below this constant */
#define MEAN_CHAIN_LEN 2
#define MPATH_EXPIRED(mpath) ((mpath->flags & MESH_PATH_ACTIVE) && \
time_after(jiffies, mpath->exp_time) && \
!(mpath->flags & MESH_PATH_FIXED))
struct mpath_node {
struct hlist_node list;
struct rcu_head rcu;
/* This indirection allows two different tables to point to the same
* mesh_path structure, useful when resizing
*/
struct mesh_path *mpath;
};
static struct mesh_table *mesh_paths;
/* This lock will have the grow table function as writer and add / delete nodes
* as readers. When reading the table (i.e. doing lookups) we are well protected
* by RCU
*/
static DEFINE_RWLOCK(pathtbl_resize_lock);
/**
*
* mesh_path_assign_nexthop - update mesh path next hop
*
* @mpath: mesh path to update
* @sta: next hop to assign
*
* Locking: mpath->state_lock must be held when calling this function
*/
void mesh_path_assign_nexthop(struct mesh_path *mpath, struct sta_info *sta)
{
rcu_assign_pointer(mpath->next_hop, sta);
}
/**
* mesh_path_lookup - look up a path in the mesh path table
* @dst: hardware address (ETH_ALEN length) of destination
* @dev: local interface
*
* Returns: pointer to the mesh path structure, or NULL if not found
*
* Locking: must be called within a read rcu section.
*/
struct mesh_path *mesh_path_lookup(u8 *dst, struct net_device *dev)
{
struct mesh_path *mpath;
struct hlist_node *n;
struct hlist_head *bucket;
struct mesh_table *tbl;
struct mpath_node *node;
tbl = rcu_dereference(mesh_paths);
bucket = &tbl->hash_buckets[mesh_table_hash(dst, dev, tbl)];
hlist_for_each_entry_rcu(node, n, bucket, list) {
mpath = node->mpath;
if (mpath->dev == dev &&
memcmp(dst, mpath->dst, ETH_ALEN) == 0) {
if (MPATH_EXPIRED(mpath)) {
spin_lock_bh(&mpath->state_lock);
if (MPATH_EXPIRED(mpath))
mpath->flags &= ~MESH_PATH_ACTIVE;
spin_unlock_bh(&mpath->state_lock);
}
return mpath;
}
}
return NULL;
}
/**
* mesh_path_lookup_by_idx - look up a path in the mesh path table by its index
* @idx: index
* @dev: local interface, or NULL for all entries
*
* Returns: pointer to the mesh path structure, or NULL if not found.
*
* Locking: must be called within a read rcu section.
*/
struct mesh_path *mesh_path_lookup_by_idx(int idx, struct net_device *dev)
{
struct mpath_node *node;
struct hlist_node *p;
int i;
int j = 0;
for_each_mesh_entry(mesh_paths, p, node, i) {
if (dev && node->mpath->dev != dev)
continue;
if (j++ == idx) {
if (MPATH_EXPIRED(node->mpath)) {
spin_lock_bh(&node->mpath->state_lock);
if (MPATH_EXPIRED(node->mpath))
node->mpath->flags &= ~MESH_PATH_ACTIVE;
spin_unlock_bh(&node->mpath->state_lock);
}
return node->mpath;
}
}
return NULL;
}
/**
* mesh_path_add - allocate and add a new path to the mesh path table
* @addr: destination address of the path (ETH_ALEN length)
* @dev: local interface
*
* Returns: 0 on sucess
*
* State: the initial state of the new path is set to 0
*/
int mesh_path_add(u8 *dst, struct net_device *dev)
{
struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
struct mesh_path *mpath, *new_mpath;
struct mpath_node *node, *new_node;
struct hlist_head *bucket;
struct hlist_node *n;
int grow = 0;
int err = 0;
u32 hash_idx;
if (memcmp(dst, dev->dev_addr, ETH_ALEN) == 0)
/* never add ourselves as neighbours */
return -ENOTSUPP;
if (is_multicast_ether_addr(dst))
return -ENOTSUPP;
if (atomic_add_unless(&sdata->u.sta.mpaths, 1, MESH_MAX_MPATHS) == 0)
return -ENOSPC;
new_mpath = kzalloc(sizeof(struct mesh_path), GFP_KERNEL);
if (!new_mpath) {
atomic_dec(&sdata->u.sta.mpaths);
err = -ENOMEM;
goto endadd2;
}
new_node = kmalloc(sizeof(struct mpath_node), GFP_KERNEL);
if (!new_node) {
kfree(new_mpath);
atomic_dec(&sdata->u.sta.mpaths);
err = -ENOMEM;
goto endadd2;
}
read_lock(&pathtbl_resize_lock);
memcpy(new_mpath->dst, dst, ETH_ALEN);
new_mpath->dev = dev;
new_mpath->flags = 0;
skb_queue_head_init(&new_mpath->frame_queue);
new_node->mpath = new_mpath;
new_mpath->timer.data = (unsigned long) new_mpath;
new_mpath->timer.function = mesh_path_timer;
new_mpath->exp_time = jiffies;
spin_lock_init(&new_mpath->state_lock);
init_timer(&new_mpath->timer);
hash_idx = mesh_table_hash(dst, dev, mesh_paths);
bucket = &mesh_paths->hash_buckets[hash_idx];
spin_lock(&mesh_paths->hashwlock[hash_idx]);
hlist_for_each_entry(node, n, bucket, list) {
mpath = node->mpath;
if (mpath->dev == dev && memcmp(dst, mpath->dst, ETH_ALEN)
== 0) {
err = -EEXIST;
atomic_dec(&sdata->u.sta.mpaths);
kfree(new_node);
kfree(new_mpath);
goto endadd;
}
}
hlist_add_head_rcu(&new_node->list, bucket);
if (atomic_inc_return(&mesh_paths->entries) >=
mesh_paths->mean_chain_len * (mesh_paths->hash_mask + 1))
grow = 1;
endadd:
spin_unlock(&mesh_paths->hashwlock[hash_idx]);
read_unlock(&pathtbl_resize_lock);
if (!err && grow) {
struct mesh_table *oldtbl, *newtbl;
write_lock(&pathtbl_resize_lock);
oldtbl = mesh_paths;
newtbl = mesh_table_grow(mesh_paths);
if (!newtbl) {
write_unlock(&pathtbl_resize_lock);
return -ENOMEM;
}
rcu_assign_pointer(mesh_paths, newtbl);
write_unlock(&pathtbl_resize_lock);
synchronize_rcu();
mesh_table_free(oldtbl, false);
}
endadd2:
return err;
}
/**
* mesh_plink_broken - deactivates paths and sends perr when a link breaks
*
* @sta: broken peer link
*
* This function must be called from the rate control algorithm if enough
* delivery errors suggest that a peer link is no longer usable.
*/
void mesh_plink_broken(struct sta_info *sta)
{
struct mesh_path *mpath;
struct mpath_node *node;
struct hlist_node *p;
struct net_device *dev = sta->sdata->dev;
int i;
rcu_read_lock();
for_each_mesh_entry(mesh_paths, p, node, i) {
mpath = node->mpath;
spin_lock_bh(&mpath->state_lock);
if (mpath->next_hop == sta &&
mpath->flags & MESH_PATH_ACTIVE &&
!(mpath->flags & MESH_PATH_FIXED)) {
mpath->flags &= ~MESH_PATH_ACTIVE;
++mpath->dsn;
spin_unlock_bh(&mpath->state_lock);
mesh_path_error_tx(mpath->dst,
cpu_to_le32(mpath->dsn),
dev->broadcast, dev);
} else
spin_unlock_bh(&mpath->state_lock);
}
rcu_read_unlock();
}
EXPORT_SYMBOL(mesh_plink_broken);
/**
* mesh_path_flush_by_nexthop - Deletes mesh paths if their next hop matches
*
* @sta - mesh peer to match
*
* RCU notes: this function is called when a mesh plink transitions from
* PLINK_ESTAB to any other state, since PLINK_ESTAB state is the only one that
* allows path creation. This will happen before the sta can be freed (because
* sta_info_destroy() calls this) so any reader in a rcu read block will be
* protected against the plink disappearing.
*/
void mesh_path_flush_by_nexthop(struct sta_info *sta)
{
struct mesh_path *mpath;
struct mpath_node *node;
struct hlist_node *p;
int i;
for_each_mesh_entry(mesh_paths, p, node, i) {
mpath = node->mpath;
if (mpath->next_hop == sta)
mesh_path_del(mpath->dst, mpath->dev);
}
}
void mesh_path_flush(struct net_device *dev)
{
struct mesh_path *mpath;
struct mpath_node *node;
struct hlist_node *p;
int i;
for_each_mesh_entry(mesh_paths, p, node, i) {
mpath = node->mpath;
if (mpath->dev == dev)
mesh_path_del(mpath->dst, mpath->dev);
}
}
static void mesh_path_node_reclaim(struct rcu_head *rp)
{
struct mpath_node *node = container_of(rp, struct mpath_node, rcu);
struct ieee80211_sub_if_data *sdata =
IEEE80211_DEV_TO_SUB_IF(node->mpath->dev);
del_timer_sync(&node->mpath->timer);
atomic_dec(&sdata->u.sta.mpaths);
kfree(node->mpath);
kfree(node);
}
/**
* mesh_path_del - delete a mesh path from the table
*
* @addr: dst address (ETH_ALEN length)
* @dev: local interface
*
* Returns: 0 if succesful
*/
int mesh_path_del(u8 *addr, struct net_device *dev)
{
struct mesh_path *mpath;
struct mpath_node *node;
struct hlist_head *bucket;
struct hlist_node *n;
int hash_idx;
int err = 0;
read_lock(&pathtbl_resize_lock);
hash_idx = mesh_table_hash(addr, dev, mesh_paths);
bucket = &mesh_paths->hash_buckets[hash_idx];
spin_lock(&mesh_paths->hashwlock[hash_idx]);
hlist_for_each_entry(node, n, bucket, list) {
mpath = node->mpath;
if (mpath->dev == dev &&
memcmp(addr, mpath->dst, ETH_ALEN) == 0) {
spin_lock_bh(&mpath->state_lock);
mpath->flags |= MESH_PATH_RESOLVING;
hlist_del_rcu(&node->list);
call_rcu(&node->rcu, mesh_path_node_reclaim);
atomic_dec(&mesh_paths->entries);
spin_unlock_bh(&mpath->state_lock);
goto enddel;
}
}
err = -ENXIO;
enddel:
spin_unlock(&mesh_paths->hashwlock[hash_idx]);
read_unlock(&pathtbl_resize_lock);
return err;
}
/**
* mesh_path_tx_pending - sends pending frames in a mesh path queue
*
* @mpath: mesh path to activate
*
* Locking: the state_lock of the mpath structure must NOT be held when calling
* this function.
*/
void mesh_path_tx_pending(struct mesh_path *mpath)
{
struct sk_buff *skb;
while ((skb = skb_dequeue(&mpath->frame_queue)) &&
(mpath->flags & MESH_PATH_ACTIVE))
dev_queue_xmit(skb);
}
/**
* mesh_path_discard_frame - discard a frame whose path could not be resolved
*
* @skb: frame to discard
* @dev: network device the frame was to be sent through
*
* If the frame was beign forwarded from another MP, a PERR frame will be sent
* to the precursor.
*
* Locking: the function must me called within a rcu_read_lock region
*/
void mesh_path_discard_frame(struct sk_buff *skb, struct net_device *dev)
{
struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
struct mesh_path *mpath;
u32 dsn = 0;
if (skb->pkt_type == PACKET_OTHERHOST) {
struct ieee80211s_hdr *prev_meshhdr;
int mshhdrlen;
u8 *ra, *da;
prev_meshhdr = ((struct ieee80211s_hdr *)skb->cb);
mshhdrlen = ieee80211_get_mesh_hdrlen(prev_meshhdr);
da = skb->data;
ra = MESH_PREQ(skb);
mpath = mesh_path_lookup(da, dev);
if (mpath)
dsn = ++mpath->dsn;
mesh_path_error_tx(skb->data, cpu_to_le32(dsn), ra, dev);
}
kfree_skb(skb);
sdata->u.sta.mshstats.dropped_frames_no_route++;
}
/**
* mesh_path_flush_pending - free the pending queue of a mesh path
*
* @mpath: mesh path whose queue has to be freed
*
* Locking: the function must me called withing a rcu_read_lock region
*/
void mesh_path_flush_pending(struct mesh_path *mpath)
{
struct ieee80211_sub_if_data *sdata;
struct sk_buff *skb;
sdata = IEEE80211_DEV_TO_SUB_IF(mpath->dev);
while ((skb = skb_dequeue(&mpath->frame_queue)) &&
(mpath->flags & MESH_PATH_ACTIVE))
mesh_path_discard_frame(skb, mpath->dev);
}
/**
* mesh_path_fix_nexthop - force a specific next hop for a mesh path
*
* @mpath: the mesh path to modify
* @next_hop: the next hop to force
*
* Locking: this function must be called holding mpath->state_lock
*/
void mesh_path_fix_nexthop(struct mesh_path *mpath, struct sta_info *next_hop)
{
spin_lock_bh(&mpath->state_lock);
mesh_path_assign_nexthop(mpath, next_hop);
mpath->dsn = 0xffff;
mpath->metric = 0;
mpath->hop_count = 0;
mpath->exp_time = 0;
mpath->flags |= MESH_PATH_FIXED;
mesh_path_activate(mpath);
spin_unlock_bh(&mpath->state_lock);
mesh_path_tx_pending(mpath);
}
static void mesh_path_node_free(struct hlist_node *p, bool free_leafs)
{
struct mesh_path *mpath;
struct mpath_node *node = hlist_entry(p, struct mpath_node, list);
mpath = node->mpath;
hlist_del_rcu(p);
synchronize_rcu();
if (free_leafs)
kfree(mpath);
kfree(node);
}
static void mesh_path_node_copy(struct hlist_node *p, struct mesh_table *newtbl)
{
struct mesh_path *mpath;
struct mpath_node *node, *new_node;
u32 hash_idx;
node = hlist_entry(p, struct mpath_node, list);
mpath = node->mpath;
new_node = kmalloc(sizeof(struct mpath_node), GFP_KERNEL);
new_node->mpath = mpath;
hash_idx = mesh_table_hash(mpath->dst, mpath->dev, newtbl);
hlist_add_head(&new_node->list,
&newtbl->hash_buckets[hash_idx]);
}
int mesh_pathtbl_init(void)
{
mesh_paths = mesh_table_alloc(INIT_PATHS_SIZE_ORDER);
mesh_paths->free_node = &mesh_path_node_free;
mesh_paths->copy_node = &mesh_path_node_copy;
mesh_paths->mean_chain_len = MEAN_CHAIN_LEN;
if (!mesh_paths)
return -ENOMEM;
return 0;
}
void mesh_path_expire(struct net_device *dev)
{
struct mesh_path *mpath;
struct mpath_node *node;
struct hlist_node *p;
int i;
read_lock(&pathtbl_resize_lock);
for_each_mesh_entry(mesh_paths, p, node, i) {
if (node->mpath->dev != dev)
continue;
mpath = node->mpath;
spin_lock_bh(&mpath->state_lock);
if ((!(mpath->flags & MESH_PATH_RESOLVING)) &&
(!(mpath->flags & MESH_PATH_FIXED)) &&
time_after(jiffies,
mpath->exp_time + MESH_PATH_EXPIRE)) {
spin_unlock_bh(&mpath->state_lock);
mesh_path_del(mpath->dst, mpath->dev);
} else
spin_unlock_bh(&mpath->state_lock);
}
read_unlock(&pathtbl_resize_lock);
}
void mesh_pathtbl_unregister(void)
{
mesh_table_free(mesh_paths, true);
}
