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linux-next/net/batman-adv/originator.h
Antonio Quartulli 08bf0ed29c batman-adv: avoid potential race condition when adding a new neighbour
When adding a new neighbour it is important to atomically
perform the following:
- check if the neighbour already exists
- append the neighbour to the proper list

If the two operations are not performed in an atomic context
it is possible that two concurrent insertions add the same
neighbour twice.

Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
2014-02-17 17:17:01 +01:00

127 lines
4.2 KiB
C

/* Copyright (C) 2007-2014 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, see <http://www.gnu.org/licenses/>.
*/
#ifndef _NET_BATMAN_ADV_ORIGINATOR_H_
#define _NET_BATMAN_ADV_ORIGINATOR_H_
#include "hash.h"
int batadv_compare_orig(const struct hlist_node *node, const void *data2);
int batadv_originator_init(struct batadv_priv *bat_priv);
void batadv_originator_free(struct batadv_priv *bat_priv);
void batadv_purge_orig_ref(struct batadv_priv *bat_priv);
void batadv_orig_node_free_ref(struct batadv_orig_node *orig_node);
void batadv_orig_node_free_ref_now(struct batadv_orig_node *orig_node);
struct batadv_orig_node *batadv_orig_node_new(struct batadv_priv *bat_priv,
const uint8_t *addr);
struct batadv_neigh_node *
batadv_neigh_node_get(const struct batadv_orig_node *orig_node,
const struct batadv_hard_iface *hard_iface,
const uint8_t *addr);
struct batadv_neigh_node *
batadv_neigh_node_new(struct batadv_hard_iface *hard_iface,
const uint8_t *neigh_addr,
struct batadv_orig_node *orig_node);
void batadv_neigh_node_free_ref(struct batadv_neigh_node *neigh_node);
struct batadv_neigh_node *
batadv_orig_router_get(struct batadv_orig_node *orig_node,
const struct batadv_hard_iface *if_outgoing);
struct batadv_neigh_ifinfo *
batadv_neigh_ifinfo_new(struct batadv_neigh_node *neigh,
struct batadv_hard_iface *if_outgoing);
struct batadv_neigh_ifinfo *
batadv_neigh_ifinfo_get(struct batadv_neigh_node *neigh,
struct batadv_hard_iface *if_outgoing);
void batadv_neigh_ifinfo_free_ref(struct batadv_neigh_ifinfo *neigh_ifinfo);
struct batadv_orig_ifinfo *
batadv_orig_ifinfo_get(struct batadv_orig_node *orig_node,
struct batadv_hard_iface *if_outgoing);
struct batadv_orig_ifinfo *
batadv_orig_ifinfo_new(struct batadv_orig_node *orig_node,
struct batadv_hard_iface *if_outgoing);
void batadv_orig_ifinfo_free_ref(struct batadv_orig_ifinfo *orig_ifinfo);
int batadv_orig_seq_print_text(struct seq_file *seq, void *offset);
int batadv_orig_hardif_seq_print_text(struct seq_file *seq, void *offset);
int batadv_orig_hash_add_if(struct batadv_hard_iface *hard_iface,
int max_if_num);
int batadv_orig_hash_del_if(struct batadv_hard_iface *hard_iface,
int max_if_num);
struct batadv_orig_node_vlan *
batadv_orig_node_vlan_new(struct batadv_orig_node *orig_node,
unsigned short vid);
struct batadv_orig_node_vlan *
batadv_orig_node_vlan_get(struct batadv_orig_node *orig_node,
unsigned short vid);
void batadv_orig_node_vlan_free_ref(struct batadv_orig_node_vlan *orig_vlan);
/* hashfunction to choose an entry in a hash table of given size
* hash algorithm from http://en.wikipedia.org/wiki/Hash_table
*/
static inline uint32_t batadv_choose_orig(const void *data, uint32_t size)
{
const unsigned char *key = data;
uint32_t hash = 0;
size_t i;
for (i = 0; i < 6; i++) {
hash += key[i];
hash += (hash << 10);
hash ^= (hash >> 6);
}
hash += (hash << 3);
hash ^= (hash >> 11);
hash += (hash << 15);
return hash % size;
}
static inline struct batadv_orig_node *
batadv_orig_hash_find(struct batadv_priv *bat_priv, const void *data)
{
struct batadv_hashtable *hash = bat_priv->orig_hash;
struct hlist_head *head;
struct batadv_orig_node *orig_node, *orig_node_tmp = NULL;
int index;
if (!hash)
return NULL;
index = batadv_choose_orig(data, hash->size);
head = &hash->table[index];
rcu_read_lock();
hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
if (!batadv_compare_eth(orig_node, data))
continue;
if (!atomic_inc_not_zero(&orig_node->refcount))
continue;
orig_node_tmp = orig_node;
break;
}
rcu_read_unlock();
return orig_node_tmp;
}
#endif /* _NET_BATMAN_ADV_ORIGINATOR_H_ */