7b36e8eef9
It might be possible that 2 threads access the same data in the same rcu grace period. The first thread calls call_rcu() to decrement the refcount and free the data while the second thread increases the refcount to use the data. To avoid this race condition all refcount operations have to be atomic. Reported-by: Sven Eckelmann <sven@narfation.org> Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
102 lines
2.9 KiB
C
102 lines
2.9 KiB
C
/*
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* Copyright (C) 2007-2011 B.A.T.M.A.N. contributors:
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*
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* Marek Lindner, Simon Wunderlich
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA
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*
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*/
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#ifndef _NET_BATMAN_ADV_ORIGINATOR_H_
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#define _NET_BATMAN_ADV_ORIGINATOR_H_
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#include "hash.h"
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int originator_init(struct bat_priv *bat_priv);
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void originator_free(struct bat_priv *bat_priv);
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void purge_orig_ref(struct bat_priv *bat_priv);
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void orig_node_free_ref(struct orig_node *orig_node);
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struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr);
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struct neigh_node *create_neighbor(struct orig_node *orig_node,
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struct orig_node *orig_neigh_node,
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uint8_t *neigh,
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struct batman_if *if_incoming);
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void neigh_node_free_ref(struct neigh_node *neigh_node);
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int orig_seq_print_text(struct seq_file *seq, void *offset);
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int orig_hash_add_if(struct batman_if *batman_if, int max_if_num);
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int orig_hash_del_if(struct batman_if *batman_if, int max_if_num);
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/* returns 1 if they are the same originator */
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static inline int compare_orig(struct hlist_node *node, void *data2)
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{
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void *data1 = container_of(node, struct orig_node, hash_entry);
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return (memcmp(data1, data2, ETH_ALEN) == 0 ? 1 : 0);
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}
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/* hashfunction to choose an entry in a hash table of given size */
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/* hash algorithm from http://en.wikipedia.org/wiki/Hash_table */
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static inline int choose_orig(void *data, int32_t size)
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{
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unsigned char *key = data;
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uint32_t hash = 0;
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size_t i;
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for (i = 0; i < 6; i++) {
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hash += key[i];
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hash += (hash << 10);
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hash ^= (hash >> 6);
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}
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hash += (hash << 3);
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hash ^= (hash >> 11);
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hash += (hash << 15);
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return hash % size;
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}
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static inline struct orig_node *orig_hash_find(struct bat_priv *bat_priv,
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void *data)
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{
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struct hashtable_t *hash = bat_priv->orig_hash;
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struct hlist_head *head;
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struct hlist_node *node;
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struct orig_node *orig_node, *orig_node_tmp = NULL;
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int index;
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if (!hash)
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return NULL;
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index = choose_orig(data, hash->size);
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head = &hash->table[index];
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rcu_read_lock();
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hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
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if (!compare_eth(orig_node, data))
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continue;
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if (!atomic_inc_not_zero(&orig_node->refcount))
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continue;
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orig_node_tmp = orig_node;
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break;
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}
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rcu_read_unlock();
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return orig_node_tmp;
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}
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#endif /* _NET_BATMAN_ADV_ORIGINATOR_H_ */
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