1 files changed, 163 insertions, 0 deletions
diff --git a/net/batman-adv/hash.h b/net/batman-adv/hash.h
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+/*
+ * Copyright (C) 2006-2012 B.A.T.M.A.N. contributors:
+ *
+ * Simon Wunderlich, Marek Lindner
+ *
+ * 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
+ *
+ */
+
+#ifndef _NET_BATMAN_ADV_HASH_H_
+#define _NET_BATMAN_ADV_HASH_H_
+
+#include <linux/list.h>
+
+/* callback to a compare function.  should
+ * compare 2 element datas for their keys,
+ * return 0 if same and not 0 if not
+ * same */
+typedef int (*hashdata_compare_cb)(const struct hlist_node *, const void *);
+
+/* the hashfunction, should return an index
+ * based on the key in the data of the first
+ * argument and the size the second */
+typedef uint32_t (*hashdata_choose_cb)(const void *, uint32_t);
+typedef void (*hashdata_free_cb)(struct hlist_node *, void *);
+
+struct hashtable_t {
+	struct hlist_head *table;   /* the hashtable itself with the buckets */
+	spinlock_t *list_locks;     /* spinlock for each hash list entry */
+	uint32_t size;		    /* size of hashtable */
+};
+
+/* allocates and clears the hash */
+struct hashtable_t *hash_new(uint32_t size);
+
+/* free only the hashtable and the hash itself. */
+void hash_destroy(struct hashtable_t *hash);
+
+/* remove the hash structure. if hashdata_free_cb != NULL, this function will be
+ * called to remove the elements inside of the hash.  if you don't remove the
+ * elements, memory might be leaked. */
+static inline void hash_delete(struct hashtable_t *hash,
+			       hashdata_free_cb free_cb, void *arg)
+{
+	struct hlist_head *head;
+	struct hlist_node *node, *node_tmp;
+	spinlock_t *list_lock; /* spinlock to protect write access */
+	uint32_t i;
+
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+		list_lock = &hash->list_locks[i];
+
+		spin_lock_bh(list_lock);
+		hlist_for_each_safe(node, node_tmp, head) {
+			hlist_del_rcu(node);
+
+			if (free_cb)
+				free_cb(node, arg);
+		}
+		spin_unlock_bh(list_lock);
+	}
+
+	hash_destroy(hash);
+}
+
+/**
+ *	hash_add - adds data to the hashtable
+ *	@hash: storage hash table
+ *	@compare: callback to determine if 2 hash elements are identical
+ *	@choose: callback calculating the hash index
+ *	@data: data passed to the aforementioned callbacks as argument
+ *	@data_node: to be added element
+ *
+ *	Returns 0 on success, 1 if the element already is in the hash
+ *	and -1 on error.
+ */
+
+static inline int hash_add(struct hashtable_t *hash,
+			   hashdata_compare_cb compare,
+			   hashdata_choose_cb choose,
+			   const void *data, struct hlist_node *data_node)
+{
+	uint32_t index;
+	int ret = -1;
+	struct hlist_head *head;
+	struct hlist_node *node;
+	spinlock_t *list_lock; /* spinlock to protect write access */
+
+	if (!hash)
+		goto out;
+
+	index = choose(data, hash->size);
+	head = &hash->table[index];
+	list_lock = &hash->list_locks[index];
+
+	rcu_read_lock();
+	__hlist_for_each_rcu(node, head) {
+		if (!compare(node, data))
+			continue;
+
+		ret = 1;
+		goto err_unlock;
+	}
+	rcu_read_unlock();
+
+	/* no duplicate found in list, add new element */
+	spin_lock_bh(list_lock);
+	hlist_add_head_rcu(data_node, head);
+	spin_unlock_bh(list_lock);
+
+	ret = 0;
+	goto out;
+
+err_unlock:
+	rcu_read_unlock();
+out:
+	return ret;
+}
+
+/* removes data from hash, if found. returns pointer do data on success, so you
+ * can remove the used structure yourself, or NULL on error .  data could be the
+ * structure you use with just the key filled, we just need the key for
+ * comparing. */
+static inline void *hash_remove(struct hashtable_t *hash,
+				hashdata_compare_cb compare,
+				hashdata_choose_cb choose, void *data)
+{
+	uint32_t index;
+	struct hlist_node *node;
+	struct hlist_head *head;
+	void *data_save = NULL;
+
+	index = choose(data, hash->size);
+	head = &hash->table[index];
+
+	spin_lock_bh(&hash->list_locks[index]);
+	hlist_for_each(node, head) {
+		if (!compare(node, data))
+			continue;
+
+		data_save = node;
+		hlist_del_rcu(node);
+		break;
+	}
+	spin_unlock_bh(&hash->list_locks[index]);
+
+	return data_save;
+}
+
+#endif /* _NET_BATMAN_ADV_HASH_H_ */