1 files changed, 157 insertions, 0 deletions
diff --git a/net/batman-adv/hash.h b/net/batman-adv/hash.h
new file mode 100644
index 000000000..fb251c385
--- /dev/null
+++ b/net/batman-adv/hash.h
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) B.A.T.M.A.N. contributors:
+ *
+ * Simon Wunderlich, Marek Lindner
+ */
+
+#ifndef _NET_BATMAN_ADV_HASH_H_
+#define _NET_BATMAN_ADV_HASH_H_
+
+#include "main.h"
+
+#include <linux/atomic.h>
+#include <linux/compiler.h>
+#include <linux/list.h>
+#include <linux/lockdep.h>
+#include <linux/rculist.h>
+#include <linux/spinlock.h>
+#include <linux/stddef.h>
+#include <linux/types.h>
+
+/* callback to a compare function.  should compare 2 element data for their
+ * keys
+ *
+ * Return: true if same and false if not same
+ */
+typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *,
+					   const void *);
+
+/* the hashfunction
+ *
+ * Return: an index based on the key in the data of the first argument and the
+ * size the second
+ */
+typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32);
+typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
+
+/**
+ * struct batadv_hashtable - Wrapper of simple hlist based hashtable
+ */
+struct batadv_hashtable {
+	/** @table: the hashtable itself with the buckets */
+	struct hlist_head *table;
+
+	/** @list_locks: spinlock for each hash list entry */
+	spinlock_t *list_locks;
+
+	/** @size: size of hashtable */
+	u32 size;
+
+	/** @generation: current (generation) sequence number */
+	atomic_t generation;
+};
+
+/* allocates and clears the hash */
+struct batadv_hashtable *batadv_hash_new(u32 size);
+
+/* set class key for all locks */
+void batadv_hash_set_lock_class(struct batadv_hashtable *hash,
+				struct lock_class_key *key);
+
+/* free only the hashtable and the hash itself. */
+void batadv_hash_destroy(struct batadv_hashtable *hash);
+
+/**
+ *	batadv_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
+ *
+ *	Return: 0 on success, 1 if the element already is in the hash
+ *	and -1 on error.
+ */
+static inline int batadv_hash_add(struct batadv_hashtable *hash,
+				  batadv_hashdata_compare_cb compare,
+				  batadv_hashdata_choose_cb choose,
+				  const void *data,
+				  struct hlist_node *data_node)
+{
+	u32 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];
+
+	spin_lock_bh(list_lock);
+
+	hlist_for_each(node, head) {
+		if (!compare(node, data))
+			continue;
+
+		ret = 1;
+		goto unlock;
+	}
+
+	/* no duplicate found in list, add new element */
+	hlist_add_head_rcu(data_node, head);
+	atomic_inc(&hash->generation);
+
+	ret = 0;
+
+unlock:
+	spin_unlock_bh(list_lock);
+out:
+	return ret;
+}
+
+/**
+ * batadv_hash_remove() - Removes data from hash, if found
+ * @hash: 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
+ *
+ * ata could be the structure you use with  just the key filled, we just need
+ * the key for comparing.
+ *
+ * Return: returns pointer do data on success, so you can remove the used
+ * structure yourself, or NULL on error
+ */
+static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
+				       batadv_hashdata_compare_cb compare,
+				       batadv_hashdata_choose_cb choose,
+				       void *data)
+{
+	u32 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);
+		atomic_inc(&hash->generation);
+		break;
+	}
+	spin_unlock_bh(&hash->list_locks[index]);
+
+	return data_save;
+}
+
+#endif /* _NET_BATMAN_ADV_HASH_H_ */