net/batman-adv/hash.h

Source file repositories/reference/linux-study-clean/net/batman-adv/hash.h

File Facts

System
Linux kernel
Corpus path
net/batman-adv/hash.h
Extension
.h
Size
3966 bytes
Lines
158
Domain
Networking Core
Bucket
Sockets, Protocols, Packet Path, And Network Policy
Inferred role
Networking Core: implementation source
Status
source implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

Dependency Surface

Detected Declarations

Annotated Snippet

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
 *
 * data could be the structure you use with just the key filled, we just need
 * the key for comparing.
 *
 * Return: returns pointer to 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,

Annotation

Implementation Notes