batman-adv: hash_add() has to discriminate on the return value

hash_add() returns 0 on success while returns -1 either on error and on
entry already present. The caller could use such information to select
its behaviour. For this reason it is useful that hash_add() returns -1
in case on error and returns 1 in case of entry already present.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>

1 files changed, 19 insertions, 6 deletions

diff --git a/net/batman-adv/hash.h b/net/batman-adv/hash.h
index dd5c9fd7a905..d20aa71ba1e8 100644
--- a/net/batman-adv/hash.h
+++ b/net/batman-adv/hash.h
@@ -76,19 +76,30 @@ static inline void hash_delete(struct hashtable_t *hash,
         hash_destroy(hash);
 }
 
-/* adds data to the hashtable. returns 0 on success, -1 on error */
+/**
+ *      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)
 {
-        int index;
+        int index, ret = -1;
         struct hlist_head *head;
         struct hlist_node *node;
         spinlock_t *list_lock; /* spinlock to protect write access */
 
         if (!hash)
-                goto err;
+                goto out;
 
         index = choose(data, hash->size);
         head = &hash->table[index];
@@ -99,6 +110,7 @@ static inline int hash_add(struct hashtable_t *hash,
                 if (!compare(node, data))
                         continue;
 
+                ret = 1;
                 goto err_unlock;
         }
         rcu_read_unlock();
@@ -108,12 +120,13 @@ static inline int hash_add(struct hashtable_t *hash,
         hlist_add_head_rcu(data_node, head);
         spin_unlock_bh(list_lock);
 
-        return 0;
+        ret = 0;
+        goto out;
 
 err_unlock:
         rcu_read_unlock();
-err:
-        return -1;
+out:
+        return ret;
 }
 
 /* removes data from hash, if found. returns pointer do data on success, so you