batman-adv: protect each hash row with rcu locks
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
diff --git a/net/batman-adv/hash.h b/net/batman-adv/hash.h
index eae2440..3c48c6b 100644
--- a/net/batman-adv/hash.h
+++ b/net/batman-adv/hash.h
@@ -39,10 +39,12 @@
struct element_t {
void *data; /* pointer to the data */
struct hlist_node hlist; /* bucket list pointer */
+ struct rcu_head rcu;
};
struct hashtable_t {
- struct hlist_head *table; /* the hashtable itself, with the buckets */
+ struct hlist_head *table; /* the hashtable itself with the buckets */
+ spinlock_t *list_locks; /* spinlock for each hash list entry */
int size; /* size of hashtable */
};
@@ -52,6 +54,8 @@
/* free only the hashtable and the hash itself. */
void hash_destroy(struct hashtable_t *hash);
+void bucket_free_rcu(struct rcu_head *rcu);
+
/* 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. */
@@ -61,19 +65,22 @@
struct hlist_head *head;
struct hlist_node *walk, *safe;
struct element_t *bucket;
+ spinlock_t *list_lock; /* spinlock to protect write access */
int i;
for (i = 0; i < hash->size; i++) {
head = &hash->table[i];
+ list_lock = &hash->list_locks[i];
- hlist_for_each_safe(walk, safe, head) {
- bucket = hlist_entry(walk, struct element_t, hlist);
+ spin_lock_bh(list_lock);
+ hlist_for_each_entry_safe(bucket, walk, safe, head, hlist) {
if (free_cb)
free_cb(bucket->data, arg);
- hlist_del(walk);
- kfree(bucket);
+ hlist_del_rcu(walk);
+ call_rcu(&bucket->rcu, bucket_free_rcu);
}
+ spin_unlock_bh(list_lock);
}
hash_destroy(hash);
@@ -88,29 +95,39 @@
struct hlist_head *head;
struct hlist_node *walk, *safe;
struct element_t *bucket;
+ spinlock_t *list_lock; /* spinlock to protect write access */
if (!hash)
- return -1;
+ goto err;
index = choose(data, hash->size);
head = &hash->table[index];
+ list_lock = &hash->list_locks[index];
- hlist_for_each_safe(walk, safe, head) {
- bucket = hlist_entry(walk, struct element_t, hlist);
+ rcu_read_lock();
+ hlist_for_each_entry_safe(bucket, walk, safe, head, hlist) {
if (compare(bucket->data, data))
- return -1;
+ goto err_unlock;
}
+ rcu_read_unlock();
/* no duplicate found in list, add new element */
bucket = kmalloc(sizeof(struct element_t), GFP_ATOMIC);
-
if (!bucket)
- return -1;
+ goto err;
bucket->data = data;
- hlist_add_head(&bucket->hlist, head);
+
+ spin_lock_bh(list_lock);
+ hlist_add_head_rcu(&bucket->hlist, head);
+ spin_unlock_bh(list_lock);
return 0;
+
+err_unlock:
+ rcu_read_unlock();
+err:
+ return -1;
}
/* removes data from hash, if found. returns pointer do data on success, so you
@@ -125,25 +142,31 @@
struct hlist_node *walk;
struct element_t *bucket;
struct hlist_head *head;
- void *data_save;
+ void *data_save = NULL;
index = choose(data, hash->size);
head = &hash->table[index];
+ spin_lock_bh(&hash->list_locks[index]);
hlist_for_each_entry(bucket, walk, head, hlist) {
if (compare(bucket->data, data)) {
data_save = bucket->data;
- hlist_del(walk);
- kfree(bucket);
- return data_save;
+ hlist_del_rcu(walk);
+ call_rcu(&bucket->rcu, bucket_free_rcu);
+ break;
}
}
+ spin_unlock_bh(&hash->list_locks[index]);
- return NULL;
+ return data_save;
}
-/* finds data, based on the key in keydata. returns the found data on success,
- * or NULL on error */
+/**
+ * finds data, based on the key in keydata. returns the found data on success,
+ * or NULL on error
+ *
+ * caller must lock with rcu_read_lock() / rcu_read_unlock()
+ **/
static inline void *hash_find(struct hashtable_t *hash,
hashdata_compare_cb compare,
hashdata_choose_cb choose, void *keydata)
@@ -152,6 +175,7 @@
struct hlist_head *head;
struct hlist_node *walk;
struct element_t *bucket;
+ void *bucket_data = NULL;
if (!hash)
return NULL;
@@ -159,13 +183,14 @@
index = choose(keydata , hash->size);
head = &hash->table[index];
- hlist_for_each(walk, head) {
- bucket = hlist_entry(walk, struct element_t, hlist);
- if (compare(bucket->data, keydata))
- return bucket->data;
+ hlist_for_each_entry(bucket, walk, head, hlist) {
+ if (compare(bucket->data, keydata)) {
+ bucket_data = bucket->data;
+ break;
+ }
}
- return NULL;
+ return bucket_data;
}
#endif /* _NET_BATMAN_ADV_HASH_H_ */