From fb778ea173fcd58b8fc3d75c674f07fab187b55f Mon Sep 17 00:00:00 2001 From: Marek Lindner Date: Wed, 19 Jan 2011 20:01:40 +0000 Subject: batman-adv: protect each hash row with rcu locks Signed-off-by: Marek Lindner --- net/batman-adv/hash.h | 73 ++++++++++++++++++++++++++++++++++----------------- 1 file changed, 49 insertions(+), 24 deletions(-) (limited to 'net/batman-adv/hash.h') diff --git a/net/batman-adv/hash.h b/net/batman-adv/hash.h index eae24402fd0a..3c48c6bb1acd 100644 --- a/net/batman-adv/hash.h +++ b/net/batman-adv/hash.h @@ -39,10 +39,12 @@ typedef void (*hashdata_free_cb)(void *, void *); 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 @@ struct hashtable_t *hash_new(int size); /* 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 @@ static inline void hash_delete(struct hashtable_t *hash, 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 @@ static inline int hash_add(struct hashtable_t *hash, 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 @@ static inline void *hash_remove(struct hashtable_t *hash, 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 @@ static inline void *hash_find(struct hashtable_t *hash, struct hlist_head *head; struct hlist_node *walk; struct element_t *bucket; + void *bucket_data = NULL; if (!hash) return NULL; @@ -159,13 +183,14 @@ static inline void *hash_find(struct hashtable_t *hash, 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_ */ -- cgit v1.2.3