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authorAntonio Quartulli <ordex@autistici.org>2012-07-01 16:09:12 +0400
committerAntonio Quartulli <ordex@autistici.org>2012-08-23 16:02:44 +0400
commitd657e621a0f5584cf269b5b3d733a4cbb2497900 (patch)
tree316386108a9c7f599e346df9cf8a3e0131262a11 /net/batman-adv
parent3a7f291bf6d7ef81d45c54ccad4f5eda506076b4 (diff)
downloadlinux-d657e621a0f5584cf269b5b3d733a4cbb2497900.tar.xz
batman-adv: add reference counting for type batadv_tt_orig_list_entry
The batadv_tt_orig_list_entry structure didn't have any refcounting mechanism so far. This patch introduces it and makes the structure being usable in much more complex context. Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Diffstat (limited to 'net/batman-adv')
-rw-r--r--net/batman-adv/translation-table.c75
-rw-r--r--net/batman-adv/types.h1
2 files changed, 53 insertions, 23 deletions
diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 99dd8f75b3ff..eb8490e504e2 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -152,6 +152,8 @@ static void batadv_tt_orig_list_entry_free_rcu(struct rcu_head *rcu)
static void
batadv_tt_orig_list_entry_free_ref(struct batadv_tt_orig_list_entry *orig_entry)
{
+ if (!atomic_dec_and_test(&orig_entry->refcount))
+ return;
/* to avoid race conditions, immediately decrease the tt counter */
atomic_dec(&orig_entry->orig_node->tt_size);
call_rcu(&orig_entry->rcu, batadv_tt_orig_list_entry_free_rcu);
@@ -625,50 +627,82 @@ static void batadv_tt_changes_list_free(struct batadv_priv *bat_priv)
spin_unlock_bh(&bat_priv->tt_changes_list_lock);
}
-/* find out if an orig_node is already in the list of a tt_global_entry.
- * returns 1 if found, 0 otherwise
+/* retrieves the orig_tt_list_entry belonging to orig_node from the
+ * batadv_tt_global_entry list
+ *
+ * returns it with an increased refcounter, NULL if not found
*/
-static bool
-batadv_tt_global_entry_has_orig(const struct batadv_tt_global_entry *entry,
- const struct batadv_orig_node *orig_node)
+static struct batadv_tt_orig_list_entry *
+batadv_tt_global_orig_entry_find(const struct batadv_tt_global_entry *entry,
+ const struct batadv_orig_node *orig_node)
{
- struct batadv_tt_orig_list_entry *tmp_orig_entry;
+ struct batadv_tt_orig_list_entry *tmp_orig_entry, *orig_entry = NULL;
const struct hlist_head *head;
struct hlist_node *node;
- bool found = false;
rcu_read_lock();
head = &entry->orig_list;
hlist_for_each_entry_rcu(tmp_orig_entry, node, head, list) {
- if (tmp_orig_entry->orig_node == orig_node) {
- found = true;
- break;
- }
+ if (tmp_orig_entry->orig_node != orig_node)
+ continue;
+ if (!atomic_inc_not_zero(&tmp_orig_entry->refcount))
+ continue;
+
+ orig_entry = tmp_orig_entry;
+ break;
}
rcu_read_unlock();
+
+ return orig_entry;
+}
+
+/* find out if an orig_node is already in the list of a tt_global_entry.
+ * returns true if found, false otherwise
+ */
+static bool
+batadv_tt_global_entry_has_orig(const struct batadv_tt_global_entry *entry,
+ const struct batadv_orig_node *orig_node)
+{
+ struct batadv_tt_orig_list_entry *orig_entry;
+ bool found = false;
+
+ orig_entry = batadv_tt_global_orig_entry_find(entry, orig_node);
+ if (orig_entry) {
+ found = true;
+ batadv_tt_orig_list_entry_free_ref(orig_entry);
+ }
+
return found;
}
static void
-batadv_tt_global_add_orig_entry(struct batadv_tt_global_entry *tt_global_entry,
+batadv_tt_global_orig_entry_add(struct batadv_tt_global_entry *tt_global,
struct batadv_orig_node *orig_node, int ttvn)
{
struct batadv_tt_orig_list_entry *orig_entry;
+ orig_entry = batadv_tt_global_orig_entry_find(tt_global, orig_node);
+ if (orig_entry)
+ goto out;
+
orig_entry = kzalloc(sizeof(*orig_entry), GFP_ATOMIC);
if (!orig_entry)
- return;
+ goto out;
INIT_HLIST_NODE(&orig_entry->list);
atomic_inc(&orig_node->refcount);
atomic_inc(&orig_node->tt_size);
orig_entry->orig_node = orig_node;
orig_entry->ttvn = ttvn;
+ atomic_set(&orig_entry->refcount, 2);
- spin_lock_bh(&tt_global_entry->list_lock);
+ spin_lock_bh(&tt_global->list_lock);
hlist_add_head_rcu(&orig_entry->list,
- &tt_global_entry->orig_list);
- spin_unlock_bh(&tt_global_entry->list_lock);
+ &tt_global->orig_list);
+ spin_unlock_bh(&tt_global->list_lock);
+out:
+ if (orig_entry)
+ batadv_tt_orig_list_entry_free_ref(orig_entry);
}
/* caller must hold orig_node refcount */
@@ -709,9 +743,6 @@ int batadv_tt_global_add(struct batadv_priv *bat_priv,
batadv_tt_global_entry_free_ref(tt_global_entry);
goto out_remove;
}
-
- batadv_tt_global_add_orig_entry(tt_global_entry, orig_node,
- ttvn);
} else {
/* there is already a global entry, use this one. */
@@ -728,11 +759,9 @@ int batadv_tt_global_add(struct batadv_priv *bat_priv,
tt_global_entry->roam_at = 0;
}
- if (!batadv_tt_global_entry_has_orig(tt_global_entry,
- orig_node))
- batadv_tt_global_add_orig_entry(tt_global_entry,
- orig_node, ttvn);
}
+ /* add the new orig_entry (if needed) */
+ batadv_tt_global_orig_entry_add(tt_global_entry, orig_node, ttvn);
batadv_dbg(BATADV_DBG_TT, bat_priv,
"Creating new global tt entry: %pM (via %pM)\n",
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 7812b6edda13..664ef8148555 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -282,6 +282,7 @@ struct batadv_tt_global_entry {
struct batadv_tt_orig_list_entry {
struct batadv_orig_node *orig_node;
uint8_t ttvn;
+ atomic_t refcount;
struct rcu_head rcu;
struct hlist_node list;
};