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>
diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 99dd8f7..eb8490e 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_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 @@
spin_unlock_bh(&bat_priv->tt_changes_list_lock);
}
+/* 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 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, *orig_entry = NULL;
+ const struct hlist_head *head;
+ struct hlist_node *node;
+
+ 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)
+ 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 1 if found, 0 otherwise
+ * 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 *tmp_orig_entry;
- const struct hlist_head *head;
- struct hlist_node *node;
+ struct batadv_tt_orig_list_entry *orig_entry;
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;
- }
+ 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);
}
- rcu_read_unlock();
+
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 @@
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 @@
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",