batman-adv: Fix rcu_barrier() miss due to double call_rcu() in TT code
rcu_barrier() only waits for the currently scheduled rcu functions
to finish - it won't wait for any function scheduled via another
call_rcu() within an rcu scheduled function.
Unfortunately our batadv_tt_orig_list_entry_free_ref() does just that,
via a batadv_orig_node_free_ref() call, leading to our rcu_barrier()
call potentially missing such a batadv_orig_node_free_ref().
This patch fixes this issue by calling the batadv_orig_node_free_rcu()
directly from the rcu callback, removing the unnecessary, additional
call_rcu() layer here.
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Acked-by: Antonio Quartulli <ordex@autistici.org>
diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 2f34525..fad1a20 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -156,12 +156,28 @@
kfree(orig_node);
}
+/**
+ * batadv_orig_node_free_ref - decrement the orig node refcounter and possibly
+ * schedule an rcu callback for freeing it
+ * @orig_node: the orig node to free
+ */
void batadv_orig_node_free_ref(struct batadv_orig_node *orig_node)
{
if (atomic_dec_and_test(&orig_node->refcount))
call_rcu(&orig_node->rcu, batadv_orig_node_free_rcu);
}
+/**
+ * batadv_orig_node_free_ref_now - decrement the orig node refcounter and
+ * possibly free it (without rcu callback)
+ * @orig_node: the orig node to free
+ */
+void batadv_orig_node_free_ref_now(struct batadv_orig_node *orig_node)
+{
+ if (atomic_dec_and_test(&orig_node->refcount))
+ batadv_orig_node_free_rcu(&orig_node->rcu);
+}
+
void batadv_originator_free(struct batadv_priv *bat_priv)
{
struct batadv_hashtable *hash = bat_priv->orig_hash;
diff --git a/net/batman-adv/originator.h b/net/batman-adv/originator.h
index 7df48fa..734e5a3 100644
--- a/net/batman-adv/originator.h
+++ b/net/batman-adv/originator.h
@@ -26,6 +26,7 @@
void batadv_originator_free(struct batadv_priv *bat_priv);
void batadv_purge_orig_ref(struct batadv_priv *bat_priv);
void batadv_orig_node_free_ref(struct batadv_orig_node *orig_node);
+void batadv_orig_node_free_ref_now(struct batadv_orig_node *orig_node);
struct batadv_orig_node *batadv_get_orig_node(struct batadv_priv *bat_priv,
const uint8_t *addr);
struct batadv_neigh_node *
diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 5e89dee..9e87485 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -144,7 +144,12 @@
struct batadv_tt_orig_list_entry *orig_entry;
orig_entry = container_of(rcu, struct batadv_tt_orig_list_entry, rcu);
- batadv_orig_node_free_ref(orig_entry->orig_node);
+
+ /* We are in an rcu callback here, therefore we cannot use
+ * batadv_orig_node_free_ref() and its call_rcu():
+ * An rcu_barrier() wouldn't wait for that to finish
+ */
+ batadv_orig_node_free_ref_now(orig_entry->orig_node);
kfree(orig_entry);
}