mac80211: fix and simplify mesh locking

The locking in mesh_{mpath,mpp}_table_grow not only
has an rcu_read_unlock() missing, it's also racy
(though really only technically since it's invoked
from a single function only) since it obtains the
new size of the table without any locking, so two
invocations of the function could attempt the same
resize.

Additionally, it uses synchronize_rcu() which is
rather expensive and can be avoided trivially here.

Modify the functions to only use the table lock
and use call_rcu() instead of synchronize_rcu().

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/mac80211/mesh.h b/net/mac80211/mesh.h
index e7c5fddb4804..eb733c0d61aa 100644
--- a/net/mac80211/mesh.h
+++ b/net/mac80211/mesh.h
@@ -120,6 +120,7 @@ struct mesh_path {
  *      buckets
  * @mean_chain_len: maximum average length for the hash buckets' list, if it is
  *      reached, the table will grow
+ * rcu_head: RCU head to free the table
  */
 struct mesh_table {
         /* Number of buckets will be 2^N */
@@ -132,6 +133,8 @@ struct mesh_table {
         int (*copy_node) (struct hlist_node *p, struct mesh_table *newtbl);
         int size_order;
         int mean_chain_len;
+
+        struct rcu_head rcu_head;
 };
 
 /* Recent multicast cache */