mac80211: add interface list lock

Using only the RTNL has a number of problems, most notably that
ieee80211_iterate_active_interfaces() and other interface list
traversals cannot be done from the internal workqueue because it
needs to be flushed under the RTNL.

This patch introduces a new mutex that protects the interface list
against modifications. A more detailed explanation is part of the
code change.

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

1 files changed, 2 insertions, 2 deletions

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index fc30f2940e1e..73c7d7345abd 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -468,7 +468,7 @@ void ieee80211_iterate_active_interfaces(
         struct ieee80211_local *local = hw_to_local(hw);
         struct ieee80211_sub_if_data *sdata;
 
-        rtnl_lock();
+        mutex_lock(&local->iflist_mtx);
 
         list_for_each_entry(sdata, &local->interfaces, list) {
                 switch (sdata->vif.type) {
@@ -489,7 +489,7 @@ void ieee80211_iterate_active_interfaces(
                                  &sdata->vif);
         }
 
-        rtnl_unlock();
+        mutex_unlock(&local->iflist_mtx);
 }
 EXPORT_SYMBOL_GPL(ieee80211_iterate_active_interfaces);