mac80211: don't allow registering the same rate control twice

Previously, mac80211 would allow registering the same rate control
algorithm twice. This is a programming error in the registration
and should not happen; additionally the second version could never
be selected. Disallow this and warn about it.

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

1 files changed, 10 insertions, 1 deletions

diff --git a/net/mac80211/ieee80211_rate.c b/net/mac80211/ieee80211_rate.c
index e4bd8481554d..7254bd609839 100644
--- a/net/mac80211/ieee80211_rate.c
+++ b/net/mac80211/ieee80211_rate.c
@@ -28,13 +28,22 @@ int ieee80211_rate_control_register(struct rate_control_ops *ops)
         if (!ops->name)
                 return -EINVAL;
 
+        mutex_lock(&rate_ctrl_mutex);
+        list_for_each_entry(alg, &rate_ctrl_algs, list) {
+                if (!strcmp(alg->ops->name, ops->name)) {
+                        /* don't register an algorithm twice */
+                        WARN_ON(1);
+                        return -EALREADY;
+                }
+        }
+
         alg = kzalloc(sizeof(*alg), GFP_KERNEL);
         if (alg == NULL) {
+                mutex_unlock(&rate_ctrl_mutex);
                 return -ENOMEM;
         }
         alg->ops = ops;
 
-        mutex_lock(&rate_ctrl_mutex);
         list_add_tail(&alg->list, &rate_ctrl_algs);
         mutex_unlock(&rate_ctrl_mutex);