mac80211: sparse RCU annotations

This adds sparse RCU annotations to most of
mac80211, only the mesh code remains to be
done.

Due the the previous patches, the annotations
are pretty simple. The only thing that this
actually changes is removing the RCU usage of
key->sta in debugfs since this pointer isn't
actually an RCU-managed pointer (it only has
a single assignment done before the key even
goes live). As that is otherwise harmless, I
decided to make it part of this patch.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/debugfs_key.c b/net/mac80211/debugfs_key.c
index f7ef347..33c58b8 100644
--- a/net/mac80211/debugfs_key.c
+++ b/net/mac80211/debugfs_key.c
@@ -241,16 +241,12 @@
 	if (!key->debugfs.dir)
 		return;
 
-	rcu_read_lock();
-	sta = rcu_dereference(key->sta);
-	if (sta)
+	sta = key->sta;
+	if (sta) {
 		sprintf(buf, "../../stations/%pM", sta->sta.addr);
-	rcu_read_unlock();
-
-	/* using sta as a boolean is fine outside RCU lock */
-	if (sta)
 		key->debugfs.stalink =
 			debugfs_create_symlink("station", key->debugfs.dir, buf);
+	}
 
 	DEBUGFS_ADD(keylen);
 	DEBUGFS_ADD(flags);
@@ -286,7 +282,8 @@
 	lockdep_assert_held(&sdata->local->key_mtx);
 
 	if (sdata->default_unicast_key) {
-		key = sdata->default_unicast_key;
+		key = key_mtx_dereference(sdata->local,
+					  sdata->default_unicast_key);
 		sprintf(buf, "../keys/%d", key->debugfs.cnt);
 		sdata->debugfs.default_unicast_key =
 			debugfs_create_symlink("default_unicast_key",
@@ -297,7 +294,8 @@
 	}
 
 	if (sdata->default_multicast_key) {
-		key = sdata->default_multicast_key;
+		key = key_mtx_dereference(sdata->local,
+					  sdata->default_multicast_key);
 		sprintf(buf, "../keys/%d", key->debugfs.cnt);
 		sdata->debugfs.default_multicast_key =
 			debugfs_create_symlink("default_multicast_key",
@@ -316,9 +314,8 @@
 	if (!sdata->debugfs.dir)
 		return;
 
-	/* this is running under the key lock */
-
-	key = sdata->default_mgmt_key;
+	key = key_mtx_dereference(sdata->local,
+				  sdata->default_mgmt_key);
 	if (key) {
 		sprintf(buf, "../keys/%d", key->debugfs.cnt);
 		sdata->debugfs.default_mgmt_key =