mac80211: also drop qos-nullfunc frames silently

We drop nullfunc frames, but not qos-nullfunc frames,
even though those could be used for PS state control
as well.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 52e15e0..0aa8314 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -472,7 +472,7 @@
 }
 
 /**
- * ieee80211_is_nullfunc - check if FTYPE=IEEE80211_FTYPE_DATA and STYPE=IEEE80211_STYPE_NULLFUNC
+ * ieee80211_is_nullfunc - check if frame is a regular (non-QoS) nullfunc frame
  * @fc: frame control bytes in little-endian byteorder
  */
 static inline int ieee80211_is_nullfunc(__le16 fc)
@@ -481,6 +481,16 @@
 	       cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_NULLFUNC);
 }
 
+/**
+ * ieee80211_is_qos_nullfunc - check if frame is a QoS nullfunc frame
+ * @fc: frame control bytes in little-endian byteorder
+ */
+static inline int ieee80211_is_qos_nullfunc(__le16 fc)
+{
+	return (fc & cpu_to_le16(IEEE80211_FCTL_FTYPE | IEEE80211_FCTL_STYPE)) ==
+	       cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_QOS_NULLFUNC);
+}
+
 struct ieee80211s_hdr {
 	u8 flags;
 	u8 ttl;