2 files changed, 8 insertions, 0 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 2aff4906b2ae..538d6b761887 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1737,6 +1737,12 @@ static inline void ieee80211_rx_ni(struct ieee80211_hw *hw,
         local_bh_enable();
 }
 
+/*
+ * The TX headroom reserved by mac80211 for its own tx_status functions.
+ * This is enough for the radiotap header.
+ */
+#define IEEE80211_TX_STATUS_HEADROOM    13
+
 /**
  * ieee80211_tx_status - transmit status callback
  *
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 8116d1a96a4a..0d2d94881f1f 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -515,6 +515,8 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
          * and we need some headroom for passing the frame to monitor
          * interfaces, but never both at the same time.
          */
+        BUILD_BUG_ON(IEEE80211_TX_STATUS_HEADROOM !=
+                        sizeof(struct ieee80211_tx_status_rtap_hdr));
         local->tx_headroom = max_t(unsigned int , local->hw.extra_tx_headroom,
                                    sizeof(struct ieee80211_tx_status_rtap_hdr));