From: Felix Fietkau <nbd@openwrt.org>
Date: Thu, 30 Jul 2015 14:12:25 +0200
Subject: [PATCH] mac80211: make local->tx_headroom a multiple of 4

This ensures that mac80211 generated management frames and beacons are
aligned before being passed to the driver

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---

--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -1031,6 +1031,7 @@ int ieee80211_register_hw(struct ieee802
 	 */
 	local->tx_headroom = max_t(unsigned int , local->hw.extra_tx_headroom,
 				   IEEE80211_TX_STATUS_HEADROOM);
+	local->tx_headroom = ALIGN(local->tx_headroom, 4);
 
 	debugfs_hw_add(local);