mac80211: assign needed_headroom/tailroom for netdevs

This assigns the netdev's needed_headroom/tailroom members to take
advantage of pre-allocated space for 802.11 headers.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 0 deletions

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 80954a512185..06e88a5a036d 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -54,6 +54,15 @@ int ieee80211_if_add(struct net_device *dev, const char *name,
         if (!ndev)
                 return -ENOMEM;
 
+        ndev->needed_headroom = local->tx_headroom +
+                                4*6 /* four MAC addresses */
+                                + 2 + 2 + 2 + 2 /* ctl, dur, seq, qos */
+                                + 6 /* mesh */
+                                + 8 /* rfc1042/bridge tunnel */
+                                - ETH_HLEN /* ethernet hard_header_len */
+                                + IEEE80211_ENCRYPT_HEADROOM;
+        ndev->needed_tailroom = IEEE80211_ENCRYPT_TAILROOM;
+
         ret = dev_alloc_name(ndev, ndev->name);
         if (ret < 0)
                 goto fail;