mac80211: comment allocation of mesh frames

Remove most references to magic numbers, save a few bytes and hopefully
improve readability.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 17 insertions, 11 deletions

diff --git a/net/mac80211/mesh_plink.c b/net/mac80211/mesh_plink.c
index 7e57f5d07f6..351e48c9710 100644
--- a/net/mac80211/mesh_plink.c
+++ b/net/mac80211/mesh_plink.c
@@ -153,23 +153,29 @@ static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
 		enum ieee80211_self_protected_actioncode action,
 		u8 *da, __le16 llid, __le16 plid, __le16 reason) {
 	struct ieee80211_local *local = sdata->local;
-	struct sk_buff *skb = dev_alloc_skb(local->hw.extra_tx_headroom + 400 +
-			sdata->u.mesh.ie_len);
+	struct sk_buff *skb;
 	struct ieee80211_mgmt *mgmt;
 	bool include_plid = false;
-	int ie_len = 4;
 	u16 peering_proto = 0;
-	u8 *pos;
-
+	u8 *pos, ie_len = 4;
+	int hdr_len = offsetof(struct ieee80211_mgmt, u.action.u.self_prot) +
+		      sizeof(mgmt->u.action.u.self_prot);
+
+	skb = dev_alloc_skb(local->hw.extra_tx_headroom +
+			    hdr_len +
+			    2 + /* capability info */
+			    2 + /* AID */
+			    2 + 8 + /* supported rates */
+			    2 + (IEEE80211_MAX_SUPP_RATES - 8) +
+			    2 + sdata->u.mesh.mesh_id_len +
+			    2 + sizeof(struct ieee80211_meshconf_ie) +
+			    2 + 8 + /* peering IE */
+			    sdata->u.mesh.ie_len);
 	if (!skb)
 		return -1;
 	skb_reserve(skb, local->hw.extra_tx_headroom);
-	/* 25 is the size of the common mgmt part (24) plus the size of the
-	 * common action part (1)
-	 */
-	mgmt = (struct ieee80211_mgmt *)
-		skb_put(skb, 25 + sizeof(mgmt->u.action.u.self_prot));
-	memset(mgmt, 0, 25 + sizeof(mgmt->u.action.u.self_prot));
+	mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
+	memset(mgmt, 0, hdr_len);
 	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
 					  IEEE80211_STYPE_ACTION);
 	memcpy(mgmt->da, da, ETH_ALEN);