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 7e57f5d07f66..351e48c9710c 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);