ath9k: Last fix for TX software padding.

First, we copy/paste the padding stuff from ath9k_tx to ath_tx_cabq since it
needs to same kind of padding, but for internally generated beacons.
Next, software padding done on TX needs to be removed before calling
ieee80211_tx_status. The code was already there in ath_tx_complete but it
was wrong. Fix it by using ath9k_cmn_padpos. This later code has been
tested by sending packets to a monitor interface and reading packets from the
same interface.

Signed-off-by: Benoit PAPILLAULT <benoit.papillault@free.fr>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/xmit.c

@@ -1780,7 +1780,8 @@ void ath_tx_cabq(struct ieee80211_hw *hw, struct sk_buff *skb)
 	struct ath_wiphy *aphy = hw->priv;
 	struct ath_softc *sc = aphy->sc;
 	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
-	int hdrlen, padsize;
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+	int padpos, padsize;
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 	struct ath_tx_control txctl;
 
@@ -1792,25 +1793,24 @@ void ath_tx_cabq(struct ieee80211_hw *hw, struct sk_buff *skb)
 	 * BSSes.
 	 */
 	if (info->flags & IEEE80211_TX_CTL_ASSIGN_SEQ) {
-		struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 		if (info->flags & IEEE80211_TX_CTL_FIRST_FRAGMENT)
 			sc->tx.seq_no += 0x10;
 		hdr->seq_ctrl &= cpu_to_le16(IEEE80211_SCTL_FRAG);
 		hdr->seq_ctrl |= cpu_to_le16(sc->tx.seq_no);
 	}
 
 	/* Add the padding after the header if this is not already done */
-	hdrlen = ieee80211_get_hdrlen_from_skb(skb);
-	if (hdrlen & 3) {
-		padsize = hdrlen % 4;
+	padpos = ath9k_cmn_padpos(hdr->frame_control);
+	padsize = padpos & 3;
+	if (padsize && skb->len>padpos) {
 		if (skb_headroom(skb) < padsize) {
 			ath_print(common, ATH_DBG_XMIT,
 				  "TX CABQ padding failed\n");
 			dev_kfree_skb_any(skb);
 			return;
 		}
 		skb_push(skb, padsize);
-		memmove(skb->data, skb->data + padsize, hdrlen);
+		memmove(skb->data, skb->data + padsize, padpos);
 	}
 
 	txctl.txq = sc->beacon.cabq;
@@ -1838,7 +1838,8 @@ static void ath_tx_complete(struct ath_softc *sc, struct sk_buff *skb,
 	struct ieee80211_hw *hw = sc->hw;
 	struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
 	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
-	int hdrlen, padsize;
+	struct ieee80211_hdr * hdr = (struct ieee80211_hdr *)skb->data;
+	int padpos, padsize;
 
 	ath_print(common, ATH_DBG_XMIT, "TX complete: skb: %p\n", skb);
 
@@ -1853,14 +1854,14 @@ static void ath_tx_complete(struct ath_softc *sc, struct sk_buff *skb,
 		tx_info->flags |= IEEE80211_TX_STAT_ACK;
 	}
 
-	hdrlen = ieee80211_get_hdrlen_from_skb(skb);
-	padsize = hdrlen & 3;
-	if (padsize && hdrlen >= 24) {
+	padpos = ath9k_cmn_padpos(hdr->frame_control);
+	padsize = padpos & 3;
+	if (padsize && skb->len>padpos+padsize) {
 		/*
 		 * Remove MAC header padding before giving the frame back to
 		 * mac80211.
 		 */
-		memmove(skb->data + padsize, skb->data, hdrlen);
+		memmove(skb->data + padsize, skb->data, padpos);
 		skb_pull(skb, padsize);
 	}