ath5k: correct packet length in tx descriptors

Packet length calculation (which includes frame check sequence)
should take into account whether we add a pad field or not.
Extract the calculation into a helper and use it in both places.

Changes to desc.c
Changes-licensed-under: ISC

Changes to ath5k.h, base.c
Changes-licensed-under: 3-Clause-BSD
Signed-off-by: NBob Copeland <me@bobcopeland.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath5k/ath5k.h

@@ -1350,4 +1350,9 @@ static inline u32 ath5k_hw_bitswap(u32 val, unsigned int bits)
 	return retval;
 }
 
+static inline int ath5k_pad_size(int hdrlen)
+{
+	return (hdrlen < 24) ? 0 : hdrlen & 3;
+}
+
 #endif

drivers/net/wireless/ath5k/base.c

@@ -1762,8 +1762,8 @@ ath5k_tasklet_rx(unsigned long data)
 		 * not try to remove padding from short control frames that do
 		 * not have payload. */
 		hdrlen = ieee80211_get_hdrlen_from_skb(skb);
-		padsize = hdrlen & 3;
-		if (padsize && hdrlen >= 24) {
+		padsize = ath5k_pad_size(hdrlen);
+		if (padsize) {
 			memmove(skb->data + padsize, skb->data, hdrlen);
 			skb_pull(skb, padsize);
 		}
@@ -2638,8 +2638,8 @@ ath5k_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
 	 * if this is not the case we add the padding after the header
 	 */
 	hdrlen = ieee80211_get_hdrlen_from_skb(skb);
-	padsize = hdrlen & 3;
-	if (padsize && hdrlen >= 24) {
+	padsize = ath5k_pad_size(hdrlen);
+	if (padsize) {
 
 		if (skb_headroom(skb) < padsize) {
 			ATH5K_ERR(sc, "tx hdrlen not %%4: %d not enough"

drivers/net/wireless/ath5k/desc.c

@@ -71,7 +71,7 @@ ath5k_hw_setup_2word_tx_desc(struct ath5k_hw *ah, struct ath5k_desc *desc,
 	/* Verify and set frame length */
 
 	/* remove padding we might have added before */
-	frame_len = pkt_len - (hdr_len & 3) + FCS_LEN;
+	frame_len = pkt_len - ath5k_pad_size(hdr_len) + FCS_LEN;
 
 	if (frame_len & ~AR5K_2W_TX_DESC_CTL0_FRAME_LEN)
 		return -EINVAL;
@@ -202,7 +202,7 @@ static int ath5k_hw_setup_4word_tx_desc(struct ath5k_hw *ah,
 	/* Verify and set frame length */
 
 	/* remove padding we might have added before */
-	frame_len = pkt_len - (hdr_len & 3) + FCS_LEN;
+	frame_len = pkt_len - ath5k_pad_size(hdr_len) + FCS_LEN;
 
 	if (frame_len & ~AR5K_4W_TX_DESC_CTL0_FRAME_LEN)
 		return -EINVAL;