1 files changed, 30 insertions, 24 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index cd332e3e1134..f353d9db54bc 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3078,27 +3078,18 @@ void ieee80211_clear_fast_xmit(struct sta_info *sta)
 }
 
 static bool ieee80211_amsdu_realloc_pad(struct ieee80211_local *local,
-					struct sk_buff *skb, int headroom,
-					int *subframe_len)
+					struct sk_buff *skb, int headroom)
 {
-	int amsdu_len = *subframe_len + sizeof(struct ethhdr);
-	int padding = (4 - amsdu_len) & 3;
-
-	if (skb_headroom(skb) < headroom || skb_tailroom(skb) < padding) {
+	if (skb_headroom(skb) < headroom) {
 		I802_DEBUG_INC(local->tx_expand_skb_head);
 
-		if (pskb_expand_head(skb, headroom, padding, GFP_ATOMIC)) {
+		if (pskb_expand_head(skb, headroom, 0, GFP_ATOMIC)) {
 			wiphy_debug(local->hw.wiphy,
 				    "failed to reallocate TX buffer\n");
 			return false;
 		}
 	}
 
-	if (padding) {
-		*subframe_len += padding;
-		skb_put_zero(skb, padding);
-	}
-
 	return true;
 }
 
@@ -3122,8 +3113,7 @@ static bool ieee80211_amsdu_prepare_head(struct ieee80211_sub_if_data *sdata,
 	if (info->control.flags & IEEE80211_TX_CTRL_AMSDU)
 		return true;
 
-	if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(*amsdu_hdr),
-					 &subframe_len))
+	if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(*amsdu_hdr)))
 		return false;
 
 	data = skb_push(skb, sizeof(*amsdu_hdr));
@@ -3189,7 +3179,8 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
 	void *data;
 	bool ret = false;
 	unsigned int orig_len;
-	int n = 1, nfrags;
+	int n = 2, nfrags, pad = 0;
+	u16 hdrlen;
 
 	if (!ieee80211_hw_check(&local->hw, TX_AMSDU))
 		return false;
@@ -3222,9 +3213,6 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
 	if (skb->len + head->len > max_amsdu_len)
 		goto out;
 
-	if (!ieee80211_amsdu_prepare_head(sdata, fast_tx, head))
-		goto out;
-
 	nfrags = 1 + skb_shinfo(skb)->nr_frags;
 	nfrags += 1 + skb_shinfo(head)->nr_frags;
 	frag_tail = &skb_shinfo(head)->frag_list;
@@ -3240,10 +3228,24 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
 	if (max_frags && nfrags > max_frags)
 		goto out;
 
-	if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(rfc1042_header) + 2,
-					 &subframe_len))
+	if (!ieee80211_amsdu_prepare_head(sdata, fast_tx, head))
 		goto out;
 
+	/*
+	 * Pad out the previous subframe to a multiple of 4 by adding the
+	 * padding to the next one, that's being added. Note that head->len
+	 * is the length of the full A-MSDU, but that works since each time
+	 * we add a new subframe we pad out the previous one to a multiple
+	 * of 4 and thus it no longer matters in the next round.
+	 */
+	hdrlen = fast_tx->hdr_len - sizeof(rfc1042_header);
+	if ((head->len - hdrlen) & 3)
+		pad = 4 - ((head->len - hdrlen) & 3);
+
+	if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(rfc1042_header) +
+						     2 + pad))
+		goto out_recalc;
+
 	ret = true;
 	data = skb_push(skb, ETH_ALEN + 2);
 	memmove(data, data + ETH_ALEN + 2, 2 * ETH_ALEN);
@@ -3253,15 +3255,19 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
 	memcpy(data, &len, 2);
 	memcpy(data + 2, rfc1042_header, sizeof(rfc1042_header));
 
+	memset(skb_push(skb, pad), 0, pad);
+
 	head->len += skb->len;
 	head->data_len += skb->len;
 	*frag_tail = skb;
 
-	flow->backlog += head->len - orig_len;
-	tin->backlog_bytes += head->len - orig_len;
-
-	fq_recalc_backlog(fq, tin, flow);
+out_recalc:
+	if (head->len != orig_len) {
+		flow->backlog += head->len - orig_len;
+		tin->backlog_bytes += head->len - orig_len;
 
+		fq_recalc_backlog(fq, tin, flow);
+	}
 out:
 	spin_unlock_bh(&fq->lock);