1 files changed, 12 insertions, 14 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 896e9dfbdb5c..19105b46a304 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2514,7 +2514,7 @@ void tcp_skb_collapse_tstamp(struct sk_buff *skb,
 }
 
 /* Collapses two adjacent SKB's during retransmission. */
-static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb)
+static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct sk_buff *next_skb = tcp_write_queue_next(sk, skb);
@@ -2525,13 +2525,17 @@ static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb)
 
 	BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1);
 
+	if (next_skb_size) {
+		if (next_skb_size <= skb_availroom(skb))
+			skb_copy_bits(next_skb, 0, skb_put(skb, next_skb_size),
+				      next_skb_size);
+		else if (!skb_shift(skb, next_skb, next_skb_size))
+			return false;
+	}
 	tcp_highest_sack_combine(sk, next_skb, skb);
 
 	tcp_unlink_write_queue(next_skb, sk);
 
-	skb_copy_from_linear_data(next_skb, skb_put(skb, next_skb_size),
-				  next_skb_size);
-
 	if (next_skb->ip_summed == CHECKSUM_PARTIAL)
 		skb->ip_summed = CHECKSUM_PARTIAL;
 
@@ -2560,6 +2564,7 @@ static void tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb)
 	tcp_skb_collapse_tstamp(skb, next_skb);
 
 	sk_wmem_free_skb(sk, next_skb);
+	return true;
 }
 
 /* Check if coalescing SKBs is legal. */
@@ -2567,14 +2572,11 @@ static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb)
 {
 	if (tcp_skb_pcount(skb) > 1)
 		return false;
-	/* TODO: SACK collapsing could be used to remove this condition */
-	if (skb_shinfo(skb)->nr_frags != 0)
-		return false;
 	if (skb_cloned(skb))
 		return false;
 	if (skb == tcp_send_head(sk))
 		return false;
-	/* Some heurestics for collapsing over SACK'd could be invented */
+	/* Some heuristics for collapsing over SACK'd could be invented */
 	if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)
 		return false;
 
@@ -2612,16 +2614,12 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to,
 
 		if (space < 0)
 			break;
-		/* Punt if not enough space exists in the first SKB for
-		 * the data in the second
-		 */
-		if (skb->len > skb_availroom(to))
-			break;
 
 		if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp)))
 			break;
 
-		tcp_collapse_retrans(sk, to);
+		if (!tcp_collapse_retrans(sk, to))
+			break;
 	}
 }