1 files changed, 52 insertions, 1 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 097294b7da3..8085704863f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1002,7 +1002,8 @@ static void tcp_skb_mark_lost(struct tcp_sock *tp, struct sk_buff *skb)
 	}
 }
 
-void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb)
+static void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp,
+					    struct sk_buff *skb)
 {
 	tcp_verify_retransmit_hint(tp, skb);
 
@@ -2559,6 +2560,56 @@ static void tcp_mtup_probe_success(struct sock *sk, struct sk_buff *skb)
 	tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
 }
 
+/* Do a simple retransmit without using the backoff mechanisms in
+ * tcp_timer. This is used for path mtu discovery.
+ * The socket is already locked here.
+ */
+void tcp_simple_retransmit(struct sock *sk)
+{
+	const struct inet_connection_sock *icsk = inet_csk(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *skb;
+	unsigned int mss = tcp_current_mss(sk, 0);
+	u32 prior_lost = tp->lost_out;
+
+	tcp_for_write_queue(skb, sk) {
+		if (skb == tcp_send_head(sk))
+			break;
+		if (skb->len > mss &&
+		    !(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) {
+			if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) {
+				TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
+				tp->retrans_out -= tcp_skb_pcount(skb);
+			}
+			tcp_skb_mark_lost_uncond_verify(tp, skb);
+		}
+	}
+
+	tcp_clear_retrans_hints_partial(tp);
+
+	if (prior_lost == tp->lost_out)
+		return;
+
+	if (tcp_is_reno(tp))
+		tcp_limit_reno_sacked(tp);
+
+	tcp_verify_left_out(tp);
+
+	/* Don't muck with the congestion window here.
+	 * Reason is that we do not increase amount of _data_
+	 * in network, but units changed and effective
+	 * cwnd/ssthresh really reduced now.
+	 */
+	if (icsk->icsk_ca_state != TCP_CA_Loss) {
+		tp->high_seq = tp->snd_nxt;
+		tp->snd_ssthresh = tcp_current_ssthresh(sk);
+		tp->prior_ssthresh = 0;
+		tp->undo_marker = 0;
+		tcp_set_ca_state(sk, TCP_CA_Loss);
+	}
+	tcp_xmit_retransmit_queue(sk);
+}
+
 /* Process an event, which can update packets-in-flight not trivially.
  * Main goal of this function is to calculate new estimate for left_out,
  * taking into account both packets sitting in receiver's buffer and