1 files changed, 20 insertions, 6 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index c0fcfa296468..0808110451a0 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2578,12 +2578,15 @@ static void tcp_mtup_probe_success(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct inet_connection_sock *icsk = inet_csk(sk);
+	u64 val;
 
-	/* FIXME: breaks with very large cwnd */
 	tp->prior_ssthresh = tcp_current_ssthresh(sk);
-	tp->snd_cwnd = tp->snd_cwnd *
-		       tcp_mss_to_mtu(sk, tp->mss_cache) /
-		       icsk->icsk_mtup.probe_size;
+
+	val = (u64)tp->snd_cwnd * tcp_mss_to_mtu(sk, tp->mss_cache);
+	do_div(val, icsk->icsk_mtup.probe_size);
+	WARN_ON_ONCE((u32)val != val);
+	tp->snd_cwnd = max_t(u32, 1U, val);
+
 	tp->snd_cwnd_cnt = 0;
 	tp->snd_cwnd_stamp = tcp_jiffies32;
 	tp->snd_ssthresh = tcp_current_ssthresh(sk);
@@ -3717,7 +3720,8 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 		tcp_process_tlp_ack(sk, ack, flag);
 
 	if (tcp_ack_is_dubious(sk, flag)) {
-		if (!(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP))) {
+		if (!(flag & (FLAG_SND_UNA_ADVANCED |
+			      FLAG_NOT_DUP | FLAG_DSACKING_ACK))) {
 			num_dupack = 1;
 			/* Consider if pure acks were aggregated in tcp_add_backlog() */
 			if (!(flag & FLAG_DATA))
@@ -5230,7 +5234,17 @@ static void tcp_new_space(struct sock *sk)
 	sk->sk_write_space(sk);
 }
 
-static void tcp_check_space(struct sock *sk)
+/* Caller made space either from:
+ * 1) Freeing skbs in rtx queues (after tp->snd_una has advanced)
+ * 2) Sent skbs from output queue (and thus advancing tp->snd_nxt)
+ *
+ * We might be able to generate EPOLLOUT to the application if:
+ * 1) Space consumed in output/rtx queues is below sk->sk_sndbuf/2
+ * 2) notsent amount (tp->write_seq - tp->snd_nxt) became
+ *    small enough that tcp_stream_memory_free() decides it
+ *    is time to generate EPOLLOUT.
+ */
+void tcp_check_space(struct sock *sk)
 {
 	if (sock_flag(sk, SOCK_QUEUE_SHRUNK)) {
 		sock_reset_flag(sk, SOCK_QUEUE_SHRUNK);