tcp: limit GSO packets to half cwnd

[karo-tx-linux.git] / net / ipv4 / tcp_output.c

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 3af21296d96788b899daaa25562301e38036e802..eb73a1dccf56b823a45c0ca034e40dc50fc48068 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -333,10 +333,19 @@ static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb)
 static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb)
 {
        struct tcp_sock *tp = tcp_sk(sk);
+       bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 ||
+                      tcp_ca_needs_ecn(sk);
+
+       if (!use_ecn) {
+               const struct dst_entry *dst = __sk_dst_get(sk);
+
+               if (dst && dst_feature(dst, RTAX_FEATURE_ECN))
+                       use_ecn = true;
+       }
 
        tp->ecn_flags = 0;
-       if (sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 ||
-           tcp_ca_needs_ecn(sk)) {
+
+       if (use_ecn) {
                TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR;
                tp->ecn_flags = TCP_ECN_OK;
                if (tcp_ca_needs_ecn(sk))
@@ -1553,7 +1562,7 @@ static unsigned int tcp_mss_split_point(const struct sock *sk,
 static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp,
                                         const struct sk_buff *skb)
 {
-       u32 in_flight, cwnd;
+       u32 in_flight, cwnd, halfcwnd;
 
        /* Don't be strict about the congestion window for the final FIN.  */
        if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) &&
@@ -1562,10 +1571,14 @@ static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp,
 
        in_flight = tcp_packets_in_flight(tp);
        cwnd = tp->snd_cwnd;
-       if (in_flight < cwnd)
-               return (cwnd - in_flight);
+       if (in_flight >= cwnd)
+               return 0;
 
-       return 0;
+       /* For better scheduling, ensure we have at least
+        * 2 GSO packets in flight.
+        */
+       halfcwnd = max(cwnd >> 1, 1U);
+       return min(halfcwnd, cwnd - in_flight);
 }
 
 /* Initialize TSO state of a skb.
@@ -2126,7 +2139,7 @@ bool tcp_schedule_loss_probe(struct sock *sk)
 static bool skb_still_in_host_queue(const struct sock *sk,
                                    const struct sk_buff *skb)
 {
-       if (unlikely(skb_fclone_busy(skb))) {
+       if (unlikely(skb_fclone_busy(sk, skb))) {
                NET_INC_STATS_BH(sock_net(sk),
                                 LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES);
                return true;