1 files changed, 21 insertions, 0 deletions

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 4451750b478c..3a6be23d222f 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -274,6 +274,27 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
         return err;
 }
 
+/* RFC2861 Check whether we are limited by application or congestion window
+ * This is the inverse of cwnd check in tcp_tso_should_defer
+ */
+int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight)
+{
+        const struct tcp_sock *tp = tcp_sk(sk);
+        u32 left;
+
+        if (in_flight >= tp->snd_cwnd)
+                return 1;
+
+        if (!sk_can_gso(sk))
+                return 0;
+
+        left = tp->snd_cwnd - in_flight;
+        if (sysctl_tcp_tso_win_divisor)
+                return left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd;
+        else
+                return left <= tcp_max_burst(tp);
+}
+EXPORT_SYMBOL_GPL(tcp_is_cwnd_limited);
 
 /*
  * Slow start is used when congestion window is less than slow start