tcp: fix ssthresh u16 leftover

It was once upon time so that snd_sthresh was a 16-bit quantity.
...That has not been true for long period of time. I run across
some ancient compares which still seem to trust such legacy.
Put all that magic into a single place, I hopefully found all
of them.

Compile tested, though linking of allyesconfig is ridiculous
nowadays it seems.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index b71a446d58f6..56b76027b85e 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -793,6 +793,13 @@ static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
 	return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
 }
 
+#define TCP_INFINITE_SSTHRESH	0x7fffffff
+
+static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
+{
+	return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
+}
+
 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
  * The exception is rate halving phase, when cwnd is decreasing towards
  * ssthresh.