[PATCH v4 net-next 03/14] tcp_cubic: make hystart_ack_delay() aware of BIG TCP

[Eric Dumazet <eric.dumazet@gmail.com>]

From: Eric Dumazet <edumazet@google.com>

hystart_ack_delay() had the assumption that a TSO packet
would not be bigger than GSO_MAX_SIZE.

This will no longer be true.

We should use sk->sk_gso_max_size instead.

This reduces chances of spurious Hystart ACK train detections.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/tcp_cubic.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
index 24d562dd62254d6e50dd08236f8967400d81e1ea..dfc9dc951b7404776b2246c38273fbadf03c39fd 100644
--- a/net/ipv4/tcp_cubic.c
+++ b/net/ipv4/tcp_cubic.c
@@ -372,7 +372,7 @@ static void cubictcp_state(struct sock *sk, u8 new_state)
  * We apply another 100% factor because @rate is doubled at this point.
  * We cap the cushion to 1ms.
  */
-static u32 hystart_ack_delay(struct sock *sk)
+static u32 hystart_ack_delay(const struct sock *sk)
 {
 	unsigned long rate;
 
@@ -380,7 +380,7 @@ static u32 hystart_ack_delay(struct sock *sk)
 	if (!rate)
 		return 0;
 	return min_t(u64, USEC_PER_MSEC,
-		     div64_ul((u64)GSO_MAX_SIZE * 4 * USEC_PER_SEC, rate));
+		     div64_ul((u64)sk->sk_gso_max_size * 4 * USEC_PER_SEC, rate));
 }
 
 static void hystart_update(struct sock *sk, u32 delay)
-- 
2.35.1.616.g0bdcbb4464-goog