Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c
index 4dff40d..0de6935 100644
--- a/net/ipv4/tcp_rate.c
+++ b/net/ipv4/tcp_rate.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <net/tcp.h>
 
 /* The bandwidth estimator estimates the rate at which the network
@@ -55,8 +56,10 @@
 	  * bandwidth estimate.
 	  */
 	if (!tp->packets_out) {
-		tp->first_tx_mstamp  = skb->skb_mstamp;
-		tp->delivered_mstamp = skb->skb_mstamp;
+		u64 tstamp_us = tcp_skb_timestamp_us(skb);
+
+		tp->first_tx_mstamp  = tstamp_us;
+		tp->delivered_mstamp = tstamp_us;
 	}
 
 	TCP_SKB_CB(skb)->tx.first_tx_mstamp	= tp->first_tx_mstamp;
@@ -88,13 +91,12 @@
 		rs->is_app_limited   = scb->tx.is_app_limited;
 		rs->is_retrans	     = scb->sacked & TCPCB_RETRANS;
 
-		/* Find the duration of the "send phase" of this window: */
-		rs->interval_us      = tcp_stamp_us_delta(
-						skb->skb_mstamp,
-						scb->tx.first_tx_mstamp);
-
 		/* Record send time of most recently ACKed packet: */
-		tp->first_tx_mstamp  = skb->skb_mstamp;
+		tp->first_tx_mstamp  = tcp_skb_timestamp_us(skb);
+		/* Find the duration of the "send phase" of this window: */
+		rs->interval_us = tcp_stamp_us_delta(tp->first_tx_mstamp,
+						     scb->tx.first_tx_mstamp);
+
 	}
 	/* Mark off the skb delivered once it's sacked to avoid being
 	 * used again when it's cumulatively acked. For acked packets