Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
index c81aadf..fdb715b 100644
--- a/net/ipv4/tcp_recovery.c
+++ b/net/ipv4/tcp_recovery.c
@@ -50,7 +50,7 @@
 s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb, u32 reo_wnd)
 {
 	return tp->rack.rtt_us + reo_wnd -
-	       tcp_stamp_us_delta(tp->tcp_mstamp, skb->skb_mstamp);
+	       tcp_stamp_us_delta(tp->tcp_mstamp, tcp_skb_timestamp_us(skb));
 }
 
 /* RACK loss detection (IETF draft draft-ietf-tcpm-rack-01):
@@ -91,7 +91,8 @@
 		    !(scb->sacked & TCPCB_SACKED_RETRANS))
 			continue;
 
-		if (!tcp_rack_sent_after(tp->rack.mstamp, skb->skb_mstamp,
+		if (!tcp_rack_sent_after(tp->rack.mstamp,
+					 tcp_skb_timestamp_us(skb),
 					 tp->rack.end_seq, scb->end_seq))
 			break;