Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index e02d319..81e6979 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -127,6 +127,9 @@
 
 #define TCP_CM_INQ		TCP_INQ
 
+#define TCP_TX_DELAY		37	/* delay outgoing packets by XX usec */
+
+
 #define TCP_REPAIR_ON		1
 #define TCP_REPAIR_OFF		0
 #define TCP_REPAIR_OFF_NO_WP	-1	/* Turn off without window probes */
@@ -160,15 +163,42 @@
 #define TCPI_OPT_ECN_SEEN	16 /* we received at least one packet with ECT */
 #define TCPI_OPT_SYN_DATA	32 /* SYN-ACK acked data in SYN sent or rcvd */
 
+/*
+ * Sender's congestion state indicating normal or abnormal situations
+ * in the last round of packets sent. The state is driven by the ACK
+ * information and timer events.
+ */
 enum tcp_ca_state {
+	/*
+	 * Nothing bad has been observed recently.
+	 * No apparent reordering, packet loss, or ECN marks.
+	 */
 	TCP_CA_Open = 0,
 #define TCPF_CA_Open	(1<<TCP_CA_Open)
+	/*
+	 * The sender enters disordered state when it has received DUPACKs or
+	 * SACKs in the last round of packets sent. This could be due to packet
+	 * loss or reordering but needs further information to confirm packets
+	 * have been lost.
+	 */
 	TCP_CA_Disorder = 1,
 #define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
+	/*
+	 * The sender enters Congestion Window Reduction (CWR) state when it
+	 * has received ACKs with ECN-ECE marks, or has experienced congestion
+	 * or packet discard on the sender host (e.g. qdisc).
+	 */
 	TCP_CA_CWR = 2,
 #define TCPF_CA_CWR	(1<<TCP_CA_CWR)
+	/*
+	 * The sender is in fast recovery and retransmitting lost packets,
+	 * typically triggered by ACK events.
+	 */
 	TCP_CA_Recovery = 3,
 #define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
+	/*
+	 * The sender is in loss recovery triggered by retransmission timeout.
+	 */
 	TCP_CA_Loss = 4
 #define TCPF_CA_Loss	(1<<TCP_CA_Loss)
 };
@@ -240,6 +270,12 @@
 	__u64	tcpi_bytes_retrans;  /* RFC4898 tcpEStatsPerfOctetsRetrans */
 	__u32	tcpi_dsack_dups;     /* RFC4898 tcpEStatsStackDSACKDups */
 	__u32	tcpi_reord_seen;     /* reordering events seen */
+
+	__u32	tcpi_rcv_ooopack;    /* Out-of-order packets received */
+
+	__u32	tcpi_snd_wnd;	     /* peer's advertised receive window after
+				      * scaling (bytes)
+				      */
 };
 
 /* netlink attributes types for SCM_TIMESTAMPING_OPT_STATS */
@@ -266,6 +302,7 @@
 	TCP_NLA_BYTES_RETRANS,	/* Data bytes retransmitted */
 	TCP_NLA_DSACK_DUPS,	/* DSACK blocks received */
 	TCP_NLA_REORD_SEEN,	/* reordering events seen */
+	TCP_NLA_SRTT,		/* smoothed RTT in usecs */
 };
 
 /* for TCP_MD5SIG socket option */