tcp: move tp->tcp_usec_ts to tcp_sock_read_txrx group

tp->tcp_usec_ts is a read mostly field, used in rx and tx fast paths.

Fixes: d5fed5ad ("tcp: reorganize tcp_sock fast path variables")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Coco Li <lixiaoyan@google.com>
Cc: Wei Wang <weiwan@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/net_cachelines/tcp_sock.rst

@@ -44,7 +44,7 @@ u16                           advmss                  -                   read_m
 u8                            compressed_ack                                                  
 u8:2                          dup_ack_counter                                                 
 u8:1                          tlp_retrans                                                     
-u8:1                          tcp_usec_ts                                                     
+u8:1                          tcp_usec_ts             read_mostly         read_mostly
 u32                           chrono_start            read_write          -                   tcp_chrono_start/stop(tcp_write_xmit,tcp_cwnd_validate,tcp_send_syn_data)
 u32[3]                        chrono_stat             read_write          -                   tcp_chrono_start/stop(tcp_write_xmit,tcp_cwnd_validate,tcp_send_syn_data)
 u8:2                          chrono_type             read_write          -                   tcp_chrono_start/stop(tcp_write_xmit,tcp_cwnd_validate,tcp_send_syn_data)

include/linux/tcp.h

@@ -224,6 +224,7 @@ struct tcp_sock {
 	u8	scaling_ratio;	/* see tcp_win_from_space() */
 	u8	chrono_type : 2,	/* current chronograph type */
 		repair      : 1,
+		tcp_usec_ts : 1, /* TSval values in usec */
 		is_sack_reneg:1,    /* in recovery from loss with SACK reneg? */
 		is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
 	__cacheline_group_end(tcp_sock_read_txrx);
@@ -368,8 +369,7 @@ struct tcp_sock {
 	u8	compressed_ack;
 	u8	dup_ack_counter:2,
 		tlp_retrans:1,	/* TLP is a retransmission */
-		tcp_usec_ts:1, /* TSval values in usec */
-		unused:4;
+		unused:5;
 	u8	thin_lto    : 1,/* Use linear timeouts for thin streams */
 		recvmsg_inq : 1,/* Indicate # of bytes in queue upon recvmsg */
 		fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */