tcp: move tcp_skb_cb->sacked flags to enum

Move the flag definitions for tcp_skb_cb->sacked into a new enum named
tcp_skb_cb_sacked_flags, then we can get access to them in bpf via
vmlinux.h, e.g., in tracepoints.

This patch does not change any existing functionality.
Signed-off-by: Philo Lu <lulie@linux.alibaba.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tcp.h

@@ -928,6 +928,19 @@ static inline u32 tcp_rsk_tsval(const struct tcp_request_sock *treq)
 
 #define TCPHDR_SYN_ECN	(TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
 
+/* State flags for sacked in struct tcp_skb_cb */
+enum tcp_skb_cb_sacked_flags {
+	TCPCB_SACKED_ACKED	= (1 << 0),	/* SKB ACK'd by a SACK block	*/
+	TCPCB_SACKED_RETRANS	= (1 << 1),	/* SKB retransmitted		*/
+	TCPCB_LOST		= (1 << 2),	/* SKB is lost			*/
+	TCPCB_TAGBITS		= (TCPCB_SACKED_ACKED | TCPCB_SACKED_RETRANS |
+				   TCPCB_LOST),	/* All tag bits			*/
+	TCPCB_REPAIRED		= (1 << 4),	/* SKB repaired (no skb_mstamp_ns)	*/
+	TCPCB_EVER_RETRANS	= (1 << 7),	/* Ever retransmitted frame	*/
+	TCPCB_RETRANS		= (TCPCB_SACKED_RETRANS | TCPCB_EVER_RETRANS |
+				   TCPCB_REPAIRED),
+};
+
 /* This is what the send packet queuing engine uses to pass
  * TCP per-packet control information to the transmission code.
  * We also store the host-order sequence numbers in here too.
@@ -950,15 +963,6 @@ struct tcp_skb_cb {
 	__u8		tcp_flags;	/* TCP header flags. (tcp[13])	*/
 
 	__u8		sacked;		/* State flags for SACK.	*/
-#define TCPCB_SACKED_ACKED	0x01	/* SKB ACK'd by a SACK block	*/
-#define TCPCB_SACKED_RETRANS	0x02	/* SKB retransmitted		*/
-#define TCPCB_LOST		0x04	/* SKB is lost			*/
-#define TCPCB_TAGBITS		0x07	/* All tag bits			*/
-#define TCPCB_REPAIRED		0x10	/* SKB repaired (no skb_mstamp_ns)	*/
-#define TCPCB_EVER_RETRANS	0x80	/* Ever retransmitted frame	*/
-#define TCPCB_RETRANS		(TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
-				TCPCB_REPAIRED)
-
 	__u8		ip_dsfield;	/* IPv4 tos or IPv6 dsfield	*/
 	__u8		txstamp_ack:1,	/* Record TX timestamp for ack? */
 			eor:1,		/* Is skb MSG_EOR marked? */