Export the name of the congestion control. This will be used by sockstat

and netstat.

Reviewed by:		rscheff
MFC after:		1 week
Sponsored by:		Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D26412

sys/netinet/tcp_subr.c

@@ -3457,6 +3457,8 @@ tcp_inptoxtp(const struct inpcb *inp, struct xtcpcb *xt)
 
 		bcopy(tp->t_fb->tfb_tcp_block_name, xt->xt_stack,
 		    TCP_FUNCTION_NAME_LEN_MAX);
+		bcopy(CC_ALGO(tp)->name, xt->xt_cc,
+		    TCP_CA_NAME_MAX);
 #ifdef TCP_BLACKBOX
 		(void)tcp_log_get_id(tp, xt->xt_logid);
 #endif

sys/netinet/tcp_var.h

@@ -754,7 +754,8 @@ struct xtcpcb {
 	struct xinpcb	xt_inp;
 	char		xt_stack[TCP_FUNCTION_NAME_LEN_MAX];	/* (s) */
 	char		xt_logid[TCP_LOG_ID_LEN];	/* (s) */
-	int64_t		spare64[8];
+	char		xt_cc[TCP_CA_NAME_MAX];	/* (s) */
+	int64_t		spare64[6];
 	int32_t		t_state;		/* (s,p) */
 	uint32_t	t_flags;		/* (s,p) */
 	int32_t		t_sndzerowin;		/* (s) */