From: Vitaliy Makkoveev <otto@bsdbox.dev>
Subject: Re: const global TCP variables
To: Alexander Bluhm <bluhm@openbsd.org>
Cc: tech@openbsd.org
Date: Fri, 20 Dec 2024 23:54:45 +0300

> On 20 Dec 2024, at 23:36, Alexander Bluhm <bluhm@openbsd.org> wrote:
> 
> Hi,
> 
> Some global TCP variables can be declared const.
> 
> ok?
> 

ok mvs

> bluhm
> 
> Index: netinet/tcp_fsm.h
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/tcp_fsm.h,v
> diff -u -p -r1.9 tcp_fsm.h
> --- netinet/tcp_fsm.h	5 Feb 2018 14:53:26 -0000	1.9
> +++ netinet/tcp_fsm.h	20 Dec 2024 19:35:32 -0000
> @@ -68,7 +68,7 @@
>  * determined by state, with the proviso that TH_FIN is sent only
>  * if all data queued for output is included in the segment.
>  */
> -u_char	tcp_outflags[TCP_NSTATES] = {
> +const u_char tcp_outflags[TCP_NSTATES] = {
>     TH_RST|TH_ACK, 0, TH_SYN, TH_SYN|TH_ACK,
>     TH_ACK, TH_ACK,
>     TH_FIN|TH_ACK, TH_FIN|TH_ACK, TH_FIN|TH_ACK, TH_ACK, TH_ACK,
> @@ -76,7 +76,7 @@ u_char	tcp_outflags[TCP_NSTATES] = {
> #endif /* TCPOUTFLAGS */
> 
> #ifdef	TCPSTATES
> -const char *tcpstates[] = {
> +const char *const tcpstates[] = {
> 	"CLOSED",	"LISTEN",	"SYN_SENT",	"SYN_RCVD",
> 	"ESTABLISHED",	"CLOSE_WAIT",	"FIN_WAIT_1",	"CLOSING",
> 	"LAST_ACK",	"FIN_WAIT_2",	"TIME_WAIT",
> Index: netinet/tcp_timer.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/tcp_timer.c,v
> diff -u -p -r1.76 tcp_timer.c
> --- netinet/tcp_timer.c	28 Jan 2024 20:34:25 -0000	1.76
> +++ netinet/tcp_timer.c	20 Dec 2024 19:35:32 -0000
> @@ -167,10 +167,10 @@ tcp_canceltimers(struct tcpcb *tp)
> 		TCP_TIMER_DISARM(tp, i);
> }
> 
> -int	tcp_backoff[TCP_MAXRXTSHIFT + 1] =
> +const int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
>     { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
> 
> -int tcp_totbackoff = 511;	/* sum of tcp_backoff[] */
> +const int tcp_totbackoff = 511;	/* sum of tcp_backoff[] */
> 
> /*
>  * TCP timer processing.
> Index: netinet/tcp_timer.h
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/tcp_timer.h,v
> diff -u -p -r1.21 tcp_timer.h
> --- netinet/tcp_timer.h	29 Jan 2024 22:47:13 -0000	1.21
> +++ netinet/tcp_timer.h	20 Dec 2024 19:35:32 -0000
> @@ -160,7 +160,7 @@ extern int tcp_keepidle;		/* time before
> extern int tcp_keepintvl;		/* time between keepalive probes */
> extern int tcp_maxidle;			/* time to drop after starting probes */
> extern int tcp_ttl;			/* time to live for TCP segs */
> -extern int tcp_backoff[];
> +extern const int tcp_backoff[];
> 
> void	tcp_timer_init(void);
> #endif /* _KERNEL */
>