From: Claudio Jeker <cjeker@diehard.n-r-g.com>
Subject: bgpd: simplify timer handling
To: tech@openbsd.org
Date: Mon, 14 Apr 2025 14:03:45 +0200

Instead of checking the timeout for poll against a relative timeout 
just use the abolute monotime that the timer API uses as well.
This way only right before poll we need to convert to a relative timeout.

-- 
:wq Claudio

Index: rtr.c
===================================================================
RCS file: /cvs/src/usr.sbin/bgpd/rtr.c,v
diff -u -p -r1.30 rtr.c
--- rtr.c	20 Feb 2025 19:47:31 -0000	1.30
+++ rtr.c	8 Apr 2025 14:48:24 -0000
@@ -245,7 +245,6 @@ rtr_main(int debug, int verbose)
 		timeout = timer_nextduein(&expire_timer);
 		if (!monotime_valid(timeout))
 			fatalx("roa-set expire timer no longer running");
-		timeout = monotime_sub(timeout, getmonotime());
 
 		memset(pfd, 0, sizeof(struct pollfd) * pfd_elms);
 
@@ -254,6 +253,10 @@ rtr_main(int debug, int verbose)
 
 		i = PFD_PIPE_COUNT;
 		i += rtr_poll_events(pfd + i, pfd_elms - i, &timeout);
+
+		timeout = monotime_sub(timeout, getmonotime());
+		if (!monotime_valid(timeout))
+			timeout = monotime_clear();
 
 		if (poll(pfd, i, monotime_to_msec(timeout)) == -1) {
 			if (errno == EINTR)
Index: rtr_proto.c
===================================================================
RCS file: /cvs/src/usr.sbin/bgpd/rtr_proto.c,v
diff -u -p -r1.51 rtr_proto.c
--- rtr_proto.c	20 Feb 2025 19:47:31 -0000	1.51
+++ rtr_proto.c	8 Apr 2025 14:40:14 -0000
@@ -1365,7 +1365,6 @@ size_t
 rtr_poll_events(struct pollfd *pfds, size_t npfds, monotime_t *timeout)
 {
 	struct rtr_session *rs;
-	monotime_t now = getmonotime();
 	size_t i = 0;
 
 	TAILQ_FOREACH(rs, &rtrs, entry) {
@@ -1377,7 +1376,6 @@ rtr_poll_events(struct pollfd *pfds, siz
 
 		nextaction = timer_nextduein(&rs->timers);
 		if (monotime_valid(nextaction)) {
-			monotime_sub(nextaction, now);
 			if (monotime_cmp(nextaction, *timeout) < 0)
 				*timeout = nextaction;
 		}
Index: session.c
===================================================================
RCS file: /cvs/src/usr.sbin/bgpd/session.c,v
diff -u -p -r1.524 session.c
--- session.c	26 Feb 2025 19:31:31 -0000	1.524
+++ session.c	8 Apr 2025 14:52:38 -0000
@@ -323,9 +323,9 @@ session_main(int debug, int verbose)
 			i++;
 		}
 		idx_listeners = i;
-		timeout = monotime_from_sec(MAX_TIMEOUT);
-
 		now = getmonotime();
+		timeout = monotime_add(now, monotime_from_sec(MAX_TIMEOUT));
+
 		RB_FOREACH(p, peer_head, &conf->peers) {
 			monotime_t nextaction;
 			struct timer *pt;
@@ -386,7 +386,6 @@ session_main(int debug, int verbose)
 			}
 			nextaction = timer_nextduein(&p->timers);
 			if (monotime_valid(nextaction)) {
-				nextaction = monotime_sub(nextaction, now);
 				if (monotime_cmp(nextaction, timeout) < 0)
 					timeout = nextaction;
 			}
@@ -438,11 +437,14 @@ session_main(int debug, int verbose)
 		if (i > pfd_elms)
 			fatalx("poll pfd overflow");
 
-		if (monotime_valid(pauseaccept) && monotime_cmp(timeout,
-		    monotime_from_sec(PAUSEACCEPT_TIMEOUT)) > 0)
-			timeout = monotime_from_sec(PAUSEACCEPT_TIMEOUT);
+		if (monotime_valid(pauseaccept) &&
+		    monotime_cmp(timeout, pauseaccept) > 0)
+			timeout = pauseaccept;
+
+		timeout = monotime_sub(timeout, getmonotime());
 		if (!monotime_valid(timeout))
 			timeout = monotime_clear();
+
 		if (poll(pfd, i, monotime_to_msec(timeout)) == -1) {
 			if (errno == EINTR)
 				continue;
@@ -454,8 +456,7 @@ session_main(int debug, int verbose)
 		 * for 1 second to throttle the accept() loop.
 		 */
 		if (monotime_valid(pauseaccept) &&
-		    monotime_cmp(getmonotime(), monotime_add(pauseaccept,
-		    monotime_from_sec(PAUSEACCEPT_TIMEOUT))) > 0)
+		    monotime_cmp(getmonotime(), pauseaccept) > 0)
 			pauseaccept = monotime_clear();
 
 		if (handle_pollfd(&pfd[PFD_PIPE_MAIN], ibuf_main) == -1) {
@@ -691,7 +692,8 @@ session_accept(int listenfd)
 	    (struct sockaddr *)&cliaddr, &len,
 	    SOCK_CLOEXEC | SOCK_NONBLOCK)) == -1) {
 		if (errno == ENFILE || errno == EMFILE)
-			pauseaccept = getmonotime();
+			pauseaccept = monotime_add(getmonotime(),
+			    monotime_from_sec(PAUSEACCEPT_TIMEOUT));
 		else if (errno != EWOULDBLOCK && errno != EINTR &&
 		    errno != ECONNABORTED)
 			log_warn("accept");