From: Claudio Jeker <cjeker@diehard.n-r-g.com>
Subject: bgpd rde poll busy loop fix
To: tech@openbsd.org
Date: Fri, 22 Aug 2025 08:45:11 +0200

The switch to ibufq introduced a bug with the imsg_pending tracking.
peer_imsg_flush() did not adjust imsg_pending so when a peer is reset
in the wrong moment imsg_pending becomes off and so peer_work_pending
would always return 1.

I dislike this imsg_pending tracking and decided it is better to
just walk the peertable in peer_work_pending. This is more work but less
error prone.

This seems to fix my spinning RDE at 100% issue (I hope).
-- 
:wq Claudio

Index: rde_peer.c
===================================================================
RCS file: /cvs/src/usr.sbin/bgpd/rde_peer.c,v
diff -u -p -r1.49 rde_peer.c
--- rde_peer.c	4 Jun 2025 09:11:38 -0000	1.49
+++ rde_peer.c	21 Aug 2025 19:11:14 -0000
@@ -29,7 +29,6 @@
 struct peer_tree	 peertable = RB_INITIALIZER(&peertable);
 struct peer_tree	 zombietable = RB_INITIALIZER(&zombietable);
 struct rde_peer		*peerself;
-static long		 imsg_pending;
 
 CTASSERT(sizeof(peerself->recv_eor) * 8 >= AID_MAX);
 CTASSERT(sizeof(peerself->sent_eor) * 8 >= AID_MAX);
@@ -666,9 +665,17 @@ peer_reaper(struct rde_peer *peer)
 int
 peer_work_pending(void)
 {
+	struct rde_peer *p;
+
 	if (!RB_EMPTY(&zombietable))
 		return 1;
-	return imsg_pending != 0;
+
+	RB_FOREACH(p, peer_tree, &peertable) {
+		if (ibufq_queuelen(p->ibufq) != 0)
+			return 1;
+	}
+
+	return 0;
 }
 
 /*
@@ -678,7 +685,6 @@ void
 peer_imsg_push(struct rde_peer *peer, struct imsg *imsg)
 {
 	imsg_ibufq_push(peer->ibufq, imsg);
-	imsg_pending++;
 }
 
 /*
@@ -692,7 +698,6 @@ peer_imsg_pop(struct rde_peer *peer, str
 	case 0:
 		return 0;
 	case 1:
-		imsg_pending--;
 		return 1;
 	default:
 		fatal("imsg_ibufq_pop");