Rewrite some comments to hopefully be easier to understand.

No code change.

diff --git a/usr.sbin/bgpd/rde_decide.c b/usr.sbin/bgpd/rde_decide.c
index 9c42758..3a0f6eb 100644 (file)
--- a/usr.sbin/bgpd/rde_decide.c
+++ b/usr.sbin/bgpd/rde_decide.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: rde_decide.c,v 1.87 2022/02/06 09:51:19 claudio Exp $ */
+/*     $OpenBSD: rde_decide.c,v 1.88 2022/03/01 09:46:22 claudio Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Claudio Jeker <claudio@openbsd.org>
@@ -281,7 +281,7 @@ prefix_cmp(struct prefix *p1, struct prefix *p2, int *testall)
        if (i > 0)
                return -1;
 
-       /* XXX RFC7911 does not specify this but it is needed. */
+       /* RFC7911 does not specify this but something like this is needed. */
        /* 13. lowest path identifier wins */
        if (p1->path_id < p2->path_id)
                return 1;
@@ -305,7 +305,7 @@ prefix_insert(struct prefix *new, struct prefix *ep, struct rib_entry *re)
        struct prefix *xp, *np, *tailp = NULL, *insertp = ep;
        int testall, selected = 0;
 
-       /* start scan at the entry point (ep) or if the head if ep == NULL */
+       /* start scan at the entry point (ep) or the head if ep == NULL */
        if (ep == NULL)
                ep = LIST_FIRST(&re->prefix_h);
 
@@ -339,10 +339,13 @@ prefix_insert(struct prefix *new, struct prefix *ep, struct rib_entry *re)
                        }
                } else {
                        /*
-                        * p is less preferred, remember insertion point
-                        * If p got selected during a testall traverse 
-                        * do not alter the insertion point unless this
-                        * happened on an actual MED check.
+                        * xp is preferred over new.
+                        * Remember insertion point for later unless the
+                        * traverse is just looking for a possible MED
+                        * inversion (selected == 1).
+                        * If the last comparison's tie-breaker was the MED
+                        * check reset selected and with it insertp since
+                        * this was an actual MED priority inversion.
                         */
                        if (testall == 2)
                                selected = 0;