commit da2af3ac496403f12598bebd4b3474f4bad787e9
from: Stefan Sperling <stsp@stsp.name>
date: Mon Sep 02 15:14:35 2024 UTC

silence ifconfig errors related to carp demotion at boot time

This happens when nsh is started by /etc/rc.d/nsh during boot.
The /etc/rc script starts package scripts with carp-interlock already
enabled, and both ifconfig and nsh would attempt to reset the carp
demotion counter. Generally, this is harmless, apart from an error
message displayed by ifconfig which might mislead users into assuming
there was a problem:

  starting package daemons: nsh.
  ifconfig: carp: SIOCSIFGATTR: Invalid argument

To avoid this issue, nsh can check whether the demotion counter has
already been set to the desired level and only change the counter if
changing it is indeed required.

test + ok Tom

commit - ddce9e236b5cbab80ad195840f427d4e19f39b97
commit + da2af3ac496403f12598bebd4b3474f4bad787e9
blob - 0a982b5cb1935a92641e2b017794a5c5bb1463f6
blob + 00d468e4f2977eda1ed8ea03f5c1659914056b36
--- carp.c
+++ carp.c
@@ -469,7 +469,13 @@ intcdev(char *ifname, int ifs, int argc, char **argv)
 	return (0);
 }
 
-void
+/* 
+ * Change the carp demotion counter.
+ * Return 1 if the counter was changed.
+ * Return 0 if the counter was already at or beyond the desired "lock" value.
+ * Return -1 on error.
+ */
+int
 carplock(int lock)
 {
 	int ifs;
@@ -481,12 +487,27 @@ carplock(int lock)
 	ifs = socket(AF_INET, SOCK_DGRAM, 0);
 	if (ifs == -1) {
 		printf("%% carplock: socket: %s\n", strerror(errno));
-		return;
+		return -1;
 	}
 
+	if (ioctl(ifs, SIOCGIFGATTR, (caddr_t)&ifgr) == -1) {
+		printf("%% carplock: SIOCGIFGATTR %s: %s\n",
+		    ifgr.ifgr_name, strerror(errno));
+		close(ifs);
+		return -1;
+	}
+
+	if ((lock >= 0 && ifgr.ifgr_attrib.ifg_carp_demoted >= lock) ||
+	    (lock < 0 && ifgr.ifgr_attrib.ifg_carp_demoted <= lock)) {
+		close(ifs);
+		return 0; /* already "locked" */
+	}
+
 	ifgr.ifgr_attrib.ifg_carp_demoted = lock;
 
 	if (ioctl(ifs, SIOCSIFGATTR, (caddr_t)&ifgr) == -1)
 		printf("%% carplock: SIOCSIFGATTR: %s\n", strerror(errno));
 	close(ifs);
+
+	return 1;
 }
blob - 985ec7948a08869736e55a9f66fd385275c9cbf7
blob + e56534fea6e9c18e5ce36a0801be214dcae3f482
--- externs.h
+++ externs.h
@@ -463,7 +463,7 @@ int intcnode(char *, int, int, char **);
 int conf_carp(FILE *, int, char *);
 int carp_state(int, char *, FILE *);
 int intcdev(char *, int, int, char **);
-void carplock(int);
+int carplock(int);
 
 /* trunk.c */
 int inttrunkport(char *, int, int, char **);
blob - f1fe7d6526e5195906ff0082f8d42871d1680ec4
blob + d12f005cec3778de6c80aa47a81d64b27ae2ad63
--- main.c
+++ main.c
@@ -258,6 +258,8 @@ main(int argc, char *argv[])
 	}
 
 	if (iflag) {
+		int carp_locked;
+
 		/*
 		 * Interpret config file and exit
 		 */
@@ -270,14 +272,15 @@ main(int argc, char *argv[])
 		/*
 		 * Set carp group carpdemote to 128 during initialization
 		 */
-		carplock(128);
+		carp_locked = carplock(128);
 
 		cmdrc(rc);
 
 		/*
-		 * Initialization over
+		 * Initialization over; reset carpdemote if it was raised by us.
 		 */
-		carplock(-128);
+		if (carp_locked == 1)
+			carplock(-128);
 
 		exit(0);
 	}