How to debug rc hangs?

[Doug Barton]

On Wed, 24 Oct 2007, John Marshall wrote:

> [blush] I actually fixed this 12 months ago on 6.n and forgot all about it. I 
> let the 7.0 mergemaster overwrite the rc.d/ypset because I didn't think I had 
> touched it.
>
> Here is the fix. All happy now - but not much the wiser as to rc 
> troubleshooting techniques.
>
> -----------------------------------------------
> --- /usr/src/etc/rc.d/ypset     2007-10-12 12:38:42.000000000 +1000
> +++ /etc/rc.d/ypset  2007-10-24 02:31:32.000000000 +1000
> @@ -5,6 +5,7 @@
>
> # PROVIDE: ypset
> # REQUIRE: ypbind
> +# BEFORE:  mountd
>
> . /etc/rc.subr

John,

Thanks for digging into this yourself, always nice when someone answers 
their own questions. :)

In regards to your proposed solution, I would like to explore this with 
you a little. In general it would be preferred to add REQUIRE: ypset in 
mountd instead of using BEFORE. This makes debugging easier down the road.

The other thing I'm interested in is the relationship between this change 
and the other yp* stuff. I've attached a patch that I use to debug the 
rcorder stuff. If you could copy your /etc/rc to a handy directory, apply 
the patch, and then run 'sh rc'. If you could do that before and after 
applying the change you suggested (using REQUIRE instead of BEFORE if you 
don't mind) I'd be interested if anything else changes besides the 
ypset/mountd relationship.

My concern is that in my rcorder (basically stock RELENG_6 with some 
ports) ypxfrd, ypudated, and ypset are all running in that order, and late 
in the overall order. I'm concerned that if we move ypset earlier (and 
mountd is run a lot earlier than those 3) it will have other side effects. 
I also noticed that ypserv and ypbind are run much than even mountd, and 
since I don't use NIS I don't really know what those side effects might be 
(if any).

I may be a little overcautious here, but experience has taught us that 
even seemingly small changes can have large and unanticipated 
consequences.

Doug

-- 

     This .signature sanitized for your protection
-------------- next part --------------
--- /etc/rc	2007-07-06 22:26:09.000000000 -0700
+++ rc	2007-10-23 10:35:03.000000000 -0700
@@ -85,8 +47,12 @@
 #
 files=`rcorder ${skip} /etc/rc.d/* 2>/dev/null`
 
+# XXX
+rm -f rc.early* rc.late
+
 for _rc_elem in ${files}; do
-	run_rc_script ${_rc_elem} ${_boot}
+	#run_rc_script ${_rc_elem} ${_boot}
+	echo $_rc_elem >> rc.early1
 
 	case "$_rc_elem" in
 	*/${early_late_divider})	break ;;
@@ -107,16 +73,22 @@
 _skip_early=1
 for _rc_elem in ${files}; do
 	case "$_skip_early" in
-	1)	case "$_rc_elem" in
+	1)
+		echo $_rc_elem >> rc.early2
+		case "$_rc_elem" in
 		*/${early_late_divider})	_skip_early=0 ;;
 		esac
 		continue
 		;;
 	esac
 
-	run_rc_script ${_rc_elem} ${_boot}
+	echo $_rc_elem >> rc.late
+
+	#run_rc_script ${_rc_elem} ${_boot}
 done
 
+diff -u rc.early*
+
 echo ''
 date
 exit 0