From: AMEET M. PARANJAPE <aparanja@redhat.com>
Date: Thu, 15 Jan 2009 10:10:32 -0500
Subject: [powerpc] wait for a panic_timeout > 0 before reboot
Message-id: 20090115150928.26532.7777.sendpatchset@squad5-lp1.lab.bos.redhat.com
O-Subject: [PATCH RHEL5.4 BZ446120] Ensure kernel waits for a panic_timeout > 0 before reboot
Bugzilla: 446120
RH-Acked-by: Jerome Marchand <jmarchan@redhat.com>
RH-Acked-by: David Howells <dhowells@redhat.com>

RHBZ#:
======
https://bugzilla.redhat.com/show_bug.cgi?id=446120

Description:
===========
Patch to ensure a system hangs for a given panic_timeout value > 0.

In this environment Kdump and xmon are disabled while /proc/sys/kernel/panic
is set to a value >0 before a kernel panic is called. When a kernel panic is
triggered, the expected behaviour is for the system to wait the expected
timeout value after the panic and then reboot.

RHEL Version Found:
================
RHEL 5.3

kABI Status:
============
No symbols were harmed.

Brew:
=====
Built on all platforms.
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1646426

Upstream Status:
================
I could not find the specific GIT ID, but the patch is in the latest 2.6.28 and
2.6.29-rc1 kernels.

>From 2.6.29-rc1 GIT tree:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=arch/powerpc/kernel/rtas.c;h=fdfe14c4bdefc735640745625cb559fc4908a2fa;hb=HEAD

665
666 void rtas_os_term(char *str)
667 {
668         int status;
669
670         if (panic_timeout)<--- here
671                 return;

Test Status:
============
A testcase to induce the error is provided in the bug.  Without the patch
applied the system will panic and reboot immediately, but with the patch the
system waits the timeout value as expected after the forced panic to reboot.

===============================================================
Ameet Paranjape 978-392-3903 ext 23903
IBM on-site partner

Proposed Patch:
===============

diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 1ab7346..a980907 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -643,6 +643,9 @@ void rtas_os_term(char *str)
 {
 	int status;
 
+	if (panic_timeout)
+		return;
+
 	if (RTAS_UNKNOWN_SERVICE == rtas_token("ibm,os-term"))
 		return;