From: Konrad Rzeszutek <konradr@redhat.com>
Date: Mon, 23 Jul 2007 15:59:23 -0400
Subject: [misc] Prevent NMI watchdog triggering during sysrq-T
Message-id: 20070723195923.GA10931@mars.boston.redhat.com
O-Subject: [RHEL5 U2 PATCH] RHBZ# 248392: LTC32322-Prevent NMI watchdog triggering during long sysrq-T outputs.
Bugzilla: 248392

RHBZ#:
------
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=248392

Description:
------------
Prevent NMI watchdog triggering during long sysrq-T outputs.

RHEL Version Found:
------------------
RHEL5 GA

Upstream Status:
----------------
In v2.6.23-rc1

Test Status:
------------
Tested for regression on machines with 2,4,32GB and 1,2,4,16 CPUs. No
regressions found.  The call adds a 5% slow-down. The alt-sysrq-t call
on average (of the machines I used) take about 12 milliseconds. The printk
part of the function takes 1/100th of a second to seconds depending on the
speed of the output (VGA screen to slow serial link).  In summary, this
patch will make the operation on average 0.6 milliseconds slower.

Proposed Patch:
---------------
This patch is based on 2.6.18-34

Acked-by: Larry Woodman <lwoodman@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---
 arch/i386/kernel/traps.c       |    1 +
 arch/x86_64/kernel/traps-xen.c |    1 +
 arch/x86_64/kernel/traps.c     |    1 +
 3 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index ad0e358..3217dc3 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -218,6 +218,7 @@ static void print_trace_address(void *data, unsigned long addr)
 {
 	printk("%s [<%08lx>] ", (char *)data, addr);
 	print_symbol("%s\n", addr);
+	touch_nmi_watchdog();
 }
 
 static struct stacktrace_ops print_trace_ops = {
diff --git a/arch/x86_64/kernel/traps-xen.c b/arch/x86_64/kernel/traps-xen.c
index ffd9dea..9357d42 100644
--- a/arch/x86_64/kernel/traps-xen.c
+++ b/arch/x86_64/kernel/traps-xen.c
@@ -354,6 +354,7 @@ static int print_trace_stack(void *data, char *name)
 static void print_trace_address(void *data, unsigned long addr)
 {
 	printk_address(addr);
+	touch_nmi_watchdog();
 }
 
 static struct stacktrace_ops print_trace_ops = {
diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 1a6edc1..97a7b4b 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -353,6 +353,7 @@ static int print_trace_stack(void *data, char *name)
 static void print_trace_address(void *data, unsigned long addr)
 {
 	printk_address(addr);
+	touch_nmi_watchdog();
 }
 
 static struct stacktrace_ops print_trace_ops = {
-- 
1.5.3.5.645.gbb47