This is a note to let you know that I've just added the patch titled
powerpc/ftrace: Do not trace restore_interrupts()
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-ftrace-do-not-trace-restore_interrupts.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 2d773aa4810d4a612d1c879faacc38594cc3f841 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <[email protected]>
Date: Mon, 4 Jun 2012 16:27:54 +0000
Subject: powerpc/ftrace: Do not trace restore_interrupts()
From: Steven Rostedt <[email protected]>
commit 2d773aa4810d4a612d1c879faacc38594cc3f841 upstream.
As I was adding code that affects all archs, I started testing function
tracer against PPC64 and found that it currently locks up with 3.4
kernel. I figured it was due to tracing a function that shouldn't be, so
I went through the following process to bisect to find the culprit:
cat /debug/tracing/available_filter_functions > t
num=`wc -l t`
sed -ne "1,${num}p" t > t1
let num=num+1
sed -ne "${num},$p" t > t2
cat t1 > /debug/tracing/set_ftrace_filter
echo function /debug/tracing/current_tracer
<failed? bisect t1, if not bisect t2>
It finally came down to this function: restore_interrupts()
I'm not sure why this locks up the system. It just seems to prevent
scheduling from occurring. Interrupts seem to still work, as I can ping
the box. But all user processes freeze.
When restore_interrupts() is not traced, function tracing works fine.
Signed-off-by: Steven Rostedt <[email protected]>
Signed-off-by: Benjamin Herrenschmidt <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/powerpc/kernel/irq.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -277,7 +277,7 @@ EXPORT_SYMBOL(arch_local_irq_restore);
* NOTE: This is called with interrupts hard disabled but not marked
* as such in paca->irq_happened, so we need to resync this.
*/
-void restore_interrupts(void)
+void notrace restore_interrupts(void)
{
if (irqs_disabled()) {
local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/powerpc-ftrace-do-not-trace-restore_interrupts.patch
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