From: Steven Rostedt <srostedt@redhat.com>
Date: Sat, 15 Nov 2008 00:21:19 +0000 (-0800)
Subject: powerpc: ftrace, do not latency trace idle
X-Git-Tag: v2.6.29-rc1~586^2~49^6^2~4
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=6d07bb47354174a9b52d3b03f9e38b069a93d341;p=linux-2.6-omap-h63xx.git

powerpc: ftrace, do not latency trace idle

Impact: fix for irq off latency tracer

When idle is called, interrupts are disabled, but the idle function
will still wake up on an interrupt. The problem is that the interrupt
disabled latency tracer will take this call to idle as a latency.

This patch disables the latency tracing when going into idle.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---

diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
index 31982d05d81..88d9c1d5e5f 100644
--- a/arch/powerpc/kernel/idle.c
+++ b/arch/powerpc/kernel/idle.c
@@ -69,10 +69,15 @@ void cpu_idle(void)
 				smp_mb();
 				local_irq_disable();
 
+				/* Don't trace irqs off for idle */
+				stop_critical_timings();
+
 				/* check again after disabling irqs */
 				if (!need_resched() && !cpu_should_die())
 					ppc_md.power_save();
 
+				start_critical_timings();
+
 				local_irq_enable();
 				set_thread_flag(TIF_POLLING_NRFLAG);