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 31982d05d81a8814d73dfc8b5a562cd90b66e5d3..88d9c1d5e5fb0aea1e74757ae9ac1133e9f352ef 100644 (file)
--- 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);