From 632448f65001c4935ed0d3bb362017d773da2eca Mon Sep 17 00:00:00 2001
From: Heiko Carstens <heiko.carstens@de.ibm.com>
Date: Fri, 14 Nov 2008 18:18:04 +0100
Subject: [PATCH] [S390] ftrace: disable tracing on idle psw

Disable tracing on idle psw. Otherwise it would give us huge
preempt off times for idle. Which is rather pointless.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
 arch/s390/kernel/process.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 3e2c05cb6a873..04f8c67a61018 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -136,9 +136,12 @@ static void default_idle(void)
 		return;
 	}
 	trace_hardirqs_on();
+	/* Don't trace preempt off for idle. */
+	stop_critical_timings();
 	/* Wait for external, I/O or machine check interrupt. */
 	__load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
 			PSW_MASK_IO | PSW_MASK_EXT);
+	start_critical_timings();
 }
 
 void cpu_idle(void)
-- 
2.30.2