linux-kernel - [PATCH] Calling check_system_tsc_reliable before unsynchronized

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Message-ID: <f02f774b-1840-a8d5-0235-e9ee2b501c26@oracle.com>
Date:   Thu, 8 Jun 2017 19:43:03 +0800
From:   Zhenzhong Duan <zhenzhong.duan@...cle.com>
To:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com
Cc:     x86@...nel.org, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] Calling check_system_tsc_reliable before unsynchronized_tsc

unsynchronized_tsc() checks value of tsc_clocksource_reliable which is set by
check_system_tsc_reliable(). It's better to move check_system_tsc_reliable() at
front, or else this check makes no sense.

Though X86_FEATURE_CONSTANT_TSC is usually set for TSC reliable system, just in
case.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...cle.com>
---
  arch/x86/kernel/tsc.c |    4 ++--
  1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 714dfba..a316bdd 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1412,11 +1412,11 @@ void __init tsc_init(void)
  
  	use_tsc_delay();
  
+	check_system_tsc_reliable();
+
  	if (unsynchronized_tsc())
  		mark_tsc_unstable("TSCs unsynchronized");
  
-	check_system_tsc_reliable();
-
  	detect_art();
  }
  
-- 
1.7.3