From: Bhavana Nagendra <bnagendr@redhat.com>
Date: Mon, 14 Jan 2008 14:29:01 -0500
Subject: [x86] fix TSC feature flag check on AMD
Message-id: 20080114192900.19849.86639.sendpatchset@localhost.localdomain
O-Subject: [RHEL5.2 PATCH] Fix a bug in the TSC synchronize code
Bugzilla: 428479

Resolves BZ 428479

The code snippet that checks the constant TSC feature flag (X86_FEATURE_CONSTANT_TSC)
was in the wrong place, that would cause it to not be executed on AMD systems.

Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1109674

Please ACK.

Acked-by: Brian Maly <bmaly@redhat.com>
Acked-by: Alexander Viro <aviro@redhat.com>

diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index efa5efd..867760d 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -1022,6 +1022,12 @@ __cpuinit int unsynchronized_tsc(void)
 	if (apic_is_clustered_box())
 		return 1;
 #endif
+
+	/* AMD systems with constant TSCs have synchronized clocks */
+	if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
+		(boot_cpu_has(X86_FEATURE_CONSTANT_TSC)))
+	return 0;
+
 	/* Most intel systems have synchronized TSCs except for
 	   multi node systems */
  	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
@@ -1029,11 +1035,6 @@ __cpuinit int unsynchronized_tsc(void)
 		/* But TSC doesn't tick in C3 so don't use it there */
 		if (acpi_fadt.length > 0 && acpi_fadt.plvl3_lat < 1000)
 			return 1;
-
-		/* AMD systems with constant TSCs have synchronized clocks */
-		if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) && 
-			(boot_cpu_has(X86_FEATURE_CONSTANT_TSC)))
-			return 0;
 #endif
  		return 0;
 	}