From c5d65600aa68f3dd150752753a2009792a1216a4 Mon Sep 17 00:00:00 2001
From: Andi Kleen <ak@suse.de>
Date: Wed, 11 Jan 2006 22:45:15 +0100
Subject: [PATCH] --- yaml --- r: 17983 b: refs/heads/master c:
 737c5c3bde5641af9c24e3a60366674af72a43ef h: refs/heads/master i:   17981:
 dcb67846080f31106b02650e5e2a8e45b0936d9b   17979:
 feb353210af55f17587f56b8de7c69e87b89a3a7   17975:
 13672911cef925e3fcc17702a916c2516383c989   17967:
 f8e8f2eea703d1c6df0ce55c589ee313d9c71f0d   17951:
 79bf74f69ec70f52e5424b7992d9f0f2e88d9f4f   17919:
 75e8ca1c5d5316a0863a96672c14ecfbc0182bed v: v3

---
 [refs]                             | 2 +-
 trunk/arch/x86_64/kernel/smpboot.c | 8 +++++++-
 trunk/arch/x86_64/kernel/time.c    | 4 ++--
 trunk/include/asm-x86_64/proto.h   | 2 ++
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 5613f7be2447..57742805f117 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3c0217511313a46039137d2dab30fdb1c5a65e64
+refs/heads/master: 737c5c3bde5641af9c24e3a60366674af72a43ef
diff --git a/trunk/arch/x86_64/kernel/smpboot.c b/trunk/arch/x86_64/kernel/smpboot.c
index e6af93b51dce..994728564d6b 100644
--- a/trunk/arch/x86_64/kernel/smpboot.c
+++ b/trunk/arch/x86_64/kernel/smpboot.c
@@ -335,7 +335,13 @@ static __cpuinit void sync_tsc(unsigned int master)
 
 static void __cpuinit tsc_sync_wait(void)
 {
-	if (notscsync || !cpu_has_tsc)
+	/*
+	 * When the CPU has synchronized TSCs assume the BIOS
+  	 * or the hardware already synced.  Otherwise we could
+	 * mess up a possible perfect synchronization with a
+	 * not-quite-perfect algorithm.
+	 */
+	if (notscsync || !cpu_has_tsc || !unsynchronized_tsc())
 		return;
 	sync_tsc(0);
 }
diff --git a/trunk/arch/x86_64/kernel/time.c b/trunk/arch/x86_64/kernel/time.c
index 211bf0e51d9d..f8d4b69388d2 100644
--- a/trunk/arch/x86_64/kernel/time.c
+++ b/trunk/arch/x86_64/kernel/time.c
@@ -953,7 +953,7 @@ void __init time_init(void)
  * Make an educated guess if the TSC is trustworthy and synchronized
  * over all CPUs.
  */
-static __init int unsynchronized_tsc(void)
+__init int unsynchronized_tsc(void)
 {
 #ifdef CONFIG_SMP
 	if (oem_force_hpet_timer())
@@ -964,7 +964,7 @@ static __init int unsynchronized_tsc(void)
  		return 0;
 #endif
  	/* Assume multi socket systems are not synchronized */
- 	return num_online_cpus() > 1;
+ 	return num_present_cpus() > 1;
 }
 
 /*
diff --git a/trunk/include/asm-x86_64/proto.h b/trunk/include/asm-x86_64/proto.h
index 56dc70b7a6e4..115e496c6139 100644
--- a/trunk/include/asm-x86_64/proto.h
+++ b/trunk/include/asm-x86_64/proto.h
@@ -89,6 +89,8 @@ extern void check_efer(void);
 
 extern int unhandled_signal(struct task_struct *tsk, int sig);
 
+extern int unsynchronized_tsc(void);
+
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
 
 extern void gart_parse_options(char *);