From 1fa744e6e91a895750b9980d13fcfc5791a0cd91 Mon Sep 17 00:00:00 2001
From: Shaohua Li <shaohua.li@intel.com>
Date: Fri, 6 Jan 2006 00:12:20 -0800
Subject: [PATCH] cpu hotplug/x86_64: disable interrupt in play_dead
With physical CPU hotplug, the CPU is hot removed and it should not receive
any interrupts. Disabling interrupt is much safer. This basically is what we
do in ia64 & x86.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
arch/x86_64/kernel/process.c | 5 +++--
include/asm-x86_64/system.h | 2 ++
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
index 7519fc520e..3060ed97b7 100644
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -157,7 +157,7 @@ EXPORT_SYMBOL_GPL(cpu_idle_wait);
DECLARE_PER_CPU(int, cpu_state);
#include <asm/nmi.h>
-/* We don't actually take CPU down, just spin without interrupts. */
+/* We halt the CPU with physical CPU hotplug */
static inline void play_dead(void)
{
idle_task_exit();
@@ -166,8 +166,9 @@ static inline void play_dead(void)
/* Ack it */
__get_cpu_var(cpu_state) = CPU_DEAD;
+ local_irq_disable();
while (1)
- safe_halt();
+ halt();
}
#else
static inline void play_dead(void)
diff --git a/include/asm-x86_64/system.h b/include/asm-x86_64/system.h
index 85348e02ad..b34cc2ee22 100644
--- a/include/asm-x86_64/system.h
+++ b/include/asm-x86_64/system.h
@@ -315,6 +315,8 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
#define local_irq_enable() __asm__ __volatile__("sti": : :"memory")
/* used in the idle loop; sti takes one instruction cycle to complete */
#define safe_halt() __asm__ __volatile__("sti; hlt": : :"memory")
+/* used when interrupts are already enabled or to shutdown the processor */
+#define halt() __asm__ __volatile__("hlt": : :"memory")
#define irqs_disabled() \
({ \
--
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