From f1de9494554381ae317d613b0c6836c938d87e55 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Wed, 30 May 2012 11:47:00 -0400
Subject: [PATCH] --- yaml --- r: 310397 b: refs/heads/master c:
 f8988175fd70874d1fb3712b1c5d3bfc6d455202 h: refs/heads/master i:   310395:
 17c367bc5caa07e8ce942349f8c2ce0f541ca266 v: v3

---
 [refs]                             | 2 +-
 trunk/arch/x86/kernel/cpu/common.c | 8 +++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index a01cc84af35a..23b3b3d21810 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c0525a6972d3f1fb83058ef503e183475d6e4e26
+refs/heads/master: f8988175fd70874d1fb3712b1c5d3bfc6d455202
diff --git a/trunk/arch/x86/kernel/cpu/common.c b/trunk/arch/x86/kernel/cpu/common.c
index 82f29e70d058..6b9333b429ba 100644
--- a/trunk/arch/x86/kernel/cpu/common.c
+++ b/trunk/arch/x86/kernel/cpu/common.c
@@ -1101,14 +1101,20 @@ int is_debug_stack(unsigned long addr)
 		 addr > (__get_cpu_var(debug_stack_addr) - DEBUG_STKSZ));
 }
 
+static DEFINE_PER_CPU(u32, debug_stack_use_ctr);
+
 void debug_stack_set_zero(void)
 {
+	this_cpu_inc(debug_stack_use_ctr);
 	load_idt((const struct desc_ptr *)&nmi_idt_descr);
 }
 
 void debug_stack_reset(void)
 {
-	load_idt((const struct desc_ptr *)&idt_descr);
+	if (WARN_ON(!this_cpu_read(debug_stack_use_ctr)))
+		return;
+	if (this_cpu_dec_return(debug_stack_use_ctr) == 0)
+		load_idt((const struct desc_ptr *)&idt_descr);
 }
 
 #else	/* CONFIG_X86_64 */