2 files changed, 18 insertions, 42 deletions

diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index 8749b10d3805..8f42659ef9d2 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -100,22 +100,18 @@ EXPORT_SYMBOL(enable_hlt);
  */
 void default_idle(void)
 {
-        local_irq_enable();
-
         if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
                 current_thread_info()->status &= ~TS_POLLING;
                 smp_mb__after_clear_bit();
-                while (!need_resched()) {
-                        local_irq_disable();
-                        if (!need_resched())
-                                safe_halt();
-                        else
-                                local_irq_enable();
-                }
+                local_irq_disable();
+                if (!need_resched())
+                        safe_halt();    /* enables interrupts racelessly */
+                else
+                        local_irq_enable();
                 current_thread_info()->status |= TS_POLLING;
         } else {
-                while (!need_resched())
-                        cpu_relax();
+                /* loop is done by the caller */
+                cpu_relax();
         }
 }
 #ifdef CONFIG_APM_MODULE
@@ -129,14 +125,7 @@ EXPORT_SYMBOL(default_idle);
  */
 static void poll_idle (void)
 {
-        local_irq_enable();
-
-        asm volatile(
-                "2:"
-                "testl %0, %1;"
-                "rep; nop;"
-                "je 2b;"
-                : : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags));
+        cpu_relax();
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -257,8 +246,7 @@ void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
 static void mwait_idle(void)
 {
         local_irq_enable();
-        while (!need_resched())
-                mwait_idle_with_hints(0, 0);
+        mwait_idle_with_hints(0, 0);
 }
 
 void __devinit select_idle_routine(const struct cpuinfo_x86 *c)
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
index 7451a4c43c16..0b7b4caa4f74 100644
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -108,17 +108,15 @@ void exit_idle(void)
  */
 static void default_idle(void)
 {
-        local_irq_enable();
-
         current_thread_info()->status &= ~TS_POLLING;
         smp_mb__after_clear_bit();
-        while (!need_resched()) {
-                local_irq_disable();
-                if (!need_resched())
-                        safe_halt();
-                else
-                        local_irq_enable();
-        }
+        local_irq_disable();
+        if (!need_resched()) {
+                /* Enables interrupts one instruction before HLT.
+                   x86 special cases this so there is no race. */
+                safe_halt();
+        } else
+                local_irq_enable();
         current_thread_info()->status |= TS_POLLING;
 }
 
@@ -129,16 +127,7 @@ static void default_idle(void)
  */
 static void poll_idle (void)
 {
-        local_irq_enable();
-
-        asm volatile(
-                "2:"
-                "testl %0,%1;"
-                "rep; nop;"
-                "je 2b;"
-                : :
-                "i" (_TIF_NEED_RESCHED),
-                "m" (current_thread_info()->flags));
+        cpu_relax();
 }
 
 void cpu_idle_wait(void)
@@ -257,8 +246,7 @@ void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
 static void mwait_idle(void)
 {
         local_irq_enable();
-        while (!need_resched())
-                mwait_idle_with_hints(0,0);
+        mwait_idle_with_hints(0,0);
 }
 
 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)