1 files changed, 19 insertions, 13 deletions

diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index b0a07801d9d..dd53c58f64f 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -205,7 +205,7 @@ void cpu_idle(void)
 void cpu_idle_wait(void)
 {
 	unsigned int cpu, this_cpu = get_cpu();
-	cpumask_t map;
+	cpumask_t map, tmp = current->cpus_allowed;
 
 	set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
 	put_cpu();
@@ -227,6 +227,8 @@ void cpu_idle_wait(void)
 		}
 		cpus_and(map, map, cpu_online_map);
 	} while (!cpus_empty(map));
+
+	set_cpus_allowed(current, tmp);
 }
 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 
@@ -236,20 +238,28 @@ EXPORT_SYMBOL_GPL(cpu_idle_wait);
  * We execute MONITOR against need_resched and enter optimized wait state
  * through MWAIT. Whenever someone changes need_resched, we would be woken
  * up from MWAIT (without an IPI).
+ *
+ * New with Core Duo processors, MWAIT can take some hints based on CPU
+ * capability.
  */
-static void mwait_idle(void)
+void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
 {
-	local_irq_enable();
-
-	while (!need_resched()) {
+	if (!need_resched()) {
 		__monitor((void *)&current_thread_info()->flags, 0, 0);
 		smp_mb();
-		if (need_resched())
-			break;
-		__mwait(0, 0);
+		if (!need_resched())
+			__mwait(eax, ecx);
 	}
 }
 
+/* Default MONITOR/MWAIT with no hints, used for default C1 state */
+static void mwait_idle(void)
+{
+	local_irq_enable();
+	while (!need_resched())
+		mwait_idle_with_hints(0, 0);
+}
+
 void __devinit select_idle_routine(const struct cpuinfo_x86 *c)
 {
 	if (cpu_has(c, X86_FEATURE_MWAIT)) {
@@ -328,7 +338,6 @@ extern void kernel_thread_helper(void);
 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 {
 	struct pt_regs regs;
-	int err;
 
 	memset(&regs, 0, sizeof(regs));
 
@@ -343,10 +352,7 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 	regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
 
 	/* Ok, create the new process.. */
-	err = do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
-	if (err == 0) /* terminate kernel stack */
-		task_pt_regs(current)->eip = 0;
-	return err;
+	return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 }
 EXPORT_SYMBOL(kernel_thread);