1 files changed, 19 insertions, 13 deletions

diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index b0a07801d9df..dd53c58f64f1 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);