1 files changed, 57 insertions, 16 deletions

diff --git a/arch/sh/kernel/idle.c b/arch/sh/kernel/idle.c
index 27ff2dc093c7..8e61241230cb 100644
--- a/arch/sh/kernel/idle.c
+++ b/arch/sh/kernel/idle.c
@@ -21,7 +21,7 @@
 #include <asm/atomic.h>
 
 static int hlt_counter;
-void (*pm_idle)(void);
+void (*pm_idle)(void) = NULL;
 void (*pm_power_off)(void);
 EXPORT_SYMBOL(pm_power_off);
 
@@ -39,41 +39,68 @@ static int __init hlt_setup(char *__unused)
 }
 __setup("hlt", hlt_setup);
 
+static inline int hlt_works(void)
+{
+        return !hlt_counter;
+}
+
+/*
+ * On SMP it's slightly faster (but much more power-consuming!)
+ * to poll the ->work.need_resched flag instead of waiting for the
+ * cross-CPU IPI to arrive. Use this option with caution.
+ */
+static void poll_idle(void)
+{
+        local_irq_enable();
+        while (!need_resched())
+                cpu_relax();
+}
+
 void default_idle(void)
 {
-        if (!hlt_counter) {
+        if (hlt_works()) {
                 clear_thread_flag(TIF_POLLING_NRFLAG);
                 smp_mb__after_clear_bit();
-                set_bl_bit();
-                stop_critical_timings();
 
-                while (!need_resched())
+                if (!need_resched()) {
+                        local_irq_enable();
                         cpu_sleep();
+                }
 
-                start_critical_timings();
-                clear_bl_bit();
                 set_thread_flag(TIF_POLLING_NRFLAG);
         } else
-                while (!need_resched())
-                        cpu_relax();
+                poll_idle();
 }
 
+/*
+ * The idle thread. There's no useful work to be done, so just try to conserve
+ * power and have a low exit latency (ie sit in a loop waiting for somebody to
+ * say that they'd like to reschedule)
+ */
 void cpu_idle(void)
 {
+        unsigned int cpu = smp_processor_id();
+
         set_thread_flag(TIF_POLLING_NRFLAG);
 
         /* endless idle loop with no priority at all */
         while (1) {
-                void (*idle)(void) = pm_idle;
+                tick_nohz_stop_sched_tick(1);
 
-                if (!idle)
-                        idle = default_idle;
+                while (!need_resched() && cpu_online(cpu)) {
+                        local_irq_disable();
+                        /* Don't trace irqs off for idle */
+                        stop_critical_timings();
+                        pm_idle();
+                        /*
+                         * Sanity check to ensure that pm_idle() returns
+                         * with IRQs enabled
+                         */
+                        WARN_ON(irqs_disabled());
+                        start_critical_timings();
+                }
 
-                tick_nohz_stop_sched_tick(1);
-                while (!need_resched())
-                        idle();
                 tick_nohz_restart_sched_tick();
-
                 preempt_enable_no_resched();
                 schedule();
                 preempt_disable();
@@ -81,6 +108,20 @@ void cpu_idle(void)
         }
 }
 
+void __cpuinit select_idle_routine(void)
+{
+        /*
+         * If a platform has set its own idle routine, leave it alone.
+         */
+        if (pm_idle)
+                return;
+
+        if (hlt_works())
+                pm_idle = default_idle;
+        else
+                pm_idle = poll_idle;
+}
+
 static void do_nothing(void *unused)
 {
 }