sh: cache secondary CPUs idle loop.

This provides a cache of the secondary CPUs idle loop for the cases where
hotplug simply enters a low power state instead of resetting or powering
off the core.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c
index 3711a76..21e7f8a 100644
--- a/arch/sh/kernel/smp.c
+++ b/arch/sh/kernel/smp.c
@@ -125,10 +125,15 @@
 	struct task_struct *tsk;
 	unsigned long timeout;
 
-	tsk = fork_idle(cpu);
-	if (IS_ERR(tsk)) {
-		printk(KERN_ERR "Failed forking idle task for cpu %d\n", cpu);
-		return PTR_ERR(tsk);
+	tsk = cpu_data[cpu].idle;
+	if (!tsk) {
+		tsk = fork_idle(cpu);
+		if (IS_ERR(tsk)) {
+			pr_err("Failed forking idle task for cpu %d\n", cpu);
+			return PTR_ERR(tsk);
+		}
+
+		cpu_data[cpu].idle = tsk;
 	}
 
 	per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;