arm: Use generic idle thread allocation

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Tested-by: Frank Rowand <frank.rowand@am.sony.com>
Link: http://lkml.kernel.org/r/20120420124557.448826362@linutronix.de

arch/arm/Kconfig

@@ -34,6 +34,7 @@ config ARM
 	select CPU_PM if (SUSPEND || CPU_IDLE)
 	select GENERIC_PCI_IOMAP
 	select HAVE_BPF_JIT if NET
+	select GENERIC_SMP_IDLE_THREAD
 	help
 	  The ARM series is a line of low-power-consumption RISC chip designs
 	  licensed by ARM Ltd and targeted at embedded applications and

arch/arm/include/asm/cpu.h

@@ -16,7 +16,6 @@
 struct cpuinfo_arm {
 	struct cpu	cpu;
 #ifdef CONFIG_SMP
-	struct task_struct *idle;
 	unsigned int	loops_per_jiffy;
 #endif
 };

arch/arm/kernel/smp.c

@@ -60,31 +60,10 @@ enum ipi_msg_type {
 
 static DECLARE_COMPLETION(cpu_running);
 
-int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
+int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle)
 {
-	struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
-	struct task_struct *idle = ci->idle;
 	int ret;
 
-	/*
-	 * Spawn a new process manually, if not already done.
-	 * Grab a pointer to its task struct so we can mess with it
-	 */
-	if (!idle) {
-		idle = fork_idle(cpu);
-		if (IS_ERR(idle)) {
-			printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
-			return PTR_ERR(idle);
-		}
-		ci->idle = idle;
-	} else {
-		/*
-		 * Since this idle thread is being re-used, call
-		 * init_idle() to reinitialize the thread structure.
-		 */
-		init_idle(idle, cpu);
-	}
-
 	/*
 	 * We need to tell the secondary core where to find
 	 * its stack and the page tables.
@@ -318,9 +297,6 @@ void __init smp_cpus_done(unsigned int max_cpus)
 
 void __init smp_prepare_boot_cpu(void)
 {
-	unsigned int cpu = smp_processor_id();
-
-	per_cpu(cpu_data, cpu).idle = current;
 }
 
 void __init smp_prepare_cpus(unsigned int max_cpus)