alpha: 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: Matt Turner <mattst88@gmail.com>
Link: http://lkml.kernel.org/r/20120420124557.914631081@linutronix.de

arch/alpha/Kconfig

@@ -15,6 +15,7 @@ config ALPHA
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_OPTIONAL_GPIOLIB
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
+	select GENERIC_SMP_IDLE_THREAD
 	help
 	  The Alpha is a 64-bit general-purpose processor designed and
 	  marketed by the Digital Equipment Corporation of blessed memory,

arch/alpha/kernel/smp.c

@@ -357,24 +357,10 @@ secondary_cpu_start(int cpuid, struct task_struct *idle)
  * Bring one cpu online.
  */
 static int __cpuinit
-smp_boot_one_cpu(int cpuid)
+smp_boot_one_cpu(int cpuid, struct task_struct *idle)
 {
-	struct task_struct *idle;
 	unsigned long timeout;
 
-	/* Cook up an idler for this guy.  Note that the address we
-	   give to kernel_thread is irrelevant -- it's going to start
-	   where HWRPB.CPU_restart says to start.  But this gets all
-	   the other task-y sort of data structures set up like we
-	   wish.  We can't use kernel_thread since we must avoid
-	   rescheduling the child.  */
-	idle = fork_idle(cpuid);
-	if (IS_ERR(idle))
-		panic("failed fork for CPU %d", cpuid);
-
-	DBGS(("smp_boot_one_cpu: CPU %d state 0x%lx flags 0x%lx\n",
-	      cpuid, idle->state, idle->flags));
-
 	/* Signal the secondary to wait a moment.  */
 	smp_secondary_alive = -1;
 
@@ -489,7 +475,7 @@ smp_prepare_boot_cpu(void)
 int __cpuinit
 __cpu_up(unsigned int cpu, struct task_struct *tidle)
 {
-	smp_boot_one_cpu(cpu);
+	smp_boot_one_cpu(cpu, tidle);
 
 	return cpu_online(cpu) ? 0 : -ENOSYS;
 }