s390: 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>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20120420124557.652574928@linutronix.de

2 files changed, 3 insertions, 31 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 9015060919a0..15cab3ee44e8 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -122,6 +122,7 @@ config S390
         select ARCH_INLINE_WRITE_UNLOCK_BH
         select ARCH_INLINE_WRITE_UNLOCK_IRQ
         select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
+        select GENERIC_SMP_IDLE_THREAD
 
 config SCHED_OMIT_FRAME_POINTER
         def_bool y
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index fc827aa8f9ca..992b7b93a574 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -85,7 +85,6 @@ enum {
 
 struct pcpu {
         struct cpu cpu;
-        struct task_struct *idle;       /* idle process for the cpu */
         struct _lowcore *lowcore;       /* lowcore page(s) for the cpu */
         unsigned long async_stack;      /* async stack for the cpu */
         unsigned long panic_stack;      /* panic stack for the cpu */
@@ -721,26 +720,9 @@ static void __cpuinit smp_start_secondary(void *cpuvoid)
         cpu_idle();
 }
 
-struct create_idle {
-        struct work_struct work;
-        struct task_struct *idle;
-        struct completion done;
-        int cpu;
-};
-
-static void __cpuinit smp_fork_idle(struct work_struct *work)
-{
-        struct create_idle *c_idle;
-
-        c_idle = container_of(work, struct create_idle, work);
-        c_idle->idle = fork_idle(c_idle->cpu);
-        complete(&c_idle->done);
-}
-
 /* Upping and downing of CPUs */
 int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
 {
-        struct create_idle c_idle;
         struct pcpu *pcpu;
         int rc;
 
@@ -750,22 +732,12 @@ int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
         if (pcpu_sigp_retry(pcpu, sigp_initial_cpu_reset, 0) !=
             sigp_order_code_accepted)
                 return -EIO;
-        if (!pcpu->idle) {
-                c_idle.done = COMPLETION_INITIALIZER_ONSTACK(c_idle.done);
-                INIT_WORK_ONSTACK(&c_idle.work, smp_fork_idle);
-                c_idle.cpu = cpu;
-                schedule_work(&c_idle.work);
-                wait_for_completion(&c_idle.done);
-                if (IS_ERR(c_idle.idle))
-                        return PTR_ERR(c_idle.idle);
-                pcpu->idle = c_idle.idle;
-        }
-        init_idle(pcpu->idle, cpu);
+
         rc = pcpu_alloc_lowcore(pcpu, cpu);
         if (rc)
                 return rc;
         pcpu_prepare_secondary(pcpu, cpu);
-        pcpu_attach_task(pcpu, pcpu->idle);
+        pcpu_attach_task(pcpu, tidle);
         pcpu_start_fn(pcpu, smp_start_secondary, NULL);
         while (!cpu_online(cpu))
                 cpu_relax();
@@ -852,7 +824,6 @@ void __init smp_prepare_boot_cpu(void)
         struct pcpu *pcpu = pcpu_devices;
 
         boot_cpu_address = stap();
-        pcpu->idle = current;
         pcpu->state = CPU_STATE_CONFIGURED;
         pcpu->address = boot_cpu_address;
         pcpu->lowcore = (struct _lowcore *)(unsigned long) store_prefix();