powerpc: 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: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Link: http://lkml.kernel.org/r/20120420124557.311212868@linutronix.de

2 files changed, 6 insertions, 69 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index feab3bad6d0..c8155350836 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -144,6 +144,7 @@ config PPC
         select HAVE_BPF_JIT if (PPC64 && NET)
         select HAVE_ARCH_JUMP_LABEL
         select ARCH_HAVE_NMI_SAFE_CMPXCHG
+        select GENERIC_SMP_IDLE_THREAD
 
 config EARLY_PRINTK
         bool
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index d38030fb347..e4cb34322de 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -57,27 +57,9 @@
 #define DBG(fmt...)
 #endif
 
-
-/* Store all idle threads, this can be reused instead of creating
-* a new thread. Also avoids complicated thread destroy functionality
-* for idle threads.
-*/
 #ifdef CONFIG_HOTPLUG_CPU
-/*
- * Needed only for CONFIG_HOTPLUG_CPU because __cpuinitdata is
- * removed after init for !CONFIG_HOTPLUG_CPU.
- */
-static DEFINE_PER_CPU(struct task_struct *, idle_thread_array);
-#define get_idle_for_cpu(x)      (per_cpu(idle_thread_array, x))
-#define set_idle_for_cpu(x, p)   (per_cpu(idle_thread_array, x) = (p))
-
 /* State of each CPU during hotplug phases */
 static DEFINE_PER_CPU(int, cpu_state) = { 0 };
-
-#else
-static struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ;
-#define get_idle_for_cpu(x)      (idle_thread_array[(x)])
-#define set_idle_for_cpu(x, p)   (idle_thread_array[(x)] = (p))
 #endif
 
 struct thread_info *secondary_ti;
@@ -429,57 +411,16 @@ int generic_check_cpu_restart(unsigned int cpu)
 }
 #endif
 
-struct create_idle {
-        struct work_struct work;
-        struct task_struct *idle;
-        struct completion done;
-        int cpu;
-};
-
-static void __cpuinit do_fork_idle(struct work_struct *work)
+static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle)
 {
-        struct create_idle *c_idle =
-                container_of(work, struct create_idle, work);
-
-        c_idle->idle = fork_idle(c_idle->cpu);
-        complete(&c_idle->done);
-}
-
-static int __cpuinit create_idle(unsigned int cpu)
-{
-        struct thread_info *ti;
-        struct create_idle c_idle = {
-                .cpu    = cpu,
-                .done   = COMPLETION_INITIALIZER_ONSTACK(c_idle.done),
-        };
-        INIT_WORK_ONSTACK(&c_idle.work, do_fork_idle);
-
-        c_idle.idle = get_idle_for_cpu(cpu);
-
-        /* We can't use kernel_thread since we must avoid to
-         * reschedule the child. We use a workqueue because
-         * we want to fork from a kernel thread, not whatever
-         * userspace process happens to be trying to online us.
-         */
-        if (!c_idle.idle) {
-                schedule_work(&c_idle.work);
-                wait_for_completion(&c_idle.done);
-        } else
-                init_idle(c_idle.idle, cpu);
-        if (IS_ERR(c_idle.idle)) {              
-                pr_err("Failed fork for CPU %u: %li", cpu, PTR_ERR(c_idle.idle));
-                return PTR_ERR(c_idle.idle);
-        }
-        ti = task_thread_info(c_idle.idle);
+        struct thread_info *ti = task_thread_info(idle);
 
 #ifdef CONFIG_PPC64
-        paca[cpu].__current = c_idle.idle;
+        paca[cpu].__current = idle;
         paca[cpu].kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD;
 #endif
         ti->cpu = cpu;
-        current_set[cpu] = ti;
-
-        return 0;
+        secondary_ti = current_set[cpu] = ti;
 }
 
 int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
@@ -490,12 +431,7 @@ int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
             (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
                 return -EINVAL;
 
-        /* Make sure we have an idle thread */
-        rc = create_idle(cpu);
-        if (rc)
-                return rc;
-
-        secondary_ti = current_set[cpu];
+        cpu_idle_thread_init(cpu, tidle);
 
         /* Make sure callin-map entry is 0 (can be leftover a CPU
          * hotplug