[S390] smp/idle: call init_idle() before starting a new cpu

Call init_idle() which (re-)initializes the idle task structure before
it gets used on a new cpu.
That way we can also get rid of the odd preempt_enable_no_resched()
call we have in the cpu offline path within cpu_idle(). That call
prevented preempt count imbalances between cpu hotplug operations.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 3 insertions, 6 deletions

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index b825b3e1cb17..c2fffb57d727 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -42,6 +42,7 @@
 #include <asm/irq.h>
 #include <asm/timer.h>
 #include <asm/nmi.h>
+#include <asm/smp.h>
 #include "entry.h"
 
 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
@@ -76,13 +77,8 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
  */
 static void default_idle(void)
 {
-        /* CPU is going idle. */
-#ifdef CONFIG_HOTPLUG_CPU
-        if (cpu_is_offline(smp_processor_id())) {
-                preempt_enable_no_resched();
+        if (cpu_is_offline(smp_processor_id()))
                 cpu_die();
-        }
-#endif
         local_irq_disable();
         if (need_resched()) {
                 local_irq_enable();
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 8e84b5af49ba..10766be524eb 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -575,6 +575,7 @@ int __cpuinit __cpu_up(unsigned int cpu)
                 idle = c_idle.idle;
                 current_set[cpu] = c_idle.idle;
         }
+        init_idle(idle, cpu);
         if (smp_alloc_lowcore(cpu))
                 return -ENOMEM;
         do {