[S390] Make sure enabled wait psw is loaded in default_idle.

If both NO_IDLE_HZ and VIRT_TIMER are disabled default_idle won't load
an enabled wait psw and busy loop instead. This is because the
idle_chain is empty and the return value of atomic_notifier_call_chain
will be NOTIFY_DONE, which causes default_idle to return instead of
loading an enabled wait psw.
Fix this by calling __atomic_notifier_call_chain instead and add proper
return value handling.

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

1 files changed, 9 insertions, 6 deletions

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index a6a4729e0e94..1c59ec161cf8 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -114,24 +114,27 @@ extern void s390_handle_mcck(void);
 static void default_idle(void)
 {
         int cpu, rc;
+        int nr_calls = 0;
+        void *hcpu;
 #ifdef CONFIG_SMP
         struct s390_idle_data *idle;
 #endif
 
         /* CPU is going idle. */
         cpu = smp_processor_id();
-
+        hcpu = (void *)(long)cpu;
         local_irq_disable();
         if (need_resched()) {
                 local_irq_enable();
                 return;
         }
 
-        rc = atomic_notifier_call_chain(&idle_chain,
-                                        S390_CPU_IDLE, (void *)(long) cpu);
-        if (rc != NOTIFY_OK && rc != NOTIFY_DONE)
-                BUG();
-        if (rc != NOTIFY_OK) {
+        rc = __atomic_notifier_call_chain(&idle_chain, S390_CPU_IDLE, hcpu, -1,
+                                          &nr_calls);
+        if (rc == NOTIFY_BAD) {
+                nr_calls--;
+                __atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
+                                             hcpu, nr_calls, NULL);
                 local_irq_enable();
                 return;
         }