[S390] idle: Fix machine check handling in idle loop.

If a machine check handling is pending when the idle loop is entered
default_idle will be left with timer ticks and virtual timer disabled.
Fix this by "calling" the idle_chain. Also a BUG_ON(!in_interrupt) in
start_hz_timer must be removed since the function now gets called from
non interrupt context as well.

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

2 files changed, 4 insertions, 2 deletions

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 1c59ec161cf8..ce203154d8ce 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -152,6 +152,10 @@ static void default_idle(void)
         local_mcck_disable();
         if (test_thread_flag(TIF_MCCK_PENDING)) {
                 local_mcck_enable();
+                /* disable monitor call class 0 */
+                __ctl_clear_bit(8, 15);
+                atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
+                                           hcpu);
                 local_irq_enable();
                 s390_handle_mcck();
                 return;
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 76a5dd1b4ce9..cb232c155360 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -209,8 +209,6 @@ static void stop_hz_timer(void)
  */
 static void start_hz_timer(void)
 {
-        BUG_ON(!in_interrupt());
-
         if (!cpu_isset(smp_processor_id(), nohz_cpu_mask))
                 return;
         account_ticks(get_clock());