[S390] smp: fix sigp stop handling

According to the architecture a cpu must not necessarily enter stopped
state after completion of a sigp instruction with "stop" order code.
So remove the BUG() statement after self sending sigp stop to avoid
that it ever gets reached.
Also add a sigp busy check to make sure that the order gets delivered.

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

1 files changed, 3 insertions, 4 deletions

diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index ee57a42e6e93..4890ac6d7faa 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -1595,10 +1595,9 @@ static void stop_run(struct shutdown_trigger *trigger)
 {
         if (strcmp(trigger->name, ON_PANIC_STR) == 0)
                 disabled_wait((unsigned long) __builtin_return_address(0));
-        else {
-                signal_processor(smp_processor_id(), sigp_stop);
-                for (;;);
-        }
+        while (signal_processor(smp_processor_id(), sigp_stop) == sigp_busy)
+                cpu_relax();
+        for (;;);
 }
 
 static struct shutdown_action stop_action = {SHUTDOWN_ACTION_STOP_STR,