[S390] console_unblank woes.

The software watchdog calls machine_restart from a timer function.
The s390 machine_restart calls console_unblank to flush the console
output. This is needed for panic to get the panic message printed.
If console_unblank is called in interrupt a BUG is triggered in
acquire_console_sem. That makes the software watchdog panic instead
of restarting the machine. To get around this problem the call to
console_unblank is made conditionally on !in_interrupt() ||
oops_in_progress.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 18 insertions, 3 deletions

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index b282034452a4..813444aac7d7 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -289,19 +289,34 @@ void (*_machine_power_off)(void) = do_machine_power_off_nonsmp;
 
 void machine_restart(char *command)
 {
-        console_unblank();
+        if (!in_interrupt() || oops_in_progress)
+                /*
+                 * Only unblank the console if we are called in enabled
+                 * context or a bust_spinlocks cleared the way for us.
+                 */
+                console_unblank();
         _machine_restart(command);
 }
 
 void machine_halt(void)
 {
-        console_unblank();
+        if (!in_interrupt() || oops_in_progress)
+                /*
+                 * Only unblank the console if we are called in enabled
+                 * context or a bust_spinlocks cleared the way for us.
+                 */
+                console_unblank();
         _machine_halt();
 }
 
 void machine_power_off(void)
 {
-        console_unblank();
+        if (!in_interrupt() || oops_in_progress)
+                /*
+                 * Only unblank the console if we are called in enabled
+                 * context or a bust_spinlocks cleared the way for us.
+                 */
+                console_unblank();
         _machine_power_off();
 }