[S390] etr/stp: fix possible deadlock
Precreate stop_machine threads in case the machine supports ETR/STP.
Otherwise we might deadlock if a time sync operation gets scheduled
and the creation of stop_machine threads would cause disk I/O.
This is just the minimal fix.
The real fix would be to only precreate stop_machine threads if
ETR/STP is actually used. But that would be a rather large and
complicated patch.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index d649600..fc468ca 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -399,8 +399,10 @@
static void __init time_init_wq(void)
{
- if (!time_sync_wq)
- time_sync_wq = create_singlethread_workqueue("timesync");
+ if (time_sync_wq)
+ return;
+ time_sync_wq = create_singlethread_workqueue("timesync");
+ stop_machine_create();
}
/*