migration: pre_save return int

Modify the pre_save method on VMStateDescription to return an int
rather than void so that it potentially can fail.

Changed zillions of devices to make them return 0; the only
case I've made it return non-0 is hw/intc/s390_flic_kvm.c that already
had an error_report/return case.

Note: If you add an error exit in your pre_save you must emit
an error_report to say why.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20170925112917.21340-2-dgilbert@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
index 363d1b5743..75ad1ba6f0 100644
--- a/hw/i386/kvm/clock.c
+++ b/hw/i386/kvm/clock.c
@@ -254,11 +254,13 @@ static const VMStateDescription kvmclock_reliable_get_clock = {
  *  final pages of memory (which happens between vm_stop()
  *  and pre_save()) takes max_downtime.
  */
-static void kvmclock_pre_save(void *opaque)
+static int kvmclock_pre_save(void *opaque)
 {
     KVMClockState *s = opaque;
 
     kvm_update_clock(s);
+
+    return 0;
 }
 
 static const VMStateDescription kvmclock_vmsd = {