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, 4 insertions, 2 deletions

diff --git a/hw/intc/s390_flic_kvm.c b/hw/intc/s390_flic_kvm.c
index 7ead17ac3e..d208cb81c4 100644
--- a/hw/intc/s390_flic_kvm.c
+++ b/hw/intc/s390_flic_kvm.c
@@ -420,7 +420,7 @@ typedef struct KVMS390FLICStateMigTmp {
     uint8_t nimm;
 } KVMS390FLICStateMigTmp;
 
-static void kvm_flic_ais_pre_save(void *opaque)
+static int kvm_flic_ais_pre_save(void *opaque)
 {
     KVMS390FLICStateMigTmp *tmp = opaque;
     KVMS390FLICState *flic = tmp->parent;
@@ -433,11 +433,13 @@ static void kvm_flic_ais_pre_save(void *opaque)
 
     if (ioctl(flic->fd, KVM_GET_DEVICE_ATTR, &attr)) {
         error_report("Failed to retrieve kvm flic ais states");
-        return;
+        return -EINVAL;
     }
 
     tmp->simm = ais.simm;
     tmp->nimm = ais.nimm;
+
+    return 0;
 }
 
 static int kvm_flic_ais_post_load(void *opaque, int version_id)