vmstate: fix failed iotests case 68 and 91

This problem affects s390x only if we are running without KVM.
Basically, S390CPU.irqstate is unused if we do not use KVM,
and thus no buffer is allocated.
This causes size=0, first_elem=NULL and n_elems=1 in
vmstate_load_state and vmstate_save_state. And the assert fails.
With this fix we can go back to the old behavior and support
VMS_VBUFFER with size 0 and nullptr.

Signed-off-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

diff --git a/migration/vmstate.c b/migration/vmstate.c
index 78b3cd4..7b4a607 100644 (file)
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -109,7 +109,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
             vmstate_handle_alloc(first_elem, field, opaque);
             if (field->flags & VMS_POINTER) {
                 first_elem = *(void **)first_elem;
-                assert(first_elem  || !n_elems);
+                assert(first_elem || !n_elems || !size);
             }
             for (i = 0; i < n_elems; i++) {
                 void *curr_elem = first_elem + size * i;
@@ -117,7 +117,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
                 if (field->flags & VMS_ARRAY_OF_POINTER) {
                     curr_elem = *(void **)curr_elem;
                 }
-                if (!curr_elem) {
+                if (!curr_elem && size) {
                     /* if null pointer check placeholder and do not follow */
                     assert(field->flags & VMS_ARRAY_OF_POINTER);
                     ret = vmstate_info_nullptr.get(f, curr_elem, size, NULL);
@@ -325,7 +325,7 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
             trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems);
             if (field->flags & VMS_POINTER) {
                 first_elem = *(void **)first_elem;
-                assert(first_elem  || !n_elems);
+                assert(first_elem || !n_elems || !size);
             }
             for (i = 0; i < n_elems; i++) {
                 void *curr_elem = first_elem + size * i;
@@ -336,7 +336,7 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                     assert(curr_elem);
                     curr_elem = *(void **)curr_elem;
                 }
-                if (!curr_elem) {
+                if (!curr_elem && size) {
                     /* if null pointer write placeholder and do not follow */
                     assert(field->flags & VMS_ARRAY_OF_POINTER);
                     vmstate_info_nullptr.put(f, curr_elem, size, NULL, NULL);