[PATCH 16/16] migration: Trivial cleanup on JSON writer of vmstate_save()

[Peter Xu <peterx@redhat.com>]

Two small cleanups in the same section of vmstate_save():

  - Check vmdesc before the "mixed null/non-null data in array" logic, to
  be crystal clear that it's only about the JSON writer, not the vmstate on
  its own in the migration stream.

  - Since we have is_null variable now, use that to replace a check.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/vmstate.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/migration/vmstate.c b/migration/vmstate.c
index 82bd005a83..047a52af89 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -459,6 +459,8 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
                 }
 
                 /*
+                 * This logic only matters when dumping VM Desc.
+                 *
                  * Due to the fake nullptr handling above, if there's mixed
                  * null/non-null data, it doesn't make sense to emit a
                  * compressed array representation spanning the entire array
@@ -466,7 +468,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
                  * vs. nullptr). Search ahead for the next null/non-null element
                  * and start a new compressed array if found.
                  */
-                if (field->flags & VMS_ARRAY_OF_POINTER &&
+                if (vmdesc && (field->flags & VMS_ARRAY_OF_POINTER) &&
                     is_null != is_prev_null) {
 
                     is_prev_null = is_null;
@@ -504,7 +506,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
                                     written_bytes);
 
                 /* If we used a fake temp field.. free it now */
-                if (inner_field != field) {
+                if (is_null) {
                     g_clear_pointer((gpointer *)&inner_field, g_free);
                 }
 
-- 
2.47.0