[PATCH 3/3] migration: Free the JSON writer during snapshots

[Fabiano Rosas <farosas@suse.de>]

The JSON writer is created at migrate_init() and freed at
migration_cleanup(). The latter is not called for snapshots. Add a
call to migration_cleanup_json_writer() to make sure it doesn't leak:

Indirect leak of 24 byte(s) in 1 object(s) allocated from:
    #0 0x55ca12aabca0 in malloc
    #1 0x7fd97d7e595d in g_malloc
    #2 0x7fd97d7ffe38 in g_slice_alloc
    #3 0x7fd97d8042e2 in g_string_sized_new
    #4 0x55ca1571dd6b in json_writer_new ../qobject/json-writer.c:36:24
    #5 0x55ca12e0de56 in migrate_init ../migration/migration.c:1718:21
    #6 0x55ca12ec8fe6 in qemu_savevm_state ../migration/savevm.c:1921:11
    #7 0x55ca12ec8b93 in save_snapshot ../migration/savevm.c:3380:11

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/migration.c | 2 +-
 migration/migration.h | 1 +
 migration/savevm.c    | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index b413d28622..d0b864a760 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1330,7 +1330,7 @@ void migrate_set_state(MigrationStatus *state, MigrationStatus old_state,
     }
 }
 
-static void migration_cleanup_json_writer(MigrationState *s)
+void migration_cleanup_json_writer(MigrationState *s)
 {
     g_clear_pointer(&s->vmdesc, json_writer_free);
 }
diff --git a/migration/migration.h b/migration/migration.h
index e47ff4e3d1..683bc7bdd5 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -633,4 +633,5 @@ void migration_bitmap_sync_precopy(bool last_stage);
 void dirty_bitmap_mig_init(void);
 bool should_send_vmdesc(void);
 
+void migration_cleanup_json_writer(MigrationState *s);
 #endif
diff --git a/migration/savevm.c b/migration/savevm.c
index 8d4bdc28ab..a31f34f25c 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -3404,7 +3404,7 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
 
  the_end:
     bdrv_drain_all_end();
-
+    migration_cleanup_json_writer(migrate_get_current());
     vm_resume(saved_state);
     return ret == 0;
 }
-- 
2.53.0