[PATCH 24/33] migration: push Error **errp into qemu_savevm_state_setup()

["Daniel P. Berrangé" <berrange@redhat.com>]

This is an incremental step in converting vmstate loading code to report
via Error objects instead of printing directly to the console/monitor.

In doing this the callers now actually honour the failures that can
be reported instead of carrying on as if everything was normal.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 migration/migration.c |  9 ++++++++-
 migration/savevm.c    | 18 ++++++++++++------
 migration/savevm.h    |  2 +-
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index a85d101ad8..e814d47796 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3522,6 +3522,7 @@ static void *migration_thread(void *opaque)
     int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
     MigThrError thr_error;
     bool urgent = false;
+    Error *local_err = NULL;
 
     rcu_register_thread();
 
@@ -3556,7 +3557,12 @@ static void *migration_thread(void *opaque)
         qemu_savevm_send_colo_enable(s->to_dst_file);
     }
 
-    qemu_savevm_state_setup(s->to_dst_file);
+    if (qemu_savevm_state_setup(s->to_dst_file, &local_err) < 0) {
+        error_report_err(local_err);
+        migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
+                          MIGRATION_STATUS_FAILED);
+        goto out;
+    }
 
     if (qemu_savevm_state_guest_unplug_pending()) {
         migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
@@ -3609,6 +3615,7 @@ static void *migration_thread(void *opaque)
 
     trace_migration_thread_after_loop();
     migration_iteration_finish(s);
+ out:
     object_unref(OBJECT(s));
     rcu_unregister_thread();
     return NULL;
diff --git a/migration/savevm.c b/migration/savevm.c
index fdf8b6edfb..318ba547bc 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1159,10 +1159,9 @@ bool qemu_savevm_state_guest_unplug_pending(void)
     return false;
 }
 
-void qemu_savevm_state_setup(QEMUFile *f)
+int qemu_savevm_state_setup(QEMUFile *f, Error **errp)
 {
     SaveStateEntry *se;
-    Error *local_err = NULL;
     int ret;
 
     trace_savevm_state_setup();
@@ -1180,14 +1179,18 @@ void qemu_savevm_state_setup(QEMUFile *f)
         ret = se->ops->save_setup(f, se->opaque);
         save_section_footer(f, se);
         if (ret < 0) {
+            error_setg_errno(errp, -ret,
+                             "Failed to setup device state handler");
             qemu_file_set_error(f, ret);
-            break;
+            return -1;
         }
     }
 
-    if (precopy_notify(PRECOPY_NOTIFY_SETUP, &local_err)) {
-        error_report_err(local_err);
+    if (precopy_notify(PRECOPY_NOTIFY_SETUP, errp)) {
+        return -1;
     }
+
+    return 0;
 }
 
 int qemu_savevm_state_resume_prepare(MigrationState *s)
@@ -1537,8 +1540,11 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp)
 
     qemu_mutex_unlock_iothread();
     qemu_savevm_state_header(f);
-    qemu_savevm_state_setup(f);
+    ret = qemu_savevm_state_setup(f, errp);
     qemu_mutex_lock_iothread();
+    if (ret < 0) {
+        goto fail;
+    }
 
     while (1) {
         ret = qemu_savevm_state_iterate(f, false, errp);
diff --git a/migration/savevm.h b/migration/savevm.h
index e187640806..b7133655f2 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -30,7 +30,7 @@
 #define QEMU_VM_SECTION_FOOTER       0x7e
 
 bool qemu_savevm_state_blocked(Error **errp);
-void qemu_savevm_state_setup(QEMUFile *f);
+int qemu_savevm_state_setup(QEMUFile *f, Error **errp);
 bool qemu_savevm_state_guest_unplug_pending(void);
 int qemu_savevm_state_resume_prepare(MigrationState *s);
 void qemu_savevm_state_header(QEMUFile *f);
-- 
2.29.2