[PULL 19/25] migration: notifier error checking

[peterx@redhat.com]

From: Steve Sistare <steven.sistare@oracle.com>

Check the status returned by migration notifiers for event type
MIG_EVENT_PRECOPY_SETUP, and report errors.  None of the notifiers
return an error status at this time.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1708622920-68779-10-git-send-email-steven.sistare@oracle.com
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/migration/misc.h |  8 +++++++-
 migration/migration.c    | 25 ++++++++++++++++---------
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/include/migration/misc.h b/include/migration/misc.h
index 4dc06a92b7..e4933b815b 100644
--- a/include/migration/misc.h
+++ b/include/migration/misc.h
@@ -72,6 +72,11 @@ typedef struct MigrationEvent {
     MigrationEventType type;
 } MigrationEvent;
 
+/*
+ * A MigrationNotifyFunc may return an error code and an Error object,
+ * but only when @e->type is MIG_EVENT_PRECOPY_SETUP.  The code is an int
+ * to allow for different failure modes and recovery actions.
+ */
 typedef int (*MigrationNotifyFunc)(NotifierWithReturn *notify,
                                    MigrationEvent *e, Error **errp);
 
@@ -93,7 +98,8 @@ void migration_add_notifier_mode(NotifierWithReturn *notify,
                                  MigrationNotifyFunc func, MigMode mode);
 
 void migration_remove_notifier(NotifierWithReturn *notify);
-void migration_call_notifiers(MigrationState *s, MigrationEventType type);
+int migration_call_notifiers(MigrationState *s, MigrationEventType type,
+                             Error **errp);
 bool migration_in_setup(MigrationState *);
 bool migration_has_finished(MigrationState *);
 bool migration_has_failed(MigrationState *);
diff --git a/migration/migration.c b/migration/migration.c
index 6a115d28b8..37c836b0b0 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1376,7 +1376,7 @@ static void migrate_fd_cleanup(MigrationState *s)
     }
     type = migration_has_failed(s) ? MIG_EVENT_PRECOPY_FAILED :
                                      MIG_EVENT_PRECOPY_DONE;
-    migration_call_notifiers(s, type);
+    migration_call_notifiers(s, type, NULL);
     block_cleanup_parameters();
     yank_unregister_instance(MIGRATION_YANK_INSTANCE);
 }
@@ -1489,13 +1489,18 @@ void migration_remove_notifier(NotifierWithReturn *notify)
     }
 }
 
-void migration_call_notifiers(MigrationState *s, MigrationEventType type)
+int migration_call_notifiers(MigrationState *s, MigrationEventType type,
+                             Error **errp)
 {
     MigMode mode = s->parameters.mode;
     MigrationEvent e;
+    int ret;
 
     e.type = type;
-    notifier_with_return_list_notify(&migration_state_notifiers[mode], &e, 0);
+    ret = notifier_with_return_list_notify(&migration_state_notifiers[mode],
+                                           &e, errp);
+    assert(!ret || type == MIG_EVENT_PRECOPY_SETUP);
+    return ret;
 }
 
 bool migration_in_setup(MigrationState *s)
@@ -2549,7 +2554,7 @@ static int postcopy_start(MigrationState *ms, Error **errp)
      * at the transition to postcopy and after the device state; in particular
      * spice needs to trigger a transition now
      */
-    migration_call_notifiers(ms, MIG_EVENT_PRECOPY_DONE);
+    migration_call_notifiers(ms, MIG_EVENT_PRECOPY_DONE, NULL);
 
     migration_downtime_end(ms);
 
@@ -2569,11 +2574,10 @@ static int postcopy_start(MigrationState *ms, Error **errp)
 
     ret = qemu_file_get_error(ms->to_dst_file);
     if (ret) {
-        error_setg(errp, "postcopy_start: Migration stream errored");
-        migrate_set_state(&ms->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
-                              MIGRATION_STATUS_FAILED);
+        error_setg_errno(errp, -ret, "postcopy_start: Migration stream error");
+        bql_lock();
+        goto fail;
     }
-
     trace_postcopy_preempt_enabled(migrate_postcopy_preempt());
 
     return ret;
@@ -2594,6 +2598,7 @@ fail:
             error_report_err(local_err);
         }
     }
+    migration_call_notifiers(ms, MIG_EVENT_PRECOPY_FAILED, NULL);
     bql_unlock();
     return -1;
 }
@@ -3613,7 +3618,9 @@ void migrate_fd_connect(MigrationState *s, Error *error_in)
         rate_limit = migrate_max_bandwidth();
 
         /* Notify before starting migration thread */
-        migration_call_notifiers(s, MIG_EVENT_PRECOPY_SETUP);
+        if (migration_call_notifiers(s, MIG_EVENT_PRECOPY_SETUP, &local_err)) {
+            goto fail;
+        }
     }
 
     migration_rate_set(rate_limit);
-- 
2.43.0