migration: Display error in query-migrate irrelevant of status

Display it as long as being set, irrelevant of FAILED status.  E.g., it may
also be applicable to PAUSED stage of postcopy, to provide hint on what has
gone wrong.

The error_mutex seems to be overlooked when referencing the error, add it
to be very safe.

This will change QAPI behavior by showing up error message outside !FAILED
status, but it's intended and doesn't expect to break anyone.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2018404
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231004220240.167175-2-peterx@redhat.com>

diff --git a/migration/migration.c b/migration/migration.c
index 2057e4213442e808c4dd42c5067216c6da9d7097..57f9e9ed0c3924b6687c7b8d41b7454ea9b4c591 100644 (file)
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1060,9 +1060,6 @@ static void fill_source_migration_info(MigrationInfo *info)
         break;
     case MIGRATION_STATUS_FAILED:
         info->has_status = true;
-        if (s->error) {
-            info->error_desc = g_strdup(error_get_pretty(s->error));
-        }
         break;
     case MIGRATION_STATUS_CANCELLED:
         info->has_status = true;
@@ -1072,6 +1069,11 @@ static void fill_source_migration_info(MigrationInfo *info)
         break;
     }
     info->status = state;
+
+    QEMU_LOCK_GUARD(&s->error_mutex);
+    if (s->error) {
+        info->error_desc = g_strdup(error_get_pretty(s->error));
+    }
 }
 
 static void fill_destination_migration_info(MigrationInfo *info)

diff --git a/qapi/migration.json b/qapi/migration.json
index d8f3bbd7b038b2b5ca88491e1ef1185919afccb7..d7dfaa5db907918fd8f0ab058409020ad2ec3845 100644 (file)
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -230,9 +230,8 @@
 #     throttled during auto-converge.  This is only present when
 #     auto-converge has started throttling guest cpus.  (Since 2.7)
 #
-# @error-desc: the human readable error description string, when
-#     @status is 'failed'. Clients should not attempt to parse the
-#     error strings.  (Since 2.7)
+# @error-desc: the human readable error description string. Clients
+#     should not attempt to parse the error strings.  (Since 2.7)
 #
 # @postcopy-blocktime: total time when all vCPU were blocked during
 #     postcopy live migration.  This is only present when the