From 552de79bfdd5e9e53847eb3c6d6e4cd898a4370e Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Wed, 13 Apr 2022 12:33:29 +0100 Subject: [PATCH] migration: Read state once The 'status' field for the migration is updated normally using an atomic operation from the migration thread. Most readers of it aren't that careful, and in most cases it doesn't matter. In query_migrate->fill_source_migration_info the 'state' is read twice; the first time to decide which state fields to fill in, and then secondly to copy the state to the status field; that can end up with a status that's inconsistent; e.g. setting up the fields for 'setup' and then having an 'active' status. In that case libvirt gets upset by the lack of ram info. The symptom is: libvirt.libvirtError: internal error: migration was active, but no RAM info was set Read the state exactly once in fill_source_migration_info. This is a possible fix for: https://bugzilla.redhat.com/show_bug.cgi?id=2074205 Signed-off-by: Dr. David Alan Gilbert Message-Id: <20220413113329.103696-1-dgilbert@redhat.com> Reviewed-by: Juan Quintela Reviewed-by: Peter Xu Signed-off-by: Dr. David Alan Gilbert --- migration/migration.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index cc00b344a9..5a31b23bd6 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -1084,6 +1084,7 @@ static void populate_disk_info(MigrationInfo *info) static void fill_source_migration_info(MigrationInfo *info) { MigrationState *s = migrate_get_current(); + int state = qatomic_read(&s->state); GSList *cur_blocker = migration_blockers; info->blocked_reasons = NULL; @@ -1103,7 +1104,7 @@ static void fill_source_migration_info(MigrationInfo *info) } info->has_blocked_reasons = info->blocked_reasons != NULL; - switch (s->state) { + switch (state) { case MIGRATION_STATUS_NONE: /* no migration has happened ever */ /* do not overwrite destination migration status */ @@ -1148,7 +1149,7 @@ static void fill_source_migration_info(MigrationInfo *info) info->has_status = true; break; } - info->status = s->state; + info->status = state; } typedef enum WriteTrackingSupport {