From 34eae2d7ef928a7e0e10cc30fe76839c005998eb Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Wed, 13 Apr 2022 12:33:29 +0100 Subject: [PATCH 07/11] migration: Read state once RH-Author: Dr. David Alan Gilbert RH-MergeRequest: 249: migration: Read state once RH-Bugzilla: 2074205 RH-Acked-by: Peter Xu RH-Acked-by: Laszlo Ersek RH-Acked-by: Jon Maloy RH-Acked-by: quintela1 RH-Commit: [1/1] 9aa47b492a646fce4e66ebd9b7d7a85286d16051 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 (cherry picked from commit 552de79bfdd5e9e53847eb3c6d6e4cd898a4370e) --- migration/migration.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index 51e6726dac..d8b24a2c91 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -1071,6 +1071,7 @@ 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; @@ -1090,7 +1091,7 @@ 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 */ @@ -1135,7 +1136,7 @@ static void fill_source_migration_info(MigrationInfo *info) info->has_status = true; break; } - info->status = s->state; + info->status = state; } typedef enum WriteTrackingSupport { -- 2.37.3