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[PULL 18/18] migration: Read state once
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[PULL 18/18] migration: Read state once |
Date: |
Thu, 21 Apr 2022 17:40:43 +0100 |
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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 <dgilbert@redhat.com>
Message-Id: <20220413113329.103696-1-dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
migration/migration.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index 03ae53074b..4bc68100b4 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 {
--
2.35.1
- [PULL 04/18] migration: fix use of TLS PSK credentials with a UNIX socket, (continued)
- [PULL 04/18] migration: fix use of TLS PSK credentials with a UNIX socket, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 06/18] tests: merge code for UNIX and TCP migration pre-copy tests, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 09/18] tests: expand the migration precopy helper to support failures, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 10/18] migration: Postpone releasing MigrationState.hostname, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 08/18] tests: switch migration FD passing test to use common precopy helper, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 05/18] tests: switch MigrateStart struct to be stack allocated, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 11/18] migration: Drop multifd tls_hostname cache, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 13/18] migration: Move migrate_allow_multifd and helpers into migration.c, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 16/18] migration: Allow migrate-recover to run multiple times, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 14/18] migration: Export ram_load_postcopy(), Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 18/18] migration: Read state once,
Dr. David Alan Gilbert (git) <=
- [PULL 12/18] migration: Add pss.postcopy_requested status, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 15/18] migration: Move channel setup out of postcopy_try_recover(), Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 17/18] migration: Fix operator type, Dr. David Alan Gilbert (git), 2022/04/21
- Re: [PULL 00/18] migration queue, Dr. David Alan Gilbert, 2022/04/21
- [PULL 00/18] migration queue, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 04/18] migration: fix use of TLS PSK credentials with a UNIX socket, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 05/18] tests: switch MigrateStart struct to be stack allocated, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 01/18] tests: improve error message when saving TLS PSK file fails, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 08/18] tests: switch migration FD passing test to use common precopy helper, Dr. David Alan Gilbert (git), 2022/04/21
- [PULL 02/18] tests: support QTEST_TRACE env variable, Dr. David Alan Gilbert (git), 2022/04/21