On Thu, Aug 07, 2025 at 01:49:10PM +0200, Juraj Marcin wrote:
> From: Juraj Marcin <[email protected]>
>
> Depending on where an error during postcopy_start() happens, the state
> can be either "active", "device" or "cancelling", but never
> "postcopy-active". Migration state is transitioned to "postcopy-active"
> only just before a successful return from the function.
>
> Accept any state except "cancelling" when transitioning to "failed"
> state.
>
> Signed-off-by: Juraj Marcin <[email protected]>
> ---
> migration/migration.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 10c216d25d..e5ce2940d5 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2872,8 +2872,9 @@ static int postcopy_start(MigrationState *ms, Error
> **errp)
> fail_closefb:
> qemu_fclose(fb);
> fail:
> - migrate_set_state(&ms->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
> - MIGRATION_STATUS_FAILED);
> + if ( ms->state != MIGRATION_STATUS_CANCELLING) {
> + migrate_set_state(&ms->state, ms->state, MIGRATION_STATUS_FAILED);
> + }
Hmm, this might have been overlooked from my commit 48814111366b. Maybe
worth a Fixes and copy stable?
For example, I would expect the old code (prior of 48814111366b) still be
able to fail postcopy and resume src QEMU if qemu_savevm_send_packaged()
failed. Now, looks like it'll be stuck at "device" state..
The other thing is it also looks like a common pattern to set FAILED
meanwhile not messing with a CANCELLING stage. It's not easy to always
remember this, so maybe we should consider having a helper function?
migrate_set_failure(MigrationState *, Error *err);
Which could set err with migrate_set_error() (likely we could also
error_report() the error), and update FAILED iff it's not CANCELLING.
I saw three of such occurances that such helper may apply, but worth double
check:
postcopy_start[2725] if (ms->state != MIGRATION_STATUS_CANCELLING) {
migration_completion[3069] if (s->state != MIGRATION_STATUS_CANCELLING) {
igration_connect[4064] if (s->state != MIGRATION_STATUS_CANCELLING) {
If the cleanup looks worthwhile, and if the Fixes apply, we could have the
cleanup patch on top of the fixes patch so patch 1 is easier to backport.
Thanks,
> migration_block_activate(NULL);
> migration_call_notifiers(ms, MIG_EVENT_PRECOPY_FAILED, NULL);
> bql_unlock();
> --
> 2.50.1
>
--
Peter Xu
