Re: [PATCH] Use multifd state to determine if multifd cleanup is needed

[Fabiano Rosas <farosas@suse.de>]

Peter Xu <peterx@redhat.com> writes:

> On Mon, Oct 07, 2024 at 03:44:51PM +0000, Shivam Kumar wrote:
>> If the client calls the QMP command to reset the migration
>> capabilities after the migration status is set to failed or cancelled
>
> Is cancelled ok?
>
> Asked because I think migrate_fd_cleanup() should still be in CANCELLING
> stage there, so no one can disable multifd capability before that, it
> should fail the QMP command.
>
> But FAILED indeed looks problematic.
>
> IIUC it's not only to multifd alone - is it a race condition that
> migrate_fd_cleanup() can be invoked without migration_is_running() keeps
> being true?  Then I wonder what happens if a concurrent QMP "migrate"
> happens together with migrate_fd_cleanup(), even with multifd always off.
>
> Do we perhaps need to cleanup everything before the state changes to
> FAILED?
>

Should we make CANCELLED the only terminal state aside from COMPLETED?
So migrate_fd_cleanup would set CANCELLED whenever it sees either
CANCELLING or FAILED.