Re: [PATCH v3 6/9] migration: Don't set FAILED state when cancelling

[Fabiano Rosas <farosas@suse.de>]

Peter Xu <peterx@redhat.com> writes:

> On Thu, Feb 13, 2025 at 02:59:24PM -0300, Fabiano Rosas wrote:
>> The expected outcome from qmp_migrate_cancel() is that the source
>> migration goes to the terminal state
>> MIGRATION_STATUS_CANCELLED. Anything different from this is a bug when
>> cancelling.
>> 
>> Make sure there is never a state transition from an unspecified state
>> into FAILED. Code that sets FAILED, should always either make sure
>> that the old state is not CANCELLING or specify the old state.
>> 
>> Note that the destination is allowed to go into FAILED, so there's no
>> issue there.
>> 
>> (I don't think this is relevant as a backport because cancelling does
>> work, it just doesn't show the right state at the end)
>> 
>> Fixes: 3dde8fdbad ("migration: Merge precopy/postcopy on switchover start")
>> Fixes: d0edb8a173 ("migration: Create the postcopy preempt channel asynchronously")
>> Fixes: 8518278a6a ("migration: implementation of background snapshot thread")
>> Fixes: bf78a046b9 ("migration: refactor migrate_fd_connect failures")
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>
> Not like migrate_set_state_failure(MigrationState *s)?  Not a huge deal,
> though..

I thought we had agreed over IRC that it was best to hold that until the
other MigrationStatus work happens?

Anyway, looking closer at this, there are places that handle CANCELLING
beforehand (_detect_error) and places that only set FAILED after
specific states (multifd), so a single helper will require more
churn. Let's postpone that please.

>
> Reviewed-by: Peter Xu <peterx@redhat.com>