On Wed, Sep 17, 2025 at 05:52:54PM -0300, Fabiano Rosas wrote: > Peter Xu <[email protected]> writes: > > > We set CANCELLED very late, it means migration_has_failed() may not work > > correctly if it's invoked before updating CANCELLING to CANCELLED. > > > > The prophecy is fulfilled. > > https://wiki.qemu.org/ToDo/LiveMigration#Migration_cancel_concurrency > > I'm not sure I'm convinced, for instance, CANCELLING is part of > migration_is_running(), while FAILED is not. This doesn't seem > right. Another point is that CANCELLING is not a final state, so we're > prone to later need a migration_has_finished_failing_now() helper. =)
Considering we only have two users so far, and the other user doesn't care about CANCELLING (while the multifd shutdown cares?), then I assume it's ok to treat CANCELLING to be "has failed"? :) I didn't try to interpret "has failed" in English, but only for the sake of an universal helper that works for both places. Or maybe it can be is_failing() too? I don't have a strong feeling. > > My mental model is that CANCELLING is a transitional, ongoing state > where we shouldn't really be making assumptions. Once FAILED is reached, > then we're sure in which general state everything is. > > How did you catch this? It was one of the cancel tests that failed? I > just noticed that multifd_send_shutdown() is called from > migration_cleanup() before it changes the state to CANCELLED. So current > code also has whatever issue you detected here. No test failed, it was only by code observation, mentioned below [1], exactly as you said. I just think when cancelling the tls sessions, we shouldn't dump the error messages anymore even if the bye failed. Or maybe we simply do not need to invoke migration_tls_channel_end() when CANCELLING / FAILED? That's relevant to your ask on the cover letter, we can discuss there. This is very trivial. Let me know how you thinks. I can also drop this patch when repost v3 but fix the postcopy warning first, which reliably reproduce now with qtest. > > > Allow that state will make migration_has_failed() working as expected even > > if it's invoked slightly earlier. > > > > One current user is the multifd code for the TLS graceful termination, > > where it's before updating to CANCELLED. [1] > > > > Signed-off-by: Peter Xu <[email protected]> > > --- > > migration/migration.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/migration/migration.c b/migration/migration.c > > index 7015c2b5e0..397917b1b3 100644 > > --- a/migration/migration.c > > +++ b/migration/migration.c > > @@ -1723,7 +1723,8 @@ int migration_call_notifiers(MigrationState *s, > > MigrationEventType type, > > > > bool migration_has_failed(MigrationState *s) > > { > > - return (s->state == MIGRATION_STATUS_CANCELLED || > > + return (s->state == MIGRATION_STATUS_CANCELLING || > > + s->state == MIGRATION_STATUS_CANCELLED || > > s->state == MIGRATION_STATUS_FAILED); > > } > -- Peter Xu
