Peter Xu <[email protected]> writes: > 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. >
I'm not nitipicking on language. I'm pointing out that CANCELLING is a transitory state, i.e. from migrate_cancel() until migrate_cleanup(), while FAILED is a terminal state, nothing happens after it. But fine, I guess it's really only *my* assumptions being broken and not the ones in the code. >> >> 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. Ok > 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. Nah, let me review the patch properly, please. > 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); >> > } >>
