On Mon, Aug 11, 2025 at 10:53:11AM -0300, Fabiano Rosas wrote: > Lukas Straub <lukasstra...@web.de> writes: > > > On Fri, 8 Aug 2025 11:37:23 -0400 > > Peter Xu <pet...@redhat.com> wrote: > > > >> On Fri, Aug 08, 2025 at 10:55:25AM -0300, Fabiano Rosas wrote: > >> > Please work with Lukas to figure out whether yank can be used here. I > >> > think that's the correct approach. If the main loop is blocked, then > >> > some out-of-band cancellation routine is needed. migrate_cancel() could > >> > be it, but at the moment it's not. Yank is the second best thing. > >> > >> I agree. > >> > >> migrate_cancel() should really be an OOB command.. It should be a superset > >> of yank features, plus anything migration speficic besides yanking the > >> channels, for example, when migration thread is blocked in PRE_SWITCHOVER. > > > > Hmm, I think the migration code should handle this properly even if the > > yank command is used. From the POV of migration, it sees that the > > connection broke with connection reset. That is the same error as if the > > other side crashes/is killed or a NAT/stateful firewall in between > > reboots. > > > > That should all work just fine. After yank or after a detectable network > failure. The issue here seems to be that the destination recv is hanging > indefinitely. I don't think we ever played with socket timeout > configurations, or even switching to non-blocking during the sync. This > is actually (AFAIK) the first time we get a hang that's not "just" a > synchronization issue in the migration code.
Based on the stack trace, whether the socket is blocking or not isn't a problem - QEMU is stuck in a sem_wait call that will delay the coroutine, and thus the thread, indefinitely. IMHO the semaphore usage needs to be removed in favour of a synchronization mechanism that can integrate with event loop such that the coroutine does not block. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
