On Wed, Apr 11, 2018 at 06:18:18PM +0100, Dr. David Alan Gilbert wrote: > * Lidong Chen (jemmy858...@gmail.com) wrote: > > The default get_return_path function of iochannel does not work for > > RDMA live migration. So add the interface to set get_return_path. > > > > Signed-off-by: Lidong Chen <lidongc...@tencent.com> > > Lets see how Dan wants this done, he knows the channel/file stuff; > to me this feels like it should be adding a member to QIOChannelClass > that gets used by QEMUFile's get_return_path.
No that doesn't really fit the model. IMHO the entire concept of a separate return path object is really wrong. The QIOChannel implementations are (almost) all capable of bi-directional I/O, which is why the the get_retun_path function just creates a second QEMUFile pointing to the same QIOChannel object we already had. Migration only needs the second QEMUFile, because that struct re-uses the same struct fields for tracking different bits of info depending on which direction you're doing I/O in. A real fix would be to stop overloading the same fields for multiple purposes in the QEMUFile, so that we only needed a single QEMUFile instance. Ignoring that though, the particular problem we're facing here is that the QIOChannelRDMA impl that is used is not written in a way that allows bi-directional I/O, despite the RDMA code it uses being capable of it. So rather than changing this get_return_path code, IMHO, the right fix to simply improve the QIOChannelRDMA impl so that it fully supports bi-directional I/O like all the other channels do. 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 :|
