Hi On Tue, Jul 5, 2016 at 12:35 AM, Michael S. Tsirkin <m...@redhat.com> wrote: > On Mon, Jul 04, 2016 at 11:56:56PM +0200, Marc-André Lureau wrote: >> Hi >> >> On Mon, Jul 4, 2016 at 5:47 PM, Michael S. Tsirkin <m...@redhat.com> wrote: >> > Why does vhost_user_set_log_base need to return error? >> > If backend is not there to handle this message, >> > then it is not changing memory so it's ok to ignore the error. >> >> How do you know it's not changing the memory? > > either it closed socket intentionally or it exited > and kernel cleaned up.
And if it closed intentionally during migration, we want to catch this as a bug since it may still modify the memory >> Furthermore, if the migration happened, it's because backend claim >> VHOST_F_LOG_ALL, thus it should really not fail > > I don't see why - could you explain pls? If the backend claims migration support, it shouldn't have bad migration behaviour such as closing the vhost-user socket. >> > Same logic applies to many other messages. >> >> Pretty much all messages, the error can't be ignored, or operations >> will just fail silentely randomly. I don't understand why vhost-user >> io error can be ignored. Also it's quite inconsistent the way the code >> is today, vhost_user_write() returns an error that is mostly ignored, >> while vhost_user_read() is checked. Why having an error later when you >> can report it earlier? I fail to understand the rationale of this >> error handling. > > It's historical. the way I see it, most errors due to disconnect > can be ignored except > maybe for the initial feature negotiation which is needed > so we know what to tell guest. The way I see it is that errors should not be ignored because it makes it harder to track what is going on. > Errors due to e.g. buffer being full should cause an assert > as it's an internal qemu error. I don't see why qemu would be responsible for say, a suspended backend. > > >> >> -- >> Marc-André Lureau -- Marc-André Lureau
