On Wed, Jul 6, 2016 at 3:40 PM, Marc-André Lureau <marcandre.lur...@gmail.com> wrote: > Hi > > On Tue, Jul 5, 2016 at 1:12 PM, Michael S. Tsirkin <m...@redhat.com> wrote: >> On Tue, Jul 05, 2016 at 11:18:38AM +0200, Marc-André Lureau wrote: >>> 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 >> >> You can't prevent backend bugs I think. > > Right, but it's best to provide an error when you can detect backend bugs. > >>> >> 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. >> >> But I don't see why it's bad. If it's not modifying memory then >> it does not need to log any changes. > > "if it's not modifying memory"... > > I fail to understand why some code path check error code, and some > don't. Ignoring error and running further may lead to wrong > assumptions and later issues. I also fail to understand why providing > more useful error messages is bad. I feel quite strongly about having > more consistent error checking in vhost-user, I don't get why you > don't. >
Fwiw, Gonglei came up with the same patch in "vhost-user: fix unreasonable return value when vhost-user read failed" and he gave extra reasons for it that are hard to deny. -- Marc-André Lureau
