On Thu 03-08-17 17:22:37, Joey Lee wrote: > On Wed, Aug 02, 2017 at 11:01:43AM +0200, Michal Hocko wrote: > > On Mon 31-07-17 15:38:45, Joey Lee wrote: [...] > > > So, the behavior is: > > > > > > Kernel received ejection event, set _Eject_ flag on container object > > > -> Kernel sends offline events to all children devices > > > -> User space performs cleaning jobs and offlines each child device > > > -> Kernel detects all children offlined > > > -> Kernel removes objects and calls power off(_EJ0) > > > > Yes this is what I've had in mind. It is the "kernel detects..." part > > which is not implemented now and that requires us to do the explicit > > eject from userspace, correct? > > > > Yes, the _Eject_ flag and _detects_ part are not implemented now. > > In this approach, kernel still relies on user space to trigger the > offline. The ejection process is still not transparent to user space. > Is it what you want?
But as long as there is no auto-offlining then there is no other choice no? Besides that userspace even shouldn't care about the fact that the eject is in progress. That is a BIOS->OS deal AFAIU. All the userspace cares about is the proper cleanup of the resources and that happens at the offline time. > > > If anyone onlined one of the children devices in the term of waiting > > > userland offlines all children, then the _Eject_ flag will be clean > > > and ejection process will be interrupted. In this situation, administrator > > > needs to trigger ejection event again. > > > > yes > > > > > Do you think that the race hurts anything? > > > > What kind of race? > > User space set a child online before all childreen offlined, then > the _Eject_ flag is cleaned and the ejection process is interrupted. Is this really a race though? Kernel will always have a full picture and if userspace wants to online some part then the eject cannot succeed. This is something that a userspace driver eject cannot possibly handle. -- Michal Hocko SUSE Labs
