On Wed 31-10-12 09:41:23, Tejun Heo wrote: > Hey, Michal. > > On Wed, Oct 31, 2012 at 03:37:51PM +0100, Michal Hocko wrote: > > > + for_each_subsys(cgrp->root, ss) > > > + if (ss->pre_destroy) > > > + WARN_ON_ONCE(ss->pre_destroy(cgrp)); > > > > Hmm, I am not sure I like this WARN_ON_ONCE. First it can happen for > > more than one controller and second we can just clear CGRP_WAIT_ON_RMDIR > > and return with EBUSY. The only possible failure at the moment is when a > > new task or a child group appear. > > I know it is not a big deal because it will disappear later in the > > series but it would be more readable IMO. > > The WARN_ON_ONCE() is just moved from the original > cgroup_call_pre_destroy(). We can add an error out there but that > makes future changes difficult. It's a chicken and egg problem. You > gotta break the loop somewhere. I do not think this is that hard. You can simply change the return path on pre_destroy error by BUG_ON in "cgroup: deactivate CSS's and mark cgroup dead before invoking ->pre_destroy()". There is no chicke&egg problem here because once the group is marked dead and css frozen then the existing callbacks cannot possibly fail. Or am I missing your point? -- Michal Hocko SUSE Labs _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
