On Wed, Jan 20, 2016 at 10:30:07AM -0500, Tejun Heo wrote: > Hello, > > On Wed, Jan 20, 2016 at 11:47:58AM +0100, Peter Zijlstra wrote: > > TJ, is css_offline guaranteed to be called in hierarchical order? I > > No, they aren't. The ancestors of a css are guaranteed to stay around > until css_free is called on the css and that's the only ordering > guarantee. > > > got properly lost in the whole cgroup destroy code. There's endless > > workqueues and rcu callbacks there. > > Yeah, it's hairy. I wondered about adding support for bouncing to > workqueue in both percpu_ref and rcu which would make things easier to > follow. Not sure how often this pattern happens tho. This came up recently offlist for call_rcu(), so that a call to (say) call_rcu_schedule_work() would do a schedule_work() after a grace period elapsed, invoking the function passed in to call_rcu_schedule_work(). There are several existing cases that do this, so special-casing it seems worthwhile. Perhaps something vaguely similar would work for percpu_ref. Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
