On 10/31/2012 08:22 AM, Tejun Heo wrote: > Because ->pre_destroy() could fail and can't be called under > cgroup_mutex, cgroup destruction did something very ugly. > > 1. Grab cgroup_mutex and verify it can be destroyed; fail otherwise. > > 2. Release cgroup_mutex and call ->pre_destroy(). > > 3. Re-grab cgroup_mutex and verify it can still be destroyed; fail > otherwise. > > 4. Continue destroying. > > In addition to being ugly, it has been always broken in various ways. > For example, memcg ->pre_destroy() expects the cgroup to be inactive > after it's done but tasks can be attached and detached between #2 and > #3 and the conditions that memcg verified in ->pre_destroy() might no > longer hold by the time control reaches #3. > > Now that ->pre_destroy() is no longer allowed to fail. We can switch > to the following. > > 1. Grab cgroup_mutex and fail if it can't be destroyed; fail > otherwise. > fail, or fail otherwise? Seems quite negative =) _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
