cgroup_enable_task_cg_lists() is used to lazyily initialize task cgroup associations on the first use to reduce fork / exit overheads on systems which don't use cgroup. Unfortunately, locking around it has never been actually correct and its value is dubious given how the vast majority of systems use cgroup right away from boot. This patch removes the optimization. For now, replace the cg_list based branches with WARN_ON_ONCE()'s to be on the safe side. We can simplify the logic further in the future.
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| @@ -150,7 +150,6 @@ struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset, · 149 unmodified lines | |||
| 150 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset, | 150 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset, |
| 151 | struct cgroup_subsys_state **dst_cssp); | 151 | struct cgroup_subsys_state **dst_cssp); |
| 152 | 152 | ||
| 153 | void cgroup_enable_task_cg_lists(void); | ||
| 154 | void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags, | 153 | void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags, |
| 155 | struct css_task_iter *it); | 154 | struct css_task_iter *it); |
| 156 | struct task_struct *css_task_iter_next(struct css_task_iter *it); | 155 | struct task_struct *css_task_iter_next(struct css_task_iter *it); |