diff options
| -rw-r--r-- | include/linux/cgroup.h | 3 | ||||
| -rw-r--r-- | kernel/cgroup/cgroup.c | 60 |
2 files changed, 39 insertions, 24 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index a7e4611e20c8..05ed2a209e74 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -43,6 +43,9 @@ /* walk all threaded css_sets in the domain */ #define CSS_TASK_ITER_THREADED (1U << 1) +/* internal flags */ +#define CSS_TASK_ITER_SKIPPED (1U << 16) + /* a css_task_iter should be treated as an opaque object */ struct css_task_iter { struct cgroup_subsys *ss; diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 217cec4e22c6..035aee466bbf 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -215,7 +215,8 @@ static struct cftype cgroup_base_files[]; static int cgroup_apply_control(struct cgroup *cgrp); static void cgroup_finalize_control(struct cgroup *cgrp, int ret); -static void css_task_iter_advance(struct css_task_iter *it); +static void css_task_iter_skip(struct css_task_iter *it, + struct task_struct *task); static int cgroup_destroy_locked(struct cgroup *cgrp); static struct cgroup_subsys_state *css_create(struct cgroup *cgrp, struct cgroup_subsys *ss); @@ -843,6 +844,21 @@ static void css_set_update_populated(struct css_set *cset, bool populated) cgroup_update_populated(link->cgrp, populated); } +/* + * @task is leaving, advance task iterators which are pointing to it so + * that they can resume at the next position. Advancing an iterator might + * remove it from the list, use safe walk. See css_task_iter_skip() for + * details. + */ +static void css_set_skip_task_iters(struct css_set *cset, + struct task_struct *task) +{ + struct css_task_iter *it, *pos; + + list_for_each_entry_safe(it, pos, &cset->task_iters, iters_node) + css_task_iter_skip(it, task); +} + /** * css_set_move_task - move a task from one css_set to another * @task: task being moved @@ -868,22 +884,9 @@ static void css_set_move_task(struct task_struct *task, css_set_update_populated(to_cset, true); if (from_cset) { - struct css_task_iter *it, *pos; - WARN_ON_ONCE(list_empty(&task->cg_list)); - /* - * @task is leaving, advance task iterators which are - * pointing to it so that they can resume at the next - * position. Advancing an iterator might remove it from - * the list, use safe walk. See css_task_iter_advance*() - * for details. - */ - list_for_each_entry_safe(it, pos, &from_cset->task_iters, - iters_node) - if (it->task_pos == &task->cg_list) - css_task_iter_advance(it); - + css_set_skip_task_iters(from_cset, task); list_del_init(&task->cg_list); if (!css_set_populated(from_cset)) css_set_update_populated(from_cset, false); @@ -4430,10 +4433,19 @@ static void css_task_iter_advance_css_set(struct css_task_iter *it) list_add(&it->iters_node, &cset->task_iters); } -static void css_task_iter_advance(struct css_task_iter *it) +static void css_task_iter_skip(struct css_task_iter *it, + struct task_struct *task) { - struct list_head *next; + lockdep_assert_held(&css_set_lock); + + if (it->task_pos == &task->cg_list) { + it->task_pos = it->task_pos->next; + it->flags |= CSS_TASK_ITER_SKIPPED; + } +} +static void css_task_iter_advance(struct css_task_iter *it) +{ lockdep_assert_held(&css_set_lock); repeat: if (it->task_pos) { @@ -4442,15 +4454,15 @@ repeat: * consumed first and then ->mg_tasks. After ->mg_tasks, * we move onto the next cset. */ - next = it->task_pos->next; - - if (next == it->tasks_head) - next = it->mg_tasks_head->next; + if (it->flags & CSS_TASK_ITER_SKIPPED) + it->flags &= ~CSS_TASK_ITER_SKIPPED; + else + it->task_pos = it->task_pos->next; - if (next == it->mg_tasks_head) + if (it->task_pos == it->tasks_head) + it->task_pos = it->mg_tasks_head->next; + if (it->task_pos == it->mg_tasks_head) css_task_iter_advance_css_set(it); - else - it->task_pos = next; } else { /* called from start, proceed to the first cset */ css_task_iter_advance_css_set(it); |