From ecb9d535df967b3ca565535e14456f612373bf5e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 15 Oct 2015 16:41:52 -0400 Subject: [PATCH] cgroup: reorganize css_task_iter functions * Rename css_advance_task_iter() to css_task_iter_advance_css_set() and make it clear it->task_pos too at the end of the iteration. * Factor out css_task_iter_advance() from css_task_iter_next(). The new function whines if called on a terminated iterator. Except for the termination check, this is pure reorganization and doesn't introduce any behavior changes. This will help the planned locking update for css_task_iter. Signed-off-by: Tejun Heo --- kernel/cgroup.c | 49 ++++++++++++++++++++++++++++--------------------- 1 file changed, 28 insertions(+), 21 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 0b6e50c67b65..56e2b772b143 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3793,12 +3793,12 @@ bool css_has_online_children(struct cgroup_subsys_state *css) } /** - * css_advance_task_iter - advance a task itererator to the next css_set + * css_task_iter_advance_css_set - advance a task itererator to the next css_set * @it: the iterator to advance * * Advance @it to the next css_set to walk. */ -static void css_advance_task_iter(struct css_task_iter *it) +static void css_task_iter_advance_css_set(struct css_task_iter *it) { struct list_head *l = it->cset_pos; struct cgrp_cset_link *link; @@ -3809,6 +3809,7 @@ static void css_advance_task_iter(struct css_task_iter *it) l = l->next; if (l == it->cset_head) { it->cset_pos = NULL; + it->task_pos = NULL; return; } @@ -3832,6 +3833,28 @@ static void css_advance_task_iter(struct css_task_iter *it) it->mg_tasks_head = &cset->mg_tasks; } +static void css_task_iter_advance(struct css_task_iter *it) +{ + struct list_head *l = it->task_pos; + + WARN_ON_ONCE(!l); + + /* + * Advance iterator to find next entry. cset->tasks is consumed + * first and then ->mg_tasks. After ->mg_tasks, we move onto the + * next cset. + */ + l = l->next; + + if (l == it->tasks_head) + l = it->mg_tasks_head->next; + + if (l == it->mg_tasks_head) + css_task_iter_advance_css_set(it); + else + it->task_pos = l; +} + /** * css_task_iter_start - initiate task iteration * @css: the css to walk tasks of @@ -3864,7 +3887,7 @@ void css_task_iter_start(struct cgroup_subsys_state *css, it->cset_head = it->cset_pos; - css_advance_task_iter(it); + css_task_iter_advance_css_set(it); } /** @@ -3878,28 +3901,12 @@ void css_task_iter_start(struct cgroup_subsys_state *css, struct task_struct *css_task_iter_next(struct css_task_iter *it) { struct task_struct *res; - struct list_head *l = it->task_pos; - /* If the iterator cg is NULL, we have no tasks */ if (!it->cset_pos) return NULL; - res = list_entry(l, struct task_struct, cg_list); - - /* - * Advance iterator to find next entry. cset->tasks is consumed - * first and then ->mg_tasks. After ->mg_tasks, we move onto the - * next cset. - */ - l = l->next; - - if (l == it->tasks_head) - l = it->mg_tasks_head->next; - - if (l == it->mg_tasks_head) - css_advance_task_iter(it); - else - it->task_pos = l; + res = list_entry(it->task_pos, struct task_struct, cg_list); + css_task_iter_advance(it); return res; }