diff options
| author | Tejun Heo <tj@kernel.org> | 2015-09-11 15:00:19 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2015-09-22 12:46:53 -0400 |
| commit | 4530eddb59494b89650d6bcd980fc7f7717ad80c (patch) | |
| tree | 0f6212afa2e7e0e4724c5f12644508f1a0baf138 /kernel/cgroup.c | |
| parent | 3df9ca0a2b8b50db5a079ae9d97c5b55435e9a6c (diff) | |
cgroup, memcg, cpuset: implement cgroup_taskset_for_each_leader()
It wasn't explicitly documented but, when a process is being migrated,
cpuset and memcg depend on cgroup_taskset_first() returning the
threadgroup leader; however, this approach is somewhat ghetto and
would no longer work for the planned multi-process migration.
This patch introduces explicit cgroup_taskset_for_each_leader() which
iterates over only the threadgroup leaders and replaces
cgroup_taskset_first() usages for accessing the leader with it.
This prepares both memcg and cpuset for multi-process migration. This
patch also updates the documentation for cgroup_taskset_for_each() to
clarify the iteration rules and removes comments mentioning task
ordering in tasksets.
v2: A previous patch which added threadgroup leader test was dropped.
Patch updated accordingly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 11 |
1 files changed, 0 insertions, 11 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 0be276ffe08a..7f4b85af03dc 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2217,13 +2217,6 @@ static void cgroup_task_migrate(struct cgroup *old_cgrp, get_css_set(new_cset); rcu_assign_pointer(tsk->cgroups, new_cset); - - /* - * Use move_tail so that cgroup_taskset_first() still returns the - * leader after migration. This works because cgroup_migrate() - * ensures that the dst_cset of the leader is the first on the - * tset's dst_csets list. - */ list_move_tail(&tsk->cg_list, &new_cset->mg_tasks); /* @@ -2419,10 +2412,6 @@ static int cgroup_migrate(struct cgroup *cgrp, struct task_struct *leader, if (!cset->mg_src_cgrp) goto next; - /* - * cgroup_taskset_first() must always return the leader. - * Take care to avoid disturbing the ordering. - */ list_move_tail(&task->cg_list, &cset->mg_tasks); if (list_empty(&cset->mg_node)) list_add_tail(&cset->mg_node, &tset.src_csets); |