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authorTejun Heo <tj@kernel.org>2013-08-09 04:11:23 +0400
committerTejun Heo <tj@kernel.org>2013-08-09 04:11:23 +0400
commit6387698699afd72d6304566fb6ccf84bffe07c56 (patch)
tree9440e96fa8e5adce62409a5b0e40984dfedaada3 /kernel/sched/cpuacct.c
parenta7c6d554aa01236ac2a9f851ab0f75704f76dfa2 (diff)
downloadlinux-6387698699afd72d6304566fb6ccf84bffe07c56.tar.xz
cgroup: add css_parent()
Currently, controllers have to explicitly follow the cgroup hierarchy to find the parent of a given css. cgroup is moving towards using cgroup_subsys_state as the main controller interface construct, so let's provide a way to climb the hierarchy using just csses. This patch implements css_parent() which, given a css, returns its parent. The function is guarnateed to valid non-NULL parent css as long as the target css is not at the top of the hierarchy. freezer, cpuset, cpu, cpuacct, hugetlb, memory, net_cls and devices are converted to use css_parent() instead of accessing cgroup->parent directly. * __parent_ca() is dropped from cpuacct and its usage is replaced with parent_ca(). The only difference between the two was NULL test on cgroup->parent which is now embedded in css_parent() making the distinction moot. Note that eventually a css->parent field will be added to css and the NULL check in css_parent() will go away. This patch shouldn't cause any behavior differences. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'kernel/sched/cpuacct.c')
-rw-r--r--kernel/sched/cpuacct.c11
1 files changed, 2 insertions, 9 deletions
diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 8ccfa10cc89f..f6926a149a71 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -50,16 +50,9 @@ static inline struct cpuacct *task_ca(struct task_struct *tsk)
return css_ca(task_css(tsk, cpuacct_subsys_id));
}
-static inline struct cpuacct *__parent_ca(struct cpuacct *ca)
-{
- return cgroup_ca(ca->css.cgroup->parent);
-}
-
static inline struct cpuacct *parent_ca(struct cpuacct *ca)
{
- if (!ca->css.cgroup->parent)
- return NULL;
- return cgroup_ca(ca->css.cgroup->parent);
+ return css_ca(css_parent(&ca->css));
}
static DEFINE_PER_CPU(u64, root_cpuacct_cpuusage);
@@ -284,7 +277,7 @@ void cpuacct_account_field(struct task_struct *p, int index, u64 val)
while (ca != &root_cpuacct) {
kcpustat = this_cpu_ptr(ca->cpustat);
kcpustat->cpustat[index] += val;
- ca = __parent_ca(ca);
+ ca = parent_ca(ca);
}
rcu_read_unlock();
}