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authorLi Zefan <lizefan@huawei.com>2013-08-19 10:05:24 +0800
committerTejun Heo <tj@kernel.org>2013-08-19 09:52:18 -0400
commit1cb650b91ba582f6737457b7d22e368585596d2c (patch)
tree1a3d8d4a219dcca229dcc6dc47876091ef0f8438 /kernel/cgroup.c
parent930913a31289202d232186b82854b26d7fb7cf4d (diff)
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cgroup: change cgroup_from_id() to css_from_id()
Now we want cgroup core to always provide the css to use to the subsystems, so change this API to css_from_id(). Uninline css_from_id(), because it's getting bigger and cgroup_css() has been unexported. While at it, remove the #ifdef, and shuffle the order of the args. Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b69b572..ff7d642 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5717,6 +5717,28 @@ struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id)
return css ? css : ERR_PTR(-ENOENT);
}
+/**
+ * css_from_id - lookup css by id
+ * @id: the cgroup id
+ * @ss: cgroup subsys to be looked into
+ *
+ * Returns the css if there's valid one with @id, otherwise returns NULL.
+ * Should be called under rcu_read_lock().
+ */
+struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
+{
+ struct cgroup *cgrp;
+
+ rcu_lockdep_assert(rcu_read_lock_held() ||
+ lockdep_is_held(&cgroup_mutex),
+ "css_from_id() needs proper protection");
+
+ cgrp = idr_find(&ss->root->cgroup_idr, id);
+ if (cgrp)
+ return cgroup_css(cgrp, ss->subsys_id);
+ return NULL;
+}
+
#ifdef CONFIG_CGROUP_DEBUG
static struct cgroup_subsys_state *
debug_css_alloc(struct cgroup_subsys_state *parent_css)
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