This patch moves cgroup_parent into cgroup.h as a static inline helper
function so that others can use it. Although this pattern is easy
to implement, having it in one place simplifies the creation
of new cgroup controllers.
Signed-off-by: Sargun Dhillon <sar...@sargun.me>
---
include/linux/cgroup.h | 16 ++++++++++++++++
kernel/cgroup.c | 9 ---------
2 files changed, 16 insertions(+), 9 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index a4414a1..b84eb6e 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -571,6 +571,22 @@ static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
pr_cont_kernfs_path(cgrp->kn);
}
+/**
+ * cgroup_parent - Get the parent of a specific cgroup
+ * @cgrp: target cgroup
+ *
+ * If the cgroup does not have a parent (top level), then this function
+ * returns NULL. Otherwise, it'll return a pointer to te the parent cgroup.
+ */
+static inline struct cgroup *cgroup_parent(struct cgroup *cgrp)
+{
+ struct cgroup_subsys_state *parent_css = cgrp->self.parent;
+
+ if (parent_css)
+ return container_of(parent_css, struct cgroup, self);
+ return NULL;
+}
+
#else /* !CONFIG_CGROUPS */
struct cgroup_subsys_state;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index d1c51b7..1ec1a4e 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -358,15 +358,6 @@ static void cgroup_idr_remove(struct idr *idr, int id)
spin_unlock_bh(&cgroup_idr_lock);
}
-static struct cgroup *cgroup_parent(struct cgroup *cgrp)
-{
- struct cgroup_subsys_state *parent_css = cgrp->self.parent;
-
- if (parent_css)
- return container_of(parent_css, struct cgroup, self);
- return NULL;
-}
-
/* subsystems visibly enabled on a cgroup */
static u16 cgroup_control(struct cgroup *cgrp)
{
--
2.7.4
