Currently, given a cgroup_subsys_state, there's no way to find out
which subsystem the css is for, which we'll need to convert the cgroup
controller API to primarily use @css instead of @cgroup. This patch
adds cgroup_subsys_state->ss which points to the subsystem the @css
belongs to.
While at it, remove the comment about accessing @css->cgroup to
determine the hierarchy. cgroup core will provide API to traverse
hierarchy of css'es and we don't want subsystems to directly walk
cgroup hierarchies anymore.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
include/linux/cgroup.h | 9 ++++-----
kernel/cgroup.c | 1 +
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 1938292..9c2f9d7 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -66,13 +66,12 @@ enum cgroup_subsys_id {
/* Per-subsystem/per-cgroup state maintained by the system. */
struct cgroup_subsys_state {
- /*
- * The cgroup that this subsystem is attached to. Useful
- * for subsystems that want to know about the cgroup
- * hierarchy structure
- */
+ /* the cgroup that this css is attached to */
struct cgroup *cgroup;
+ /* the cgroup subsystem that this css is attached to */
+ struct cgroup_subsys *ss;
+
/* reference count - access via css_[try]get() and css_put() */
struct percpu_ref refcnt;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 9d5af91..fad5498 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4179,6 +4179,7 @@ static void init_cgroup_css(struct cgroup_subsys_state *css,
struct cgroup *cgrp)
{
css->cgroup = cgrp;
+ css->ss = ss;
css->flags = 0;
css->id = NULL;
if (cgrp == cgroup_dummy_top)
--
1.8.3.1
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