cgroup: remove cgroup_subsys argument from callbacks

The argument is not used at all, and it's not necessary, because
a specific callback handler of course knows which subsys it
belongs to.

Now only ->pupulate() takes this argument, because the handlers of
this callback always call cgroup_add_file()/cgroup_add_files().

So we reduce a few lines of code, though the shrinking of object size
is minimal.

 16 files changed, 113 insertions(+), 162 deletions(-)

   text    data     bss     dec     hex filename
5486240  656987 7039960 13183187         c928d3 vmlinux.o.orig
5486170  656987 7039960 13183117         c9288d vmlinux.o

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 8b5b5d8..c43a332 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -61,8 +61,8 @@
 
 struct cgroup_subsys devices_subsys;
 
-static int devcgroup_can_attach(struct cgroup_subsys *ss,
-			struct cgroup *new_cgrp, struct cgroup_taskset *set)
+static int devcgroup_can_attach(struct cgroup *new_cgrp,
+				struct cgroup_taskset *set)
 {
 	struct task_struct *task = cgroup_taskset_first(set);
 
@@ -156,8 +156,7 @@
 /*
  * called from kernel/cgroup.c with cgroup_lock() held.
  */
-static struct cgroup_subsys_state *devcgroup_create(struct cgroup_subsys *ss,
-						struct cgroup *cgroup)
+static struct cgroup_subsys_state *devcgroup_create(struct cgroup *cgroup)
 {
 	struct dev_cgroup *dev_cgroup, *parent_dev_cgroup;
 	struct cgroup *parent_cgroup;
@@ -195,8 +194,7 @@
 	return &dev_cgroup->css;
 }
 
-static void devcgroup_destroy(struct cgroup_subsys *ss,
-			struct cgroup *cgroup)
+static void devcgroup_destroy(struct cgroup *cgroup)
 {
 	struct dev_cgroup *dev_cgroup;
 	struct dev_whitelist_item *wh, *tmp;