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/kernel/sched/core.c b/kernel/sched/core.c
index df00cb0..ff12f72 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7530,8 +7530,7 @@
 			    struct task_group, css);
 }
 
-static struct cgroup_subsys_state *
-cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
+static struct cgroup_subsys_state *cpu_cgroup_create(struct cgroup *cgrp)
 {
 	struct task_group *tg, *parent;
 
@@ -7548,15 +7547,14 @@
 	return &tg->css;
 }
 
-static void
-cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
+static void cpu_cgroup_destroy(struct cgroup *cgrp)
 {
 	struct task_group *tg = cgroup_tg(cgrp);
 
 	sched_destroy_group(tg);
 }
 
-static int cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
+static int cpu_cgroup_can_attach(struct cgroup *cgrp,
 				 struct cgroup_taskset *tset)
 {
 	struct task_struct *task;
@@ -7574,7 +7572,7 @@
 	return 0;
 }
 
-static void cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
+static void cpu_cgroup_attach(struct cgroup *cgrp,
 			      struct cgroup_taskset *tset)
 {
 	struct task_struct *task;
@@ -7584,8 +7582,8 @@
 }
 
 static void
-cpu_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp,
-		struct cgroup *old_cgrp, struct task_struct *task)
+cpu_cgroup_exit(struct cgroup *cgrp, struct cgroup *old_cgrp,
+		struct task_struct *task)
 {
 	/*
 	 * cgroup_exit() is called in the copy_process() failure path.
@@ -7935,8 +7933,7 @@
  */
 
 /* create a new cpu accounting group */
-static struct cgroup_subsys_state *cpuacct_create(
-	struct cgroup_subsys *ss, struct cgroup *cgrp)
+static struct cgroup_subsys_state *cpuacct_create(struct cgroup *cgrp)
 {
 	struct cpuacct *ca;
 
@@ -7966,8 +7963,7 @@
 }
 
 /* destroy an existing cpu accounting group */
-static void
-cpuacct_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
+static void cpuacct_destroy(struct cgroup *cgrp)
 {
 	struct cpuacct *ca = cgroup_ca(cgrp);