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>

5 files changed, 43 insertions, 60 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 43a224f167b5..865d89a580c7 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -818,7 +818,7 @@ static int cgroup_call_pre_destroy(struct cgroup *cgrp)
 
         for_each_subsys(cgrp->root, ss)
                 if (ss->pre_destroy) {
-                        ret = ss->pre_destroy(ss, cgrp);
+                        ret = ss->pre_destroy(cgrp);
                         if (ret)
                                 break;
                 }
@@ -846,7 +846,7 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
                  * Release the subsystem state objects.
                  */
                 for_each_subsys(cgrp->root, ss)
-                        ss->destroy(ss, cgrp);
+                        ss->destroy(cgrp);
 
                 cgrp->root->number_of_cgroups--;
                 mutex_unlock(&cgroup_mutex);
@@ -1015,7 +1015,7 @@ static int rebind_subsystems(struct cgroupfs_root *root,
                         list_move(&ss->sibling, &root->subsys_list);
                         ss->root = root;
                         if (ss->bind)
-                                ss->bind(ss, cgrp);
+                                ss->bind(cgrp);
                         mutex_unlock(&ss->hierarchy_mutex);
                         /* refcount was already taken, and we're keeping it */
                 } else if (bit & removed_bits) {
@@ -1025,7 +1025,7 @@ static int rebind_subsystems(struct cgroupfs_root *root,
                         BUG_ON(cgrp->subsys[i]->cgroup != cgrp);
                         mutex_lock(&ss->hierarchy_mutex);
                         if (ss->bind)
-                                ss->bind(ss, dummytop);
+                                ss->bind(dummytop);
                         dummytop->subsys[i]->cgroup = dummytop;
                         cgrp->subsys[i] = NULL;
                         subsys[i]->root = &rootnode;
@@ -1908,7 +1908,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
 
         for_each_subsys(root, ss) {
                 if (ss->can_attach) {
-                        retval = ss->can_attach(ss, cgrp, &tset);
+                        retval = ss->can_attach(cgrp, &tset);
                         if (retval) {
                                 /*
                                  * Remember on which subsystem the can_attach()
@@ -1932,7 +1932,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
 
         for_each_subsys(root, ss) {
                 if (ss->attach)
-                        ss->attach(ss, cgrp, &tset);
+                        ss->attach(cgrp, &tset);
         }
 
         synchronize_rcu();
@@ -1954,7 +1954,7 @@ out:
                                  */
                                 break;
                         if (ss->cancel_attach)
-                                ss->cancel_attach(ss, cgrp, &tset);
+                                ss->cancel_attach(cgrp, &tset);
                 }
         }
         return retval;
@@ -2067,7 +2067,7 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
          */
         for_each_subsys(root, ss) {
                 if (ss->can_attach) {
-                        retval = ss->can_attach(ss, cgrp, &tset);
+                        retval = ss->can_attach(cgrp, &tset);
                         if (retval) {
                                 failed_ss = ss;
                                 goto out_cancel_attach;
@@ -2104,7 +2104,7 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
          */
         for_each_subsys(root, ss) {
                 if (ss->attach)
-                        ss->attach(ss, cgrp, &tset);
+                        ss->attach(cgrp, &tset);
         }
 
         /*
@@ -2128,7 +2128,7 @@ out_cancel_attach:
                         if (ss == failed_ss)
                                 break;
                         if (ss->cancel_attach)
-                                ss->cancel_attach(ss, cgrp, &tset);
+                                ss->cancel_attach(cgrp, &tset);
                 }
         }
 out_free_group_list:
@@ -3756,7 +3756,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
                 set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags);
 
         for_each_subsys(root, ss) {
-                struct cgroup_subsys_state *css = ss->create(ss, cgrp);
+                struct cgroup_subsys_state *css = ss->create(cgrp);
 
                 if (IS_ERR(css)) {
                         err = PTR_ERR(css);
@@ -3770,7 +3770,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
                 }
                 /* At error, ->destroy() callback has to free assigned ID. */
                 if (clone_children(parent) && ss->post_clone)
-                        ss->post_clone(ss, cgrp);
+                        ss->post_clone(cgrp);
         }
 
         cgroup_lock_hierarchy(root);
@@ -3804,7 +3804,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
 
         for_each_subsys(root, ss) {
                 if (cgrp->subsys[ss->subsys_id])
-                        ss->destroy(ss, cgrp);
+                        ss->destroy(cgrp);
         }
 
         mutex_unlock(&cgroup_mutex);
@@ -4028,7 +4028,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
         /* Create the top cgroup state for this subsystem */
         list_add(&ss->sibling, &rootnode.subsys_list);
         ss->root = &rootnode;
-        css = ss->create(ss, dummytop);
+        css = ss->create(dummytop);
         /* We don't handle early failures gracefully */
         BUG_ON(IS_ERR(css));
         init_cgroup_css(css, ss, dummytop);
@@ -4117,7 +4117,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
          * no ss->create seems to need anything important in the ss struct, so
          * this can happen first (i.e. before the rootnode attachment).
          */
-        css = ss->create(ss, dummytop);
+        css = ss->create(dummytop);
         if (IS_ERR(css)) {
                 /* failure case - need to deassign the subsys[] slot. */
                 subsys[i] = NULL;
@@ -4135,7 +4135,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
                 int ret = cgroup_init_idr(ss, css);
                 if (ret) {
                         dummytop->subsys[ss->subsys_id] = NULL;
-                        ss->destroy(ss, dummytop);
+                        ss->destroy(dummytop);
                         subsys[i] = NULL;
                         mutex_unlock(&cgroup_mutex);
                         return ret;
@@ -4233,7 +4233,7 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
          * pointer to find their state. note that this also takes care of
          * freeing the css_id.
          */
-        ss->destroy(ss, dummytop);
+        ss->destroy(dummytop);
         dummytop->subsys[ss->subsys_id] = NULL;
 
         mutex_unlock(&cgroup_mutex);
@@ -4509,7 +4509,7 @@ void cgroup_fork_callbacks(struct task_struct *child)
                 for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
                         struct cgroup_subsys *ss = subsys[i];
                         if (ss->fork)
-                                ss->fork(ss, child);
+                                ss->fork(child);
                 }
         }
 }
@@ -4611,7 +4611,7 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks)
                                 struct cgroup *old_cgrp =
                                         rcu_dereference_raw(cg->subsys[i])->cgroup;
                                 struct cgroup *cgrp = task_cgroup(tsk, i);
-                                ss->exit(ss, cgrp, old_cgrp, tsk);
+                                ss->exit(cgrp, old_cgrp, tsk);
                         }
                 }
         }
@@ -5066,8 +5066,7 @@ struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id)
 }
 
 #ifdef CONFIG_CGROUP_DEBUG
-static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
-                                                   struct cgroup *cont)
+static struct cgroup_subsys_state *debug_create(struct cgroup *cont)
 {
         struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
 
@@ -5077,7 +5076,7 @@ static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
         return css;
 }
 
-static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
+static void debug_destroy(struct cgroup *cont)
 {
         kfree(cont->subsys[debug_subsys_id]);
 }
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index fc0646b78a64..f86e93920b62 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -128,8 +128,7 @@ struct cgroup_subsys freezer_subsys;
  *    task->alloc_lock (inside __thaw_task(), prevents race with refrigerator())
  *     sighand->siglock
  */
-static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,
-                                                  struct cgroup *cgroup)
+static struct cgroup_subsys_state *freezer_create(struct cgroup *cgroup)
 {
         struct freezer *freezer;
 
@@ -142,8 +141,7 @@ static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,
         return &freezer->css;
 }
 
-static void freezer_destroy(struct cgroup_subsys *ss,
-                            struct cgroup *cgroup)
+static void freezer_destroy(struct cgroup *cgroup)
 {
         struct freezer *freezer = cgroup_freezer(cgroup);
 
@@ -164,8 +162,7 @@ static bool is_task_frozen_enough(struct task_struct *task)
  * a write to that file racing against an attach, and hence the
  * can_attach() result will remain valid until the attach completes.
  */
-static int freezer_can_attach(struct cgroup_subsys *ss,
-                              struct cgroup *new_cgroup,
+static int freezer_can_attach(struct cgroup *new_cgroup,
                               struct cgroup_taskset *tset)
 {
         struct freezer *freezer;
@@ -185,7 +182,7 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
         return 0;
 }
 
-static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
+static void freezer_fork(struct task_struct *task)
 {
         struct freezer *freezer;
 
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index a09ac2b9a661..5d575836dba6 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1399,8 +1399,7 @@ static nodemask_t cpuset_attach_nodemask_from;
 static nodemask_t cpuset_attach_nodemask_to;
 
 /* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
-static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-                             struct cgroup_taskset *tset)
+static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 {
         struct cpuset *cs = cgroup_cs(cgrp);
         struct task_struct *task;
@@ -1436,8 +1435,7 @@ static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
         return 0;
 }
 
-static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-                          struct cgroup_taskset *tset)
+static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 {
         struct mm_struct *mm;
         struct task_struct *task;
@@ -1833,8 +1831,7 @@ static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
  * (and likewise for mems) to the new cgroup. Called with cgroup_mutex
  * held.
  */
-static void cpuset_post_clone(struct cgroup_subsys *ss,
-                              struct cgroup *cgroup)
+static void cpuset_post_clone(struct cgroup *cgroup)
 {
         struct cgroup *parent, *child;
         struct cpuset *cs, *parent_cs;
@@ -1857,13 +1854,10 @@ static void cpuset_post_clone(struct cgroup_subsys *ss,
 
 /*
  *      cpuset_create - create a cpuset
- *      ss:     cpuset cgroup subsystem
  *      cont:   control group that the new cpuset will be part of
  */
 
-static struct cgroup_subsys_state *cpuset_create(
-        struct cgroup_subsys *ss,
-        struct cgroup *cont)
+static struct cgroup_subsys_state *cpuset_create(struct cgroup *cont)
 {
         struct cpuset *cs;
         struct cpuset *parent;
@@ -1902,7 +1896,7 @@ static struct cgroup_subsys_state *cpuset_create(
  * will call async_rebuild_sched_domains().
  */
 
-static void cpuset_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
+static void cpuset_destroy(struct cgroup *cont)
 {
         struct cpuset *cs = cgroup_cs(cont);
 
diff --git a/kernel/events/core.c b/kernel/events/core.c
index a8f4ac001a00..a5d1ee92b0d9 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6906,8 +6906,7 @@ unlock:
 device_initcall(perf_event_sysfs_init);
 
 #ifdef CONFIG_CGROUP_PERF
-static struct cgroup_subsys_state *perf_cgroup_create(
-        struct cgroup_subsys *ss, struct cgroup *cont)
+static struct cgroup_subsys_state *perf_cgroup_create(struct cgroup *cont)
 {
         struct perf_cgroup *jc;
 
@@ -6924,8 +6923,7 @@ static struct cgroup_subsys_state *perf_cgroup_create(
         return &jc->css;
 }
 
-static void perf_cgroup_destroy(struct cgroup_subsys *ss,
-                                struct cgroup *cont)
+static void perf_cgroup_destroy(struct cgroup *cont)
 {
         struct perf_cgroup *jc;
         jc = container_of(cgroup_subsys_state(cont, perf_subsys_id),
@@ -6941,8 +6939,7 @@ static int __perf_cgroup_move(void *info)
         return 0;
 }
 
-static void perf_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-                               struct cgroup_taskset *tset)
+static void perf_cgroup_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 {
         struct task_struct *task;
 
@@ -6950,8 +6947,8 @@ static void perf_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
                 task_function_call(task, __perf_cgroup_move, task);
 }
 
-static void perf_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp,
-                struct cgroup *old_cgrp, struct task_struct *task)
+static void perf_cgroup_exit(struct cgroup *cgrp, struct cgroup *old_cgrp,
+                             struct task_struct *task)
 {
         /*
          * cgroup_exit() is called in the copy_process() failure path.
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index df00cb09263e..ff12f7216062 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7530,8 +7530,7 @@ static inline struct task_group *cgroup_tg(struct cgroup *cgrp)
                             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 @@ cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
         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 @@ static int cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
         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_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
 }
 
 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 @@ struct cgroup_subsys cpu_cgroup_subsys = {
  */
 
 /* 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 @@ out:
 }
 
 /* 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);