cgroup: kill cgrp_ss_priv[CGROUP_CANFORK_COUNT] and friends

Now that nobody use the "priv" arg passed to can_fork/cancel_fork/fork we can
kill CGROUP_CANFORK_COUNT/SUBSYS_TAG/etc and cgrp_ss_priv[] in copy_process().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
Change-Id: I3d38130a199fa07b43aac95c201aecd9924e0879

5 files changed, 14 insertions, 31 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ecef6cf2cb81..e3fbd9ca2df6 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5535,19 +5535,6 @@ static const struct file_operations proc_cgroupstats_operations = {
 	.release = single_release,
 };
 
-static void **subsys_canfork_priv_p(void *ss_priv[CGROUP_CANFORK_COUNT], int i)
-{
-	if (CGROUP_CANFORK_START <= i && i < CGROUP_CANFORK_END)
-		return &ss_priv[i - CGROUP_CANFORK_START];
-	return NULL;
-}
-
-static void *subsys_canfork_priv(void *ss_priv[CGROUP_CANFORK_COUNT], int i)
-{
-	void **private = subsys_canfork_priv_p(ss_priv, i);
-	return private ? *private : NULL;
-}
-
 /**
  * cgroup_fork - initialize cgroup related fields during copy_process()
  * @child: pointer to task_struct of forking parent process.
@@ -5570,14 +5557,13 @@ void cgroup_fork(struct task_struct *child)
  * returns an error, the fork aborts with that error code. This allows for
  * a cgroup subsystem to conditionally allow or deny new forks.
  */
-int cgroup_can_fork(struct task_struct *child,
-		    void *ss_priv[CGROUP_CANFORK_COUNT])
+int cgroup_can_fork(struct task_struct *child)
 {
 	struct cgroup_subsys *ss;
 	int i, j, ret;
 
 	for_each_subsys_which(ss, i, &have_canfork_callback) {
-		ret = ss->can_fork(child, subsys_canfork_priv_p(ss_priv, i));
+		ret = ss->can_fork(child);
 		if (ret)
 			goto out_revert;
 	}
@@ -5589,7 +5575,7 @@ out_revert:
 		if (j >= i)
 			break;
 		if (ss->cancel_fork)
-			ss->cancel_fork(child, subsys_canfork_priv(ss_priv, j));
+			ss->cancel_fork(child);
 	}
 
 	return ret;
@@ -5602,15 +5588,14 @@ out_revert:
  * This calls the cancel_fork() callbacks if a fork failed *after*
  * cgroup_can_fork() succeded.
  */
-void cgroup_cancel_fork(struct task_struct *child,
-			void *ss_priv[CGROUP_CANFORK_COUNT])
+void cgroup_cancel_fork(struct task_struct *child)
 {
 	struct cgroup_subsys *ss;
 	int i;
 
 	for_each_subsys(ss, i)
 		if (ss->cancel_fork)
-			ss->cancel_fork(child, subsys_canfork_priv(ss_priv, i));
+			ss->cancel_fork(child);
 }
 
 /**
@@ -5623,8 +5608,7 @@ void cgroup_cancel_fork(struct task_struct *child,
  * cgroup_task_iter_start() - to guarantee that the new task ends up on its
  * list.
  */
-void cgroup_post_fork(struct task_struct *child,
-		      void *old_ss_priv[CGROUP_CANFORK_COUNT])
+void cgroup_post_fork(struct task_struct *child)
 {
 	struct cgroup_subsys *ss;
 	int i;
@@ -5668,7 +5652,7 @@ void cgroup_post_fork(struct task_struct *child,
 	 * and addition to css_set.
 	 */
 	for_each_subsys_which(ss, i, &have_fork_callback)
-		ss->fork(child, subsys_canfork_priv(old_ss_priv, i));
+		ss->fork(child);
 }
 
 /**
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 2d3df82c54f2..1b72d56edce5 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -200,7 +200,7 @@ static void freezer_attach(struct cgroup_taskset *tset)
  * to do anything as freezer_attach() will put @task into the appropriate
  * state.
  */
-static void freezer_fork(struct task_struct *task, void *private)
+static void freezer_fork(struct task_struct *task)
 {
 	struct freezer *freezer;
 
diff --git a/kernel/cgroup_pids.c b/kernel/cgroup_pids.c
index ea8cb03dbf72..d1806c89c237 100644
--- a/kernel/cgroup_pids.c
+++ b/kernel/cgroup_pids.c
@@ -210,7 +210,7 @@ static void pids_cancel_attach(struct cgroup_taskset *tset)
  * task_css_check(true) in pids_can_fork() and pids_cancel_fork() relies
  * on threadgroup_change_begin() held by the copy_process().
  */
-static int pids_can_fork(struct task_struct *task, void **priv_p)
+static int pids_can_fork(struct task_struct *task)
 {
 	struct cgroup_subsys_state *css;
 	struct pids_cgroup *pids;
@@ -220,7 +220,7 @@ static int pids_can_fork(struct task_struct *task, void **priv_p)
 	return pids_try_charge(pids, 1);
 }
 
-static void pids_cancel_fork(struct task_struct *task, void *priv)
+static void pids_cancel_fork(struct task_struct *task)
 {
 	struct cgroup_subsys_state *css;
 	struct pids_cgroup *pids;
diff --git a/kernel/fork.c b/kernel/fork.c
index 5103cd9a2769..34d263e8595b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1313,7 +1313,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 {
 	int retval;
 	struct task_struct *p;
-	void *cgrp_ss_priv[CGROUP_CANFORK_COUNT] = {};
 
 	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
 		return ERR_PTR(-EINVAL);
@@ -1586,7 +1585,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	 * between here and cgroup_post_fork() if an organisation operation is in
 	 * progress.
 	 */
-	retval = cgroup_can_fork(p, cgrp_ss_priv);
+	retval = cgroup_can_fork(p);
 	if (retval)
 		goto bad_fork_free_pid;
 
@@ -1686,7 +1685,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	write_unlock_irq(&tasklist_lock);
 
 	proc_fork_connector(p);
-	cgroup_post_fork(p, cgrp_ss_priv);
+	cgroup_post_fork(p);
 	threadgroup_change_end(current);
 	perf_event_fork(p);
 
@@ -1698,7 +1697,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 bad_fork_cancel_cgroup:
 	spin_unlock(&current->sighand->siglock);
 	write_unlock_irq(&tasklist_lock);
-	cgroup_cancel_fork(p, cgrp_ss_priv);
+	cgroup_cancel_fork(p);
 bad_fork_free_pid:
 	threadgroup_change_end(current);
 	if (pid != &init_struct_pid)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 633139647129..6c3f46e759d2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9327,7 +9327,7 @@ static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
  * This is called before wake_up_new_task(), therefore we really only
  * have to set its group bits, all the other stuff does not apply.
  */
-static void cpu_cgroup_fork(struct task_struct *task, void *private)
+static void cpu_cgroup_fork(struct task_struct *task)
 {
 	unsigned long flags;
 	struct rq *rq;