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>

5 files changed, 14 insertions, 31 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ad35ac0..7f2f007 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5488,19 +5488,6 @@ 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.
@@ -5523,14 +5510,13 @@ 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;
 	}
@@ -5542,7 +5528,7 @@ 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;
@@ -5555,15 +5541,14 @@ 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);
 }
 
 /**
@@ -5576,8 +5561,7 @@ 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;
@@ -5621,7 +5605,7 @@ 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 2d3df82..1b72d56 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 b50d5a1..18107ae 100644
--- a/kernel/cgroup_pids.c
+++ b/kernel/cgroup_pids.c
@@ -209,7 +209,7 @@ 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;
@@ -219,7 +219,7 @@ 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 fce002e..ba7d1c0 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1249,7 +1249,6 @@ 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);
@@ -1526,7 +1525,7 @@ 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;
 
@@ -1608,7 +1607,7 @@ 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);
 
@@ -1618,7 +1617,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	return p;
 
 bad_fork_cancel_cgroup:
-	cgroup_cancel_fork(p, cgrp_ss_priv);
+	cgroup_cancel_fork(p);
 bad_fork_free_pid:
 	if (pid != &init_struct_pid)
 		free_pid(pid);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a9db4819..b7d2271 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8212,7 +8212,7 @@ static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
 	sched_offline_group(tg);
 }
 
-static void cpu_cgroup_fork(struct task_struct *task, void *private)
+static void cpu_cgroup_fork(struct task_struct *task)
 {
 	sched_move_task(task);
 }