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Commit 40e93b39 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: always use cgroup_css() 



cgroup_css() is the accessor for cgroup->subsys[] but is not used
consistently.  cgroup->subsys[] will become RCU protected and
cgroup_css() will grow synchronization sanity checks.  In preparation,
make all cgroup->subsys[] dereferences use cgroup_css() consistently.

This patch doesn't introduce any functional difference.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent bd8815a6

kernel/cgroup.c

+29 −29
Original line number Diff line number Diff line
@@ -574,7 +574,7 @@ static struct css_set *find_existing_css_set(struct css_set *old_cset, 
			/* Subsystem is in this hierarchy. So we want

			 * the subsystem state from the new

			 * cgroup */

			template[i] = cgrp->subsys[i];

			template[i] = cgroup_css(cgrp, i);

		} else {

			/* Subsystem is not in this hierarchy, so we

			 * don't want to change the subsystem state */
@@ -871,7 +871,7 @@ static void cgroup_free_fn(struct work_struct *work) 
	 * Release the subsystem state objects.

	 */

	for_each_root_subsys(cgrp->root, ss) {

		struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];

		struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);



		ss->css_free(css);

	}
@@ -1067,27 +1067,27 @@ static int rebind_subsystems(struct cgroupfs_root *root, 


		if (bit & added_mask) {

			/* We're binding this subsystem to this hierarchy */

			BUG_ON(cgrp->subsys[i]);

			BUG_ON(!cgroup_dummy_top->subsys[i]);

			BUG_ON(cgroup_dummy_top->subsys[i]->cgroup != cgroup_dummy_top);

			BUG_ON(cgroup_css(cgrp, i));

			BUG_ON(!cgroup_css(cgroup_dummy_top, i));

			BUG_ON(cgroup_css(cgroup_dummy_top, i)->cgroup != cgroup_dummy_top);



			cgrp->subsys[i] = cgroup_dummy_top->subsys[i];

			cgrp->subsys[i]->cgroup = cgrp;

			cgroup_css(cgrp, i)->cgroup = cgrp;

			list_move(&ss->sibling, &root->subsys_list);

			ss->root = root;

			if (ss->bind)

				ss->bind(cgrp->subsys[i]);

				ss->bind(cgroup_css(cgrp, i));



			/* refcount was already taken, and we're keeping it */

			root->subsys_mask |= bit;

		} else if (bit & removed_mask) {

			/* We're removing this subsystem */

			BUG_ON(cgrp->subsys[i] != cgroup_dummy_top->subsys[i]);

			BUG_ON(cgrp->subsys[i]->cgroup != cgrp);

			BUG_ON(cgroup_css(cgrp, i) != cgroup_css(cgroup_dummy_top, i));

			BUG_ON(cgroup_css(cgrp, i)->cgroup != cgrp);



			if (ss->bind)

				ss->bind(cgroup_dummy_top->subsys[i]);

			cgroup_dummy_top->subsys[i]->cgroup = cgroup_dummy_top;

				ss->bind(cgroup_css(cgroup_dummy_top, i));

			cgroup_css(cgroup_dummy_top, i)->cgroup = cgroup_dummy_top;

			cgrp->subsys[i] = NULL;

			cgroup_subsys[i]->root = &cgroup_dummy_root;

			list_move(&ss->sibling, &cgroup_dummy_root.subsys_list);
@@ -2072,7 +2072,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, 
	 * step 1: check that we can legitimately attach to the cgroup.

	 */

	for_each_root_subsys(root, ss) {

		struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];

		struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);



		if (ss->can_attach) {

			retval = ss->can_attach(css, &tset);
@@ -2114,7 +2114,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, 
	 * step 4: do subsystem attach callbacks.

	 */

	for_each_root_subsys(root, ss) {

		struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];

		struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);



		if (ss->attach)

			ss->attach(css, &tset);
@@ -2136,7 +2136,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, 
out_cancel_attach:

	if (retval) {

		for_each_root_subsys(root, ss) {

			struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];

			struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);



			if (ss == failed_ss)

				break;
@@ -2308,7 +2308,7 @@ static struct cgroup_subsys_state *cgroup_file_css(struct cfent *cfe) 
	struct cgroup *cgrp = __d_cgrp(cfe->dentry->d_parent);



	if (cft->ss)

		return cgrp->subsys[cft->ss->subsys_id];

		return cgroup_css(cgrp, cft->ss->subsys_id);

	return &cgrp->dummy_css;

}
@@ -4241,7 +4241,7 @@ static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask) 


	/* This cgroup is ready now */

	for_each_root_subsys(cgrp->root, ss) {

		struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];

		struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);

		struct css_id *id = rcu_dereference_protected(css->id, true);



		/*
@@ -4285,7 +4285,7 @@ static void init_cgroup_css(struct cgroup_subsys_state *css, 
	css->id = NULL;

	if (cgrp == cgroup_dummy_top)

		css->flags |= CSS_ROOT;

	BUG_ON(cgrp->subsys[ss->subsys_id]);

	BUG_ON(cgroup_css(cgrp, ss->subsys_id));

	cgrp->subsys[ss->subsys_id] = css;



	/*
@@ -4300,7 +4300,7 @@ static void init_cgroup_css(struct cgroup_subsys_state *css, 
/* invoke ->css_online() on a new CSS and mark it online if successful */

static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp)

{

	struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];

	struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);

	int ret = 0;



	lockdep_assert_held(&cgroup_mutex);
@@ -4315,7 +4315,7 @@ static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp) 
/* if the CSS is online, invoke ->css_offline() on it and mark it offline */

static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp)

{

	struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];

	struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);



	lockdep_assert_held(&cgroup_mutex);
@@ -4400,7 +4400,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, 
	for_each_root_subsys(root, ss) {

		struct cgroup_subsys_state *css;



		css = ss->css_alloc(parent->subsys[ss->subsys_id]);

		css = ss->css_alloc(cgroup_css(parent, ss->subsys_id));

		if (IS_ERR(css)) {

			err = PTR_ERR(css);

			goto err_free_all;
@@ -4477,7 +4477,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, 


err_free_all:

	for_each_root_subsys(root, ss) {

		struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];

		struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);



		if (css) {

			percpu_ref_cancel_init(&css->refcnt);
@@ -4590,7 +4590,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) 
	 */

	atomic_set(&cgrp->css_kill_cnt, 1);

	for_each_root_subsys(cgrp->root, ss) {

		struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];

		struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);



		/*

		 * Killing would put the base ref, but we need to keep it
@@ -4676,7 +4676,7 @@ static void cgroup_offline_fn(struct work_struct *work) 
	 * destruction happens only after all css's are released.

	 */

	for_each_root_subsys(cgrp->root, ss)

		css_put(cgrp->subsys[ss->subsys_id]);

		css_put(cgroup_css(cgrp, ss->subsys_id));



	/* delete this cgroup from parent->children */

	list_del_rcu(&cgrp->sibling);
@@ -4741,7 +4741,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) 
	/* Create the top cgroup state for this subsystem */

	list_add(&ss->sibling, &cgroup_dummy_root.subsys_list);

	ss->root = &cgroup_dummy_root;

	css = ss->css_alloc(cgroup_dummy_top->subsys[ss->subsys_id]);

	css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss->subsys_id));

	/* We don't handle early failures gracefully */

	BUG_ON(IS_ERR(css));

	init_cgroup_css(css, ss, cgroup_dummy_top);
@@ -4820,7 +4820,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) 
	 * struct, so this can happen first (i.e. before the dummy root

	 * attachment).

	 */

	css = ss->css_alloc(cgroup_dummy_top->subsys[ss->subsys_id]);

	css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss->subsys_id));

	if (IS_ERR(css)) {

		/* failure case - need to deassign the cgroup_subsys[] slot. */

		cgroup_subsys[ss->subsys_id] = NULL;
@@ -4936,7 +4936,7 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) 
	 * the cgrp->subsys pointer to find their state. note that this

	 * also takes care of freeing the css_id.

	 */

	ss->css_free(cgroup_dummy_top->subsys[ss->subsys_id]);

	ss->css_free(cgroup_css(cgroup_dummy_top, ss->subsys_id));

	cgroup_dummy_top->subsys[ss->subsys_id] = NULL;



	mutex_unlock(&cgroup_mutex);
@@ -5562,8 +5562,8 @@ static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, 
	struct css_id *child_id, *parent_id;



	subsys_id = ss->subsys_id;

	parent_css = parent->subsys[subsys_id];

	child_css = child->subsys[subsys_id];

	parent_css = cgroup_css(parent, subsys_id);

	child_css = cgroup_css(child, subsys_id);

	parent_id = rcu_dereference_protected(parent_css->id, true);

	depth = parent_id->depth + 1;
@@ -5624,7 +5624,7 @@ struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) 


	/* get cgroup */

	cgrp = __d_cgrp(f->f_dentry);

	css = cgrp->subsys[id];

	css = cgroup_css(cgrp, id);

	return css ? css : ERR_PTR(-ENOENT);

}