Skip to content

Commit

Permalink
cgroup: always use cgroup_css()
Browse files Browse the repository at this point in the history 
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: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
  • Loading branch information
Tejun Heo committed Aug 13, 2013
1 parent bd8815a commit 40e93b3
Showing 1 changed file with 29 additions and 29 deletions.
58 changes: 29 additions & 29 deletions kernel/cgroup.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand Down Expand Up @@ -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);
}
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand All @@ -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;
Expand Down Expand Up @@ -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;
}

Expand Down Expand Up @@ -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);

/*
Expand Down Expand Up @@ -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;

/*
Expand All @@ -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);
Expand All @@ -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);

Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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);
}

Expand Down

0 comments on commit 40e93b3

Please sign in to comment.