Commit 5c9d535b authored by Tejun Heo's avatar Tejun Heo

cgroup: remove css_parent()

cgroup in general is moving towards using cgroup_subsys_state as the
fundamental structural component and css_parent() was introduced to
convert from using cgroup->parent to css->parent.  It was quite some
time ago and we're moving forward with making css more prominent.

This patch drops the trivial wrapper css_parent() and let the users
dereference css->parent.  While at it, explicitly mark fields of css
which are public and immutable.

v2: New usage from device_cgroup.c converted.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Acked-by: default avatar"David S. Miller" <davem@davemloft.net>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Johannes Weiner <hannes@cmpxchg.org>
parent 3b514d24
......@@ -204,7 +204,7 @@ static inline struct blkcg *bio_blkcg(struct bio *bio)
*/
static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
{
return css_to_blkcg(css_parent(&blkcg->css));
return css_to_blkcg(blkcg->css.parent);
}
/**
......
......@@ -48,22 +48,28 @@ enum cgroup_subsys_id {
};
#undef SUBSYS
/* Per-subsystem/per-cgroup state maintained by the system. */
/*
* Per-subsystem/per-cgroup state maintained by the system. This is the
* fundamental structural building block that controllers deal with.
*
* Fields marked with "PI:" are public and immutable and may be accessed
* directly without synchronization.
*/
struct cgroup_subsys_state {
/* the cgroup that this css is attached to */
/* PI: the cgroup that this css is attached to */
struct cgroup *cgroup;
/* the cgroup subsystem that this css is attached to */
/* PI: the cgroup subsystem that this css is attached to */
struct cgroup_subsys *ss;
/* reference count - access via css_[try]get() and css_put() */
struct percpu_ref refcnt;
/* the parent css */
/* PI: the parent css */
struct cgroup_subsys_state *parent;
/*
* Subsys-unique ID. 0 is unused and root is always 1. The
* PI: Subsys-unique ID. 0 is unused and root is always 1. The
* matching css can be looked up using css_from_id().
*/
int id;
......@@ -669,19 +675,6 @@ struct cgroup_subsys {
#include <linux/cgroup_subsys.h>
#undef SUBSYS
/**
* css_parent - find the parent css
* @css: the target cgroup_subsys_state
*
* Return the parent css of @css. This function is guaranteed to return
* non-NULL parent as long as @css isn't the root.
*/
static inline
struct cgroup_subsys_state *css_parent(struct cgroup_subsys_state *css)
{
return css->parent;
}
/**
* task_css_set_check - obtain a task's css_set with extra access conditions
* @task: the task to obtain css_set for
......
......@@ -3176,10 +3176,10 @@ css_next_descendant_pre(struct cgroup_subsys_state *pos,
/* no child, visit my or the closest ancestor's next sibling */
while (pos != root) {
next = css_next_child(pos, css_parent(pos));
next = css_next_child(pos, pos->parent);
if (next)
return next;
pos = css_parent(pos);
pos = pos->parent;
}
return NULL;
......@@ -3261,12 +3261,12 @@ css_next_descendant_post(struct cgroup_subsys_state *pos,
return NULL;
/* if there's an unvisited sibling, visit its leftmost descendant */
next = css_next_child(pos, css_parent(pos));
next = css_next_child(pos, pos->parent);
if (next)
return css_leftmost_descendant(next);
/* no sibling left, visit parent */
return css_parent(pos);
return pos->parent;
}
static bool cgroup_has_live_children(struct cgroup *cgrp)
......
......@@ -59,7 +59,7 @@ static inline struct freezer *task_freezer(struct task_struct *task)
static struct freezer *parent_freezer(struct freezer *freezer)
{
return css_freezer(css_parent(&freezer->css));
return css_freezer(freezer->css.parent);
}
bool cgroup_freezing(struct task_struct *task)
......
......@@ -124,7 +124,7 @@ static inline struct cpuset *task_cs(struct task_struct *task)
static inline struct cpuset *parent_cs(struct cpuset *cs)
{
return css_cs(css_parent(&cs->css));
return css_cs(cs->css.parent);
}
#ifdef CONFIG_NUMA
......
......@@ -7586,7 +7586,7 @@ cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
{
struct task_group *tg = css_tg(css);
struct task_group *parent = css_tg(css_parent(css));
struct task_group *parent = css_tg(css->parent);
if (parent)
sched_online_group(tg, parent);
......
......@@ -46,7 +46,7 @@ static inline struct cpuacct *task_ca(struct task_struct *tsk)
static inline struct cpuacct *parent_ca(struct cpuacct *ca)
{
return css_ca(css_parent(&ca->css));
return css_ca(ca->css.parent);
}
static DEFINE_PER_CPU(u64, root_cpuacct_cpuusage);
......
......@@ -52,7 +52,7 @@ static inline bool hugetlb_cgroup_is_root(struct hugetlb_cgroup *h_cg)
static inline struct hugetlb_cgroup *
parent_hugetlb_cgroup(struct hugetlb_cgroup *h_cg)
{
return hugetlb_cgroup_from_css(css_parent(&h_cg->css));
return hugetlb_cgroup_from_css(h_cg->css.parent);
}
static inline bool hugetlb_cgroup_have_usage(struct hugetlb_cgroup *h_cg)
......
......@@ -1540,7 +1540,7 @@ static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
int mem_cgroup_swappiness(struct mem_cgroup *memcg)
{
/* root ? */
if (!css_parent(&memcg->css))
if (!memcg->css.parent)
return vm_swappiness;
return memcg->swappiness;
......@@ -4909,7 +4909,7 @@ static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
{
int retval = 0;
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup *parent_memcg = mem_cgroup_from_css(css_parent(&memcg->css));
struct mem_cgroup *parent_memcg = mem_cgroup_from_css(memcg->css.parent);
mutex_lock(&memcg_create_mutex);
......@@ -5207,8 +5207,8 @@ static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
if (!memcg->use_hierarchy)
goto out;
while (css_parent(&memcg->css)) {
memcg = mem_cgroup_from_css(css_parent(&memcg->css));
while (memcg->css.parent) {
memcg = mem_cgroup_from_css(memcg->css.parent);
if (!memcg->use_hierarchy)
break;
tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
......@@ -5443,7 +5443,7 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
struct mem_cgroup *parent = mem_cgroup_from_css(memcg->css.parent);
if (val > 100 || !parent)
return -EINVAL;
......@@ -5790,7 +5790,7 @@ static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css));
struct mem_cgroup *parent = mem_cgroup_from_css(memcg->css.parent);
/* cannot set to root cgroup and only 0 and 1 are allowed */
if (!parent || !((val == 0) || (val == 1)))
......@@ -6407,7 +6407,7 @@ static int
mem_cgroup_css_online(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(css));
struct mem_cgroup *parent = mem_cgroup_from_css(css->parent);
if (css->id > MEM_CGROUP_ID_MAX)
return -ENOSPC;
......
......@@ -42,7 +42,7 @@ cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
static int cgrp_css_online(struct cgroup_subsys_state *css)
{
struct cgroup_cls_state *cs = css_cls_state(css);
struct cgroup_cls_state *parent = css_cls_state(css_parent(css));
struct cgroup_cls_state *parent = css_cls_state(css->parent);
if (parent)
cs->classid = parent->classid;
......
......@@ -140,7 +140,7 @@ cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
static int cgrp_css_online(struct cgroup_subsys_state *css)
{
struct cgroup_subsys_state *parent_css = css_parent(css);
struct cgroup_subsys_state *parent_css = css->parent;
struct net_device *dev;
int ret = 0;
......
......@@ -182,7 +182,7 @@ static inline bool is_devcg_online(const struct dev_cgroup *devcg)
static int devcgroup_online(struct cgroup_subsys_state *css)
{
struct dev_cgroup *dev_cgroup = css_to_devcgroup(css);
struct dev_cgroup *parent_dev_cgroup = css_to_devcgroup(css_parent(css));
struct dev_cgroup *parent_dev_cgroup = css_to_devcgroup(css->parent);
int ret = 0;
mutex_lock(&devcgroup_mutex);
......@@ -455,7 +455,7 @@ static bool verify_new_ex(struct dev_cgroup *dev_cgroup,
static int parent_has_perm(struct dev_cgroup *childcg,
struct dev_exception_item *ex)
{
struct dev_cgroup *parent = css_to_devcgroup(css_parent(&childcg->css));
struct dev_cgroup *parent = css_to_devcgroup(childcg->css.parent);
if (!parent)
return 1;
......@@ -476,7 +476,7 @@ static int parent_has_perm(struct dev_cgroup *childcg,
static bool parent_allows_removal(struct dev_cgroup *childcg,
struct dev_exception_item *ex)
{
struct dev_cgroup *parent = css_to_devcgroup(css_parent(&childcg->css));
struct dev_cgroup *parent = css_to_devcgroup(childcg->css.parent);
if (!parent)
return true;
......@@ -614,7 +614,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
char temp[12]; /* 11 + 1 characters needed for a u32 */
int count, rc = 0;
struct dev_exception_item ex;
struct dev_cgroup *parent = css_to_devcgroup(css_parent(&devcgroup->css));
struct dev_cgroup *parent = css_to_devcgroup(devcgroup->css.parent);
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
......
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