Commit 9e10a130 authored by Tejun Heo's avatar Tejun Heo

cgroup: replace cgroup_on_dfl() tests in controllers with cgroup_subsys_on_dfl()

cgroup_on_dfl() tests whether the cgroup's root is the default
hierarchy; however, an individual controller is only interested in
whether the controller is attached to the default hierarchy and never
tests a cgroup which doesn't belong to the hierarchy that the
controller is attached to.

This patch replaces cgroup_on_dfl() tests in controllers with faster
static_key based cgroup_subsys_on_dfl().  This leaves cgroup core as
the only user of cgroup_on_dfl() and the function is moved from the
header file to cgroup.c.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarZefan Li <lizefan@huawei.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
parent fc5ed1e9
......@@ -369,7 +369,7 @@ static void throtl_pd_init(struct blkg_policy_data *pd)
* regardless of the position of the group in the hierarchy.
*/
sq->parent_sq = &td->service_queue;
if (cgroup_on_dfl(blkg->blkcg->css.cgroup) && blkg->parent)
if (cgroup_subsys_on_dfl(io_cgrp_subsys) && blkg->parent)
sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue;
tg->td = td;
}
......
......@@ -1581,7 +1581,7 @@ static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp)
static void cfq_cpd_init(struct blkcg_policy_data *cpd)
{
struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);
unsigned int weight = cgroup_on_dfl(blkcg_root.css.cgroup) ?
unsigned int weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
if (cpd_to_blkcg(cpd) == &blkcg_root)
......@@ -1599,7 +1599,7 @@ static void cfq_cpd_free(struct blkcg_policy_data *cpd)
static void cfq_cpd_bind(struct blkcg_policy_data *cpd)
{
struct blkcg *blkcg = cpd_to_blkcg(cpd);
bool on_dfl = cgroup_on_dfl(blkcg_root.css.cgroup);
bool on_dfl = cgroup_subsys_on_dfl(io_cgrp_subsys);
unsigned int weight = on_dfl ? CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
if (blkcg == &blkcg_root)
......
......@@ -433,64 +433,6 @@ static inline struct cgroup *task_cgroup(struct task_struct *task,
return task_css(task, subsys_id)->cgroup;
}
/**
* cgroup_on_dfl - test whether a cgroup is on the default hierarchy
* @cgrp: the cgroup of interest
*
* The default hierarchy is the v2 interface of cgroup and this function
* can be used to test whether a cgroup is on the default hierarchy for
* cases where a subsystem should behave differnetly depending on the
* interface version.
*
* The set of behaviors which change on the default hierarchy are still
* being determined and the mount option is prefixed with __DEVEL__.
*
* List of changed behaviors:
*
* - Mount options "noprefix", "xattr", "clone_children", "release_agent"
* and "name" are disallowed.
*
* - When mounting an existing superblock, mount options should match.
*
* - Remount is disallowed.
*
* - rename(2) is disallowed.
*
* - "tasks" is removed. Everything should be at process granularity. Use
* "cgroup.procs" instead.
*
* - "cgroup.procs" is not sorted. pids will be unique unless they got
* recycled inbetween reads.
*
* - "release_agent" and "notify_on_release" are removed. Replacement
* notification mechanism will be implemented.
*
* - "cgroup.clone_children" is removed.
*
* - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
* and its descendants contain no task; otherwise, 1. The file also
* generates kernfs notification which can be monitored through poll and
* [di]notify when the value of the file changes.
*
* - cpuset: tasks will be kept in empty cpusets when hotplug happens and
* take masks of ancestors with non-empty cpus/mems, instead of being
* moved to an ancestor.
*
* - cpuset: a task can be moved into an empty cpuset, and again it takes
* masks of ancestors.
*
* - memcg: use_hierarchy is on by default and the cgroup file for the flag
* is not created.
*
* - blkcg: blk-throttle becomes properly hierarchical.
*
* - debug: disallowed on the default hierarchy.
*/
static inline bool cgroup_on_dfl(const struct cgroup *cgrp)
{
return cgrp->root == &cgrp_dfl_root;
}
/* no synchronization, the result can only be used as a hint */
static inline bool cgroup_has_tasks(struct cgroup *cgrp)
{
......
......@@ -237,6 +237,64 @@ static bool cgroup_ssid_enabled(int ssid)
return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
}
/**
* cgroup_on_dfl - test whether a cgroup is on the default hierarchy
* @cgrp: the cgroup of interest
*
* The default hierarchy is the v2 interface of cgroup and this function
* can be used to test whether a cgroup is on the default hierarchy for
* cases where a subsystem should behave differnetly depending on the
* interface version.
*
* The set of behaviors which change on the default hierarchy are still
* being determined and the mount option is prefixed with __DEVEL__.
*
* List of changed behaviors:
*
* - Mount options "noprefix", "xattr", "clone_children", "release_agent"
* and "name" are disallowed.
*
* - When mounting an existing superblock, mount options should match.
*
* - Remount is disallowed.
*
* - rename(2) is disallowed.
*
* - "tasks" is removed. Everything should be at process granularity. Use
* "cgroup.procs" instead.
*
* - "cgroup.procs" is not sorted. pids will be unique unless they got
* recycled inbetween reads.
*
* - "release_agent" and "notify_on_release" are removed. Replacement
* notification mechanism will be implemented.
*
* - "cgroup.clone_children" is removed.
*
* - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
* and its descendants contain no task; otherwise, 1. The file also
* generates kernfs notification which can be monitored through poll and
* [di]notify when the value of the file changes.
*
* - cpuset: tasks will be kept in empty cpusets when hotplug happens and
* take masks of ancestors with non-empty cpus/mems, instead of being
* moved to an ancestor.
*
* - cpuset: a task can be moved into an empty cpuset, and again it takes
* masks of ancestors.
*
* - memcg: use_hierarchy is on by default and the cgroup file for the flag
* is not created.
*
* - blkcg: blk-throttle becomes properly hierarchical.
*
* - debug: disallowed on the default hierarchy.
*/
static bool cgroup_on_dfl(const struct cgroup *cgrp)
{
return cgrp->root == &cgrp_dfl_root;
}
/* IDR wrappers which synchronize using cgroup_idr_lock */
static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
gfp_t gfp_mask)
......
......@@ -473,7 +473,8 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial)
/* On legacy hiearchy, we must be a subset of our parent cpuset. */
ret = -EACCES;
if (!cgroup_on_dfl(cur->css.cgroup) && !is_cpuset_subset(trial, par))
if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
!is_cpuset_subset(trial, par))
goto out;
/*
......@@ -879,7 +880,8 @@ static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus)
* If it becomes empty, inherit the effective mask of the
* parent, which is guaranteed to have some CPUs.
*/
if (cgroup_on_dfl(cp->css.cgroup) && cpumask_empty(new_cpus))
if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
cpumask_empty(new_cpus))
cpumask_copy(new_cpus, parent->effective_cpus);
/* Skip the whole subtree if the cpumask remains the same. */
......@@ -896,7 +898,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus)
cpumask_copy(cp->effective_cpus, new_cpus);
spin_unlock_irq(&callback_lock);
WARN_ON(!cgroup_on_dfl(cp->css.cgroup) &&
WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
!cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
update_tasks_cpumask(cp);
......@@ -1135,7 +1137,8 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
* If it becomes empty, inherit the effective mask of the
* parent, which is guaranteed to have some MEMs.
*/
if (cgroup_on_dfl(cp->css.cgroup) && nodes_empty(*new_mems))
if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
nodes_empty(*new_mems))
*new_mems = parent->effective_mems;
/* Skip the whole subtree if the nodemask remains the same. */
......@@ -1152,7 +1155,7 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
cp->effective_mems = *new_mems;
spin_unlock_irq(&callback_lock);
WARN_ON(!cgroup_on_dfl(cp->css.cgroup) &&
WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
!nodes_equal(cp->mems_allowed, cp->effective_mems));
update_tasks_nodemask(cp);
......@@ -1440,7 +1443,7 @@ static int cpuset_can_attach(struct cgroup_subsys_state *css,
/* allow moving tasks into an empty cpuset if on default hierarchy */
ret = -ENOSPC;
if (!cgroup_on_dfl(css->cgroup) &&
if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
(cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
goto out_unlock;
......@@ -1952,7 +1955,7 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
cpuset_inc();
spin_lock_irq(&callback_lock);
if (cgroup_on_dfl(cs->css.cgroup)) {
if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) {
cpumask_copy(cs->effective_cpus, parent->effective_cpus);
cs->effective_mems = parent->effective_mems;
}
......@@ -2029,7 +2032,7 @@ static void cpuset_bind(struct cgroup_subsys_state *root_css)
mutex_lock(&cpuset_mutex);
spin_lock_irq(&callback_lock);
if (cgroup_on_dfl(root_css->cgroup)) {
if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) {
cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
top_cpuset.mems_allowed = node_possible_map;
} else {
......@@ -2210,7 +2213,7 @@ retry:
cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);
mems_updated = !nodes_equal(new_mems, cs->effective_mems);
if (cgroup_on_dfl(cs->css.cgroup))
if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys))
hotplug_update_tasks(cs, &new_cpus, &new_mems,
cpus_updated, mems_updated);
else
......@@ -2241,7 +2244,7 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
static cpumask_t new_cpus;
static nodemask_t new_mems;
bool cpus_updated, mems_updated;
bool on_dfl = cgroup_on_dfl(top_cpuset.css.cgroup);
bool on_dfl = cgroup_subsys_on_dfl(cpuset_cgrp_subsys);
mutex_lock(&cpuset_mutex);
......
......@@ -434,7 +434,7 @@ struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page)
memcg = page->mem_cgroup;
if (!memcg || !cgroup_on_dfl(memcg->css.cgroup))
if (!memcg || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
memcg = root_mem_cgroup;
rcu_read_unlock();
......@@ -5059,7 +5059,7 @@ static void mem_cgroup_bind(struct cgroup_subsys_state *root_css)
* guarantees that @root doesn't have any children, so turning it
* on for the root memcg is enough.
*/
if (cgroup_on_dfl(root_css->cgroup))
if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
root_mem_cgroup->use_hierarchy = true;
else
root_mem_cgroup->use_hierarchy = false;
......
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