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Date: Tue, 15 Sep 2015 21:51:25 -0400
From: Tejun Heo <tj@...nel.org>
To: lizefan@...wei.com, hannes@...xchg.org
Cc: cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
kernel-team@...com, Tejun Heo <tj@...nel.org>,
Vivek Goyal <vgoyal@...hat.com>, Jens Axboe <axboe@...nel.dk>,
Michal Hocko <mhocko@...nel.org>
Subject: [PATCH 4/4] 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: Tejun Heo <tj@...nel.org>
Cc: Vivek Goyal <vgoyal@...hat.com>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: Li Zefan <lizefan@...wei.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Michal Hocko <mhocko@...nel.org>
---
block/blk-throttle.c | 2 +-
block/cfq-iosched.c | 4 ++--
include/linux/cgroup.h | 58 --------------------------------------------------
kernel/cgroup.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++
kernel/cpuset.c | 23 +++++++++++---------
mm/memcontrol.c | 4 ++--
6 files changed, 76 insertions(+), 73 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index c75a263..2149a1d 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -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;
}
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 04de884..1f9093e 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -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)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index c3a9f1e..355bf2e 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -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)
{
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 5703ba7..c24f929 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -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)
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index f0acff0..20eedd8 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -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 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs)
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);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6ddaeba..b35c4cc 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -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;
--
2.4.3
--
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