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Subject[PATCH 03/13] cpuset: introduce ->css_on/offline()
Date
Add cpuset_css_on/offline() and rearrange css init/exit such that,

* Allocation and clearing to the default values happen in css_alloc().
Allocation now uses kzalloc().

* Config inheritance and registration happen in css_online().

* css_offline() undoes what css_online() did.

* css_free() frees.

This doesn't introduce any visible behavior changes. This will help
cleaning up locking.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
kernel/cpuset.c | 66 ++++++++++++++++++++++++++++++++++++++-------------------
1 file changed, 44 insertions(+), 22 deletions(-)

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 54b2b73..70197ba 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1790,15 +1790,12 @@ static struct cftype files[] = {

static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
{
- struct cgroup *parent_cg = cont->parent;
- struct cgroup *tmp_cg;
- struct cpuset *parent, *cs;
+ struct cpuset *cs;

- if (!parent_cg)
+ if (!cont->parent)
return &top_cpuset.css;
- parent = cgroup_cs(parent_cg);

- cs = kmalloc(sizeof(*cs), GFP_KERNEL);
+ cs = kzalloc(sizeof(*cs), GFP_KERNEL);
if (!cs)
return ERR_PTR(-ENOMEM);
if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) {
@@ -1806,22 +1803,34 @@ static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
return ERR_PTR(-ENOMEM);
}

- cs->flags = 0;
- if (is_spread_page(parent))
- set_bit(CS_SPREAD_PAGE, &cs->flags);
- if (is_spread_slab(parent))
- set_bit(CS_SPREAD_SLAB, &cs->flags);
set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
cpumask_clear(cs->cpus_allowed);
nodes_clear(cs->mems_allowed);
fmeter_init(&cs->fmeter);
cs->relax_domain_level = -1;
+ cs->parent = cgroup_cs(cont->parent);
+
+ return &cs->css;
+}
+
+static int cpuset_css_online(struct cgroup *cgrp)
+{
+ struct cpuset *cs = cgroup_cs(cgrp);
+ struct cpuset *parent = cs->parent;
+ struct cgroup *tmp_cg;
+
+ if (!parent)
+ return 0;
+
+ if (is_spread_page(parent))
+ set_bit(CS_SPREAD_PAGE, &cs->flags);
+ if (is_spread_slab(parent))
+ set_bit(CS_SPREAD_SLAB, &cs->flags);

- cs->parent = parent;
number_of_cpusets++;

- if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cont->flags))
- goto skip_clone;
+ if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags))
+ return 0;

/*
* Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
@@ -1836,19 +1845,34 @@ static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
* changed to grant parent->cpus_allowed-sibling_cpus_exclusive
* (and likewise for mems) to the new cgroup.
*/
- list_for_each_entry(tmp_cg, &parent_cg->children, sibling) {
+ list_for_each_entry(tmp_cg, &cgrp->parent->children, sibling) {
struct cpuset *tmp_cs = cgroup_cs(tmp_cg);

if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs))
- goto skip_clone;
+ return 0;
}

mutex_lock(&callback_mutex);
cs->mems_allowed = parent->mems_allowed;
cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
mutex_unlock(&callback_mutex);
-skip_clone:
- return &cs->css;
+
+ return 0;
+}
+
+static void cpuset_css_offline(struct cgroup *cgrp)
+{
+ struct cpuset *cs = cgroup_cs(cgrp);
+
+ /* css_offline is called w/o cgroup_mutex, grab it */
+ cgroup_lock();
+
+ if (is_sched_load_balance(cs))
+ update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
+
+ number_of_cpusets--;
+
+ cgroup_unlock();
}

/*
@@ -1861,10 +1885,6 @@ static void cpuset_css_free(struct cgroup *cont)
{
struct cpuset *cs = cgroup_cs(cont);

- if (is_sched_load_balance(cs))
- update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
-
- number_of_cpusets--;
free_cpumask_var(cs->cpus_allowed);
kfree(cs);
}
@@ -1872,6 +1892,8 @@ static void cpuset_css_free(struct cgroup *cont)
struct cgroup_subsys cpuset_subsys = {
.name = "cpuset",
.css_alloc = cpuset_css_alloc,
+ .css_online = cpuset_css_online,
+ .css_offline = cpuset_css_offline,
.css_free = cpuset_css_free,
.can_attach = cpuset_can_attach,
.attach = cpuset_attach,
--
1.7.11.7


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