cpuset: introduce cpuset_for_each_child()
Instead of iterating cgroup->children directly, introduce and use cpuset_for_each_child() which wraps cgroup_for_each_child() and performs online check. As it uses the generic iterator, it requires RCU read locking too. As cpuset is currently protected by cgroup_mutex, non-online cpusets aren't visible to all the iterations and this patch currently doesn't make any functional difference. This will be used to de-couple cpuset locking from cgroup core. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo
parent
efeb77b2f1
commit
ae8086ce15
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@ -200,6 +200,19 @@ static struct cpuset top_cpuset = {
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(1 << CS_MEM_EXCLUSIVE)),
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};
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/**
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* cpuset_for_each_child - traverse online children of a cpuset
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* @child_cs: loop cursor pointing to the current child
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* @pos_cgrp: used for iteration
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* @parent_cs: target cpuset to walk children of
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*
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* Walk @child_cs through the online children of @parent_cs. Must be used
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* with RCU read locked.
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*/
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#define cpuset_for_each_child(child_cs, pos_cgrp, parent_cs) \
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cgroup_for_each_child((pos_cgrp), (parent_cs)->css.cgroup) \
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if (is_cpuset_online(((child_cs) = cgroup_cs((pos_cgrp)))))
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/*
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* There are two global mutexes guarding cpuset structures. The first
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* is the main control groups cgroup_mutex, accessed via
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@ -419,48 +432,55 @@ static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
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{
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struct cgroup *cont;
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struct cpuset *c, *par;
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int ret;
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rcu_read_lock();
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/* Each of our child cpusets must be a subset of us */
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list_for_each_entry(cont, &cur->css.cgroup->children, sibling) {
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if (!is_cpuset_subset(cgroup_cs(cont), trial))
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return -EBUSY;
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}
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ret = -EBUSY;
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cpuset_for_each_child(c, cont, cur)
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if (!is_cpuset_subset(c, trial))
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goto out;
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/* Remaining checks don't apply to root cpuset */
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ret = 0;
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if (cur == &top_cpuset)
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return 0;
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goto out;
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par = cur->parent;
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/* We must be a subset of our parent cpuset */
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ret = -EACCES;
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if (!is_cpuset_subset(trial, par))
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return -EACCES;
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goto out;
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/*
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* If either I or some sibling (!= me) is exclusive, we can't
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* overlap
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*/
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list_for_each_entry(cont, &par->css.cgroup->children, sibling) {
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c = cgroup_cs(cont);
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ret = -EINVAL;
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cpuset_for_each_child(c, cont, par) {
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if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
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c != cur &&
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cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
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return -EINVAL;
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goto out;
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if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
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c != cur &&
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nodes_intersects(trial->mems_allowed, c->mems_allowed))
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return -EINVAL;
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goto out;
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}
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/* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */
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if (cgroup_task_count(cur->css.cgroup)) {
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if (cpumask_empty(trial->cpus_allowed) ||
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nodes_empty(trial->mems_allowed)) {
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return -ENOSPC;
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}
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}
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ret = -ENOSPC;
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if (cgroup_task_count(cur->css.cgroup) &&
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(cpumask_empty(trial->cpus_allowed) ||
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nodes_empty(trial->mems_allowed)))
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goto out;
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return 0;
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ret = 0;
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out:
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rcu_read_unlock();
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return ret;
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}
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#ifdef CONFIG_SMP
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@ -501,10 +521,10 @@ update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *c)
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if (is_sched_load_balance(cp))
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update_domain_attr(dattr, cp);
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list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
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child = cgroup_cs(cont);
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rcu_read_lock();
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cpuset_for_each_child(child, cont, cp)
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list_add_tail(&child->stack_list, &q);
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}
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rcu_read_unlock();
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}
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}
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@ -623,10 +643,10 @@ static int generate_sched_domains(cpumask_var_t **domains,
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continue;
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}
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list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
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child = cgroup_cs(cont);
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rcu_read_lock();
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cpuset_for_each_child(child, cont, cp)
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list_add_tail(&child->stack_list, &q);
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}
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rcu_read_unlock();
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}
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for (i = 0; i < csn; i++)
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@ -1824,7 +1844,8 @@ static int cpuset_css_online(struct cgroup *cgrp)
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{
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struct cpuset *cs = cgroup_cs(cgrp);
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struct cpuset *parent = cs->parent;
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struct cgroup *tmp_cg;
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struct cpuset *tmp_cs;
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struct cgroup *pos_cg;
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if (!parent)
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return 0;
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@ -1853,12 +1874,14 @@ static int cpuset_css_online(struct cgroup *cgrp)
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* changed to grant parent->cpus_allowed-sibling_cpus_exclusive
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* (and likewise for mems) to the new cgroup.
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*/
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list_for_each_entry(tmp_cg, &cgrp->parent->children, sibling) {
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struct cpuset *tmp_cs = cgroup_cs(tmp_cg);
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if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs))
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rcu_read_lock();
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cpuset_for_each_child(tmp_cs, pos_cg, parent) {
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if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
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rcu_read_unlock();
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return 0;
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}
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}
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rcu_read_unlock();
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mutex_lock(&callback_mutex);
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cs->mems_allowed = parent->mems_allowed;
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@ -2027,10 +2050,10 @@ static struct cpuset *cpuset_next(struct list_head *queue)
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cp = list_first_entry(queue, struct cpuset, stack_list);
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list_del(queue->next);
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list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
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child = cgroup_cs(cont);
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rcu_read_lock();
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cpuset_for_each_child(child, cont, cp)
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list_add_tail(&child->stack_list, queue);
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}
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rcu_read_unlock();
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return cp;
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}
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