cpuset: remove cpuset->parent

cgroup already tracks the hierarchy.  Follow cgroup->parent to find
the parent and drop cpuset->parent.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Li Zefan <lizefan@huawei.com>

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 0ddb48d..6aa5bbb 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -87,8 +87,6 @@ struct cpuset {
        cpumask_var_t cpus_allowed;     /* CPUs allowed to tasks in cpuset */
        nodemask_t mems_allowed;        /* Memory Nodes allowed to tasks */
 
-       struct cpuset *parent;          /* my parent */
-
        struct fmeter fmeter;           /* memory_pressure filter */
 
        /*
@@ -120,6 +118,15 @@ static inline struct cpuset *task_cs(struct task_struct *task)
                            struct cpuset, css);
 }
 
+static inline struct cpuset *parent_cs(const struct cpuset *cs)
+{
+       struct cgroup *pcgrp = cs->css.cgroup->parent;
+
+       if (pcgrp)
+               return cgroup_cs(pcgrp);
+       return NULL;
+}
+
 #ifdef CONFIG_NUMA
 static inline bool task_has_mempolicy(struct task_struct *task)
 {
@@ -323,7 +330,7 @@ static void guarantee_online_cpus(const struct cpuset *cs,
                                  struct cpumask *pmask)
 {
        while (cs && !cpumask_intersects(cs->cpus_allowed, cpu_online_mask))
-               cs = cs->parent;
+               cs = parent_cs(cs);
        if (cs)
                cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask);
        else
@@ -348,7 +355,7 @@ static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask)
 {
        while (cs && !nodes_intersects(cs->mems_allowed,
                                        node_states[N_MEMORY]))
-               cs = cs->parent;
+               cs = parent_cs(cs);
        if (cs)
                nodes_and(*pmask, cs->mems_allowed,
                                        node_states[N_MEMORY]);
@@ -461,7 +468,7 @@ static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
        if (cur == &top_cpuset)
                goto out;
 
-       par = cur->parent;
+       par = parent_cs(cur);
 
        /* We must be a subset of our parent cpuset */
        ret = -EACCES;
@@ -1866,7 +1873,6 @@ static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
        fmeter_init(&cs->fmeter);
        INIT_WORK(&cs->hotplug_work, cpuset_propagate_hotplug_workfn);
        cs->relax_domain_level = -1;
-       cs->parent = cgroup_cs(cont->parent);
 
        return &cs->css;
 }
@@ -1874,7 +1880,7 @@ static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
 static int cpuset_css_online(struct cgroup *cgrp)
 {
        struct cpuset *cs = cgroup_cs(cgrp);
-       struct cpuset *parent = cs->parent;
+       struct cpuset *parent = parent_cs(cs);
        struct cpuset *tmp_cs;
        struct cgroup *pos_cg;
 
@@ -2058,10 +2064,10 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
         * Find its next-highest non-empty parent, (top cpuset
         * has online cpus, so can't be empty).
         */
-       parent = cs->parent;
+       parent = parent_cs(cs);
        while (cpumask_empty(parent->cpus_allowed) ||
                        nodes_empty(parent->mems_allowed))
-               parent = parent->parent;
+               parent = parent_cs(parent);
 
        move_member_tasks_to_cpuset(cs, parent);
 }
@@ -2373,8 +2379,8 @@ int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
  */
 static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
 {
-       while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && cs->parent)
-               cs = cs->parent;
+       while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
+               cs = parent_cs(cs);
        return cs;
 }