cgroup/cpuset: remove use_parent_ecpus of cpuset

use_parent_ecpus is used to track whether the children are using the
parent's effective_cpus. When a parent's effective_cpus is changed
due to changes in a child partition's effective_xcpus, any child
using parent'effective_cpus must call update_cpumasks_hier. However,
if a child is not a valid partition, it is sufficient to determine
whether to call update_cpumasks_hier based on whether the child's
effective_cpus is going to change. To make the code more succinct,
it is suggested to remove use_parent_ecpus.

Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 92e79ddc8188188071f73eaef5290afc888c9817..7db55eed63cf95f8254cfa0919d2b49ccf4a5cfd 100644 (file)
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -185,12 +185,6 @@ struct cpuset {
        /* partition root state */
        int partition_root_state;
 
-       /*
-        * Default hierarchy only:
-        * use_parent_ecpus - set if using parent's effective_cpus
-        */
-       int use_parent_ecpus;
-
        /*
         * number of SCHED_DEADLINE tasks attached to this cpuset, so that we
         * know when to rebuild associated root domain bandwidth information.
@@ -1505,11 +1499,8 @@ static void reset_partition_data(struct cpuset *cs)
                if (is_cpu_exclusive(cs))
                        clear_bit(CS_CPU_EXCLUSIVE, &cs->flags);
        }
-       if (!cpumask_and(cs->effective_cpus,
-                        parent->effective_cpus, cs->cpus_allowed)) {
-               cs->use_parent_ecpus = true;
+       if (!cpumask_and(cs->effective_cpus, parent->effective_cpus, cs->cpus_allowed))
                cpumask_copy(cs->effective_cpus, parent->effective_cpus);
-       }
 }
 
 /*
@@ -1683,8 +1674,6 @@ static int remote_partition_enable(struct cpuset *cs, int new_prs,
        spin_lock_irq(&callback_lock);
        isolcpus_updated = partition_xcpus_add(new_prs, NULL, tmp->new_cpus);
        list_add(&cs->remote_sibling, &remote_children);
-       if (cs->use_parent_ecpus)
-               cs->use_parent_ecpus = false;
        spin_unlock_irq(&callback_lock);
        update_unbound_workqueue_cpumask(isolcpus_updated);
 
@@ -2309,13 +2298,8 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
                 * it is a partition root that has explicitly distributed
                 * out all its CPUs.
                 */
-               if (is_in_v2_mode() && !remote && cpumask_empty(tmp->new_cpus)) {
+               if (is_in_v2_mode() && !remote && cpumask_empty(tmp->new_cpus))
                        cpumask_copy(tmp->new_cpus, parent->effective_cpus);
-                       if (!cp->use_parent_ecpus)
-                               cp->use_parent_ecpus = true;
-               } else if (cp->use_parent_ecpus) {
-                       cp->use_parent_ecpus = false;
-               }
 
                if (remote)
                        goto get_css;
@@ -2452,8 +2436,7 @@ static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs,
         * Check all its siblings and call update_cpumasks_hier()
         * if their effective_cpus will need to be changed.
         *
-        * With the addition of effective_xcpus which is a subset of
-        * cpus_allowed. It is possible a change in parent's effective_cpus
+        * It is possible a change in parent's effective_cpus
         * due to a change in a child partition's effective_xcpus will impact
         * its siblings even if they do not inherit parent's effective_cpus
         * directly.
@@ -2467,8 +2450,7 @@ static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs,
        cpuset_for_each_child(sibling, pos_css, parent) {
                if (sibling == cs)
                        continue;
-               if (!sibling->use_parent_ecpus &&
-                   !is_partition_valid(sibling)) {
+               if (!is_partition_valid(sibling)) {
                        compute_effective_cpumask(tmp->new_cpus, sibling,
                                                  parent);
                        if (cpumask_equal(tmp->new_cpus, sibling->effective_cpus))
@@ -4128,7 +4110,6 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
        if (is_in_v2_mode()) {
                cpumask_copy(cs->effective_cpus, parent->effective_cpus);
                cs->effective_mems = parent->effective_mems;
-               cs->use_parent_ecpus = true;
        }
        spin_unlock_irq(&callback_lock);
 
@@ -4194,9 +4175,6 @@ static void cpuset_css_offline(struct cgroup_subsys_state *css)
            is_sched_load_balance(cs))
                update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
 
-       if (cs->use_parent_ecpus)
-               cs->use_parent_ecpus = false;
-
        cpuset_dec();
        clear_bit(CS_ONLINE, &cs->flags);