cgroup/cpuset: Streamline rm_siblings_excl_cpus()

If exclusive_cpus is set, effective_xcpus must be a subset of
exclusive_cpus. Currently, rm_siblings_excl_cpus() checks both
exclusive_cpus and effective_xcpus consecutively. It is simpler
to check only exclusive_cpus if non-empty or just effective_xcpus
otherwise.

No functional change is expected.

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

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 221da921b4f910e85cc90d204ecca786a0e57725..da2b3b51630e4eb4bc547906a8e1e5506e2239b4 100644 (file)
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1355,23 +1355,29 @@ static int rm_siblings_excl_cpus(struct cpuset *parent, struct cpuset *cs,
        int retval = 0;
 
        if (cpumask_empty(excpus))
-               return retval;
+               return 0;
 
        /*
-        * Exclude exclusive CPUs from siblings
+        * Remove exclusive CPUs from siblings
         */
        rcu_read_lock();
        cpuset_for_each_child(sibling, css, parent) {
+               struct cpumask *sibling_xcpus;
+
                if (sibling == cs)
                        continue;
 
-               if (cpumask_intersects(excpus, sibling->exclusive_cpus)) {
-                       cpumask_andnot(excpus, excpus, sibling->exclusive_cpus);
-                       retval++;
-                       continue;
-               }
-               if (cpumask_intersects(excpus, sibling->effective_xcpus)) {
-                       cpumask_andnot(excpus, excpus, sibling->effective_xcpus);
+               /*
+                * If exclusive_cpus is defined, effective_xcpus will always
+                * be a subset. Otherwise, effective_xcpus will only be set
+                * in a valid partition root.
+                */
+               sibling_xcpus = cpumask_empty(sibling->exclusive_cpus)
+                             ? sibling->effective_xcpus
+                             : sibling->exclusive_cpus;
+
+               if (cpumask_intersects(excpus, sibling_xcpus)) {
+                       cpumask_andnot(excpus, excpus, sibling_xcpus);
                        retval++;
                }
        }