cpuset: refactor cpus_allowed_validate_change

Refactor cpus_allowed_validate_change to handle the special case where
cpuset.cpus can be set even when violating partition sibling CPU
exclusivity rules. This differs from the general validation logic in
validate_change. Add a wrapper function to properly handle this
exceptional case.

The trialcs->prs_err field is cleared before performing validation checks
for both CPU changes and partition errors. If cpus_allowed_validate_change
fails its validation, trialcs->prs_err is set to PERR_NOTEXCL. If partition
validation fails, the specific error code returned by validate_partition
is assigned to trialcs->prs_err.

With the partition validation status now directly available through
trialcs->prs_err, the local boolean variable 'invalidate' becomes
redundant and can be safely removed.

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 2e963e2ef8eae8a6bef3acfd74f864df0ed4660f..cc3837899d4d19a4dd747fbe27896a5c21bbafbc 100644 (file)
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2417,6 +2417,42 @@ static enum prs_errcode validate_partition(struct cpuset *cs, struct cpuset *tri
        return PERR_NONE;
 }
 
+static int cpus_allowed_validate_change(struct cpuset *cs, struct cpuset *trialcs,
+                                       struct tmpmasks *tmp)
+{
+       int retval;
+       struct cpuset *parent = parent_cs(cs);
+
+       retval = validate_change(cs, trialcs);
+
+       if ((retval == -EINVAL) && cpuset_v2()) {
+               struct cgroup_subsys_state *css;
+               struct cpuset *cp;
+
+               /*
+                * The -EINVAL error code indicates that partition sibling
+                * CPU exclusivity rule has been violated. We still allow
+                * the cpumask change to proceed while invalidating the
+                * partition. However, any conflicting sibling partitions
+                * have to be marked as invalid too.
+                */
+               trialcs->prs_err = PERR_NOTEXCL;
+               rcu_read_lock();
+               cpuset_for_each_child(cp, css, parent) {
+                       struct cpumask *xcpus = user_xcpus(trialcs);
+
+                       if (is_partition_valid(cp) &&
+                           cpumask_intersects(xcpus, cp->effective_xcpus)) {
+                               rcu_read_unlock();
+                               update_parent_effective_cpumask(cp, partcmd_invalidate, NULL, tmp);
+                               rcu_read_lock();
+                       }
+               }
+               rcu_read_unlock();
+               retval = 0;
+       }
+       return retval;
+}
 
 /**
  * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
@@ -2429,8 +2465,6 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
 {
        int retval;
        struct tmpmasks tmp;
-       struct cpuset *parent = parent_cs(cs);
-       bool invalidate = false;
        bool force = false;
        int old_prs = cs->partition_root_state;
        enum prs_errcode prs_err;
@@ -2447,12 +2481,10 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
                return -ENOMEM;
 
        compute_trialcs_excpus(trialcs, cs);
+       trialcs->prs_err = PERR_NONE;
 
-       prs_err = validate_partition(cs, trialcs);
-       if (prs_err) {
-               invalidate = true;
-               cs->prs_err = prs_err;
-       }
+       if (cpus_allowed_validate_change(cs, trialcs, &tmp) < 0)
+               goto out_free;
 
        /*
         * Check all the descendants in update_cpumasks_hier() if
@@ -2460,40 +2492,14 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
         */
        force = !cpumask_equal(cs->effective_xcpus, trialcs->effective_xcpus);
 
-       retval = validate_change(cs, trialcs);
-
-       if ((retval == -EINVAL) && cpuset_v2()) {
-               struct cgroup_subsys_state *css;
-               struct cpuset *cp;
-
-               /*
-                * The -EINVAL error code indicates that partition sibling
-                * CPU exclusivity rule has been violated. We still allow
-                * the cpumask change to proceed while invalidating the
-                * partition. However, any conflicting sibling partitions
-                * have to be marked as invalid too.
-                */
-               invalidate = true;
-               rcu_read_lock();
-               cpuset_for_each_child(cp, css, parent) {
-                       struct cpumask *xcpus = user_xcpus(trialcs);
-
-                       if (is_partition_valid(cp) &&
-                           cpumask_intersects(xcpus, cp->effective_xcpus)) {
-                               rcu_read_unlock();
-                               update_parent_effective_cpumask(cp, partcmd_invalidate, NULL, &tmp);
-                               rcu_read_lock();
-                       }
-               }
-               rcu_read_unlock();
-               retval = 0;
+       prs_err = validate_partition(cs, trialcs);
+       if (prs_err) {
+               trialcs->prs_err = prs_err;
+               cs->prs_err = prs_err;
        }
 
-       if (retval < 0)
-               goto out_free;
-
        if (is_partition_valid(cs) ||
-          (is_partition_invalid(cs) && !invalidate)) {
+          (is_partition_invalid(cs) && !trialcs->prs_err)) {
                struct cpumask *xcpus = trialcs->effective_xcpus;
 
                if (cpumask_empty(xcpus) && is_partition_invalid(cs))
@@ -2504,7 +2510,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
                 */
                if (is_remote_partition(cs))
                        remote_cpus_update(cs, NULL, xcpus, &tmp);
-               else if (invalidate)
+               else if (trialcs->prs_err)
                        update_parent_effective_cpumask(cs, partcmd_invalidate,
                                                        NULL, &tmp);
                else