From: Li Zefan <lizefan@huawei.com>
Date: Wed, 21 Aug 2013 02:22:28 +0000 (+0800)
Subject: cpuset: fix a regression in validating config change
X-Git-Tag: v3.11-rc7~9^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=1c09b195d37fa459844036f429a0f378e70c3db6;p=profile%2Fivi%2Fkernel-x86-ivi.git

cpuset: fix a regression in validating config change

It's not allowed to clear masks of a cpuset if there're tasks in it,
but it's broken:

  # mkdir /cgroup/sub
  # echo 0 > /cgroup/sub/cpuset.cpus
  # echo 0 > /cgroup/sub/cpuset.mems
  # echo $$ > /cgroup/sub/tasks
  # echo > /cgroup/sub/cpuset.cpus
  (should fail)

This bug was introduced by commit 88fa523bff295f1d60244a54833480b02f775152
("cpuset: allow to move tasks to empty cpusets").

tj: Dropped temp bool variables and nestes the conditionals directly.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 010a008..ea1966d 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -475,13 +475,17 @@ static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
 
 	/*
 	 * Cpusets with tasks - existing or newly being attached - can't
-	 * have empty cpus_allowed or mems_allowed.
+	 * be changed to have empty cpus_allowed or mems_allowed.
 	 */
 	ret = -ENOSPC;
-	if ((cgroup_task_count(cur->css.cgroup) || cur->attach_in_progress) &&
-	    (cpumask_empty(trial->cpus_allowed) &&
-	     nodes_empty(trial->mems_allowed)))
-		goto out;
+	if ((cgroup_task_count(cur->css.cgroup) || cur->attach_in_progress)) {
+		if (!cpumask_empty(cur->cpus_allowed) &&
+		    cpumask_empty(trial->cpus_allowed))
+			goto out;
+		if (!nodes_empty(cur->mems_allowed) &&
+		    nodes_empty(trial->mems_allowed))
+			goto out;
+	}
 
 	ret = 0;
 out: