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SubjectRe: [PATCH] cpuset: fix a regression in validating config change
Hello, Li.

I dropped the make_*_empty variables and just put the conditionals
directly inside the outer if. Please scream if I messed it up.
Applied to cgroup/for-3.11-fixes.

Thanks.

------- 8< --------
From 1c09b195d37fa459844036f429a0f378e70c3db6 Mon Sep 17 00:00:00 2001
From: Li Zefan <lizefan@huawei.com>
Date: Wed, 21 Aug 2013 10:22:28 +0800
Subject: [PATCH] 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>
---
kernel/cpuset.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)

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:
--
1.8.3.1


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