[Devel] [PATCH 2/4] freezer_cg: remove redundant check in freezer_can_attach()

[Li Zefan]

It is sufficient to check if @task is frozen, and no need to check if
the original freezer is frozen.

Signed-off-by: Li Zefan <lizf at cn.fujitsu.com>
---
 kernel/cgroup_freezer.c |   16 +++++++---------
 1 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 7f54d1c..6fadafe 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -162,9 +162,13 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
 			      struct task_struct *task)
 {
 	struct freezer *freezer;
-	int retval;
 
-	/* Anything frozen can't move or be moved to/from */
+	/*
+	 * Anything frozen can't move or be moved to/from.
+	 *
+	 * Since orig_freezer->state == FROZEN means that @task has been
+	 * frozen, so it's sufficient to check the latter condition.
+	 */
 
 	if (is_task_frozen_enough(task))
 		return -EBUSY;
@@ -173,13 +177,7 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
 	if (freezer->state == CGROUP_FROZEN)
 		return -EBUSY;
 
-	retval = 0;
-	task_lock(task);
-	freezer = task_freezer(task);
-	if (freezer->state == CGROUP_FROZEN)
-		retval = -EBUSY;
-	task_unlock(task);
-	return retval;
+	return 0;
 }
 
 static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
-- 
1.5.4.rc3

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