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-rw-r--r--kernel/cgroup_freezer.c19
1 files changed, 16 insertions, 3 deletions
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 7fa476f..fb249e2 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -184,9 +184,20 @@ static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
{
struct freezer *freezer;
- task_lock(task);
+ /*
+ * No lock is needed, since the task isn't on tasklist yet,
+ * so it can't be moved to another cgroup, which means the
+ * freezer won't be removed and will be valid during this
+ * function call.
+ */
freezer = task_freezer(task);
- task_unlock(task);
+
+ /*
+ * The root cgroup is non-freezable, so we can skip the
+ * following check.
+ */
+ if (!freezer->css.cgroup->parent)
+ return;
spin_lock_irq(&freezer->lock);
BUG_ON(freezer->state == CGROUP_FROZEN);
@@ -331,7 +342,7 @@ static int freezer_write(struct cgroup *cgroup,
else if (strcmp(buffer, freezer_state_strs[CGROUP_FROZEN]) == 0)
goal_state = CGROUP_FROZEN;
else
- return -EIO;
+ return -EINVAL;
if (!cgroup_lock_live_group(cgroup))
return -ENODEV;
@@ -350,6 +361,8 @@ static struct cftype files[] = {
static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
{
+ if (!cgroup->parent)
+ return 0;
return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
}
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