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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 7fa476f01d05..fb249e2bcada 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)
184{ 184{
185 struct freezer *freezer; 185 struct freezer *freezer;
186 186
187 task_lock(task); 187 /*
188 * No lock is needed, since the task isn't on tasklist yet,
189 * so it can't be moved to another cgroup, which means the
190 * freezer won't be removed and will be valid during this
191 * function call.
192 */
188 freezer = task_freezer(task); 193 freezer = task_freezer(task);
189 task_unlock(task); 194
195 /*
196 * The root cgroup is non-freezable, so we can skip the
197 * following check.
198 */
199 if (!freezer->css.cgroup->parent)
200 return;
190 201
191 spin_lock_irq(&freezer->lock); 202 spin_lock_irq(&freezer->lock);
192 BUG_ON(freezer->state == CGROUP_FROZEN); 203 BUG_ON(freezer->state == CGROUP_FROZEN);
@@ -331,7 +342,7 @@ static int freezer_write(struct cgroup *cgroup,
331 else if (strcmp(buffer, freezer_state_strs[CGROUP_FROZEN]) == 0) 342 else if (strcmp(buffer, freezer_state_strs[CGROUP_FROZEN]) == 0)
332 goal_state = CGROUP_FROZEN; 343 goal_state = CGROUP_FROZEN;
333 else 344 else
334 return -EIO; 345 return -EINVAL;
335 346
336 if (!cgroup_lock_live_group(cgroup)) 347 if (!cgroup_lock_live_group(cgroup))
337 return -ENODEV; 348 return -ENODEV;
@@ -350,6 +361,8 @@ static struct cftype files[] = {
350 361
351static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup) 362static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
352{ 363{
364 if (!cgroup->parent)
365 return 0;
353 return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files)); 366 return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
354} 367}
355 368