diff options
| author | Tejun Heo <tj@kernel.org> | 2014-05-13 12:10:59 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2014-05-13 12:10:59 -0400 |
| commit | 0cee8b7786467907e12d1d8f872e6dc73bc95204 (patch) | |
| tree | ef6db71c2426ce12ed2f558790d0efe76bffd4a7 /kernel/cgroup.c | |
| parent | f21a4f7594a122dcaabc08ce03bfb63fdc34de1b (diff) | |
cgroup: fix offlining child waiting in cgroup_subtree_control_write()
cgroup_subtree_control_write() waits for offline to complete
child-by-child before enabling a controller; however, it has a couple
bugs.
* It doesn't initialize the wait_queue_t. This can lead to infinite
hang on the following schedule() among other things.
* It forgets to pin the child before releasing cgroup_tree_mutex and
performing schedule(). The child may already be gone by the time it
wakes up and invokes finish_wait(). Pin the child being waited on.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 9db1a9629a5..95fc66b1609 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2594,16 +2594,18 @@ retry: * cases, wait till it's gone using offline_waitq. */ cgroup_for_each_live_child(child, cgrp) { - wait_queue_t wait; + DEFINE_WAIT(wait); if (!cgroup_css(child, ss)) continue; + cgroup_get(child); prepare_to_wait(&child->offline_waitq, &wait, TASK_UNINTERRUPTIBLE); mutex_unlock(&cgroup_tree_mutex); schedule(); finish_wait(&child->offline_waitq, &wait); + cgroup_put(child); goto retry; } |