diff options
Diffstat (limited to 'kernel/cgroup_freezer.c')
| -rw-r--r-- | kernel/cgroup_freezer.c | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c index da5e1397553..ce71ed53e88 100644 --- a/kernel/cgroup_freezer.c +++ b/kernel/cgroup_freezer.c @@ -89,10 +89,10 @@ struct cgroup_subsys freezer_subsys; /* Locks taken and their ordering * ------------------------------ - * css_set_lock * cgroup_mutex (AKA cgroup_lock) - * task->alloc_lock (AKA task_lock) * freezer->lock + * css_set_lock + * task->alloc_lock (AKA task_lock) * task->sighand->siglock * * cgroup code forces css_set_lock to be taken before task->alloc_lock @@ -100,33 +100,38 @@ struct cgroup_subsys freezer_subsys; * freezer_create(), freezer_destroy(): * cgroup_mutex [ by cgroup core ] * - * can_attach(): - * cgroup_mutex + * freezer_can_attach(): + * cgroup_mutex (held by caller of can_attach) * - * cgroup_frozen(): + * cgroup_freezing_or_frozen(): * task->alloc_lock (to get task's cgroup) * * freezer_fork() (preserving fork() performance means can't take cgroup_mutex): - * task->alloc_lock (to get task's cgroup) * freezer->lock * sighand->siglock (if the cgroup is freezing) * * freezer_read(): * cgroup_mutex * freezer->lock + * write_lock css_set_lock (cgroup iterator start) + * task->alloc_lock * read_lock css_set_lock (cgroup iterator start) * * freezer_write() (freeze): * cgroup_mutex * freezer->lock + * write_lock css_set_lock (cgroup iterator start) + * task->alloc_lock * read_lock css_set_lock (cgroup iterator start) - * sighand->siglock + * sighand->siglock (fake signal delivery inside freeze_task()) * * freezer_write() (unfreeze): * cgroup_mutex * freezer->lock + * write_lock css_set_lock (cgroup iterator start) + * task->alloc_lock * read_lock css_set_lock (cgroup iterator start) - * task->alloc_lock (to prevent races with freeze_task()) + * task->alloc_lock (inside thaw_process(), prevents race with refrigerator()) * sighand->siglock */ static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss, @@ -205,9 +210,12 @@ static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *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. + * function call. Nevertheless, apply RCU read-side critical + * section to suppress RCU lockdep false positives. */ + rcu_read_lock(); freezer = task_freezer(task); + rcu_read_unlock(); /* * The root cgroup is non-freezable, so we can skip the |