cgroup: remove gratuituous BUG_ON()s from rebind_subsystems()

rebind_subsystems() performs santiy checks even on subsystems which
aren't specified to be added or removed and the checks aren't all that
useful given that these are in a very cold path while the violations
they check would trip up in much hotter paths.

Let's remove these from rebind_subsystems().

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 2a8cf1a..345fac8 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1077,15 +1077,6 @@ static int rebind_subsystems(struct cgroupfs_root *root,
                        /* subsystem is now free - drop reference on module */
                        module_put(ss->module);
                        root->subsys_mask &= ~bit;
-               } else if (bit & root->subsys_mask) {
-                       /* Subsystem state should already exist */
-                       BUG_ON(!cgrp->subsys[i]);
-#ifdef CONFIG_MODULE_UNLOAD
-                       BUG_ON(ss->module && !module_refcount(ss->module));
-#endif
-               } else {
-                       /* Subsystem state shouldn't exist */
-                       BUG_ON(cgrp->subsys[i]);
                }
        }