cgroup: clean up obsolete comment for parse_cgroupfs_options()

1d5be6b287c8efc87 ("cgroup: move module ref handling into
rebind_subsystems()") makes parse_cgroupfs_options() no longer takes
refcounts on subsystems.

And unified hierachy makes parse_cgroupfs_options not need to call
with cgroup_mutex held to protect the cgroup_subsys[].

So this patch removes BUG_ON() and the comment.  As the comment
doesn't contain useful information afterwards, the whole comment is
removed.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 0f986f7..fb848be 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1221,12 +1221,6 @@ struct cgroup_sb_opts {
        bool none;
 };
 
-/*
- * Convert a hierarchy specifier into a bitmask of subsystems and
- * flags. Call with cgroup_mutex held to protect the cgroup_subsys[]
- * array. This function takes refcounts on subsystems to be used, unless it
- * returns error, in which case no refcounts are taken.
- */
 static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 {
        char *token, *o = data;
@@ -1235,8 +1229,6 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
        struct cgroup_subsys *ss;
        int i;
 
-       BUG_ON(!mutex_is_locked(&cgroup_mutex));
-
 #ifdef CONFIG_CPUSETS
        mask = ~(1UL << cpuset_cgrp_id);
 #endif