There's no point in using kmalloc() instead of the clearing variant
for trivial stuff. We can live dangerously elsewhere. Use kzalloc()
instead and drop 0 inits.
While at it, do trivial code reorganization in cgroup_file_open().
This patch doesn't introduce any functional changes.
v2: I was caught in the very distant past where list_del() didn't
poison and the initial version converted list_del()s to
list_del_init()s too. Li and Kent took me out of the stasis
chamber.
Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com>