cgroup: enable cgroup_get_from_file() on cgroup1

cgroup_get_from_file() currently fails with -EBADF if called on cgroup
v1. However, the current implementation works on cgroup v1 as well, so
the restriction is unnecessary.

This enabled cgroup_get_from_fd() to work on cgroup v1, which would be
the only thing stopping bpf cgroup_iter from supporting cgroup v1.

Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20220805214821.1058337-3-haoluo@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index ffaccd6..5f4502a 100644 (file)
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6132,11 +6132,6 @@ static struct cgroup *cgroup_get_from_file(struct file *f)
                return ERR_CAST(css);
 
        cgrp = css->cgroup;
-       if (!cgroup_on_dfl(cgrp)) {
-               cgroup_put(cgrp);
-               return ERR_PTR(-EBADF);
-       }
-
        return cgrp;
 }