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Date:   Fri, 10 Jun 2022 19:44:28 +0000
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Subject: [PATCH bpf-next v2 1/8] cgroup: enable cgroup_get_from_file() on cgroup1
From:   Yosry Ahmed <yosryahmed@google.com>
To:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>, Hao Luo <haoluo@google.com>,
        Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Shuah Khan <shuah@kernel.org>, Michal Hocko <mhocko@kernel.org>
Cc:     Roman Gushchin <roman.gushchin@linux.dev>,
        David Rientjes <rientjes@google.com>,
        Stanislav Fomichev <sdf@google.com>,
        Greg Thelen <gthelen@google.com>,
        Shakeel Butt <shakeelb@google.com>,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        bpf@vger.kernel.org, cgroups@vger.kernel.org,
        Yosry Ahmed <yosryahmed@google.com>
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Precedence: bulk

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>
---
 kernel/cgroup/cgroup.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 1779ccddb734d..9943fcb1e574d 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6090,11 +6090,6 @@ 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;
 }
 
-- 
2.36.1.476.g0c4daa206d-goog