linux-kernel - Re: [PATCH bpf-next v2 1/3] selftests/bpf: do not disable /dev/null device access in cgroup dev test

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Message-ID: <39781c99-95db-4c48-b363-a482a426e3b0@oracle.com>
Date: Mon, 29 Jul 2024 17:59:44 +0100
From: Alan Maguire <alan.maguire@...cle.com>
To: Alexis Lothoré (eBPF Foundation)
 <alexis.lothore@...tlin.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Eduard Zingerman
 <eddyz87@...il.com>, Song Liu <song@...nel.org>,
        Yonghong Song <yonghong.song@...ux.dev>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>
Cc: ebpf@...uxfoundation.org, Thomas Petazzoni
 <thomas.petazzoni@...tlin.com>,
        bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v2 1/3] selftests/bpf: do not disable /dev/null
 device access in cgroup dev test

On 29/07/2024 09:20, Alexis Lothoré (eBPF Foundation) wrote:
> test_dev_cgroup currently loads a small bpf program allowing any access on
> urandom and zero devices, disabling access to any other device. It makes
> migrating this test to test_progs impossible, since this one manipulates
> extensively /dev/null.
> 
> Allow /dev/null manipulation in dev_cgroup program to make its usage in
> test_progs framework possible. Update test_dev_cgroup.c as well to match
> this change while it has not been removed.
> 
> Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@...tlin.com>
> ---
>  tools/testing/selftests/bpf/progs/dev_cgroup.c |  4 ++--
>  tools/testing/selftests/bpf/test_dev_cgroup.c  | 18 +++++++++---------

Not a big deal, but I found it a bit confusing that this file was
modified then deleted in patch 2. Would it work having patch 1 stop
building the standalone test/remove it and .gitignore entry, patch 2
updating progs/dev_cgroup.c to allow /dev/zero, /dev/urandom access,
patch 3 add cgroup_dev.c test support, and patch 4 add the device type
subtest? Or are there issues with doing things that way? Thanks!

Alan