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Subject: Re: [PATCH v3 sysctl-next] bpf: move bpf sysctls from kernel/sysctl.c
 to bpf module
To:     Luis Chamberlain <mcgrof@kernel.org>, Yan Zhu <zhuyan34@huawei.com>
Cc:     andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
        john.fastabend@gmail.com, kafai@fb.com, keescook@chromium.org,
        kpsingh@kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, liucheng32@huawei.com,
        netdev@vger.kernel.org, nixiaoming@huawei.com,
        songliubraving@fb.com, xiechengliang1@huawei.com, yhs@fb.com,
        yzaikin@google.com, zengweilin@huawei.com
References: <Yh1dtBTeRtjD0eGp@bombadil.infradead.org>
 <20220302020412.128772-1-zhuyan34@huawei.com>
 <Yh/V5QN1OhN9IKsI@bombadil.infradead.org>
From:   Daniel Borkmann <daniel@iogearbox.net>
Message-ID: <d8843ebe-b8df-8aa0-a930-c0742af98157@iogearbox.net>
Date:   Fri, 4 Mar 2022 00:44:48 +0100
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On 3/2/22 9:39 PM, Luis Chamberlain wrote:
> On Wed, Mar 02, 2022 at 10:04:12AM +0800, Yan Zhu wrote:
>> We're moving sysctls out of kernel/sysctl.c as its a mess. We
>> already moved all filesystem sysctls out. And with time the goal is
>> to move all sysctls out to their own susbsystem/actual user.
>>
>> kernel/sysctl.c has grown to an insane mess and its easy to run
>> into conflicts with it. The effort to move them out is part of this.
>>
>> Signed-off-by: Yan Zhu <zhuyan34@huawei.com>
> 
> Daniel, let me know if this makes more sense now, and if so I can
> offer take it through sysctl-next to avoid conflicts more sysctl knobs
> get moved out from kernel/sysctl.c.

If this is a whole ongoing effort rather than drive-by patch, then it's
fine with me. Btw, the patch itself should also drop the linux/bpf.h
include from kernel/sysctl.c since nothing else is using it after the
patch.

Btw, related to cleanups.. historically, we have a bunch of other knobs
for BPF under net (in net_core_table), that is:

   /proc/sys/net/core/bpf_jit_enable
   /proc/sys/net/core/bpf_jit_harden
   /proc/sys/net/core/bpf_jit_kallsyms
   /proc/sys/net/core/bpf_jit_limit

Would be nice to consolidate all under e.g. /proc/sys/kernel/bpf_* for
future going forward, and technically, they should be usable also w/o
net configured into kernel. Is there infra to point the sysctl knobs
e.g. under net/core/ to kernel/, or best way would be to have single
struct ctl_table and register for both?

Cheers,
Daniel