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 <6b4b7165-5438-df65-3a43-7dcb576dab93@huawei.com>
Date:   Tue, 03 Aug 2021 11:59:34 +0200
From:   "Hannes Frederic Sowa" <hannes@stressinduktion.org>
To:     "Kefeng Wang" <wangkefeng.wang@huawei.com>,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Cc:     "Daniel Borkmann" <daniel@iogearbox.net>,
        "David Miller" <davem@davemloft.net>,
        "Eric Dumazet" <edumazet@google.com>,
        "Minmin chen" <chenmingmin@huawei.com>,
        "Jakub Kicinski" <kuba@kernel.org>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        "Andrew Morton" <akpm@linux-foundation.org>
Subject: Re: [PATCH] once: Fix panic when module unload
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Hello,

On Tue, Aug 3, 2021, at 04:11, Kefeng Wang wrote:
> Hi ALL, I don't know who maintain the lib/once.c, add Greg and Andrew =
too,
>=20
> Hi David, I check the history, the lib/once.c is from net/core/utils.c=
=20
> since
>=20
> commit 46234253b9363894a254844a6550b4cc5f3edfe8
> Author: Hannes Frederic Sowa <hannes@stressinduktion.org>
> Date:=C2=A0=C2=A0 Thu Oct 8 01:20:35 2015 +0200
>=20
>  =C2=A0=C2=A0=C2=A0 net: move net_get_random_once to lib
>=20
> This bug is found in our product test, we want to make sure that wheth=
er=20
> this solution
>=20
> is correct or not, so could David or any others help to review this pa=
tch.
>=20
> Many thinks.

Thanks for the patch.

I see that it got marked as not applicable for the net trees:
<https://patchwork.kernel.org/project/netdevbpf/patch/20210622022138.230=
48-1-wangkefeng.wang@huawei.com/>

Back then I added this code via the net/ tree thus I think it should get=

picked up nonetheless hopefully.

Regarding your patch, I think it mostly looks fine:

It might be worthwhile to increment the reference counter inside the
preempt disabled bracket in find_module_by_key (and thus also rename
that function to make this fact more clear).

The other option would be to use the macro DO_ONCE and always pass in
THIS_MODULE from there, increment its ref counter in once_disable_jump.
This might be more canonical.

Thanks and sorry for the delay,
Hannes