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Date:   Tue, 16 Aug 2022 16:44:35 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     David Howells <dhowells@redhat.com>
Cc:     Hawkins Jiawei <yin31149@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        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>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org,
        linux-kernel-mentees@lists.linuxfoundation.org,
        bpf@vger.kernel.org, Jakub Sitnicki <jakub@cloudflare.com>
Subject: Re: [PATCH] net: Fix suspicious RCU usage in
 bpf_sk_reuseport_detach()
Message-ID: <20220816164435.0558ef94@kernel.org>
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On Tue, 16 Aug 2022 22:16:46 +0100 David Howells wrote:
> So either __rcu_dereference_sk_user_data_with_flags_check() has to be a macro,
> or we need to go with something like the first version of my patch where I
> don't pass the condition through.  Do you have a preference?

I like your version because it documents what the lock protecting this
field is. 

In fact should we also add && sock_owned_by_user(). Martin, WDYT? Would
that work for reuseport? Jakub S is fixing l2tp to hold the socket lock
while setting this field, yet most places take the callback lock...

One the naming - maybe just drop the _with_flags() ? There's no version
of locked helper which does not take the flags. And not underscores?