netdev - Re: [PATCH bpf-next] bpf, sockmap: Bundle psock->sk_redir and redir

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Date: Mon, 13 Nov 2023 10:02:49 +0100
From: Jakub Sitnicki <jakub@...udflare.com>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>, Pengcheng Yang
 <yangpc@...gsu.com>
Cc: John Fastabend <john.fastabend@...il.com>, bpf <bpf@...r.kernel.org>,
 Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf-next] bpf, sockmap: Bundle psock->sk_redir and
 redir_ingress into a tagged pointer

On Fri, Nov 10, 2023 at 07:42 AM -08, Alexei Starovoitov wrote:
> On Fri, Nov 10, 2023 at 1:44 AM Pengcheng Yang <yangpc@...gsu.com> wrote:
>>
>> Like skb->_sk_redir, we bundle the sock redirect pointer and
>> the ingress bit to manage them together.
>>
>> Suggested-by: Jakub Sitnicki <jakub@...udflare.com>
>> Link: https://lore.kernel.org/bpf/87cz97cnz8.fsf@cloudflare.com
>> Signed-off-by: Pengcheng Yang <yangpc@...gsu.com>
>> ---
>>  include/linux/skmsg.h | 30 ++++++++++++++++++++++++++++--
>>  net/core/skmsg.c      | 18 ++++++++++--------
>>  net/ipv4/tcp_bpf.c    | 13 +++++++------
>>  net/tls/tls_sw.c      | 11 ++++++-----
>>  4 files changed, 51 insertions(+), 21 deletions(-)
>>
>> diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
>> index c1637515a8a4..ae021f511f46 100644
>> --- a/include/linux/skmsg.h
>> +++ b/include/linux/skmsg.h
>> @@ -78,11 +78,10 @@ struct sk_psock_work_state {
>>
>>  struct sk_psock {
>>         struct sock                     *sk;
>> -       struct sock                     *sk_redir;
>> +       unsigned long                   _sk_redir;
>
> Please don't.
> There is no need to bundle them together.

Seeing how the code turned out, I agree - it didn't work out.
Code is not any simpler. My gut feeling was wrong here.

I gotta ask for, for the future, though -
this is not a "no" to tagged pointers in general, right?