netdev - Re: [PATCH 2/2] net/tcp: Disable TCP-MD5 static key on tcp_md5sig

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Date:   Thu, 3 Nov 2022 15:40:11 +0000
From:   Dmitry Safonov <dima@...sta.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     linux-kernel@...r.kernel.org, David Ahern <dsahern@...nel.org>,
        Bob Gilligan <gilligan@...sta.com>,
        "David S. Miller" <davem@...emloft.net>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Francesco Ruggeri <fruggeri@...sta.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Salam Noureddine <noureddine@...sta.com>,
        netdev@...r.kernel.org
Subject: Re: [PATCH 2/2] net/tcp: Disable TCP-MD5 static key on
 tcp_md5sig_info destruction

On 11/2/22 21:53, Eric Dumazet wrote:
> On Wed, Nov 2, 2022 at 2:49 PM Eric Dumazet <edumazet@...gle.com> wrote:
> 
>>
>> Are you sure ?
>>
>> static_branch_inc() is what we want here, it is a nice wrapper around
>> the correct internal details,
>> and ultimately boils to an atomic_inc(). It is safe for all contexts.
>>
>> But if/when jump labels get refcount_t one day, we will not have to
>> change TCP stack because
>> it made some implementation assumptions.
> 
> Oh, I think I understand this better now.
> 
> Please provide a helper like
> 
> static inline void static_key_fast_inc(struct static_key *key)
> {
>        atomic_inc(&key->enabled);
> }
> 
> Something like that.

Sure, that sounds like a better thing to do, rather than the hack I had.

Thanks, will send v2 soon,
          Dmitry