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

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Message-ID: <CANn89i+UxgHwm9apzBXV-afpcfXfuX2S+6i4vPzF2ec4Dr6X0A@mail.gmail.com>
Date:   Wed, 2 Nov 2022 14:53:42 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     Dmitry Safonov <dima@...sta.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 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.