Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <ad9be7ae-aeec-b208-8252-7a566534ded4@arista.com>
Date:   Thu, 3 Nov 2022 15:40:11 +0000
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.3.3
Subject: Re: [PATCH 2/2] net/tcp: Disable TCP-MD5 static key on
 tcp_md5sig_info destruction
Content-Language: en-US
To:     Eric Dumazet <edumazet@google.com>
Cc:     linux-kernel@vger.kernel.org, David Ahern <dsahern@kernel.org>,
        Bob Gilligan <gilligan@arista.com>,
        "David S. Miller" <davem@davemloft.net>,
        Dmitry Safonov <0x7f454c46@gmail.com>,
        Francesco Ruggeri <fruggeri@arista.com>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Salam Noureddine <noureddine@arista.com>,
        netdev@vger.kernel.org
References: <20221102211350.625011-1-dima@arista.com>
 <20221102211350.625011-3-dima@arista.com>
 <CANn89iLbOikuG9+Tna9M0Gr-diF2vFpfMV8MDP8rBuN49+Mwrg@mail.gmail.com>
 <483848f5-8807-fd97-babc-44740db96db4@arista.com>
 <CANn89i+XyQhh0eNMJWNn6NNLDaMtrzX3sq9Atu-ic7P5uqDODg@mail.gmail.com>
 <CANn89i+UxgHwm9apzBXV-afpcfXfuX2S+6i4vPzF2ec4Dr6X0A@mail.gmail.com>
From:   Dmitry Safonov <dima@arista.com>
In-Reply-To: <CANn89i+UxgHwm9apzBXV-afpcfXfuX2S+6i4vPzF2ec4Dr6X0A@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 11/2/22 21:53, Eric Dumazet wrote:
> On Wed, Nov 2, 2022 at 2:49 PM Eric Dumazet <edumazet@google.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