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Date:   Tue, 26 Apr 2022 07:55:00 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Hannes Reinecke <hare@suse.de>
Cc:     Chuck Lever <chuck.lever@oracle.com>, netdev@vger.kernel.org,
        linux-nfs@vger.kernel.org, linux-nvme@lists.infradead.org,
        linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        ak@tempesta-tech.com, borisp@nvidia.com, simo@redhat.com
Subject: Re: [PATCH RFC 4/5] net/tls: Add support for PF_TLSH (a TLS
 handshake listener)
Message-ID: <20220426075500.34776cd5@kernel.org>
In-Reply-To: <66077b73-c1a4-d2ae-c8e4-3e19e9053171@suse.de>
References: <165030051838.5073.8699008789153780301.stgit@oracle-102.nfsv4.dev>
        <165030059051.5073.16723746870370826608.stgit@oracle-102.nfsv4.dev>
        <20220425101459.15484d17@kernel.org>
        <66077b73-c1a4-d2ae-c8e4-3e19e9053171@suse.de>
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Precedence: bulk

On Tue, 26 Apr 2022 11:43:37 +0200 Hannes Reinecke wrote:
> > Create the socket in user space, do all the handshakes you need there
> > and then pass it to the kernel.  This is how NBD + TLS works.  Scales
> > better and requires much less kernel code.
> >   
> But we can't, as the existing mechanisms (at least for NVMe) creates the 
> socket in-kernel.
> Having to create the socket in userspace would require a completely new 
> interface for nvme and will not be backwards compatible.
> Not to mention having to rework the nvme driver to accept sockets from 
> userspace instead of creating them internally.
> 
> With this approach we can keep existing infrastructure, and can get a 
> common implementation for either transport.

You add 1.5kLoC and require running a user space agent, surely you're
adding new interfaces and are not backward-compatible already.

I don't understand your argument, maybe you could rephrase / dumb it
down for me?