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From:   Xie He <xie.he.0141@gmail.com>
Date:   Mon, 16 Nov 2020 12:16:15 -0800
Message-ID: <CAJht_EM-ic4-jtN7e9F6zcJgG3OTw_ePXiiH1i54M+Sc8zq6bg@mail.gmail.com>
Subject: Re: [PATCH net-next v2 5/6] net/lapb: support netdev events
To:     Martin Schiller <ms@dev.tdt.de>
Cc:     Andrew Hendry <andrew.hendry@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Linux X25 <linux-x25@vger.kernel.org>,
        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Mon, Nov 16, 2020 at 6:01 AM Martin Schiller <ms@dev.tdt.de> wrote:
>
> This makes it possible to handle carrier loss and detection.
> In case of Carrier Loss, layer 2 is terminated
> In case of Carrier Detection, we start timer t1 on a DCE interface,
> and on a DTE interface we change to state LAPB_STATE_1 and start
> sending SABM(E).

> +                               lapb_dbg(0, "(%p): Carrier detected: %s\n",
> +                                        dev, dev->name);
> +                               if (lapb->mode & LAPB_DCE) {
> +                                       lapb_start_t1timer(lapb);
> +                               } else {
> +                                       if (lapb->state == LAPB_STATE_0) {
> +                                               lapb->state = LAPB_STATE_1;
> +                                               lapb_establish_data_link(lapb);
> +                                       }
> +                               }

Do you mean we will now automatically establish LAPB connections
without upper layers instructing us to do so?

If that is the case, is the one-byte header for instructing the LAPB
layer to connect / disconnect no longer needed?