From: Martin Schiller <ms@dev.tdt.de>
To: Xie He <xie.he.0141@gmail.com>
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>
Subject: Re: [PATCH net-next v4 2/5] net/lapb: support netdev events
Date: Mon, 23 Nov 2020 11:38:34 +0100 [thread overview]
Message-ID: <16b7e74e6e221f43420da7836659d7df@dev.tdt.de> (raw)
In-Reply-To: <CAJht_EO+enBOFMkVVB5y6aRnyMEsOZtUBJcAvOFBS91y7CauyQ@mail.gmail.com>
On 2020-11-23 11:08, Xie He wrote:
> On Mon, Nov 23, 2020 at 1:36 AM Xie He <xie.he.0141@gmail.com> wrote:
>>
>> Some drivers don't support carrier status and will never change it.
>> Their carrier status will always be UP. There will not be a
>> NETDEV_CHANGE event.
Well, one could argue that we would have to repair these drivers, but I
don't think that will get us anywhere.
From this point of view it will be the best to handle the NETDEV_UP in
the lapb event handler and establish the link analog to the
NETDEV_CHANGE event if the carrier is UP.
>>
>> lapbether doesn't change carrier status. I also have my own virtual
>> HDLC WAN driver (for testing) which also doesn't change carrier
>> status.
>>
>> I just tested with lapbether. When I bring up the interface, there
>> will only be NETDEV_PRE_UP and then NETDEV_UP. There will not be
>> NETDEV_CHANGE. The carrier status is alway UP.
>>
>> I haven't tested whether a device can receive NETDEV_CHANGE when it is
>> down. It's possible for a device driver to call netif_carrier_on when
>> the interface is down. Do you know what will happen if a device driver
>> calls netif_carrier_on when the interface is down?
>
> I just did a test on lapbether and saw there would be no NETDEV_CHANGE
> event when the netif is down, even if netif_carrier_on/off is called.
> So we can rest assured of this part.
next prev parent reply other threads:[~2020-11-23 10:38 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 5:40 [PATCH net-next v4 0/5] net/x25: netdev event handling Martin Schiller
2020-11-20 5:40 ` [PATCH net-next v4 1/5] net/x25: handle additional netdev events Martin Schiller
2020-11-20 5:40 ` [PATCH net-next v4 2/5] net/lapb: support " Martin Schiller
2020-11-20 23:11 ` Xie He
2020-11-20 23:50 ` Xie He
2020-11-23 6:55 ` Martin Schiller
2020-11-23 8:31 ` Xie He
2020-11-23 9:00 ` Martin Schiller
2020-11-23 9:36 ` Xie He
2020-11-23 10:08 ` Xie He
2020-11-23 10:38 ` Martin Schiller [this message]
2020-11-23 11:17 ` Xie He
2020-11-23 19:36 ` Jakub Kicinski
2020-11-23 22:09 ` Xie He
2020-11-24 5:29 ` Martin Schiller
2020-11-20 5:40 ` [PATCH net-next v4 3/5] net/lapb: fix t1 timer handling for LAPB_STATE_0 Martin Schiller
2020-11-20 5:40 ` [PATCH net-next v4 4/5] net/x25: fix restart request/confirm handling Martin Schiller
2020-11-20 5:40 ` [PATCH net-next v4 5/5] net/x25: remove x25_kill_by_device() Martin Schiller
2020-11-20 22:40 ` [PATCH net-next v4 0/5] net/x25: netdev event handling Xie He
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