From: Martin Schiller <ms@dev.tdt.de>
To: Xie He <xie.he.0141@gmail.com>
Cc: Jakub Kicinski <kuba@kernel.org>,
Leon Romanovsky <leon@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Linux X25 <linux-x25@vger.kernel.org>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Krzysztof Halasa <khc@pm.waw.pl>,
Jonathan Corbet <corbet@lwn.net>,
linux-doc@vger.kernel.org
Subject: Re: [PATCH net-next RFC v4] net: hdlc_x25: Queue outgoing LAPB frames
Date: Mon, 22 Feb 2021 08:14:07 +0100 [thread overview]
Message-ID: <906d8114f1965965749f1890680f2547@dev.tdt.de> (raw)
In-Reply-To: <CAJht_EOru3pW6AHN4QVjiaERpLSfg-0G0ZEaqU_hkhX1acv0HQ@mail.gmail.com>
On 2021-02-19 21:28, Xie He wrote:
> On Fri, Feb 19, 2021 at 10:39 AM Jakub Kicinski <kuba@kernel.org>
> wrote:
>>
>> Not entirely sure what the argument is about but adding constants
>> would
>> certainly help.
>
> Leon wants me to replace this:
>
> dev->needed_headroom = 3 - 1;
>
> with this:
>
> /* 2 is the result of 3 - 1 */
> dev->needed_headroom = 2;
>
> But I don't feel his way is better than my way.
>
>> More fundamentally IDK if we can make such a fundamental change here.
>> When users upgrade from older kernel are all their scripts going to
>> work the same? Won't they have to bring the new netdev up?
>
> Yes, this patch will break backward compatibility. Users with old
> scripts will find them no longer working.
>
> However, it's hard for me to find a better way to solve the problem
> described in the commit message.
>
> So I sent this as an RFC to see what people think about this. (Martin
> Schiller seems to be OK with this.)
Well, I said I would like to test it.
I'm not really happy with this change because it breaks compatibility.
We then suddenly have 2 interfaces; the X.25 routings are to be set via
the "new" hdlc<x>_x25 interfaces instead of the hdlc<x> interfaces.
I currently just don't have a nicer solution to fix this queueing
problem either. On the other hand, since the many years we have been
using the current state, I have never noticed any problems with
discarded frames. So it might be more a theoretical problem than a
practical one.
>
> I think users who don't use scripts can adapt quickly and users who
> use scripts can also trivally fix their scripts.
>
> Actually many existing commits in the kernel also (more or less) cause
> some user-visible changes. But I admit this patch is a really big
> change.
next prev parent reply other threads:[~2021-02-22 7:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-16 20:18 [PATCH net-next RFC v4] net: hdlc_x25: Queue outgoing LAPB frames Xie He
2021-02-18 8:57 ` Leon Romanovsky
2021-02-18 9:07 ` Xie He
2021-02-18 10:37 ` Leon Romanovsky
2021-02-18 17:36 ` Xie He
2021-02-18 19:55 ` Leon Romanovsky
2021-02-18 20:06 ` Xie He
2021-02-18 20:23 ` Xie He
2021-02-19 18:39 ` Jakub Kicinski
2021-02-19 20:28 ` Xie He
2021-02-21 6:39 ` Leon Romanovsky
2021-02-21 19:13 ` Xie He
2021-02-22 7:14 ` Martin Schiller [this message]
2021-02-22 8:56 ` Xie He
2021-02-26 14:20 ` Martin Schiller
2021-02-26 23:03 ` Xie He
2021-03-01 6:56 ` Martin Schiller
2021-03-01 8:56 ` Xie He
2021-03-02 7:04 ` Martin Schiller
2021-03-02 23:30 ` Jakub Kicinski
2021-03-03 13:26 ` Martin Schiller
2021-03-03 20:23 ` Xie He
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