Re: [PATCH net-next RFC v4] net: hdlc_x25: Queue outgoing LAPB frames

[Martin Schiller <ms@dev.tdt.de>]

On 2021-03-01 09:56, Xie He wrote:
> On Sun, Feb 28, 2021 at 10:56 PM Martin Schiller <ms@dev.tdt.de> wrote:
>> 
>> >> Also, I have a hard time assessing if such a wrap is really
>> >> enforceable.
>> >
>> > Sorry. I don't understand what you mean. What "wrap" are you referring
>> > to?
>> 
>> I mean the change from only one hdlc<x> interface to both hdlc<x> and
>> hdlc<x>_x25.
>> 
>> I can't estimate how many users are out there and how their setup 
>> looks
>> like.
> 
> I'm also thinking about solving this issue by adding new APIs to the
> HDLC subsystem (hdlc_stop_queue / hdlc_wake_queue) for hardware
> drivers to call instead of netif_stop_queue / netif_wake_queue. This
> way we can preserve backward compatibility.
> 
> However I'm reluctant to change the code of all the hardware drivers
> because I'm afraid of introducing bugs, etc. When I look at the code
> of "wan/lmc/lmc_main.c", I feel I'm not able to make sure there are no
> bugs (related to stop_queue / wake_queue) after my change (and even
> before my change, actually). There are even serious style problems:
> the majority of its lines are indented by spaces.
> 
> So I don't want to mess with all the hardware drivers. Hardware driver
> developers (if they wish to properly support hdlc_x25) should do the
> change themselves. This is not a problem for me, because I use my own
> out-of-tree hardware driver. However if I add APIs with no user code
> in the kernel, other developers may think these APIs are not
> necessary.

I don't think a change that affects the entire HDLC subsystem is
justified, since the actual problem only affects the hdlc_x25 area.

The approach with the additional hdlc<x>_x25 is clean and purposeful and
I personally could live with it.

I just don't see myself in the position to decide such a change at the
moment.

@Jakub: What is your opinion on this.