[PATCH v12 00/13] net: tcp: improve tcp support in legacy stack

[Tom Rini]

On Tue, Nov 05, 2024 at 09:59:57PM +0300, Mikhail Kshevetskiy wrote:
> 
> On 05.11.2024 21:26, Tom Rini wrote:
> > On Tue, Nov 05, 2024 at 09:07:17AM -0700, Simon Glass wrote:
> >> Hi Tom,
> >>
> >> On Tue, 5 Nov 2024 at 08:47, Tom Rini <trini at konsulko.com> wrote:
> >>> On Tue, Nov 05, 2024 at 08:15:25AM -0700, Simon Glass wrote:
> >>>> Hi Peter,
> >>>>
> >>>> On Tue, 5 Nov 2024 at 06:10, Peter Robinson <pbrobinson at gmail.com> wrote:
> >>>>> On Tue, 5 Nov 2024 at 13:03, Simon Glass <sjg at chromium.org> wrote:
> >>>>>> Hi Tom,
> >>>>>>
> >>>>>> On Mon, 4 Nov 2024 at 16:32, Tom Rini <trini at konsulko.com> wrote:
> >>>>>>> On Mon, Oct 28, 2024 at 05:31:30PM +0300, Mikhail Kshevetskiy wrote:
> >>>>>>>
> >>>>>>>> Legacy TCP stack is bad. Here are some of the known issues:
> >>>>>>>>  * tcp packet from other connection can break a current one
> >>>>>>>>  * tcp send sequence always starts from zero
> >>>>>>>>  * bad tcp options processing
> >>>>>>>>  * strange assumptions on packet size for selective acknowledge
> >>>>>>>>  * tcp interface assumes one of the two scenarios:
> >>>>>>>>      - data downloading from remote host to a board
> >>>>>>>>      - request-response exchange with a small packets
> >>>>>>>>    so it's not possible to upload large amount of data from the
> >>>>>>>>    board to remote host.
> >>>>>>>>  * wget test generate bad tcp stream, test should fail but it passes instead
> >>>>>>>>
> >>>>>>>> This series of patches fixes all of the above issues.
> >>>>>>> I know Peter asked on the last one, but I want to ask as well. With lwIP
> >>>>>>> merged, why do we want to add features to the old stack? I can see
> >>>>>>> fixing issues, but not adding new functionality as well. Thanks.
> >>>>>>>
> >>>>>> Let's apply this. It has tests and the old stack is still used by a
> >>>>>> lot of boards. At present lwip is only used on one. There is more work
> >>>>>> to do on the new stack, including finishing off the sandbox
> >>>>>> implementation.
> >>>>> I agree with applying the fixes pieces, I do not agree with apply the
> >>>>> HTTP server pieces. This series should actually be split into 3
> >>>> But what is your objection?
> >>>>
> >>>> I would much rather just apply it ASAP. It has already gone through 12
> >>>> versions, during which lwip has been prepared and applied.
> >>> Yes, and to be blunt, the first bit of feedback I provided was "can you
> >>> please look at the lwIP series instead?".
> >>>
> >>>> The HTTP server is a useful feature and we should be able to use it to
> >>>> test networking in U-Boot in a more self-contained and performant
> >>>> manner.
> >>> I very much do not want to add more features to the legacy TCP stack.
> >>> We're likely, long term, to still need some cut-back version of the old
> >>> stack for the limited SPL cases.
> >> This series has been in progress for a long time and it seems unfair
> >> to just drop it, with one one board on the new stack.
> > Well, I continue to not say that we should drop the series, but that we
> > should take the fixes and not the new features. Because as far as I can
> > tell, the current TCP stack is in such a shape that it's not
> > production-usable anywhere and so the number of users argument is
> > irrelevant.
> >
> I expected something like this when lwip was finally merged.
> I was a bit surprised when Simon decide to merge this patch series.
> 
> At the moment we have no plans to update u-boot or backport lwip patches
> to u-boot-2023.10.

I'm sure it would be engineering-wise prohibitive. And, thank you for
contributing your TCP related fixes upstream, it is appreciated and in
the absence of the lwIP work would have been entirely uncontroversial.

> So we will use our solution based on a legacy stack. I understand that
> we should switch to lwip somewhere in the future. Unfortunately it's 
> not a fast and easy process (update u-boot, rewrite http based firmware
> upgrade, test new u-boot for several hardware configurations, test
> customer devices migrations and so on).

That is always a challenge, yes.

> Also we are limited in resources, so I am able to put my hands on u-boot
> only from time to time.
> So this is a long story.
> 
> Tom, Simon, Peter: what patches do you want to accept?

In a quick look, 1-10 look like bugfixes to the stack with 11 being
netcat and 12/13 being httpd, and I assume that's what Peter meant by 3
series instead of 1. So those first 10. And thanks again!

-- 
Tom
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