Message-ID: <aCGhXcuqBDuceCqk@smile.fi.intel.com>
Date: Mon, 12 May 2025 10:21:01 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Jason Xing <kerneljasonxing@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, corbet@....net,
	linux-doc@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	linux@...blig.org, viro@...iv.linux.org.uk,
	Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH] relay: Remove unused relay_late_setup_files

On Mon, May 12, 2025 at 02:53:56PM +0800, Jason Xing wrote:
> On Mon, May 12, 2025 at 2:15 PM Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com> wrote:
> > On Mon, May 12, 2025 at 09:12:56AM +0800, Jason Xing wrote:
> > >
> > > I noticed this patch "relay: Remove unused relay_late_setup_files"
> > > appears in the mm branch already[1], which I totally missed. Sorry for
> > > joining the party late.
> > >
> > > I have a different opinion on this. For me, I'm very cautious about
> > > what those so-called legacy interfaces are and how they can work in
> > > different cases and what the use case might be... There are still a
> > > small number of out-of-tree users like me heavily relying on relayfs
> > > mechanism. So my humble opinion is that if you want to remove
> > > so-called dead code, probably clearly state why it cannot be used
> > > anymore in the future.
> > >
> > > Dr. David, I appreciate your patch, but please do not simply do the
> > > random cleanup work __here__. If you take a deep look at the relayfs,
> > > you may find there are other interfaces/functions no one uses in the
> > > kernel tree.
> > >
> > > I'm now checking this kind of patch in relayfs one by one to avoid
> > > such a thing happening. I'm trying to maintain it as much as possible
> > > since we internally use it in the networking area to output useful
> > > information in the hot paths, a little bit like blktrace. BTW, relayfs
> > > is really a wonderful one that helps kernel modules communicate with
> > > userspace very efficiently. I'm trying to revive it if I can.
> >
> > Jason, with all of the respect, if you are interested in keeping things going
> > on, please add yourself to the MAINTAINERS. It will makes the users of the
> > legacy code, Andrew and others, who are doing maintainer's/reviewer's job,
> > and you happy.
> 
> I didn't subscribe to LKML because they're too many emails everyday.
> Because of this, I missed most of changes in relayfs.

And how is this relevant to my proposal?

Moreover with `lei` you can filter out from time to time the lore archive for
these, no need to be subscribed and read LKML in full.

> Sure, I'm happy to do so, but I'm not sure how/what the detailed
> process is here. I would like to ask the core maintainers/developers
> in advance.
> 
> Any thoughts on this? Andrew, Jens.

Just send a patch to the LKML which adds a relevant record into MAINTAINERS.
I believe all stakeholders here will be happy to accept that kind of change.

At least you can get my Ack, FWIW (I am not a stakeholder here).

> > Also note, we usually do not care about the out-of-tree users. The main Q here
> > why are they out-of-tree for so long time?
> 
> It's due to the history problem. Back then, developers were trying to
> develop various file systems to add more debuginfo. As you may notice,
> blktrace is the one which manifests the answer.

Then provide a roadmap on the upstreaming the necessary parts. Otherwise
there is no room for a dead code in the Linux kernel. This is the rule:
we do not add one, and we do not leave it dangling after removing the last
user.

> > > [1]: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/commit/?h=mm-everything&id=46aa76118ee365c25911806e34d28fc2aa5ef997

-- 
With Best Regards,
Andy Shevchenko

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