linux-kernel - Re: [PATCH 01/40] lib/string_helpers: Drop space in string_get

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Message-ID: <CAHp75Vd_VMOh1zxJvr0KqhxYBXAU1X+Ax7YA1sJ0G_abEpn-Dg@mail.gmail.com>
Date:   Wed, 3 May 2023 12:12:12 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Kent Overstreet <kent.overstreet@...ux.dev>
Cc:     James Bottomley <James.Bottomley@...senpartnership.com>,
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        Noralf Trï¿½nnes <noralf@...nnes.org>
Subject: Re: [PATCH 01/40] lib/string_helpers: Drop space in string_get_size's output

On Wed, May 3, 2023 at 10:13 AM Kent Overstreet
<kent.overstreet@...ux.dev> wrote:
> On Wed, May 03, 2023 at 09:30:11AM +0300, Andy Shevchenko wrote:
> > On Wed, May 3, 2023 at 5:07 AM Kent Overstreet
> > <kent.overstreet@...ux.dev> wrote:
> > > On Tue, May 02, 2023 at 06:19:27PM +0300, Andy Shevchenko wrote:
> > > > On Tue, May 2, 2023 at 9:22 AM Kent Overstreet
> > > > <kent.overstreet@...ux.dev> wrote:
> > > > > On Tue, May 02, 2023 at 08:33:57AM +0300, Andy Shevchenko wrote:
> > > > > > Actually instead of producing zillions of variants, do a %p extension
> > > > > > to the printf() and that's it. We have, for example, %pt with T and
> > > > > > with space to follow users that want one or the other variant. Same
> > > > > > can be done with string_get_size().
> > > > >
> > > > > God no.
> > > >
> > > > Any elaboration what's wrong with that?
> > >
> > > I'm really not a fan of %p extensions in general (they are what people
> > > reach for because we can't standardize on a common string output API),
> >
> > The whole story behind, for example, %pt is to _standardize_ the
> > output of the same stanza in the kernel.
>
> Wtf does this have to do with the rest of the discussion? The %p thing
> seems like a total non sequitar and a distraction.
>
> I'm not getting involved with that. All I'm interested in is fixing the
> memory allocation profiling output to make it more usable.
>
> > > but when we'd be passing it bare integers the lack of type safety would
> > > be a particularly big footgun.
> >
> > There is no difference to any other place in the kernel where we can
> > shoot into our foot.
>
> Yeah, no, absolutely not. Passing different size integers to
> string_get_size() is fine; passing pointers to different size integers
> to a %p extension will explode and the compiler won't be able to warn.

This is another topic. Yes, there is a discussion to have a compiler
plugin to check this.

> > > > God no for zillion APIs for almost the same. Today you want space,
> > > > tomorrow some other (special) delimiter.
> > >
> > > No, I just want to delete the space and output numbers the same way
> > > everyone else does. And if we are stuck with two string_get_size()
> > > functions, %p extensions in no way improve the situation.
> >
> > I think it's exactly for the opposite, i.e. standardize that output
> > once and for all.
>
> So, are you dropping your NACK then, so we can standardize the kernel on
> the way everything else does it?

No, you are breaking existing users. The NAK stays.
The whole discussion after that is to make the way on how users can
utilize your format and existing format without multiplying APIs.


-- 
With Best Regards,
Andy Shevchenko