linux-kernel - RE: [PATCH v2 1/8] minmax: Put all the clamp() definitions together

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Message-ID: <8928e9a416204001ac73442d47ab3b70@AcuMS.aculab.com>
Date: Sun, 28 Jul 2024 21:53:41 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Linus Torvalds' <torvalds@...uxfoundation.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Jens Axboe
	<axboe@...nel.dk>, "Matthew Wilcox (Oracle)" <willy@...radead.org>,
	"Christoph Hellwig" <hch@...radead.org>, Andrew Morton
	<akpm@...ux-foundation.org>, "Andy Shevchenko"
	<andriy.shevchenko@...ux.intel.com>, Dan Carpenter
	<dan.carpenter@...aro.org>, Arnd Bergmann <arnd@...nel.org>,
	"Jason@...c4.com" <Jason@...c4.com>, "pedro.falcato@...il.com"
	<pedro.falcato@...il.com>, Mateusz Guzik <mjguzik@...il.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>, Lorenzo Stoakes
	<lorenzo.stoakes@...cle.com>
Subject: RE: [PATCH v2 1/8] minmax: Put all the clamp() definitions together

From: Linus Torvalds
> Sent: 28 July 2024 22:01
> 
> On Sun, 28 Jul 2024 at 13:23, David Laight <David.Laight@...lab.com> wrote:
> >
> > At least you can 'just do it' :-)
> 
> I decided to use my powers for good. Or at least goodish.
> 
> I went through a lot of 'min_t()' and 'max_t()' users, and I think I
> found them all. There's a possibility that some driver that I can't
> easily build-test has issues, but I tried to manually check all the
> architecture ones, and did an allmodconfig build on arm64 and x86-64.
> 
> And by visual inspection I found a 32-bit x86 PAE case. Which makes me
> think my visual inspection was not entirely broken.

I've been through a lot of them in the past.
About 95% could now just be min/max.
The 'fun' ones are where the cast reduces the size of one type.
One of those got fixed because it was a real bug.
But there are some strange (u8) ones in some terminal window size
code which manage to convert 0 to -1 then ~0u and finally to the
max size - which might even be desirable!

> Anyway, I don't love the timing, since I'm going to cut 6.11-rc1 asap,
> but I also don't want to unnecessarily leave this pending for later,
> so I just committed the simplifications for min_t/max_t.

Better than just before -rc6!
At least these changes tend to generate build errors.

	David

> Doing the same for min/max (no more C constant expression worries!)
> would be very good, but I think that's going to be for later.
> 
>                 Linus

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