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

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Message-ID: <e718056c1999497ebf8726af49475701@AcuMS.aculab.com>
Date: Sun, 28 Jul 2024 20:09:17 +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 <torvalds@...uxfoundation.org>
> Sent: 28 July 2024 20:55
> 
> On Sun, 28 Jul 2024 at 11:12, David Laight <David.Laight@...lab.com> wrote:
> >
> > Although min_t(type,x,y) should just be
> >         type __x = x;
> >         type __y = y;
> >         __x < __y ? __x : __y;
> > Absolutely no point doing anything else.
> 
> I tried it. Doesn't quite work:
> 
>   net/ipv4/proc.c: In function ‘snmp_seq_show_tcp_udp’:
>   net/ipv4/proc.c:414:9: error: ISO C90 forbids variable length array
> ‘buff’ [-Werror=vla]
>     414 |         unsigned long buff[TCPUDP_MIB_MAX];
>         |         ^~~~~~~~
...

Ah, the constants.
I think they just need to be MIN_CONST() (without the casts).
One might need a cast of one of its constants.
But maybe the signedness test can be ignored if there is a
test for it being a constant.

But (as you said earlier in the year) that should just be MIN().
Except there are a few places that is used that need changing first.

	David

> 
> I guess all of these could just be made to use MIN_T()/MAX_T instead.
> We're not talking hundreds of cases, it seems to be just a small
> handful.
> 
> Let me go check.
> 
>                Linus

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