From: David Laight <David.Laight@ACULAB.COM>
To: 'Andy Shevchenko' <andriy.shevchenko@linux.intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Steven Rostedt <rostedt@goodmis.org>,
"'Joe Perches'" <joe@perches.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: RE: [PATCH 0/1] Slightly relax the type checking done by min() and max().
Date: Fri, 25 Nov 2022 15:27:07 +0000 [thread overview]
Message-ID: <7e594ad64e444d448c747688b8f28249@AcuMS.aculab.com> (raw)
In-Reply-To: <Y4DdQIMiFGk7YYcJ@smile.fi.intel.com>
From: Andy Shevchenko
> Sent: 25 November 2022 15:21
>
> On Fri, Nov 25, 2022 at 03:00:40PM +0000, David Laight wrote:
> > The min() and max() defines include a type check to avoid the unexpected
> > behaviour when a negative value is compared against and unsigned value.
> > However a lot of code hits this check and uses min_t() to avoid the error.
> > Many of these are just plain wrong.
> >
> > Those casting to u8 or u16 are particularly suspect, eg:
> > drivers/usb/misc/usb251xb.c:528:
> > hub->max_current_sp = min_t(u8, property_u32 / 2000, 50);
>
> I don't buy this. What's exactly wrong with this code?
Consider what happens if propery_u32 is 512000.
The returned value is 0 not 50.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2022-11-25 15:27 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-25 15:00 David Laight
2022-11-25 15:17 ` Andy Shevchenko
2022-11-25 15:22 ` David Laight
2022-11-25 15:20 ` Andy Shevchenko
2022-11-25 15:27 ` David Laight [this message]
2022-11-25 15:58 ` 'Andy Shevchenko'
2022-11-25 16:14 ` David Laight
2022-11-25 17:48 ` 'Andy Shevchenko'
2022-11-25 19:47 ` David Laight
2022-11-26 0:02 ` Andrew Morton
2022-11-26 10:21 ` David Laight
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=7e594ad64e444d448c747688b8f28249@AcuMS.aculab.com \
--to=david.laight@aculab.com \
--cc=akpm@linux-foundation.org \
--cc=andriy.shevchenko@linux.intel.com \
--cc=joe@perches.com \
--cc=linux-kernel@vger.kernel.org \
--cc=rostedt@goodmis.org \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®