From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: David Howells <dhowells@redhat.com>
Cc: "'linux-arch@vger.kernel.org'" <linux-arch@vger.kernel.org>,
"'linux@arm.linux.org.uk'" <linux@arm.linux.org.uk>,
"Wang, Yalin" <Yalin.Wang@sonymobile.com>,
"'arnd@arndb.de'" <arnd@arndb.de>,
"'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>,
"'linux-arm-kernel@lists.infradead.org'"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC] change non-atomic bitops method
Date: Tue, 3 Feb 2015 20:10:38 +0100 [thread overview]
Message-ID: <20150203191038.GF10842@pengutronix.de> (raw)
In-Reply-To: <30242.1422976483@warthog.procyon.org.uk>
Hello,
[added some more context again]
On Tue, Feb 03, 2015 at 03:14:43PM +0000, David Howells wrote:
> > > - *p |= mask;
> > > + if ((*p & mask) == 0)
> > > + *p |= mask;
> > Care to fix the double space here while touching the code?
> >
> > I think the more natural check here is:
> >
> > if ((~*p & mask) != 0)
> > *p |= mask;
> >
> > Might be a matter of taste, but this check is equivalent to
> >
> > *p != (*p | mask)
> >
> > which is what you really want to test for.
> I would argue that this is less clear as to what's going on.
OK, I admit that this equivalence is not obvious. Then maybe let the
compiler find the equivalence and do:
- *p |= mask;
+ if (*p != (*p | mask))
+ p |= mask;
?
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
next prev parent reply other threads:[~2015-02-03 19:10 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-02 3:55 [RFC] change non-atomic bitops method Wang, Yalin
2015-02-02 3:55 ` Wang, Yalin
2015-02-02 18:53 ` Laura Abbott
2015-02-02 19:31 ` Uwe Kleine-König
2015-02-03 15:14 ` David Howells
2015-02-03 19:10 ` Uwe Kleine-König [this message]
2015-02-02 23:29 ` Andrew Morton
2015-02-02 23:29 ` Andrew Morton
2015-02-02 23:31 ` Russell King - ARM Linux
2015-02-02 23:31 ` Russell King - ARM Linux
2015-02-03 1:17 ` Kirill A. Shutemov
2015-02-03 2:13 ` Wang, Yalin
2015-02-03 5:42 ` Wang, Yalin
2015-02-03 5:42 ` Wang, Yalin
2015-02-03 6:38 ` Andrew Morton
2015-02-03 7:03 ` Wang, Yalin
2015-02-03 7:03 ` Wang, Yalin
2015-02-03 8:42 ` Wang, Yalin
2015-02-03 10:59 ` Andrew Morton
2015-02-09 8:18 ` Wang, Yalin
2015-02-09 20:34 ` Andrew Morton
2015-02-10 7:05 ` Wang, Yalin
2015-02-09 21:42 ` Rasmus Villemoes
2015-02-03 8:40 ` David Miller
2015-02-03 8:40 ` David Miller
2015-02-03 8:48 ` Andrew Morton
2015-02-03 8:48 ` Andrew Morton
2015-02-03 9:34 ` Rasmus Villemoes
2015-02-03 9:34 ` Rasmus Villemoes
2015-02-03 9:41 ` Wang, Yalin
2015-02-03 10:39 ` Kirill A. Shutemov
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=20150203191038.GF10842@pengutronix.de \
--to=u.kleine-koenig@pengutronix.de \
--cc=Yalin.Wang@sonymobile.com \
--cc=arnd@arndb.de \
--cc=dhowells@redhat.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@arm.linux.org.uk \
/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