From: Linus Torvalds <torvalds@linux-foundation.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Steven Rostedt (Red Hat)" <rostedt@goodmis.org>,
Peter Zijlstra <peterz@infradead.org>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Michal Nazarewicz <mina86@mina86.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [RFC][PATCH 5/5] abs(): Provide build error on passing 64bit value to abs()
Date: Tue, 15 Sep 2015 16:52:20 -0700 [thread overview]
Message-ID: <CA+55aFzjZqt-8HhvbvLb7s3vR_G3Hjmf=buKBBKTnmKm+KVK-Q@mail.gmail.com> (raw)
In-Reply-To: <20150915052202.GB14215@gmail.com>
On Mon, Sep 14, 2015 at 10:22 PM, Ingo Molnar <mingo@kernel.org> wrote:
>
> I think this should be a compiletime_warning() - that will be visible enough.
So the problem with this is that by now most kernel developers are on 64-bit.
And that "sizeof(typeof(x)) > sizeof(long))" would effectively never
trigger on 64-bit architectures, so almost no core developers would
see it. Yes, it would be caught by buildbots etc, but that's really
not very convenient. The new errors would be noticed too late, because
the actual *developers* wouldn't see them.
(Not to mention that the "typeof()" in that expression is redundant ;)
So I think the "auto-expand to 's64' using __builtin_choose_expr()" is
the preferable model, and get rid of abs64() entirely. It has very few
uses.
Linus
next prev parent reply other threads:[~2015-09-15 23:52 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-15 1:05 [RFC][PATCH 0/5] Fixes for abs() usage on 64bit values John Stultz
2015-09-15 1:05 ` [RFC][PATCH 1/5] clocksource: Fix abs() usage w/ " John Stultz
2015-10-02 20:57 ` [tip:timers/urgent] " tip-bot for John Stultz
2015-09-15 1:05 ` [RFC][PATCH 2/5] time: Fix abs() usage with 64-bit values John Stultz
2015-09-15 1:05 ` [RFC][PATCH 3/5] ext4: Fix abs() usage in ext4_mb_check_group_pa John Stultz
2015-09-15 1:05 ` [RFC][PATCH 4/5] percpu: Fix abs() usage in percpu_counter_compare() John Stultz
2015-09-15 1:05 ` [RFC][PATCH 5/5] abs(): Provide build error on passing 64bit value to abs() John Stultz
2015-09-15 5:22 ` Ingo Molnar
2015-09-15 23:52 ` Linus Torvalds [this message]
2015-09-16 12:57 ` [PATCH] kernel.h: make abs() work with 64-bit types Michal Nazarewicz
2015-09-18 3:12 ` John Stultz
2015-09-15 1:49 ` [RFC][PATCH 0/5] Fixes for abs() usage on 64bit values Tejun Heo
2015-09-15 3:27 ` John Stultz
2015-09-15 3:46 ` Tejun Heo
2015-09-15 12:09 ` Jeff Epler
2015-09-15 21:21 ` Andrew Morton
2015-09-15 22:54 ` Michal Nazarewicz
2015-09-15 5:20 ` Ingo Molnar
2015-09-15 23:43 ` Linus Torvalds
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='CA+55aFzjZqt-8HhvbvLb7s3vR_G3Hjmf=buKBBKTnmKm+KVK-Q@mail.gmail.com' \
--to=torvalds@linux-foundation.org \
--cc=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=john.stultz@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=masami.hiramatsu.pt@hitachi.com \
--cc=mina86@mina86.com \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.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;
as well as URLs for NNTP newsgroup(s).