From: Segher Boessenkool <segher@kernel.crashing.org>
To: Chris Snook <csnook@redhat.com>
Cc: wjiang@resilience.com, wensong@linux-vs.org,
heiko.carstens@de.ibm.com, linux-kernel@vger.kernel.org,
ak@suse.de, cfriesen@nortel.com, netdev@vger.kernel.org,
horms@verge.net.au, akpm@linux-foundation.org,
linux-arch@vger.kernel.org, torvalds@linux-foundation.org,
schwidefsky@de.ibm.com, davem@davemloft.net, zlynx@acm.org,
rpjday@mindspring.com, jesper.juhl@gmail.com
Subject: Re: [PATCH 24/24] document volatile atomic_read() behavior
Date: Thu, 9 Aug 2007 17:59:29 +0200 [thread overview]
Message-ID: <8f6bb8a9e4f2819a161d732bdb6c70c0@kernel.crashing.org> (raw)
In-Reply-To: <20070809142430.GA19817@shell.boston.redhat.com>
> Historically this has been
> +accomplished by declaring the counter itself to be volatile, but the
> +ambiguity of the C standard on the semantics of volatile make this
> practice
> +vulnerable to overly creative interpretation by compilers.
It's even worse when accessing through a volatile casted pointer;
see for example the recent(*) GCC bugs in that area.
(*) Well, not _all_ that recent. No one should be using the 3.x
series anymore, right?
> Explicit
> +casting in atomic_read() ensures consistent behavior across
> architectures
> +and compilers.
Even modulo compiler bugs, what makes you believe that?
Segher
next prev parent reply other threads:[~2007-08-09 16:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-09 14:24 [PATCH 24/24] document volatile atomic_read() behavior Chris Snook
2007-08-09 15:59 ` Segher Boessenkool [this message]
2007-08-09 16:26 ` Chris Snook
2007-08-09 19:42 ` Segher Boessenkool
2007-08-09 20:05 ` Chris Snook
2007-08-09 22:34 ` Segher Boessenkool
2007-08-09 20:10 ` Chris Friesen
2007-08-09 22:23 ` Segher Boessenkool
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=8f6bb8a9e4f2819a161d732bdb6c70c0@kernel.crashing.org \
--to=segher@kernel.crashing.org \
--cc=ak@suse.de \
--cc=akpm@linux-foundation.org \
--cc=cfriesen@nortel.com \
--cc=csnook@redhat.com \
--cc=davem@davemloft.net \
--cc=heiko.carstens@de.ibm.com \
--cc=horms@verge.net.au \
--cc=jesper.juhl@gmail.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=rpjday@mindspring.com \
--cc=schwidefsky@de.ibm.com \
--cc=torvalds@linux-foundation.org \
--cc=wensong@linux-vs.org \
--cc=wjiang@resilience.com \
--cc=zlynx@acm.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).