From: Brent Casavant <bcasavan@sgi.com>
To: linux-ia64@vger.kernel.org
Subject: atomic_cmpxchg and 64-bit values
Date: Wed, 17 Jan 2007 20:57:05 +0000 [thread overview]
Message-ID: <20070117144850.U8085@pkunk.americas.sgi.com> (raw)
Hello,
I have what I hope is an easy to answer question.
The IA64 atomic_cmpxchg macro reads as follows (line continuation inserted):
#define atomic_cmpxchg(v, old, new) \
((int)cmpxchg(&((v)->counter), old, new))
Note that there's an integer cast on the return from cmpxchg().
This seems strange considering that the entire compxchg() code
path takes care to make sure that correctly-sized data types are
used throughout, including the return path. The atomic_xchg()
macro
Is there some particular reason we need the cast to int on the
return path for atomic_cmpxchg()? It looks to me as if this
macro would work equally well with an atomic_t or an atomic64_t.
Thanks,
Brent
--
Brent Casavant All music is folk music. I ain't
bcasavan@sgi.com never heard a horse sing a song.
Silicon Graphics, Inc. -- Louis Armstrong
next reply other threads:[~2007-01-17 20:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-17 20:57 Brent Casavant [this message]
2007-01-17 21:36 ` atomic_cmpxchg and 64-bit values Andreas Schwab
2007-01-18 18:13 ` Christoph Lameter
2007-01-18 23:43 ` Brent Casavant
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=20070117144850.U8085@pkunk.americas.sgi.com \
--to=bcasavan@sgi.com \
--cc=linux-ia64@vger.kernel.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