From: akpm@linux-foundation.org
To: mm-commits@vger.kernel.org
Cc: rmk@arm.linux.org.uk, linux-arch@vger.kernel.org,
rmk+kernel@arm.linux.org.uk, torvalds@linux-foundation.org
Subject: + documentation-volatile-considered-harmfultxt-correct-cpu_relax-documentation.patch added to -mm tree
Date: Thu, 18 Mar 2010 14:41:42 -0700 [thread overview]
Message-ID: <201003182141.o2ILfgB0017286@imap1.linux-foundation.org> (raw)
The patch titled
Documentation/volatile-considered-harmful.txt: correct cpu_relax() documentation
has been added to the -mm tree. Its filename is
documentation-volatile-considered-harmfultxt-correct-cpu_relax-documentation.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: Documentation/volatile-considered-harmful.txt: correct cpu_relax() documentation
From: Russell King <rmk@arm.linux.org.uk>
cpu_relax() is documented in volatile-considered-harmful.txt to be a
memory barrier. However, everyone with the exception of Blackfin and
possibly ia64 defines cpu_relax() to be a compiler barrier.
Make the documentation reflect the general concensus.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: <linux-arch@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
Documentation/volatile-considered-harmful.txt | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -puN Documentation/volatile-considered-harmful.txt~documentation-volatile-considered-harmfultxt-correct-cpu_relax-documentation Documentation/volatile-considered-harmful.txt
--- a/Documentation/volatile-considered-harmful.txt~documentation-volatile-considered-harmfultxt-correct-cpu_relax-documentation
+++ a/Documentation/volatile-considered-harmful.txt
@@ -63,9 +63,9 @@ way to perform a busy wait is:
cpu_relax();
The cpu_relax() call can lower CPU power consumption or yield to a
-hyperthreaded twin processor; it also happens to serve as a memory barrier,
-so, once again, volatile is unnecessary. Of course, busy-waiting is
-generally an anti-social act to begin with.
+hyperthreaded twin processor; it also happens to serve as a compiler
+barrier, so, once again, volatile is unnecessary. Of course, busy-
+waiting is generally an anti-social act to begin with.
There are still a few rare situations where volatile makes sense in the
kernel:
_
Patches currently in -mm which might be from rmk@arm.linux.org.uk are
origin.patch
documentation-volatile-considered-harmfultxt-correct-cpu_relax-documentation.patch
arm-convert-proc-cpu-aligment-to-seq_file.patch
arch-arm-include-asm-elfh-forward-declare-the-task-struct.patch
bitops-rename-for_each_bit-to-for_each_set_bit-mtd.patch
next reply other threads:[~2010-03-18 21:42 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-18 21:41 akpm [this message]
2010-03-18 21:54 ` + documentation-volatile-considered-harmfultxt-correct-cpu_relax-documentation.patch added to -mm tree 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=201003182141.o2ILfgB0017286@imap1.linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=linux-arch@vger.kernel.org \
--cc=mm-commits@vger.kernel.org \
--cc=rmk+kernel@arm.linux.org.uk \
--cc=rmk@arm.linux.org.uk \
--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