From: David Mosberger <davidm@hpl.hp.com>
To: Richard Henderson <rth@twiddle.net>
Cc: Paul Mackerras <paulus@samba.org>,
torvalds@transmeta.com, linux-kernel@vger.kernel.org,
davem@redhat.com, davidm@hpl.hp.com
Subject: Re: [PATCH] avoid unnecessary cache flushes
Date: Mon, 3 Sep 2001 13:27:02 -0700 [thread overview]
Message-ID: <15251.59286.154267.431231@napali.hpl.hp.com> (raw)
In-Reply-To: <20010903131436.A16069@twiddle.net>
In-Reply-To: <15247.29338.3671.548678@cargo.ozlabs.ibm.com> <20010903131436.A16069@twiddle.net>
>>>>> On Mon, 3 Sep 2001 13:14:36 -0700, Richard Henderson <rth@twiddle.net> said:
Richard> On Fri, Aug 31, 2001 at 09:18:50PM +1000, Paul Mackerras wrote:
>> + if (!test_bit(PG_arch_1, &page->flags)) {
>> + __flush_dcache_icache((unsigned long)kmap(page));
>> + kunmap(page);
>> + set_bit(PG_arch_1, &page->flags);
Richard> Race. Use test_and_set_bit.
Nope, the old code is correct: you must turn on PG_arch_1 *after*
flushing the cache. Yes, you might sometimes double flush, but that's
both safe and rare.
--david
next prev parent reply other threads:[~2001-09-03 20:27 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-08-31 11:18 Paul Mackerras
2001-08-31 22:45 ` David S. Miller
2001-09-01 8:55 ` David S. Miller
2001-09-01 12:24 ` David S. Miller
2001-09-01 8:35 ` Paul Mackerras
2001-09-01 11:47 ` Paul Mackerras
2001-09-03 20:14 ` Richard Henderson
2001-09-03 20:27 ` David Mosberger [this message]
2001-09-03 20:41 ` Richard Henderson
2001-09-03 21:00 ` David Mosberger
2001-09-04 16:37 ` Richard Henderson
2001-09-04 17:06 ` David Mosberger
2001-09-04 1:53 ` Paul Mackerras
2001-09-04 2:31 ` Andrea Arcangeli
2001-09-04 4:08 ` Paul Mackerras
2001-09-04 12:58 ` Andrea Arcangeli
2001-09-04 16:44 ` Richard Henderson
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=15251.59286.154267.431231@napali.hpl.hp.com \
--to=davidm@hpl.hp.com \
--cc=davem@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=paulus@samba.org \
--cc=rth@twiddle.net \
--cc=torvalds@transmeta.com \
/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
all inboxes | Powered by JetHome®