From: Pavel Machek <pavel@ucw.cz>
To: Jiri Slaby <jirislaby@gmail.com>
Cc: linux-pm@lists.linux-foundation.org,
linux-kernel@vger.kernel.org,
Nigel Cunningham <ncunningham@crca.org.au>,
"Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [RFC 09/15] PM / Hibernate: user, implement user_ops writer
Date: Thu, 25 Mar 2010 22:36:42 +0100 [thread overview]
Message-ID: <20100325213642.GF22902@elf.ucw.cz> (raw)
In-Reply-To: <4BAA86E8.5090108@gmail.com>
On Wed 2010-03-24 22:40:56, Jiri Slaby wrote:
> On 03/24/2010 09:42 PM, Pavel Machek wrote:
> >> + if (test_bit(TODO_CLOSED, to_do_flags))
> >> + return -EIO;
> >> +
> >> + to_do_buf = buf;
> >> + wmb();
> >> + set_bit(TODO_WORK, to_do_flags);
> >> + wake_up_interruptible(&to_do_wait);
> >
> > Uhuh, open-coded barriers... these need to be commented, and I guess
> > you just should not play this kind of trickery.
>
> It's just to ensure the to_do_buf store is not reordered with the
> set_bit. I wanted to avoid locks as too heavy tools here.
Locks are the only sane choice here. Open coding them is not an option.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2010-03-25 21:37 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-23 16:17 [RFC 01/15] FS: libfs, implement simple_write_to_buffer Jiri Slaby
2010-03-23 16:17 ` [RFC 02/15] PM / Hibernate: snapshot cleanup Jiri Slaby
2010-03-24 20:29 ` Pavel Machek
2010-03-24 22:35 ` Rafael J. Wysocki
2010-03-25 5:29 ` Pavel Machek
2010-03-23 16:17 ` [RFC 03/15] PM / Hibernate: separate block_io Jiri Slaby
2010-03-24 20:30 ` Pavel Machek
2010-03-24 21:22 ` Jiri Slaby
2010-03-24 22:58 ` Nigel Cunningham
2010-03-25 2:35 ` [linux-pm] " Nigel Cunningham
2010-03-25 20:12 ` Rafael J. Wysocki
2010-03-25 20:13 ` Nigel Cunningham
2010-03-25 20:33 ` Rafael J. Wysocki
2010-03-25 20:36 ` Nigel Cunningham
2010-03-29 13:30 ` Pavel Machek
2010-03-25 14:29 ` Pavel Machek
2010-03-23 16:17 ` [RFC 04/15] PM / Hibernate: move the first_sector out of swsusp_write Jiri Slaby
2010-03-24 20:31 ` Pavel Machek
2010-03-25 21:26 ` Rafael J. Wysocki
2010-03-23 16:17 ` [RFC 05/15] PM / Hibernate: group swap ops Jiri Slaby
2010-03-25 21:28 ` Rafael J. Wysocki
2010-03-23 16:17 ` [RFC 06/15] PM / Hibernate: swap, remove swap_map_handle usages Jiri Slaby
2010-03-24 20:33 ` Pavel Machek
2010-03-24 21:29 ` Jiri Slaby
2010-03-25 21:35 ` Rafael J. Wysocki
2010-03-23 16:17 ` [RFC 07/15] PM / Hibernate: add sws_modules_ops Jiri Slaby
2010-03-24 20:36 ` Pavel Machek
2010-03-24 21:31 ` Jiri Slaby
2010-03-25 22:02 ` Rafael J. Wysocki
2010-03-23 16:17 ` [RFC 08/15] PM / Hibernate: add user module_ops Jiri Slaby
2010-03-25 22:07 ` Rafael J. Wysocki
2010-03-26 9:43 ` Jiri Slaby
2010-03-23 16:17 ` [RFC 09/15] PM / Hibernate: user, implement user_ops writer Jiri Slaby
2010-03-24 20:42 ` Pavel Machek
2010-03-24 21:40 ` Jiri Slaby
2010-03-25 21:36 ` Pavel Machek [this message]
2010-03-25 22:14 ` Rafael J. Wysocki
2010-03-26 9:34 ` Jiri Slaby
2010-03-26 22:04 ` Rafael J. Wysocki
2010-03-29 15:33 ` Jiri Slaby
2010-03-27 7:02 ` Pavel Machek
2010-03-23 16:17 ` [RFC 10/15] PM / Hibernate: user, implement user_ops reader Jiri Slaby
2010-03-25 5:30 ` what the patches do " Pavel Machek
2010-03-25 5:42 ` Nigel Cunningham
2010-03-25 6:12 ` [linux-pm] " Nigel Cunningham
2010-03-25 20:14 ` Rafael J. Wysocki
2010-03-25 20:21 ` Nigel Cunningham
2010-03-25 20:29 ` Rafael J. Wysocki
2010-03-25 20:35 ` Nigel Cunningham
2010-03-25 21:13 ` Rafael J. Wysocki
2010-03-25 21:26 ` Pavel Machek
2010-03-25 21:49 ` [linux-pm] " Nigel Cunningham
2010-04-02 6:36 ` Pavel Machek
2010-04-02 17:03 ` Rafael J. Wysocki
2010-03-25 22:21 ` Rafael J. Wysocki
2010-03-23 16:17 ` [RFC 11/15] PM / Hibernate: add chunk i/o support Jiri Slaby
2010-03-25 22:38 ` Rafael J. Wysocki
2010-03-26 9:09 ` Jiri Slaby
2010-03-26 10:02 ` Nigel Cunningham
2010-03-23 16:17 ` [RFC 12/15] PM / Hibernate: split snapshot_read_next Jiri Slaby
2010-03-25 22:44 ` Rafael J. Wysocki
2010-03-23 16:17 ` [RFC 13/15] PM / Hibernate: split snapshot_write_next Jiri Slaby
2010-03-25 22:46 ` Rafael J. Wysocki
2010-03-23 16:17 ` [RFC 14/15] PM / Hibernate: dealign swsusp_info Jiri Slaby
2010-03-25 22:46 ` Rafael J. Wysocki
2010-03-23 16:17 ` [RFC 15/15] PM / Hibernate: move non-swap code to snapshot.c Jiri Slaby
2010-03-25 22:50 ` Rafael J. Wysocki
2010-03-23 21:51 ` [RFC 01/15] FS: libfs, implement simple_write_to_buffer Rafael J. Wysocki
2010-03-23 22:09 ` [linux-pm] " Nigel Cunningham
2010-03-24 22:13 ` Rafael J. Wysocki
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