From: David Howells <dhowells@redhat.com>
To: Michel Lespinasse <walken@google.com>
Cc: dhowells@redhat.com,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Waychison <mikew@google.com>,
Suleiman Souhlal <suleiman@google.com>,
Ying Han <yinghan@google.com>
Subject: Re: [PATCH 02/10] rwsem: fully separate code pathes to wake writers vs readers
Date: Wed, 19 May 2010 13:04:42 +0100 [thread overview]
Message-ID: <2767.1274270682@redhat.com> (raw)
In-Reply-To: <1274135154-24082-3-git-send-email-walken@google.com>
Michel Lespinasse <walken@google.com> wrote:
> + readers_only:
> + if (!downgrading) {
> +
There's an unnecessary blank line here.
> + /* if we came through an up_xxxx() call, we only only wake
> + * someone up if we can transition the active part of the
> + * count from 0 -> 1
> + */
> + try_again_read:
I hate code that jumps into braced blocks with goto. Would it be possible for
you to do:
readers_only:
if (downgrading)
goto wake_readers;
...
wake_readers:
/* Grant an infinite number of read locks to the readers at the front
...
instead, please?
Also, since the labels 'undo' and 'try_again' are now specific to the writer
path, can you label them 'undo_write' and 'try_again_write' just to make it
obvious?
Other than that, no particular objections to this patch.
David
next prev parent reply other threads:[~2010-05-19 12:05 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-17 22:25 [PATCH 00/10] V3: rwsem changes + down_read_critical() proposal Michel Lespinasse
2010-05-17 22:25 ` [PATCH 01/10] x86 rwsem: minor cleanups Michel Lespinasse
2010-05-17 22:25 ` [PATCH 02/10] rwsem: fully separate code pathes to wake writers vs readers Michel Lespinasse
2010-05-17 22:25 ` [PATCH 03/10] rwsem: lighter active count checks when waking up readers Michel Lespinasse
2010-05-17 22:25 ` [PATCH 04/10] rwsem: let RWSEM_WAITING_BIAS represent any number of waiting threads Michel Lespinasse
2010-05-17 22:25 ` [PATCH 05/10] rwsem: wake queued readers when writer blocks on active read lock Michel Lespinasse
2010-05-17 22:25 ` [PATCH 06/10] rwsem: smaller wrappers around rwsem_down_failed_common Michel Lespinasse
2010-05-17 22:25 ` [PATCH 07/10] generic rwsem: implement down_read_critical() / up_read_critical() Michel Lespinasse
2010-05-17 22:44 ` Linus Torvalds
2010-05-17 23:13 ` Michel Lespinasse
2010-05-17 23:20 ` Michel Lespinasse
2010-05-19 13:21 ` David Howells
2010-05-19 23:47 ` Michel Lespinasse
2010-05-21 3:35 ` Michel Lespinasse
2010-05-17 22:25 ` [PATCH 08/10] rwsem: down_read_critical infrastructure support Michel Lespinasse
2010-05-17 22:25 ` [PATCH 09/10] x86 rwsem: down_read_critical implementation Michel Lespinasse
2010-05-17 22:25 ` [PATCH 10/10] Use down_read_critical() for /sys/<pid>/exe and /sys/<pid>/maps files Michel Lespinasse
2010-05-19 11:47 ` [PATCH 01/10] x86 rwsem: minor cleanups David Howells
2010-05-20 21:37 ` Michel Lespinasse
2010-05-19 12:04 ` David Howells [this message]
2010-05-20 21:48 ` [PATCH 02/10] rwsem: fully separate code pathes to wake writers vs readers Michel Lespinasse
2010-05-19 12:25 ` [PATCH 03/10] rwsem: lighter active count checks when waking up readers David Howells
2010-05-20 22:33 ` Michel Lespinasse
2010-05-21 8:06 ` David Howells
2010-05-19 12:33 ` [PATCH 04/10] rwsem: let RWSEM_WAITING_BIAS represent any number of waiting threads David Howells
2010-05-19 12:44 ` [PATCH 05/10] rwsem: wake queued readers when writer blocks on active read lock David Howells
2010-05-19 12:51 ` [PATCH 06/10] rwsem: smaller wrappers around rwsem_down_failed_common David Howells
2010-05-19 13:34 ` [PATCH 08/10] rwsem: down_read_critical infrastructure support David Howells
2010-05-20 23:30 ` Michel Lespinasse
2010-05-21 8:03 ` David Howells
2010-05-19 14:36 ` [PATCH 09/10] x86 rwsem: down_read_critical implementation David Howells
2010-05-19 15:21 ` [PATCH 10/10] Use down_read_critical() for /sys/<pid>/exe and /sys/<pid>/maps files David Howells
2010-05-21 2:44 ` Michel Lespinasse
2010-05-22 1:49 ` Michel Lespinasse
2010-05-25 9:42 ` David Howells
-- strict thread matches above, loose matches on Subject: below --
2010-05-14 12:39 [PATCH 00/10] V2: rwsem changes + down_read_unfair() proposal Michel Lespinasse
2010-05-14 12:39 ` [PATCH 02/10] rwsem: fully separate code pathes to wake writers vs readers Michel Lespinasse
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=2767.1274270682@redhat.com \
--to=dhowells@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mikew@google.com \
--cc=mingo@elte.hu \
--cc=suleiman@google.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=walken@google.com \
--cc=yinghan@google.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;
as well as URLs for NNTP newsgroup(s).