From: Frederic Weisbecker <fweisbec@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>, Ingo Molnar <mingo@elte.hu>,
LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ming Lei <tom.leiming@gmail.com>
Subject: Re: [PATCH 2/2] lockdep: Don't only check recursive read locks once in a sequence
Date: Fri, 20 Nov 2009 01:57:46 +0100 [thread overview]
Message-ID: <20091120005743.GJ4967@nowhere> (raw)
In-Reply-To: <1258650828.3931.437.camel@laptop>
On Thu, Nov 19, 2009 at 06:13:48PM +0100, Peter Zijlstra wrote:
> On Thu, 2009-11-19 at 16:55 +0100, Frederic Weisbecker wrote:
> > And btw I
> > don't understand why rwsem read locks are not considered as
> > recursive in lockdep.
>
> Because they're not.
>
> rwsems are FIFO fair, so a double read can deadlock when there's a
> pending writer inbetween.
>
Aah ok. That's the subtle thing I was missing :)
Thanks.
prev parent reply other threads:[~2009-11-20 0:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-18 1:06 [PATCH 0/2] lockdep: Improvements for rwlocks dependency inversion detection Frederic Weisbecker
2009-11-18 1:06 ` [PATCH 1/2] lockdep: Include recursive read-locks dependencies in the tree Frederic Weisbecker
2009-11-18 10:26 ` Peter Zijlstra
2009-11-19 16:07 ` Frederic Weisbecker
2009-11-18 1:06 ` [PATCH 2/2] lockdep: Don't only check recursive read locks once in a sequence Frederic Weisbecker
2009-11-18 9:43 ` Lai Jiangshan
2009-11-19 15:55 ` Frederic Weisbecker
2009-11-19 17:13 ` Peter Zijlstra
2009-11-20 0:57 ` Frederic Weisbecker [this message]
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=20091120005743.GJ4967@nowhere \
--to=fweisbec@gmail.com \
--cc=laijs@cn.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=tom.leiming@gmail.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