linux-kernel - Re: [PATCH 2/5] TOMOYO: Clarify lock protected section.

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Message-ID: <20090602024306.GB21564@hallyn.com>
Date:	Mon, 1 Jun 2009 21:43:06 -0500
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:	lizf@...fujitsu.com, linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] TOMOYO: Clarify lock protected section.

Quoting Tetsuo Handa (penguin-kernel@...ove.sakura.ne.jp):
> Li Zefan wrote:
> > Tetsuo Handa wrote:
> > > Enclose reader section in
> > > 	/***** READER SECTION START *****/
> > > and
> > > 	/***** READER SECTION END *****/
> > > and writer section in
> > > 	/***** WRITER SECTION START *****/
> > > and
> > > 	/***** WRITER SECTION END *****/
> > > in order to avoid oversighting lock protected section.
> > > 
> > 
> > This makes me a bit uncomfortable..
> > 
> > IMHO this seems ugly, useless, and even harmful. If it's helpful,
> > we'd be doing this for the whole kernel tree, which is crazy..
> > 
> > Or does tomoyo do this for it's special reason?
> 
> I intended to help reviewers to visualize the range of protected section
> at a glance. But if reviewers feel noisy, I can remove these markers.

No, the real problem is that you have "protected sections" at all.

You should be locking data, not code.  (Apparently a quote to be attributed
to Alan Cox - huh)

See the bottom of:
http://www.kernel.org/pub/linux/kernel/people/rusty/kernel-locking/x376.html

-serge
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