linux-kernel - Re: [PATCH, RFC] Remove fasync() BKL usage, take 3325

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Message-ID: <20090122222141.4a9501e1@tpl>
Date:	Thu, 22 Jan 2009 22:21:41 -0700
From:	Jonathan Corbet <corbet@....net>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, andi@...stfloor.org,
	viro@...IV.linux.org.uk, oleg@...hat.com,
	linux-api@...r.kernel.org, alan@...rguk.ukuu.org.uk
Subject: Re: [PATCH, RFC] Remove fasync() BKL usage, take 3325

On Thu, 22 Jan 2009 17:09:35 +0100
Andi Kleen <andi@...stfloor.org> wrote:

> > OK, replacing a lock_kernel() with a spin_lock(&global_lock) is
> > pretty straightforwad.  But it's really really sad.  It basically
> > leaves a great big FIXME in there.  It'd be better to fix it.  
> 
> Also it might be that it's even worse than the BKL.

I don't quite see how now.  Like the BKL, it's a spinlock.

> It would still require a bitlock because some state in the low
> level fasync needs to be protected.
> 
> Oleg has a proposal to do this using a flag bit which seemed
> reasonable to me.

I didn't see a reason to add a one-off custom locking regime for such a
non-hot-path situation.  But it would certainly work; if we want to go
that way I'll not fight it.

jon
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