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Date: Fri, 2 Jan 2009 19:54:46 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>, LKML <linux-kernel@vger.kernel.org>,
       Andi Kleen <andi@firstfloor.org>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       bfields@fieldses.org, xfs-masters@oss.sgi.com
Subject: Re: RFC: Fix f_flags races without the BKL
Message-ID: <20090102195446.GJ28946@ZenIV.linux.org.uk>
References: <20081229041352.6bbdf57c@tpl> <20090102184232.GH28946@ZenIV.linux.org.uk> <20090102190902.GA25969@redhat.com>
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On Fri, Jan 02, 2009 at 08:09:03PM +0100, Oleg Nesterov wrote:
> On 01/02, Al Viro wrote:
> >
> > Bloating with mutex is over the top, indeed, but why can't we simply keep
> > a pointer to fasync_struct in there?  Do we ever have a struct file with
> > several fasync_struct?
> 
> pipe_rdwr_fasync() ?

Ho-hum...  Right you are ;-/

FWIW, it's still bloody tempting to try.  How about hlist from struct file
through fasync_struct?  Possibly with reference from fasync_struct back
to the queue it's on, while we are at it - would make fasync_helper simpler...