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Date: Tue, 31 Jan 2017 14:17:59 +0100
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Marek Vasut <marex@denx.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
        Joel Becker <jlbec@evilplan.org>
Subject: Re: [PATCH] [RFC] fs: Possible filp_open race experiment
Message-ID: <20170131131759.GA24789@kroah.com>
References: <20170117231600.10186-1-marex@denx.de>
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On Tue, Jan 31, 2017 at 01:58:14PM +0100, Christoph Hellwig wrote:
> On Tue, Jan 31, 2017 at 11:21:02AM +0100, Greg Kroah-Hartman wrote:
> > 
> > -next isn't Linus's tree, sometimes stuff sits in there for years :)
> > 
> > Anyway, if this is a configfs issue, Christoph and Joel can take a look
> > at it.  Any reason you didn't cc: Joel as well (the MAINTAINERS file is
> > your friend...)
> 
> It's really a mismatched assumption.  The configfs binary file
> code just chunks updates up into a buffer, which only gets flushed
> at ->release time.  If we'd move that to ->flush the issue Marek reports
> would be fixed.
> 
> But I don't think we want that - triggering a filp_open from the update
> of a _binary_ attribute for a start is wrong.  And second doing this
> using ->fs of a random calling process is bound to cause problems.
> 
> I think he is using the wrong kind of interface for the job.

Ah, that's why no one has seen this before :)

So, the DT overlay code needs to be fixed...

thanks,

greg k-h