Date: Mon, 1 Apr 2013 22:21:42 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Dave Jones <davej@redhat.com>,
        Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: Yet another pipe related oops.
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On Mon, Apr 01, 2013 at 02:00:29PM -0700, Greg Kroah-Hartman wrote:

> > IOW, how do we deal with a race between attempt to open a debugfs file and
> > its removal on driver unload?  Greg?
> 
> Hm, I thought the i_fop->owner thing would be the needed protection, but

It will be, if you manage to fetch it...

> I guess you are right, it will not.  I guess we need to do what
> character devices do and have an "intermediate" fops in order to protect
> this.  Would that work?

You mean, with reassigning ->f_op in ->open()?  That'll work, as long as
we have exclusion between removal and fetching the sucker in primary
->open()...  Where would you prefer to stash fops?
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