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From: Johannes Berg <johannes@sipsolutions.net>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, nstange@suse.de,
	ap420073@gmail.com, David.Laight@aculab.com,
	netdev@vger.kernel.org, linux-wireless@vger.kernel.org,
	rafael@kernel.org
Subject: Re: [CRAZY-RFF] debugfs: track open files and release on remove
Date: Fri, 09 Oct 2020 10:19:02 +0200	[thread overview]
Message-ID: <1ec056cf3ec0953d2d1abaa05e37e89b29c7cc63.camel@sipsolutions.net> (raw)
In-Reply-To: <20201009081624.GA401030@kroah.com>

On Fri, 2020-10-09 at 10:16 +0200, Greg KH wrote:
> On Fri, Oct 09, 2020 at 10:06:14AM +0200, Johannes Berg wrote:
> > We used to say the proxy_fops weren't needed and it wasn't an issue, and
> > then still implemented it. Dunno. I'm not really too concerned about it
> > myself, only root can hold the files open and remove modules ...
> 
> proxy_fops were needed because devices can be removed from the system at
> any time, causing their debugfs files to want to also be removed.  It
> wasn't because of unloading kernel code.

Indeed, that's true. Still, we lived with it for years.

Anyway, like I said, I really just did this more to see that it _could_
be done, not to suggest that it _should_ :-)

I think adding the .owner everywhere would be good, and perhaps we can
somehow put a check somewhere like

	WARN_ON(is_module_address((unsigned long)fops) && !fops->owner);

to prevent the issue in the future?

johannes


  reply	other threads:[~2020-10-09  8:19 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-08 15:48 [PATCH net 000/117] net: avoid to remove module when its debugfs is being used Taehee Yoo
2020-10-08 15:59 ` David Laight
2020-10-08 15:59   ` David Laight
2020-10-08 16:14   ` Johannes Berg
2020-10-08 16:14     ` Johannes Berg
2020-10-08 16:37     ` Taehee Yoo
2020-10-08 16:37       ` Taehee Yoo
2020-10-09  5:38       ` Nicolai Stange
2020-10-09  5:38         ` Nicolai Stange
2020-10-09 10:07         ` Taehee Yoo
2020-10-09 10:07           ` Taehee Yoo
2020-10-09  5:09     ` Nicolai Stange
2020-10-09  5:09       ` Nicolai Stange
2020-10-09  7:45       ` Johannes Berg
2020-10-09  7:45         ` Johannes Berg
2020-10-09 10:15         ` Taehee Yoo
2020-10-09 10:15           ` Taehee Yoo
2020-10-09 10:21           ` Johannes Berg
2020-10-09 10:21             ` Johannes Berg
2020-10-09 10:41             ` [RFC] debugfs: protect against rmmod while files are open Johannes Berg
2020-10-09 10:48               ` Johannes Berg
2020-10-09 10:56                 ` David Laight
2020-10-09 10:56                   ` Johannes Berg
2020-10-09 11:15                   ` gregkh
2020-10-09 15:33             ` [PATCH net 000/117] net: avoid to remove module when its debugfs is being used Steve deRosier
2020-10-09 15:33               ` Steve deRosier
2020-10-09  7:53       ` [CRAZY-RFF] debugfs: track open files and release on remove Johannes Berg
2020-10-09  8:03         ` Greg KH
2020-10-09  8:06           ` Johannes Berg
2020-10-09  8:16             ` Greg KH
2020-10-09  8:19               ` Johannes Berg [this message]
2020-10-09  8:34                 ` David Laight
2020-10-09  8:44                   ` Johannes Berg
2020-10-09  9:00                     ` David Laight
2020-10-09  8:47                 ` Greg KH
2020-10-09  8:48                   ` Johannes Berg
2020-10-10  9:38                     ` Greg KH
2020-10-10 10:47                       ` Johannes Berg

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