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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 10:06:14 +0200	[thread overview]
Message-ID: <be61c6a38d0f6ca1aa0bc3f0cb45bbb216a12982.camel@sipsolutions.net> (raw)
In-Reply-To: <20201009080355.GA398994@kroah.com>

On Fri, 2020-10-09 at 10:03 +0200, Greg KH wrote:

> For lots of debugfs files, .owner should already be set, if you use the
> DEFINE_SIMPLE_ATTRIBUTE() or DEFINE_DEBUGFS_ATTRIBUTE() macros.
> 
> But yes, not all.

Right.

You didn't see the original thread:

https://lore.kernel.org/netdev/20201008155048.17679-1-ap420073@gmail.com/

> I thought the proxy-ops stuff was supposed to fix this issue already.
> Why isn't it, what is broken in them that causes this to still crash?

Well exactly what I described - the proxy_fops *release* doesn't get
proxied, since we don't have any knowledge of the open files (without
this patch) when the proxy_fops are redirected to nothing when a file is
removed.

Nicolai also discussed it a bit here:

https://lore.kernel.org/netdev/87v9fkgf4i.fsf@suse.de/

> And of course, removing kernel modules is never a guaranteed operation,
> nor is it anything that ever happens automatically, so is this really an
> issue?  :)

:)

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 ...

johannes


  reply	other threads:[~2020-10-09  8:06 UTC|newest]

Thread overview: 28+ 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 16:14   ` Johannes Berg
2020-10-08 16:37     ` Taehee Yoo
2020-10-09  5:38       ` Nicolai Stange
2020-10-09 10:07         ` Taehee Yoo
2020-10-09  5:09     ` Nicolai Stange
2020-10-09  7:45       ` Johannes Berg
2020-10-09 10:15         ` Taehee Yoo
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  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 [this message]
2020-10-09  8:16             ` Greg KH
2020-10-09  8:19               ` Johannes Berg
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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