linux-kernel - Re: [CRAZY-RFF] debugfs: track open files and release on remove

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Message-ID: <01fcaf4985f57d97ac03fc0b7deb2c225a2fbca1.camel@sipsolutions.net>
Date:   Fri, 09 Oct 2020 10:48:09 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, nstange@...e.de, ap420073@...il.com,
        David.Laight@...lab.com, netdev@...r.kernel.org,
        linux-wireless@...r.kernel.org, rafael@...nel.org
Subject: Re: [CRAZY-RFF] debugfs: track open files and release on remove

On Fri, 2020-10-09 at 10:47 +0200, Greg KH wrote:

> > 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?
> 
> That will fail for all of the debugfs_create_* operations, as there is
> only one set of file operations for all of the different files created
> with these calls.

Why would it fail? Those have their fops in the core debugfs code, which
might have a .owner assigned but is probably built-in anyway?

> Which, now that I remember it, is why we went down the proxy "solution"
> in the first place :(

Not sure I understand. That was related more to (arbitrary) files having
to be disappeared rather than anything else?

johannes