linux-kernel - Re: [PATCH v3] dynamic_debug: allow to work if debugfs is disabled

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Date:   Thu, 23 Jan 2020 18:55:36 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     "Theodore Y. Ts'o" <tytso@....edu>
Cc:     Jason Baron <jbaron@...mai.com>, Will Deacon <will@...nel.org>,
        linux-kernel@...r.kernel.org, kernel-team@...roid.com
Subject: Re: [PATCH v3] dynamic_debug: allow to work if debugfs is disabled

On Thu, Jan 23, 2020 at 10:53:40AM -0500, Theodore Y. Ts'o wrote:
> On Wed, Jan 22, 2020 at 08:31:18PM +0100, Greg Kroah-Hartman wrote:
> > With the realization that having debugfs enabled on "production" systems is
> > generally not a good idea, debugfs is being disabled from more and more
> > platforms over time.  However, the functionality of dynamic debugging still is
> > needed at times, and since it relies on debugfs for its user api, having
> > debugfs disabled also forces dynamic debug to be disabled.
> > 
> > To get around this, move the "control" file for dynamic_debug to procfs IFF
> > debugfs is disabled.  This lets people turn on debugging as needed at runtime
> > for individual driverfs and subsystems.
> 
> Instead of moving the control file IFF debugfs is enabled, what about
> always making it available in /proc, and marking the control file for
> dynamic_debug in debugfs as deprecated?  It would seem to me that this
> would cause less confusion in the future....

Why deprecate it?  It's fine where it is, and most developer's have
debugfs enabled so all is good.  I'd rather only use /proc as a
last-resort.

thanks,

greg k-h