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

[Theodore Y. Ts'o]

On Thu, Jan 23, 2020 at 06:55:36PM +0100, Greg Kroah-Hartman wrote:
> > 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.

This makes life difficult for scripts that manipulate the control
file, since they now need to check two different locations -- either
/sys/kernel/debug or /proc.  It's likely that people who normally use
distribution kernels where debugfs is disabled will have scripts which
are hard-coded to look in /proc, and then when they build a kernel
with debugfs enabled, the /proc entry will go **poof**, and their
script will break.

So regardless of what we do with the control file in debugfs, it might
be nice if moving forward, scripts can count on the /proc file
existing.

Cheers,

					- Ted