Re: [Xen-devel] [PATCH 1/3] xen/privcmd: return -ENOSYS for unimplemented IOCTLs

From: Boris Ostrovsky
Date: Thu Feb 09 2017 - 14:39:17 EST

On 02/09/2017 09:40 AM, Jan Beulich wrote:
On 09.02.17 at 15:17, <paul.durrant@xxxxxxxxxx> wrote:
The code goes so far as to set the default return code to -ENOSYS but
then overrides this to -EINVAL in the switch() statement's default

If you already change this, isn't -ENOTTY the traditional way of
indicating unsupported ioctls?

In fact, a while ago David submitted a patch to do just that:

but it never went anywhere.

My question is whether anyone might be relying on current error return behavior.