Subject: Re: [iproute2][PATCH v2] tc: mirred target: do not report non-existing devices

From: Stephen Hemminger <[email-masked]>
Date: Tue, 4 Sep 2012 08:40:29 -0700

On Sun,  2 Sep 2012 13:48:02 +0300
[email-masked] wrote:

> From: Dan Kenigsberg <[email-masked]>
> 
> Currently, if a mirred target device is removed, `tc filter show`
> does not reveal the fact. Instead, it replaces the original name of the
> device with the default output of ll_map:ll_idx_n2a().
> 
> This is unfortunate, since one cannot differ between this case and a valid
> mirroring target device named 'if17'.
> 
> It seems that the original code meant to report an error message in this
> case, but it does not, since ll_index_to_name() never returns 0. I would
> not like to bail out in case of an error, since the user would still be
> interested to know what are the other details of the action.
> 
> v2: properly declare the new function ll_index_exsits()

I am okay with the concept but  "missing-if1" is still a possible
but unlikely name for a device.  Maybe better to use something more
obvious like [unknown-1] or UNKNOWN?