Re: [PATCH iproute2-next] tc: mqprio: reject queues count/offset pair count higher than num_tc

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 13 May 2020 21:47:17 +0200
Maciej Fijalkowski <maciej.fijalkowski@intel.com> wrote:

> Provide a sanity check that will make sure whether queues count/offset
> pair count will not exceed the actual number of TCs being created.
> 
> Example command that is invalid because there are 4 count/offset pairs
> whereas num_tc is only 2.
> 
>  # tc qdisc add dev enp96s0f0 root mqprio num_tc 2 map 0 0 0 0 1 1 1 1
> queues 4@0 4@4 4@8 4@12 hw 1 mode channel
> 
> Store the parsed count/offset pair count onto a dedicated variable that
> will be compared against opt.num_tc after all of the command line
> arguments were parsed. Bail out if this count is higher than opt.num_tc
> and let user know about it.
> 
> Drivers were swallowing such commands as they were iterating over
> count/offset pairs where num_tc was used as a delimiter, so this is not
> a big deal, but better catch such misconfiguration at the command line
> argument parsing level.
> 
> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>

This doesn't have to wait for iproute2-next.
Can pick it up on the master side (after review).