Re: [PATCH net v1 1/3] taprio: Fix enabling offload with wrong number of traffic classes

[Andre Guedes <andre.guedes@linux.intel.com>]

Hi Vinicius,

Quoting Vinicius Costa Gomes (2020-01-24 16:53:18)
> diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
> index c609373c8661..ad0dadcfcdba 100644
> --- a/net/sched/sch_taprio.c
> +++ b/net/sched/sch_taprio.c
> @@ -1444,6 +1444,19 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt,
>  
>         taprio_set_picos_per_byte(dev, q);
>  
> +       if (mqprio) {
> +               netdev_set_num_tc(dev, mqprio->num_tc);
> +               for (i = 0; i < mqprio->num_tc; i++)
> +                       netdev_set_tc_queue(dev, i,
> +                                           mqprio->count[i],
> +                                           mqprio->offset[i]);
> +
> +               /* Always use supplied priority mappings */
> +               for (i = 0; i <= TC_BITMASK; i++)
> +                       netdev_set_prio_tc_map(dev, i,
> +                                              mqprio->prio_tc_map[i]);
> +       }
> +
>         if (FULL_OFFLOAD_IS_ENABLED(taprio_flags))
>                 err = taprio_enable_offload(dev, mqprio, q, new_admin, extack);
>         else

If something goes wrong later within this function (e.g.
taprio_enable_offload() returns error), don't we want to roll back these
changes to the netdev object?

- Andre