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

From: Vinicius Costa Gomes <[email-masked]>
Date: Mon, 27 Jan 2020 11:18:51 -0800

Hi Andre,

Andre Guedes <[email-masked]> writes:

> 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?

If something goes wrong, and change() returns an error, taprio_destroy()
is called, and the changes are undone.

Cheers,
--
Vinicius