Subject: Re: [PATCH 6/7] Make qdisc changeable.

From: Corey Hickey <[email-masked]>
Date: Sun, 05 Aug 2007 19:47:26 -0700

Patrick McHardy wrote:
>> +	if ((err = sfq_q_init(&tmp, opt)))
>> +		return err;
> 
> 
> This will also use defaults for all unspecified values. It would
> be more consistent with other qdiscs to only change those values
> that are actually specified, so something like "tc qdisc change ...
> perturb 10" will *only* change the perturbation parameter.

I'm fixed this for all the parameters except one--your example above.
Since 0 is a valid value for perturb, I can't see any clever way to
differentiate between the user specifying "perturb 0" or leaving perturb
unspecified. Either way, opt->perturb_period is 0.

The only way I can see would be to add another member, say,
opt->perturb_specified, and use that accordingly. Unfortunately, this
would break usage of sfq with older versions of tc, so I'm hoping
there's a better approach.

Do you have any suggestions? I've looked at the other qdisc files and I 
don't see any other instances like this.

Thanks,
Corey