Corey Hickey wrote:
> This fixes the ambiguity between, for example:
> tc qdisc change ... perturb 0
> tc qdisc change ...
>
> Without this patch, there is no way for SFQ to differentiate between
> a parameter specified to be 0 and a parameter that was omitted.
>
> diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
> index 170fd37..36197f6 100644
> --- a/net/sched/sch_sfq.c
> +++ b/net/sched/sch_sfq.c
> @@ -428,25 +428,31 @@ sfq_q_init(struct sfq_sched_data *q, struct rtattr *opt)
> * the previous values (sfq_change). So, overwrite the parameters as
> * specified. */
> if (opt) {
> - struct tc_sfq_qopt *ctl = RTA_DATA(opt);
> -
> - if (opt->rta_len < RTA_LENGTH(sizeof(*ctl)))
> - return -EINVAL;
> -
> - if (ctl->quantum)
> - q->quantum = ctl->quantum;
> - if (ctl->perturb_period)
> - q->perturb_period = ctl->perturb_period;
> - if (ctl->divisor)
> - q->hash_divisor = ctl->divisor;
> - if (ctl->flows)
> - q->depth = ctl->flows;
> - if (ctl->limit)
> - q->limit = ctl->limit;
> -
> + struct tc_sfq_qopt *ctl;
> + struct rtattr *tb[TCA_SFQ_MAX];
> +
> + if (rtattr_parse_nested_compat(tb, TCA_SFQ_MAX, opt, ctl,
> + sizeof(*ctl)))
> + goto rtattr_failure;
> +
> +#define GET_PARAM(dst, nest, compat) do { \
> + struct rtattr *rta = tb[(nest) - 1]; \
> + if (rta) \
> + (dst) = RTA_GET_U32(rta); \
> + else if ((compat)) \
> + (dst) = (compat); \
> +} while (0)
An inline function and a comment why this is done would increase
readability.
> +
> + GET_PARAM(q->quantum, TCA_SFQ_QUANTUM, ctl->quantum);
> + GET_PARAM(q->perturb_period, TCA_SFQ_PERTURB,
> + ctl->perturb_period);
> + GET_PARAM(q->hash_divisor, TCA_SFQ_DIVISOR, ctl->divisor);
> + GET_PARAM(q->depth, TCA_SFQ_FLOWS, ctl->flows);
> + GET_PARAM(q->limit, TCA_SFQ_LIMIT, ctl->limit);
> +
> if (q->perturb_period > SFQ_MAX_PERTURB ||
> q->depth > SFQ_MAX_DEPTH)
> - return -EINVAL;
> + goto rtattr_failure;
> }
> q->limit = min_t(u32, q->limit, q->depth - 2);
> q->tail = q->depth;
> @@ -482,6 +488,8 @@ sfq_q_init(struct sfq_sched_data *q, struct rtattr *opt)
> for (i=0; i < q->depth; i++)
> sfq_link(q, i);
> return 0;
> +rtattr_failure:
> + return -EINVAL;
> err_case:
> sfq_q_destroy(q);
> return -ENOBUFS;
> @@ -559,17 +567,26 @@ static int sfq_dump(struct Qdisc *sch, struct sk_buff
> *skb)
> {
> struct sfq_sched_data *q = qdisc_priv(sch);
> unsigned char *b = skb_tail_pointer(skb);
> + struct rtattr *nest;
> struct tc_sfq_qopt opt;
>
> opt.quantum = q->quantum;
> opt.perturb_period = q->perturb_period;
> -
> opt.limit = q->limit;
> opt.divisor = q->hash_divisor;
> opt.flows = q->depth;
>
> + nest = RTA_NEST_COMPAT(skb, TCA_OPTIONS, sizeof(opt), &opt);
> +
> + RTA_PUT_U32(skb, TCA_SFQ_QUANTUM, q->quantum);
> + RTA_PUT_U32(skb, TCA_SFQ_PERTURB, q->perturb_period);
> + RTA_PUT_U32(skb, TCA_SFQ_LIMIT, q->limit);
> + RTA_PUT_U32(skb, TCA_SFQ_DIVISOR, q->hash_divisor);
> + RTA_PUT_U32(skb, TCA_SFQ_FLOWS, q->depth);
> RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
This is wrong, RTA_NEST_COMPAT already dumps the structure.
>
> + RTA_NEST_COMPAT_END(skb, nest);
> +
> return skb->len;
>
> rtattr_failure:
-
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