-static struct sk_buff *codel_dequeue(struct Qdisc *sch,
- struct codel_params *params,
- struct codel_vars *vars,
- struct codel_stats *stats,
- codel_skb_dequeue_t dequeue_func)
-{
- struct sk_buff *skb = dequeue_func(vars, sch);
- codel_time_t now;
- bool drop;
-
- if (!skb) {
- vars->dropping = false;
- return skb;
- }
- now = codel_get_time();
- drop = codel_should_drop(skb, sch, vars, params, stats, now);
- if (vars->dropping) {
- if (!drop) {
- /* sojourn time below target - leave dropping state */
- vars->dropping = false;
- } else if (codel_time_after_eq(now, vars->drop_next)) {
- /* It's time for the next drop. Drop the current
- * packet and dequeue the next. The dequeue might
- * take us out of dropping state.
- * If not, schedule the next drop.
- * A large backlog might result in drop rates so high
- * that the next drop should happen now,
- * hence the while loop.
- */
- while (vars->dropping &&
- codel_time_after_eq(now, vars->drop_next)) {
- vars->count++; /* dont care of possible wrap
- * since there is no more divide
- */
- codel_Newton_step(vars);
- if (params->ecn && INET_ECN_set_ce(skb)) {
- stats->ecn_mark++;
- vars->drop_next =
- codel_control_law(vars->drop_next,
- params->interval,
- vars->rec_inv_sqrt);
- goto end;
- }
- stats->drop_len += qdisc_pkt_len(skb);
- qdisc_drop(skb, sch);
- stats->drop_count++;
- skb = dequeue_func(vars, sch);
- if (!codel_should_drop(skb, sch,
- vars, params, stats, now)) {
- /* leave dropping state */
- vars->dropping = false;
- } else {
- /* and schedule the next drop */
- vars->drop_next =
- codel_control_law(vars->drop_next,
- params->interval,
- vars->rec_inv_sqrt);
- }
- }
- }
- } else if (drop) {
- u32 delta;
-
- if (params->ecn && INET_ECN_set_ce(skb)) {
- stats->ecn_mark++;
- } else {
- stats->drop_len += qdisc_pkt_len(skb);
- qdisc_drop(skb, sch);
- stats->drop_count++;
-
- skb = dequeue_func(vars, sch);
- drop = codel_should_drop(skb, sch, vars, params,
- stats, now);
- }
- vars->dropping = true;
- /* if min went above target close to when we last went below it
- * assume that the drop rate that controlled the queue on the
- * last cycle is a good starting point to control it now.
- */
- delta = vars->count - vars->lastcount;
- if (delta > 1 &&
- codel_time_before(now - vars->drop_next,
- 16 * params->interval)) {
- vars->count = delta;
- /* we dont care if rec_inv_sqrt approximation
- * is not very precise :
- * Next Newton steps will correct it quadratically.
- */
- codel_Newton_step(vars);
- } else {
- vars->count = 1;
- vars->rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT;
- }
- vars->lastcount = vars->count;
- vars->drop_next = codel_control_law(now, params->interval,
- vars->rec_inv_sqrt);
- }
-end:
- if (skb && codel_time_after(vars->ldelay, params->ce_threshold) &&
- INET_ECN_set_ce(skb))
- stats->ce_mark++;
- return skb;
-}