net_sched: TCQ_F_CAN_BYPASS generalization
Now qdisc stab is handled before TCQ_F_CAN_BYPASS test in
__dev_xmit_skb(), we can generalize TCQ_F_CAN_BYPASS to other qdiscs
than pfifo_fast : pfifo, bfifo, pfifo_head_drop and sfq
SFQ is special because it can have external classifiers, and in these
cases, we cannot bypass queue discipline (packet could be dropped by
classifier) without admin asking it, or further changes.
Its worth doing this, especially for SFQ, avoiding dirtying memory in
case no packets are already waiting in queue.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_fifo.c b/net/sched/sch_fifo.c
index b3075f8..f7290d2 100644
--- a/net/sched/sch_fifo.c
+++ b/net/sched/sch_fifo.c
@@ -64,11 +64,13 @@
static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
{
struct fifo_sched_data *q = qdisc_priv(sch);
+ bool bypass;
+ bool is_bfifo = sch->ops == &bfifo_qdisc_ops;
if (opt == NULL) {
u32 limit = qdisc_dev(sch)->tx_queue_len ? : 1;
- if (sch->ops == &bfifo_qdisc_ops)
+ if (is_bfifo)
limit *= psched_mtu(qdisc_dev(sch));
q->limit = limit;
@@ -81,6 +83,15 @@
q->limit = ctl->limit;
}
+ if (is_bfifo)
+ bypass = q->limit >= psched_mtu(qdisc_dev(sch));
+ else
+ bypass = q->limit >= 1;
+
+ if (bypass)
+ sch->flags |= TCQ_F_CAN_BYPASS;
+ else
+ sch->flags &= ~TCQ_F_CAN_BYPASS;
return 0;
}