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authorFlorian Westphal <fw@strlen.de>2016-09-18 00:57:34 +0200
committerDavid S. Miller <davem@davemloft.net>2016-09-19 01:47:18 -0400
commit48da34b7a74201f15315cb1fc40bb9a7bd2b4940 (patch)
tree123595224534ee49f1175b6ef8371728b6d31538 /net/sched/sch_netem.c
parented760cb8aae7c2b84c193d4a7637b0c9e752f07e (diff)
downloadlinux-48da34b7a74201f15315cb1fc40bb9a7bd2b4940.tar.bz2
sched: add and use qdisc_skb_head helpers
This change replaces sk_buff_head struct in Qdiscs with new qdisc_skb_head. Its similar to the skb_buff_head api, but does not use skb->prev pointers. Qdiscs will commonly enqueue at the tail of a list and dequeue at head. While skb_buff_head works fine for this, enqueue/dequeue needs to also adjust the prev pointer of next element. The ->prev pointer is not required for qdiscs so we can just leave it undefined and avoid one cacheline write access for en/dequeue. Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/sch_netem.c')
-rw-r--r--net/sched/sch_netem.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 0a964b35f8c7..9f7b380cf0a3 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -413,6 +413,16 @@ static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch,
return segs;
}
+static void netem_enqueue_skb_head(struct qdisc_skb_head *qh, struct sk_buff *skb)
+{
+ skb->next = qh->head;
+
+ if (!qh->head)
+ qh->tail = skb;
+ qh->head = skb;
+ qh->qlen++;
+}
+
/*
* Insert one skb into qdisc.
* Note: parent depends on return value to account for queue length.
@@ -523,7 +533,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff *last;
if (sch->q.qlen)
- last = skb_peek_tail(&sch->q);
+ last = sch->q.tail;
else
last = netem_rb_to_skb(rb_last(&q->t_root));
if (last) {
@@ -552,7 +562,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
cb->time_to_send = psched_get_time();
q->counter = 0;
- __skb_queue_head(&sch->q, skb);
+ netem_enqueue_skb_head(&sch->q, skb);
sch->qstats.requeues++;
}