From 56b174256b6936ec4c1ed8f3407109ac6929d3ca Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 3 Nov 2014 08:19:53 -0800 Subject: net: add rbnode to struct sk_buff Yaogong replaces TCP out of order receive queue by an RB tree. As netem already does a private skb->{next/prev/tstamp} union with a 'struct rb_node', lets do this in a cleaner way. Signed-off-by: Eric Dumazet Cc: Yaogong Wang Signed-off-by: David S. Miller --- net/sched/sch_netem.c | 27 +++++++-------------------- 1 file changed, 7 insertions(+), 20 deletions(-) (limited to 'net/sched/sch_netem.c') diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c index b34331967e02..179f1c8c0d8b 100644 --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -139,33 +139,20 @@ struct netem_sched_data { /* Time stamp put into socket buffer control block * Only valid when skbs are in our internal t(ime)fifo queue. + * + * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp, + * and skb->next & skb->prev are scratch space for a qdisc, + * we save skb->tstamp value in skb->cb[] before destroying it. */ struct netem_skb_cb { psched_time_t time_to_send; ktime_t tstamp_save; }; -/* Because space in skb->cb[] is tight, netem overloads skb->next/prev/tstamp - * to hold a rb_node structure. - * - * If struct sk_buff layout is changed, the following checks will complain. - */ -static struct rb_node *netem_rb_node(struct sk_buff *skb) -{ - BUILD_BUG_ON(offsetof(struct sk_buff, next) != 0); - BUILD_BUG_ON(offsetof(struct sk_buff, prev) != - offsetof(struct sk_buff, next) + sizeof(skb->next)); - BUILD_BUG_ON(offsetof(struct sk_buff, tstamp) != - offsetof(struct sk_buff, prev) + sizeof(skb->prev)); - BUILD_BUG_ON(sizeof(struct rb_node) > sizeof(skb->next) + - sizeof(skb->prev) + - sizeof(skb->tstamp)); - return (struct rb_node *)&skb->next; -} static struct sk_buff *netem_rb_to_skb(struct rb_node *rb) { - return (struct sk_buff *)rb; + return container_of(rb, struct sk_buff, rbnode); } static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb) @@ -403,8 +390,8 @@ static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch) else p = &parent->rb_left; } - rb_link_node(netem_rb_node(nskb), parent, p); - rb_insert_color(netem_rb_node(nskb), &q->t_root); + rb_link_node(&nskb->rbnode, parent, p); + rb_insert_color(&nskb->rbnode, &q->t_root); sch->q.qlen++; } -- cgit v1.2.3