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 <edumazet@google.com>
Cc: Yaogong Wang <wygivan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6c8b6f6..5ad9675 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -20,6 +20,7 @@
#include <linux/time.h>
#include <linux/bug.h>
#include <linux/cache.h>
+#include <linux/rbtree.h>
#include <linux/atomic.h>
#include <asm/types.h>
@@ -440,6 +441,7 @@
* @next: Next buffer in list
* @prev: Previous buffer in list
* @tstamp: Time we arrived/left
+ * @rbnode: RB tree node, alternative to next/prev for netem/tcp
* @sk: Socket we are owned by
* @dev: Device we arrived on/are leaving by
* @cb: Control buffer. Free for use by every layer. Put private vars here
@@ -504,15 +506,19 @@
*/
struct sk_buff {
- /* These two members must be first. */
- struct sk_buff *next;
- struct sk_buff *prev;
-
union {
- ktime_t tstamp;
- struct skb_mstamp skb_mstamp;
- };
+ struct {
+ /* These two members must be first. */
+ struct sk_buff *next;
+ struct sk_buff *prev;
+ union {
+ ktime_t tstamp;
+ struct skb_mstamp skb_mstamp;
+ };
+ };
+ struct rb_node rbnode; /* used in netem & tcp stack */
+ };
struct sock *sk;
struct net_device *dev;
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index b343319..179f1c8 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -139,33 +139,20 @@
/* 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 @@
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++;
}