[NETEM]: Support time based reordering

Change netem to support packets getting reordered because of variations in
delay. Introduce a special case version of FIFO that queues packets in order
based on the netem delay.

Since netem is classful, those users that don't want jitter based reordering
can just insert a pfifo instead of the default.

This required changes to generic skbuff code to allow finer grain manipulation
of sk_buff_head.  Insertion into the middle and reverse walk.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

1 files changed, 30 insertions, 8 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4286d832166f..fdfb8fe8c38c 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -603,23 +603,23 @@ static inline void skb_queue_head_init(struct sk_buff_head *list)
  */
 
 /**
- *      __skb_queue_head - queue a buffer at the list head
+ *      __skb_queue_after - queue a buffer at the list head
  *      @list: list to use
+ *      @prev: place after this buffer
  *      @newsk: buffer to queue
  *
- *      Queue a buffer at the start of a list. This function takes no locks
+ *      Queue a buffer int the middle of a list. This function takes no locks
  *      and you must therefore hold required locks before calling it.
  *
  *      A buffer cannot be placed on two lists at the same time.
  */
-extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
-static inline void __skb_queue_head(struct sk_buff_head *list,
-                                    struct sk_buff *newsk)
+static inline void __skb_queue_after(struct sk_buff_head *list,
+                                     struct sk_buff *prev,
+                                     struct sk_buff *newsk)
 {
-        struct sk_buff *prev, *next;
-
+        struct sk_buff *next;
         list->qlen++;
-        prev = (struct sk_buff *)list;
+
         next = prev->next;
         newsk->next = next;
         newsk->prev = prev;
@@ -627,6 +627,23 @@ static inline void __skb_queue_head(struct sk_buff_head *list,
 }
 
 /**
+ *      __skb_queue_head - queue a buffer at the list head
+ *      @list: list to use
+ *      @newsk: buffer to queue
+ *
+ *      Queue a buffer at the start of a list. This function takes no locks
+ *      and you must therefore hold required locks before calling it.
+ *
+ *      A buffer cannot be placed on two lists at the same time.
+ */
+extern void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
+static inline void __skb_queue_head(struct sk_buff_head *list,
+                                    struct sk_buff *newsk)
+{
+        __skb_queue_after(list, (struct sk_buff *)list, newsk);
+}
+
+/**
  *      __skb_queue_tail - queue a buffer at the list tail
  *      @list: list to use
  *      @newsk: buffer to queue
@@ -1203,6 +1220,11 @@ static inline void kunmap_skb_frag(void *vaddr)
                      prefetch(skb->next), (skb != (struct sk_buff *)(queue));   \
                      skb = skb->next)
 
+#define skb_queue_reverse_walk(queue, skb) \
+                for (skb = (queue)->prev;                                       \
+                     prefetch(skb->prev), (skb != (struct sk_buff *)(queue));   \
+                     skb = skb->prev)
+
 
 extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
                                          int noblock, int *err);