[NET]: Store skb->timestamp as offset to a base timestamp

Reduces skb size by 8 bytes on 64-bit.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 45 insertions, 2 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 60b32151f7..32635c401d 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -155,13 +155,20 @@ struct skb_shared_info {
 #define SKB_DATAREF_SHIFT 16
 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
 
+extern struct timeval skb_tv_base;
+
+struct skb_timeval {
+        u32     off_sec;
+        u32     off_usec;
+};
+
 /** 
  *      struct sk_buff - socket buffer
  *      @next: Next buffer in list
  *      @prev: Previous buffer in list
  *      @list: List we are on
  *      @sk: Socket we are owned by
- *      @stamp: Time we arrived
+ *      @tstamp: Time we arrived stored as offset to skb_tv_base
  *      @dev: Device we arrived on/are leaving by
  *      @input_dev: Device we arrived on
  *      @h: Transport layer header
@@ -202,7 +209,7 @@ struct sk_buff {
         struct sk_buff          *prev;
 
         struct sock             *sk;
-        struct timeval          stamp;
+        struct skb_timeval      tstamp;
         struct net_device       *dev;
         struct net_device       *input_dev;
 
@@ -1213,6 +1220,42 @@ static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
 extern void skb_init(void);
 extern void skb_add_mtu(int mtu);
 
+/**
+ *      skb_get_timestamp - get timestamp from a skb
+ *      @skb: skb to get stamp from
+ *      @stamp: pointer to struct timeval to store stamp in
+ *
+ *      Timestamps are stored in the skb as offsets to a base timestamp.
+ *      This function converts the offset back to a struct timeval and stores
+ *      it in stamp.
+ */
+static inline void skb_get_timestamp(struct sk_buff *skb, struct timeval *stamp)
+{
+        stamp->tv_sec  = skb->tstamp.off_sec;
+        stamp->tv_usec = skb->tstamp.off_usec;
+        if (skb->tstamp.off_sec) {
+                stamp->tv_sec  += skb_tv_base.tv_sec;
+                stamp->tv_usec += skb_tv_base.tv_usec;
+        }
+}
+
+/**
+ *      skb_set_timestamp - set timestamp of a skb
+ *      @skb: skb to set stamp of
+ *      @stamp: pointer to struct timeval to get stamp from
+ *
+ *      Timestamps are stored in the skb as offsets to a base timestamp.
+ *      This function converts a struct timeval to an offset and stores
+ *      it in the skb.
+ */
+static inline void skb_set_timestamp(struct sk_buff *skb, struct timeval *stamp)
+{
+        skb->tstamp.off_sec  = stamp->tv_sec - skb_tv_base.tv_sec;
+        skb->tstamp.off_usec = stamp->tv_usec - skb_tv_base.tv_usec;
+}
+
+extern void __net_timestamp(struct sk_buff *skb);
+
 #ifdef CONFIG_NETFILTER
 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
 {