[NET]: Fix packet timestamping.
I've found the problem in general. It affects any 64-bit
architecture. The problem occurs when you change the system time.
Suppose that when you boot your system clock is forward by a day.
This gets recorded down in skb_tv_base. You then wind the clock back
by a day. From that point onwards the offset will be negative which
essentially overflows the 32-bit variables they're stored in.
In fact, why don't we just store the real time stamp in those 32-bit
variables? After all, we're not going to overflow for quite a while
yet.
When we do overflow, we'll need a better solution of course.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 2741c0c..466c879 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -155,8 +155,6 @@
#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;
@@ -175,7 +173,7 @@
* @prev: Previous buffer in list
* @list: List we are on
* @sk: Socket we are owned by
- * @tstamp: Time we arrived stored as offset to skb_tv_base
+ * @tstamp: Time we arrived
* @dev: Device we arrived on/are leaving by
* @input_dev: Device we arrived on
* @h: Transport layer header
@@ -1255,10 +1253,6 @@
{
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;
- }
}
/**
@@ -1272,8 +1266,8 @@
*/
static inline void skb_set_timestamp(struct sk_buff *skb, const 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;
+ skb->tstamp.off_sec = stamp->tv_sec;
+ skb->tstamp.off_usec = stamp->tv_usec;
}
extern void __net_timestamp(struct sk_buff *skb);