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[NET]: Fix packet timestamping.

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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>
This commit is contained in:
Herbert Xu
2005-10-03 13:57:23 -07:00
committed by David S. Miller
parent ddea7be0ec
commit 325ed82393
8 changed files with 15 additions and 26 deletions
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4
net/packet/af_packet.c
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@ -654,8 +654,8 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packe
__net_timestamp(skb);
sock_enable_timestamp(sk);
}
h->tp_sec = skb_tv_base.tv_sec + skb->tstamp.off_sec;
h->tp_usec = skb_tv_base.tv_usec + skb->tstamp.off_usec;
h->tp_sec = skb->tstamp.off_sec;
h->tp_usec = skb->tstamp.off_usec;
sll = (struct sockaddr_ll*)((u8*)h + TPACKET_ALIGN(sizeof(*h)));
sll->sll_halen = 0;