Commit:     50f17787e9b0222ce65cc831407c3ba4790db3ff
Parent:     c7261872256f9172eb26438b96725b6f2115e955
Author:     Stephen Hemminger <[EMAIL PROTECTED]>
AuthorDate: Thu Sep 6 13:55:02 2007 +0100
Committer:  David S. Miller <[EMAIL PROTECTED]>
CommitDate: Wed Oct 10 16:48:59 2007 -0700

    [AF_PACKET]: Don't enable global timestamps.
    Andi mentioned he did something like this already, but never submitted
    The dhcp client application uses AF_PACKET with a packet filter to
    receive data. The application doesn't even use timestamps, but because
    the AF_PACKET API has timestamps, they get turned on globally which
    causes an expensive time of day lookup for every packet received on
    any system that uses the standard DHCP client.
    The fix is to not enable the timestamp (but use if if available).
    This causes the time lookup to only occur on those packets that are
    destined for the AF_PACKET socket.  The timestamping occurs after
    packet filtering so all packets dropped by filtering to not cause a
    clock call.
    The one downside of this a a few microseconds additional delay added
    from the normal timestamping location (netif_rx) until the receive
    callback in AF_PACKET. But since the offset is fairly consistent it
    should not upset applications that do want really use timestamps, like
    Signed-off-by: Stephen Hemminger <[EMAIL PROTECTED]>
    Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
 net/packet/af_packet.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 1322d62..9c26dd9 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -640,11 +640,10 @@ static int tpacket_rcv(struct sk_buff *skb, struct 
net_device *dev, struct packe
        h->tp_snaplen = snaplen;
        h->tp_mac = macoff;
        h->tp_net = netoff;
-       if (skb->tstamp.tv64 == 0) {
-               __net_timestamp(skb);
-               sock_enable_timestamp(sk);
-       }
-       tv = ktime_to_timeval(skb->tstamp);
+       if (skb->tstamp.tv64)
+               tv = ktime_to_timeval(skb->tstamp);
+       else
+               do_gettimeofday(&tv);
        h->tp_sec = tv.tv_sec;
        h->tp_usec = tv.tv_usec;
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