[RFC] af_packet: allow disabling timestamps

[Stephen Hemminger <shemminger@linux-foundation.org>]

Currently, af_packet does not allow disabling timestamps. This patch changes
that but doesn't force global timestamps on.

This shows up in bugzilla as:
	http://bugzilla.kernel.org/show_bug.cgi?id=4809

Patch against net-2.6.24 tree.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>

--- a/net/core/sock.c	2007-09-12 15:08:43.000000000 +0200
+++ b/net/core/sock.c	2007-09-13 12:10:19.000000000 +0200
@@ -259,7 +259,8 @@ static void sock_disable_timestamp(struc
 {
 	if (sock_flag(sk, SOCK_TIMESTAMP)) {
 		sock_reset_flag(sk, SOCK_TIMESTAMP);
-		net_disable_timestamp();
+		if (sk->sk_family != PF_PACKET)
+			net_disable_timestamp();
 	}
 }
 
@@ -1645,7 +1646,8 @@ void sock_enable_timestamp(struct sock *
 {
 	if (!sock_flag(sk, SOCK_TIMESTAMP)) {
 		sock_set_flag(sk, SOCK_TIMESTAMP);
-		net_enable_timestamp();
+		if (sk->sk_family != PF_PACKET)
+			net_enable_timestamp();
 	}
 }
 EXPORT_SYMBOL(sock_enable_timestamp);
--- a/net/packet/af_packet.c	2007-09-12 17:07:00.000000000 +0200
+++ b/net/packet/af_packet.c	2007-09-13 12:09:10.000000000 +0200
@@ -572,7 +572,6 @@ static int tpacket_rcv(struct sk_buff *s
 	unsigned long status = TP_STATUS_LOSING|TP_STATUS_USER;
 	unsigned short macoff, netoff;
 	struct sk_buff *copy_skb = NULL;
-	struct timeval tv;
 
 	if (dev->nd_net != &init_net)
 		goto drop;
@@ -650,12 +649,19 @@ static int tpacket_rcv(struct sk_buff *s
 	h->tp_snaplen = snaplen;
 	h->tp_mac = macoff;
 	h->tp_net = netoff;
-	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;
+
+	if (sock_flag(sk, SOCK_TIMESTAMP)) {
+		struct timeval tv;
+		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;
+	} else {
+		h->tp_sec = 0;
+		h->tp_usec = 0;
+	}
 
 	sll = (struct sockaddr_ll*)((u8*)h + TPACKET_ALIGN(sizeof(*h)));
 	sll->sll_halen = 0;
@@ -1014,6 +1020,7 @@ static int packet_create(struct net *net
 		sock->ops = &packet_ops_spkt;
 
 	sock_init_data(sock, sk);
+	sock_set_flag(sk, SOCK_TIMESTAMP);
 
 	po = pkt_sk(sk);
 	sk->sk_family = PF_PACKET;