ip: support for TX timestamps on UDP and RAW sockets

Instructions for time stamping outgoing packets are take from the
socket layer and later copied into the new skb.
Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/timestamping.txt

@@ -56,6 +56,8 @@ and including the link layer, the scm_timestamping control message and
 a sock_extended_err control message with ee_errno==ENOMSG and
 ee_origin==SO_EE_ORIGIN_TIMESTAMPING. A socket with such a pending
 bounced packet is ready for reading as far as select() is concerned.
+If the outgoing packet has to be fragmented, then only the first
+fragment is time stamped and returned to the sending socket.
 
 All three values correspond to the same event in time, but were
 generated in different ways. Each of these values may be empty (= all

include/net/ip.h

@@ -55,6 +55,7 @@ struct ipcm_cookie
 	__be32			addr;
 	int			oif;
 	struct ip_options	*opt;
+	union skb_shared_tx	shtx;
 };
 
 #define IPCB(skb) ((struct inet_skb_parm*)((skb)->cb))

net/can/raw.c

@@ -646,6 +646,9 @@ static int raw_sendmsg(struct kiocb *iocb, struct socket *sock,
 		goto put_dev;
 
 	err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
+	if (err < 0)
+		goto free_skb;
+	err = sock_tx_timestamp(msg, sk, skb_tx(skb));
 	if (err < 0)
 		goto free_skb;
 	skb->dev = dev;

net/ipv4/icmp.c

@@ -375,6 +375,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 	inet->tos = ip_hdr(skb)->tos;
 	daddr = ipc.addr = rt->rt_src;
 	ipc.opt = NULL;
+	ipc.shtx.flags = 0;
 	if (icmp_param->replyopts.optlen) {
 		ipc.opt = &icmp_param->replyopts;
 		if (ipc.opt->srr)
@@ -532,6 +533,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 	inet_sk(sk)->tos = tos;
 	ipc.addr = iph->saddr;
 	ipc.opt = &icmp_param.replyopts;
+	ipc.shtx.flags = 0;
 
 	{
 		struct flowi fl = {

net/ipv4/ip_output.c

@@ -935,6 +935,10 @@ alloc_new_skb:
 							   sk->sk_allocation);
 				if (unlikely(skb == NULL))
 					err = -ENOBUFS;
+				else
+					/* only the initial fragment is
+					   time stamped */
+					ipc->shtx.flags = 0;
 			}
 			if (skb == NULL)
 				goto error;
@@ -945,6 +949,7 @@ alloc_new_skb:
 			skb->ip_summed = csummode;
 			skb->csum = 0;
 			skb_reserve(skb, hh_len);
+			*skb_tx(skb) = ipc->shtx;
 
 			/*
 			 *	Find where to start putting bytes.
@@ -1364,6 +1369,7 @@ void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *ar
 
 	daddr = ipc.addr = rt->rt_src;
 	ipc.opt = NULL;
+	ipc.shtx.flags = 0;
 
 	if (replyopts.opt.optlen) {
 		ipc.opt = &replyopts.opt;

net/ipv4/raw.c

@@ -493,6 +493,7 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
 	ipc.addr = inet->saddr;
 	ipc.opt = NULL;
+	ipc.shtx.flags = 0;
 	ipc.oif = sk->sk_bound_dev_if;
 
 	if (msg->msg_controllen) {

net/ipv4/udp.c

@@ -596,6 +596,7 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 		return -EOPNOTSUPP;
 
 	ipc.opt = NULL;
+	ipc.shtx.flags = 0;
 
 	if (up->pending) {
 		/*
@@ -643,6 +644,9 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	ipc.addr = inet->saddr;
 
 	ipc.oif = sk->sk_bound_dev_if;
+	err = sock_tx_timestamp(msg, sk, &ipc.shtx);
+	if (err)
+		return err;
 	if (msg->msg_controllen) {
 		err = ip_cmsg_send(sock_net(sk), msg, &ipc);
 		if (err)