[NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support

Now that network timestamps use ktime_t infrastructure, we can add a new
SOL_SOCKET sockopt  SO_TIMESTAMPNS.

This command is similar to SO_TIMESTAMP, but permits transmission of
a 'timespec struct' instead of a 'timeval struct' control message.
(nanosecond resolution instead of microsecond)

Control message is labelled SCM_TIMESTAMPNS instead of SCM_TIMESTAMP

A socket cannot mix SO_TIMESTAMP and SO_TIMESTAMPNS : the two modes are
mutually exclusive.

sock_recv_timestamp() became too big to be fully inlined so I added a
__sock_recv_timestamp() helper function.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
CC: linux-arch@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 52 insertions, 3 deletions

diff --git a/net/compat.c b/net/compat.c
index 0e407563ae8..9a0f5f2b90c 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -215,6 +215,7 @@ Efault:
 int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *data)
 {
 	struct compat_timeval ctv;
+	struct compat_timespec cts;
 	struct compat_cmsghdr __user *cm = (struct compat_cmsghdr __user *) kmsg->msg_control;
 	struct compat_cmsghdr cmhdr;
 	int cmlen;
@@ -229,7 +230,14 @@ int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *dat
 		ctv.tv_sec = tv->tv_sec;
 		ctv.tv_usec = tv->tv_usec;
 		data = &ctv;
-		len = sizeof(struct compat_timeval);
+		len = sizeof(ctv);
+	}
+	if (level == SOL_SOCKET && type == SO_TIMESTAMPNS) {
+		struct timespec *ts = (struct timespec *)data;
+		cts.tv_sec = ts->tv_sec;
+		cts.tv_nsec = ts->tv_nsec;
+		data = &cts;
+		len = sizeof(cts);
 	}
 
 	cmlen = CMSG_COMPAT_LEN(len);
diff --git a/net/core/sock.c b/net/core/sock.c
index 792ae39804a..f9e6991d372 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -521,11 +521,18 @@ set_rcvbuf:
 		break;
 
 	case SO_TIMESTAMP:
+	case SO_TIMESTAMPNS:
 		if (valbool)  {
+			if (optname == SO_TIMESTAMP)
+				sock_reset_flag(sk, SOCK_RCVTSTAMPNS);
+			else
+				sock_set_flag(sk, SOCK_RCVTSTAMPNS);
 			sock_set_flag(sk, SOCK_RCVTSTAMP);
 			sock_enable_timestamp(sk);
-		} else
+		} else {
 			sock_reset_flag(sk, SOCK_RCVTSTAMP);
+			sock_reset_flag(sk, SOCK_RCVTSTAMPNS);
+		}
 		break;
 
 	case SO_RCVLOWAT:
@@ -715,7 +722,12 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
 		break;
 
 	case SO_TIMESTAMP:
-		v.val = sock_flag(sk, SOCK_RCVTSTAMP);
+		v.val = sock_flag(sk, SOCK_RCVTSTAMP) &&
+				!sock_flag(sk, SOCK_RCVTSTAMPNS);
+		break;
+
+	case SO_TIMESTAMPNS:
+		v.val = sock_flag(sk, SOCK_RCVTSTAMPNS);
 		break;
 
 	case SO_RCVTIMEO:
diff --git a/net/socket.c b/net/socket.c
index cf18c5eb592..a7bd0df115b 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -585,6 +585,35 @@ int kernel_sendmsg(struct socket *sock, struct msghdr *msg,
 	return result;
 }
 
+/*
+ * called from sock_recv_timestamp() if sock_flag(sk, SOCK_RCVTSTAMP)
+ */
+void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
+	struct sk_buff *skb)
+{
+	ktime_t kt = skb->tstamp;
+
+	if (!sock_flag(sk, SOCK_RCVTSTAMPNS)) {
+		struct timeval tv;
+		/* Race occurred between timestamp enabling and packet
+		   receiving.  Fill in the current time for now. */
+		if (kt.tv64 == 0)
+			kt = ktime_get_real();
+		skb->tstamp = kt;
+		tv = ktime_to_timeval(kt);
+		put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMP, sizeof(tv), &tv);
+	} else {
+		struct timespec ts;
+		/* Race occurred between timestamp enabling and packet
+		   receiving.  Fill in the current time for now. */
+		if (kt.tv64 == 0)
+			kt = ktime_get_real();
+		skb->tstamp = kt;
+		ts = ktime_to_timespec(kt);
+		put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMPNS, sizeof(ts), &ts);
+	}
+}
+
 static inline int __sock_recvmsg(struct kiocb *iocb, struct socket *sock,
 				 struct msghdr *msg, size_t size, int flags)
 {