[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>

1 files changed, 29 insertions, 0 deletions

diff --git a/net/socket.c b/net/socket.c
index cf18c5eb592e..a7bd0df115b2 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)
 {