net: socket: move ktime2ts to ktime header api

Currently, ktime2ts is a small helper function that is only used in
net/socket.c. Move this helper into the ktime API as a small inline
function, so that i) it's maintained together with ktime routines,
and ii) also other files can make use of it. The function is named
ktime_to_timespec_cond() and placed into the generic part of ktime,
since we internally make use of ktime_to_timespec(). ktime_to_timespec()
itself does not check the ktime variable for zero, hence, we name
this function ktime_to_timespec_cond() for only a conditional
conversion, and adapt its users to it.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/socket.c b/net/socket.c
index 36883fe..280283f 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -681,16 +681,6 @@
 }
 EXPORT_SYMBOL(kernel_sendmsg);
 
-static int ktime2ts(ktime_t kt, struct timespec *ts)
-{
-	if (kt.tv64) {
-		*ts = ktime_to_timespec(kt);
-		return 1;
-	} else {
-		return 0;
-	}
-}
-
 /*
  * called from sock_recv_timestamp() if sock_flag(sk, SOCK_RCVTSTAMP)
  */
@@ -723,17 +713,15 @@
 
 
 	memset(ts, 0, sizeof(ts));
-	if (skb->tstamp.tv64 &&
-	    sock_flag(sk, SOCK_TIMESTAMPING_SOFTWARE)) {
-		skb_get_timestampns(skb, ts + 0);
+	if (sock_flag(sk, SOCK_TIMESTAMPING_SOFTWARE) &&
+	    ktime_to_timespec_cond(skb->tstamp, ts + 0))
 		empty = 0;
-	}
 	if (shhwtstamps) {
 		if (sock_flag(sk, SOCK_TIMESTAMPING_SYS_HARDWARE) &&
-		    ktime2ts(shhwtstamps->syststamp, ts + 1))
+		    ktime_to_timespec_cond(shhwtstamps->syststamp, ts + 1))
 			empty = 0;
 		if (sock_flag(sk, SOCK_TIMESTAMPING_RAW_HARDWARE) &&
-		    ktime2ts(shhwtstamps->hwtstamp, ts + 2))
+		    ktime_to_timespec_cond(shhwtstamps->hwtstamp, ts + 2))
 			empty = 0;
 	}
 	if (!empty)