y2038: socket: use __kernel_old_timespec instead of timespec

The 'timespec' type definition and helpers like ktime_to_timespec()
or timespec64_to_timespec() should no longer be used in the kernel so
we can remove them and avoid introducing y2038 issues in new code.

Change the socket code that needs to pass a timespec to user space for
backward compatibility to use __kernel_old_timespec instead.  This type
has the same layout but with a clearer defined name.

Slightly reformat tcp_recv_timestamp() for consistency after the removal
of timespec64_to_timespec().
Acked-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

include/linux/skbuff.h

@@ -3656,9 +3656,12 @@ static inline void skb_get_new_timestamp(const struct sk_buff *skb,
 }
 
 static inline void skb_get_timestampns(const struct sk_buff *skb,
-				       struct timespec *stamp)
+				       struct __kernel_old_timespec *stamp)
 {
-	*stamp = ktime_to_timespec(skb->tstamp);
+	struct timespec64 ts = ktime_to_timespec64(skb->tstamp);
+
+	stamp->tv_sec = ts.tv_sec;
+	stamp->tv_nsec = ts.tv_nsec;
 }
 
 static inline void skb_get_new_timestampns(const struct sk_buff *skb,

net/compat.c

@@ -232,7 +232,7 @@ int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *dat
 		    (type == SO_TIMESTAMPNS_OLD || type == SO_TIMESTAMPING_OLD)) {
 			int count = type == SO_TIMESTAMPNS_OLD ? 1 : 3;
 			int i;
-			struct timespec *ts = (struct timespec *)data;
+			struct __kernel_old_timespec *ts = data;
 			for (i = 0; i < count; i++) {
 				cts[i].tv_sec = ts[i].tv_sec;
 				cts[i].tv_nsec = ts[i].tv_nsec;

net/ipv4/tcp.c

@@ -1864,29 +1864,33 @@ static void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,
 		if (sock_flag(sk, SOCK_RCVTSTAMP)) {
 			if (sock_flag(sk, SOCK_RCVTSTAMPNS)) {
 				if (new_tstamp) {
-					struct __kernel_timespec kts = {tss->ts[0].tv_sec, tss->ts[0].tv_nsec};
-
+					struct __kernel_timespec kts = {
+						.tv_sec = tss->ts[0].tv_sec,
+						.tv_nsec = tss->ts[0].tv_nsec,
+					};
 					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPNS_NEW,
 						 sizeof(kts), &kts);
 				} else {
-					struct timespec ts_old = timespec64_to_timespec(tss->ts[0]);
-
+					struct __kernel_old_timespec ts_old = {
+						.tv_sec = tss->ts[0].tv_sec,
+						.tv_nsec = tss->ts[0].tv_nsec,
+					};
 					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPNS_OLD,
 						 sizeof(ts_old), &ts_old);
 				}
 			} else {
 				if (new_tstamp) {
-					struct __kernel_sock_timeval stv;
-
-					stv.tv_sec = tss->ts[0].tv_sec;
-					stv.tv_usec = tss->ts[0].tv_nsec / 1000;
+					struct __kernel_sock_timeval stv = {
+						.tv_sec = tss->ts[0].tv_sec,
+						.tv_usec = tss->ts[0].tv_nsec / 1000,
+					};
 					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP_NEW,
 						 sizeof(stv), &stv);
 				} else {
-					struct __kernel_old_timeval tv;
-
-					tv.tv_sec = tss->ts[0].tv_sec;
-					tv.tv_usec = tss->ts[0].tv_nsec / 1000;
+					struct __kernel_old_timeval tv = {
+						.tv_sec = tss->ts[0].tv_sec,
+						.tv_usec = tss->ts[0].tv_nsec / 1000,
+					};
 					put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP_OLD,
 						 sizeof(tv), &tv);
 				}

net/socket.c

@@ -793,7 +793,7 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
 				put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPNS_NEW,
 					 sizeof(ts), &ts);
 			} else {
-				struct timespec ts;
+				struct __kernel_old_timespec ts;
 
 				skb_get_timestampns(skb, &ts);
 				put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPNS_OLD,