net-timestamp: move timestamp flags out of sk_flags

sk_flags is reaching its limit. New timestamping options will not fit.
Move all of them into a new field sk->sk_tsflags.

Added benefit is that this removes boilerplate code to convert between
SOF_TIMESTAMPING_.. and SOCK_TIMESTAMPING_.. in getsockopt/setsockopt.

SOCK_TIMESTAMPING_RX_SOFTWARE is also used to toggle the receive
timestamp logic (netstamp_needed). That can be simplified and this
last key removed, but will leave that for a separate patch.

Signed-off-by: Willem de Bruijn <willemb@google.com>

----

The u16 in sock can be moved into a 16-bit hole below sk_gso_max_segs,
though that scatters tstamp fields throughout the struct.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/socket.c b/net/socket.c
index dc0cc5d..255d9b8 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -613,9 +613,9 @@
 void sock_tx_timestamp(struct sock *sk, __u8 *tx_flags)
 {
 	*tx_flags = 0;
-	if (sock_flag(sk, SOCK_TIMESTAMPING_TX_HARDWARE))
+	if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_HARDWARE)
 		*tx_flags |= SKBTX_HW_TSTAMP;
-	if (sock_flag(sk, SOCK_TIMESTAMPING_TX_SOFTWARE))
+	if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_SOFTWARE)
 		*tx_flags |= SKBTX_SW_TSTAMP;
 	if (sock_flag(sk, SOCK_WIFI_STATUS))
 		*tx_flags |= SKBTX_WIFI_STATUS;
@@ -723,12 +723,12 @@
 	}
 
 	memset(&tss, 0, sizeof(tss));
-	if ((sock_flag(sk, SOCK_TIMESTAMPING_SOFTWARE) ||
+	if ((sk->sk_tsflags & SOF_TIMESTAMPING_SOFTWARE ||
 	     skb_shinfo(skb)->tx_flags & SKBTX_ANY_SW_TSTAMP) &&
 	    ktime_to_timespec_cond(skb->tstamp, tss.ts + 0))
 		empty = 0;
 	if (shhwtstamps &&
-	    sock_flag(sk, SOCK_TIMESTAMPING_RAW_HARDWARE) &&
+	    (sk->sk_tsflags & SOF_TIMESTAMPING_RAW_HARDWARE) &&
 	    ktime_to_timespec_cond(shhwtstamps->hwtstamp, tss.ts + 2))
 		empty = 0;
 	if (!empty)