Bluetooth: increment TX timestamping tskey always for stream sockets

Documentation/networking/timestamping.rst implies TX timestamping OPT_ID
tskey increments for each sendmsg.  In practice: TCP socket increments
it for all sendmsg, timestamping on or off, but UDP only when
timestamping is on. The user-visible counter resets when OPT_ID is
turned on, so difference can be seen only if timestamping is enabled for
some packets only (eg. via SO_TIMESTAMPING CMSG).

Fix BT sockets to work in the same way: stream sockets increment tskey
for all sendmsg (seqpacket already increment for timestamped only).

Fixes: 134f4b3 ("Bluetooth: add support for skb TX SND/COMPLETION timestamping")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

net/bluetooth/hci_conn.c

@@ -3072,6 +3072,7 @@ void hci_setup_tx_timestamp(struct sk_buff *skb, size_t key_offset,
 			    const struct sockcm_cookie *sockc)
 {
 	struct sock *sk = skb ? skb->sk : NULL;
+	int key;
 
 	/* This shall be called on a single skb of those generated by user
 	 * sendmsg(), and only when the sendmsg() does not return error to
@@ -3087,13 +3088,16 @@ void hci_setup_tx_timestamp(struct sk_buff *skb, size_t key_offset,
 
 	sock_tx_timestamp(sk, sockc, &skb_shinfo(skb)->tx_flags);
 
+	if (sk->sk_type == SOCK_STREAM)
+		key = atomic_add_return(key_offset, &sk->sk_tskey);
+
 	if (sockc->tsflags & SOF_TIMESTAMPING_OPT_ID &&
 	    sockc->tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK) {
 		if (sockc->tsflags & SOCKCM_FLAG_TS_OPT_ID) {
 			skb_shinfo(skb)->tskey = sockc->ts_opt_id;
 		} else {
-			int key = atomic_add_return(key_offset, &sk->sk_tskey);
-
+			if (sk->sk_type != SOCK_STREAM)
+				key = atomic_inc_return(&sk->sk_tskey);
 			skb_shinfo(skb)->tskey = key - 1;
 		}
 	}