packet: enable hardware tx timestamping on tpacket ring

Currently, we only have software timestamping for the TX ring buffer
path, but this limitation stems rather from the implementation. By
just reusing tpacket_get_timestamp(), we can also allow hardware
timestamping just as in the RX path.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/packet/af_packet.c

@@ -339,14 +339,33 @@ static int __packet_get_status(struct packet_sock *po, void *frame)
 	}
 }
 
+static bool tpacket_get_timestamp(struct sk_buff *skb, struct timespec *ts,
+				  unsigned int flags)
+{
+	struct skb_shared_hwtstamps *shhwtstamps = skb_hwtstamps(skb);
+
+	if (shhwtstamps) {
+		if ((flags & SOF_TIMESTAMPING_SYS_HARDWARE) &&
+		    ktime_to_timespec_cond(shhwtstamps->syststamp, ts))
+			return true;
+		if ((flags & SOF_TIMESTAMPING_RAW_HARDWARE) &&
+		    ktime_to_timespec_cond(shhwtstamps->hwtstamp, ts))
+			return true;
+	}
+
+	if (ktime_to_timespec_cond(skb->tstamp, ts))
+		return true;
+
+	return false;
+}
+
 static void __packet_set_timestamp(struct packet_sock *po, void *frame,
-				   ktime_t tstamp)
+				   struct sk_buff *skb)
 {
 	union tpacket_uhdr h;
 	struct timespec ts;
 
-	if (!ktime_to_timespec_cond(tstamp, &ts) ||
-	    !sock_flag(&po->sk, SOCK_TIMESTAMPING_SOFTWARE))
+	if (!tpacket_get_timestamp(skb, &ts, po->tp_tstamp))
 		return;
 
 	h.raw = frame;
@@ -1688,26 +1707,6 @@ drop:
 	return 0;
 }
 
-static void tpacket_get_timestamp(struct sk_buff *skb, struct timespec *ts,
-				  unsigned int flags)
-{
-	struct skb_shared_hwtstamps *shhwtstamps = skb_hwtstamps(skb);
-
-	if (shhwtstamps) {
-		if ((flags & SOF_TIMESTAMPING_SYS_HARDWARE) &&
-		    ktime_to_timespec_cond(shhwtstamps->syststamp, ts))
-			return;
-		if ((flags & SOF_TIMESTAMPING_RAW_HARDWARE) &&
-		    ktime_to_timespec_cond(shhwtstamps->hwtstamp, ts))
-			return;
-	}
-
-	if (ktime_to_timespec_cond(skb->tstamp, ts))
-		return;
-
-	getnstimeofday(ts);
-}
-
 static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 		       struct packet_type *pt, struct net_device *orig_dev)
 {
@@ -1804,7 +1803,8 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 	spin_unlock(&sk->sk_receive_queue.lock);
 
 	skb_copy_bits(skb, 0, h.raw + macoff, snaplen);
-	tpacket_get_timestamp(skb, &ts, po->tp_tstamp);
+	if (!tpacket_get_timestamp(skb, &ts, po->tp_tstamp))
+		getnstimeofday(&ts);
 
 	switch (po->tp_version) {
 	case TPACKET_V1:
@@ -1908,7 +1908,7 @@ static void tpacket_destruct_skb(struct sk_buff *skb)
 		ph = skb_shinfo(skb)->destructor_arg;
 		BUG_ON(atomic_read(&po->tx_ring.pending) == 0);
 		atomic_dec(&po->tx_ring.pending);
-		__packet_set_timestamp(po, ph, skb->tstamp);
+		__packet_set_timestamp(po, ph, skb);
 		__packet_set_status(po, ph, TP_STATUS_AVAILABLE);
 	}