selftests: xsk: Allow for invalid packets

Allow for invalid packets to be sent. These are verified by the Rx
thread not to be received. Or put in another way, if they are
received, the test will fail. This feature will be used to eliminate
an if statement for a stats test and will also be used by other tests
in later patches. The previous code could only deal with valid
packets.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/20210907071928.9750-16-magnus.karlsson@gmail.com

tools/testing/selftests/bpf/xdpxceiver.c

@@ -473,6 +473,11 @@ static struct pkt_stream *pkt_stream_generate(struct xsk_umem_info *umem, u32 nb
 		pkt_stream->pkts[i].addr = (i % umem->num_frames) * umem->frame_size;
 		pkt_stream->pkts[i].len = pkt_len;
 		pkt_stream->pkts[i].payload = i;
+
+		if (pkt_len > umem->frame_size)
+			pkt_stream->pkts[i].valid = false;
+		else
+			pkt_stream->pkts[i].valid = true;
 	}
 
 	return pkt_stream;
@@ -658,7 +663,7 @@ static void receive_pkts(struct pkt_stream *pkt_stream, struct xsk_socket_info *
 static u32 __send_pkts(struct ifobject *ifobject, u32 pkt_nb)
 {
 	struct xsk_socket_info *xsk = ifobject->xsk;
-	u32 i, idx;
+	u32 i, idx, valid_pkts = 0;
 
 	while (xsk_ring_prod__reserve(&xsk->tx, BATCH_SIZE, &idx) < BATCH_SIZE)
 		complete_pkts(xsk, BATCH_SIZE);
@@ -673,14 +678,13 @@ static u32 __send_pkts(struct ifobject *ifobject, u32 pkt_nb)
 		tx_desc->addr = pkt->addr;
 		tx_desc->len = pkt->len;
 		pkt_nb++;
+		if (pkt->valid)
+			valid_pkts++;
 	}
 
 	xsk_ring_prod__submit(&xsk->tx, i);
-	if (stat_test_type != STAT_TEST_TX_INVALID)
-		xsk->outstanding_tx += i;
-	else if (xsk_ring_prod__needs_wakeup(&xsk->tx))
-		kick_tx(xsk);
-	complete_pkts(xsk, i);
+	xsk->outstanding_tx += valid_pkts;
+	complete_pkts(xsk, BATCH_SIZE);
 
 	return i;
 }

tools/testing/selftests/bpf/xdpxceiver.h

@@ -96,6 +96,7 @@ struct pkt {
 	u64 addr;
 	u32 len;
 	u32 payload;
+	bool valid;
 };
 
 struct pkt_stream {