selftests/xsk: Add packet stream replacement function

Add pkt_stream_replace_ifobject function to replace the packet stream for
a given ifobject.

Enable separate TX and RX packet replacement, allowing RX side packet
length adjustments using bpf_xdp_adjust_tail() in the upcoming patch.
Currently, pkt_stream_replace() works on both TX and RX packet streams,
and this new function provides the ability to modify one of them.

Signed-off-by: Tushar Vyavahare <[email protected]>

Author: tvyavaha

tools/testing/selftests/bpf/xskxceiver.c

@@ -757,14 +757,15 @@ static struct pkt_stream *pkt_stream_clone(struct pkt_stream *pkt_stream)
 	return pkt_stream_generate(pkt_stream->nb_pkts, pkt_stream->pkts[0].len);
 }
 
-static void pkt_stream_replace(struct test_spec *test, u32 nb_pkts, u32 pkt_len)
+static void pkt_stream_replace_ifobject(struct ifobject *ifobj, u32 nb_pkts, u32 pkt_len)
 {
-	struct pkt_stream *pkt_stream;
+	ifobj->xsk->pkt_stream = pkt_stream_generate(nb_pkts, pkt_len);
+}
 
-	pkt_stream = pkt_stream_generate(nb_pkts, pkt_len);
-	test->ifobj_tx->xsk->pkt_stream = pkt_stream;
-	pkt_stream = pkt_stream_generate(nb_pkts, pkt_len);
-	test->ifobj_rx->xsk->pkt_stream = pkt_stream;
+static void pkt_stream_replace(struct test_spec *test, u32 nb_pkts, u32 pkt_len)
+{
+	pkt_stream_replace_ifobject(test->ifobj_tx, nb_pkts, pkt_len);
+	pkt_stream_replace_ifobject(test->ifobj_rx, nb_pkts, pkt_len);
 }
 
 static void __pkt_stream_replace_half(struct ifobject *ifobj, u32 pkt_len,