[PATCH 5.16 0420/1017] selftests, xsk: Fix rx_full stats test

[Greg Kroah-Hartman]

From: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>

[ Upstream commit b4ec6a19231224f6b08dc54ea07da4c4090e8ee3 ]

Fix the rx_full stats test so that it correctly reports pass even when
the fill ring is not full of buffers.

Fixes: 872a1184dbf2 ("selftests: xsk: Put the same buffer only once in the fill ring")
Signed-off-by: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Tested-by: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
Link: https://lore.kernel.org/bpf/20220121123508.12759-1-magnus.karlsson@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 tools/testing/selftests/bpf/xdpxceiver.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/xdpxceiver.c b/tools/testing/selftests/bpf/xdpxceiver.c
index 621342ec30c4..37d4873d9a2e 100644
--- a/tools/testing/selftests/bpf/xdpxceiver.c
+++ b/tools/testing/selftests/bpf/xdpxceiver.c
@@ -902,7 +902,10 @@ static bool rx_stats_are_valid(struct ifobject *ifobject)
 			return true;
 		case STAT_TEST_RX_FULL:
 			xsk_stat = stats.rx_ring_full;
-			expected_stat -= RX_FULL_RXQSIZE;
+			if (ifobject->umem->num_frames < XSK_RING_PROD__DEFAULT_NUM_DESCS)
+				expected_stat = ifobject->umem->num_frames - RX_FULL_RXQSIZE;
+			else
+				expected_stat = XSK_RING_PROD__DEFAULT_NUM_DESCS - RX_FULL_RXQSIZE;
 			break;
 		case STAT_TEST_RX_FILL_EMPTY:
 			xsk_stat = stats.rx_fill_ring_empty_descs;
-- 
2.34.1