[PATCH v3 net 5/8] selftests: bpf: fix pkt grow tests
From: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Date: 2026-03-23 19:25:24
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest, xdp sockets (af_xdp) · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Shuah Khan, Linus Torvalds, Magnus Karlsson, Maciej Fijalkowski
Skip tail adjust tests in xskxceiver for SKB mode as it is not very friendly for it. multi-buffer case does not work as xdp_rxq_info that is registered for generic XDP does not report ::frag_size. The non-mbuf path copies packet via skb_pp_cow_data() which only accounts for headroom, leaving us with no tailroom and causing underlying XDP prog to drop packets therefore. For multi-buffer test on other modes, change the amount of bytes we use for growth, assume worst-case scenario and take care of headroom and tailroom. Reviewed-by: Björn Töpel <bjorn@kernel.org> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com> --- .../selftests/bpf/prog_tests/test_xsk.c | 25 ++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/test_xsk.c b/tools/testing/selftests/bpf/prog_tests/test_xsk.c
index 7e38ec6e656b..95cbbf425e9a 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_xsk.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_xsk.c@@ -35,6 +35,7 @@ #define XSK_UMEM__INVALID_FRAME_SIZE (MAX_ETH_JUMBO_SIZE + 1) #define XSK_UMEM__LARGE_FRAME_SIZE (3 * 1024) #define XSK_UMEM__MAX_FRAME_SIZE (4 * 1024) +#define XSK_UMEM__PACKET_TAILROOM 320 static const u8 g_mac[ETH_ALEN] = {0x55, 0x44, 0x33, 0x22, 0x11, 0x00};
@@ -2551,16 +2552,34 @@ int testapp_adjust_tail_shrink_mb(struct test_spec *test) int testapp_adjust_tail_grow(struct test_spec *test) { + if (test->mode == TEST_MODE_SKB) + return TEST_SKIP; + /* Grow by 4 bytes for testing purpose */ return testapp_adjust_tail(test, 4, MIN_PKT_SIZE * 2); } int testapp_adjust_tail_grow_mb(struct test_spec *test) { + u32 grow_size; + + if (test->mode == TEST_MODE_SKB) + return TEST_SKIP; + + /* worst case scenario is when underlying setup will work on 3k + * buffers, let us account for it; given that we will use 6k as + * pkt_len, expect that it will be broken down to 2 descs each + * with 3k payload; + * + * 4k is truesize, 3k payload, 256 HR, 320 TR; + */ + grow_size = XSK_UMEM__MAX_FRAME_SIZE - + XSK_UMEM__LARGE_FRAME_SIZE - + XDP_PACKET_HEADROOM - + XSK_UMEM__PACKET_TAILROOM; test->mtu = MAX_ETH_JUMBO_SIZE; - /* Grow by (frag_size - last_frag_Size) - 1 to stay inside the last fragment */ - return testapp_adjust_tail(test, (XSK_UMEM__MAX_FRAME_SIZE / 2) - 1, - XSK_UMEM__LARGE_FRAME_SIZE * 2); + + return testapp_adjust_tail(test, grow_size, XSK_UMEM__LARGE_FRAME_SIZE * 2); } int testapp_tx_queue_consumer(struct test_spec *test)
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2.43.0