Re: [PATCH net v4 2/2] bpf: selftests: send packet to devmap redirect XDP

From: Martin KaFai Lau
Date: Wed Oct 02 2024 - 17:24:26 EST


On 9/11/24 1:41 AM, Florian Kauer wrote:
@@ -25,14 +28,11 @@ static void test_xdp_with_devmap_helpers(void)
if (!ASSERT_OK_PTR(skel, "test_xdp_with_devmap_helpers__open_and_load"))
return;
- dm_fd = bpf_program__fd(skel->progs.xdp_redir_prog);
- err = bpf_xdp_attach(IFINDEX_LO, dm_fd, XDP_FLAGS_SKB_MODE, NULL);
+ dm_fd_redir = bpf_program__fd(skel->progs.xdp_redir_prog);
+ err = bpf_xdp_attach(IFINDEX_LO, dm_fd_redir, XDP_FLAGS_SKB_MODE, NULL);
if (!ASSERT_OK(err, "Generic attach of program with 8-byte devmap"))
goto out_close;
- err = bpf_xdp_detach(IFINDEX_LO, XDP_FLAGS_SKB_MODE, NULL);
- ASSERT_OK(err, "XDP program detach");
-
dm_fd = bpf_program__fd(skel->progs.xdp_dummy_dm);
map_fd = bpf_map__fd(skel->maps.dm_ports);
err = bpf_prog_get_info_by_fd(dm_fd, &info, &len);
@@ -47,6 +47,23 @@ static void test_xdp_with_devmap_helpers(void)
ASSERT_OK(err, "Read devmap entry");
ASSERT_EQ(info.id, val.bpf_prog.id, "Match program id to devmap entry prog_id");
+ /* send a packet to trigger any potential bugs in there */
+ char data[10] = {};
+ DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
+ .data_in = &data,
+ .data_size_in = 10,
+ .flags = BPF_F_TEST_XDP_LIVE_FRAMES,
+ .repeat = 1,
+ );
+ err = bpf_prog_test_run_opts(dm_fd_redir, &opts);

I am seeing pr_warn on "Driver unsupported XDP return value on prog xdp_redir_prog...". There is an existing bug in xdp_redir_prog(). I fixed it with this:

SEC("xdp")
int xdp_redir_prog(struct xdp_md *ctx)
{
- return bpf_redirect_map(&dm_ports, 1, 0);
+ return bpf_redirect_map(&dm_ports, 0, 0);
}

and also wrapped the above "lo" test in its own netns also.

Applied to the bpf tree. Thanks.