On Tue, Jun 16, 2026 at 05:31:03PM +0800, Sun Jian wrote:
> prog_run_opts already verifies that BPF_PROG_TEST_RUN returns -ENOSPC
> for a short data_out buffer while still reporting the full output size
> through data_size_out.
>
> Add the same coverage for non-linear test_run output. Use pass-through
> TC and XDP programs with a 9000-byte packet, a 64-byte linear data area,
> and a 100-byte data_out buffer. The expected output spans both the linear
> data and the first fragment.
>
> Verify that test_run returns -ENOSPC, reports the full packet length
> through data_size_out, and copies the packet prefix into data_out for
> both non-linear skb and XDP frags paths.
>
> Signed-off-by: Sun Jian <[email protected]>
> ---
> .../selftests/bpf/prog_tests/prog_run_opts.c | 72 +++++++++++++++++++
> .../selftests/bpf/progs/test_pkt_access.c | 12 ++++
> 2 files changed, 84 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/prog_run_opts.c
> b/tools/testing/selftests/bpf/prog_tests/prog_run_opts.c
> index 01f1d1b6715a..71af1ff02023 100644
> --- a/tools/testing/selftests/bpf/prog_tests/prog_run_opts.c
> +++ b/tools/testing/selftests/bpf/prog_tests/prog_run_opts.c
> @@ -4,6 +4,10 @@
>
> #include "test_pkt_access.skel.h"
>
> +#define NONLINEAR_PKT_LEN 9000
> +#define NONLINEAR_LINEAR_DATA_LEN 64
> +#define SHORT_OUT_LEN 100
> +
> static const __u32 duration;
>
> static void check_run_cnt(int prog_fd, __u64 run_cnt)
> @@ -20,6 +24,71 @@ static void check_run_cnt(int prog_fd, __u64 run_cnt)
> "incorrect number of repetitions, want %llu have %llu\n",
> run_cnt, info.run_cnt);
> }
>
> +static void init_pkt(__u8 *pkt, size_t len)
> +{
> + size_t i;
> +
> + for (i = 0; i < len; i++)
> + pkt[i] = i & 0xff;
> +}
> +
> +static void test_skb_nonlinear_data_out_partial(struct test_pkt_access *skel)
> +{
> + LIBBPF_OPTS(bpf_test_run_opts, topts);
> + __u8 pkt[NONLINEAR_PKT_LEN];
> + __u8 out[SHORT_OUT_LEN];
> + struct __sk_buff skb = {};
> + int prog_fd, err;
> +
> + init_pkt(pkt, sizeof(pkt));
Can't we reuse pkt_v4 by reducing the linear area to ETH_HLEN?
> + memset(out, 0xa5, sizeof(out));
Why is this needed?
> +
> + skb.data_end = NONLINEAR_LINEAR_DATA_LEN;
> +
> + topts.data_in = pkt;
> + topts.data_size_in = sizeof(pkt);
> + topts.data_out = out;
> + topts.data_size_out = sizeof(out);
> + topts.ctx_in = &skb;
> + topts.ctx_size_in = sizeof(skb);
> +
> + prog_fd = bpf_program__fd(skel->progs.tc_pass_prog);
> + err = bpf_prog_test_run_opts(prog_fd, &topts);
> +
> + ASSERT_EQ(err, -ENOSPC, "skb_nonlinear_partial_err");
> + ASSERT_EQ(topts.data_size_out, sizeof(pkt),
> "skb_nonlinear_partial_data_size_out");
> + ASSERT_OK(memcmp(out, pkt, sizeof(out)),
> "skb_nonlinear_partial_data_out");
> +}
> +
> +static void test_xdp_nonlinear_data_out_partial(struct test_pkt_access *skel)
> +{
> + LIBBPF_OPTS(bpf_test_run_opts, topts);
> + __u8 pkt[NONLINEAR_PKT_LEN];
> + __u8 out[SHORT_OUT_LEN];
> + struct xdp_md ctx = {};
> + int prog_fd, err;
> +
> + init_pkt(pkt, sizeof(pkt));
> + memset(out, 0xa5, sizeof(out));
> +
> + ctx.data = 0;
> + ctx.data_end = NONLINEAR_LINEAR_DATA_LEN;
> +
> + topts.data_in = pkt;
> + topts.data_size_in = sizeof(pkt);
> + topts.data_out = out;
> + topts.data_size_out = sizeof(out);
> + topts.ctx_in = &ctx;
> + topts.ctx_size_in = sizeof(ctx);
> +
> + prog_fd = bpf_program__fd(skel->progs.xdp_frags_pass_prog);
> + err = bpf_prog_test_run_opts(prog_fd, &topts);
> +
> + ASSERT_EQ(err, -ENOSPC, "xdp_nonlinear_partial_err");
> + ASSERT_EQ(topts.data_size_out, sizeof(pkt),
> "xdp_nonlinear_partial_data_size_out");
> + ASSERT_OK(memcmp(out, pkt, sizeof(out)),
> "xdp_nonlinear_partial_data_out");
> +}
> +
> void test_prog_run_opts(void)
> {
> struct test_pkt_access *skel;
> @@ -69,6 +138,9 @@ void test_prog_run_opts(void)
> run_cnt += topts.repeat;
> check_run_cnt(prog_fd, run_cnt);
>
> + test_skb_nonlinear_data_out_partial(skel);
> + test_xdp_nonlinear_data_out_partial(skel);
> +
> cleanup:
> if (skel)
> test_pkt_access__destroy(skel);
> diff --git a/tools/testing/selftests/bpf/progs/test_pkt_access.c
> b/tools/testing/selftests/bpf/progs/test_pkt_access.c
> index bce7173152c6..cd284401eebd 100644
> --- a/tools/testing/selftests/bpf/progs/test_pkt_access.c
> +++ b/tools/testing/selftests/bpf/progs/test_pkt_access.c
> @@ -150,3 +150,15 @@ int test_pkt_access(struct __sk_buff *skb)
>
> return TC_ACT_UNSPEC;
> }
> +
> +SEC("tc")
> +int tc_pass_prog(struct __sk_buff *skb)
> +{
> + return TC_ACT_OK;
> +}
Once we're reusing pkt_v4, maybe we can also reuse the existing BPF
program?
> +
> +SEC("xdp.frags")
> +int xdp_frags_pass_prog(struct xdp_md *ctx)
> +{
> + return XDP_PASS;
> +}
> --
> 2.43.0
>
