Re: [PATCH bpf-next v2 4/4] libbpf: add selftests for TC-BPF API

[Andrii Nakryiko]

On Mon, Apr 19, 2021 at 5:18 AM Kumar Kartikeya Dwivedi
<memxor@xxxxxxxxx> wrote:
>
> This adds some basic tests for the low level bpf_tc_cls_* API.
>
> Reviewed-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
> ---
>  .../selftests/bpf/prog_tests/test_tc_bpf.c    | 112 ++++++++++++++++++
>  .../selftests/bpf/progs/test_tc_bpf_kern.c    |  12 ++
>  2 files changed, 124 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/test_tc_bpf.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_tc_bpf_kern.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/test_tc_bpf.c b/tools/testing/selftests/bpf/prog_tests/test_tc_bpf.c
> new file mode 100644
> index 000000000000..945f3a1a72f8
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/test_tc_bpf.c
> @@ -0,0 +1,112 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/bpf.h>
> +#include <linux/err.h>
> +#include <linux/limits.h>
> +#include <bpf/libbpf.h>
> +#include <errno.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <test_progs.h>
> +#include <linux/if_ether.h>
> +
> +#define LO_IFINDEX 1
> +
> +static int test_tc_cls_internal(int fd, __u32 parent_id)
> +{
> +       DECLARE_LIBBPF_OPTS(bpf_tc_cls_opts, opts, .handle = 1, .priority = 10,
> +                           .class_id = TC_H_MAKE(1UL << 16, 1),
> +                           .chain_index = 5);
> +       struct bpf_tc_cls_attach_id id = {};
> +       struct bpf_tc_cls_info info = {};
> +       int ret;
> +
> +       ret = bpf_tc_cls_attach(fd, LO_IFINDEX, parent_id, &opts, &id);
> +       if (CHECK_FAIL(ret < 0))
> +               return ret;
> +
> +       ret = bpf_tc_cls_get_info(fd, LO_IFINDEX, parent_id, NULL, &info);
> +       if (CHECK_FAIL(ret < 0))
> +               goto end;
> +
> +       ret = -1;
> +
> +       if (CHECK_FAIL(info.id.handle != id.handle) ||
> +           CHECK_FAIL(info.id.chain_index != id.chain_index) ||
> +           CHECK_FAIL(info.id.priority != id.priority) ||
> +           CHECK_FAIL(info.id.handle != 1) ||
> +           CHECK_FAIL(info.id.priority != 10) ||
> +           CHECK_FAIL(info.class_id != TC_H_MAKE(1UL << 16, 1)) ||
> +           CHECK_FAIL(info.id.chain_index != 5))
> +               goto end;
> +
> +       ret = bpf_tc_cls_replace(fd, LO_IFINDEX, parent_id, &opts, &id);
> +       if (CHECK_FAIL(ret < 0))
> +               return ret;
> +
> +       if (CHECK_FAIL(info.id.handle != 1) ||
> +           CHECK_FAIL(info.id.priority != 10) ||
> +           CHECK_FAIL(info.class_id != TC_H_MAKE(1UL << 16, 1)))
> +               goto end;
> +
> +       /* Demonstrate changing attributes */
> +       opts.class_id = TC_H_MAKE(1UL << 16, 2);
> +
> +       ret = bpf_tc_cls_change(fd, LO_IFINDEX, parent_id, &opts, &info.id);
> +       if (CHECK_FAIL(ret < 0))
> +               goto end;
> +
> +       ret = bpf_tc_cls_get_info(fd, LO_IFINDEX, parent_id, NULL, &info);
> +       if (CHECK_FAIL(ret < 0))
> +               goto end;
> +
> +       if (CHECK_FAIL(info.class_id != TC_H_MAKE(1UL << 16, 2)))
> +               goto end;
> +       if (CHECK_FAIL((info.bpf_flags & TCA_BPF_FLAG_ACT_DIRECT) != 1))
> +               goto end;
> +
> +end:
> +       ret = bpf_tc_cls_detach(LO_IFINDEX, parent_id, &id);
> +       CHECK_FAIL(ret < 0);
> +       return ret;
> +}
> +
> +void test_test_tc_bpf(void)
> +{
> +       const char *file = "./test_tc_bpf_kern.o";
> +       struct bpf_program *clsp;
> +       struct bpf_object *obj;
> +       int cls_fd, ret;
> +
> +       obj = bpf_object__open(file);
> +       if (CHECK_FAIL(IS_ERR_OR_NULL(obj)))
> +               return;
> +
> +       clsp = bpf_object__find_program_by_title(obj, "classifier");
> +       if (CHECK_FAIL(IS_ERR_OR_NULL(clsp)))
> +               goto end;
> +
> +       ret = bpf_object__load(obj);
> +       if (CHECK_FAIL(ret < 0))
> +               goto end;
> +
> +       cls_fd = bpf_program__fd(clsp);
> +
> +       system("tc qdisc del dev lo clsact");
> +
> +       ret = test_tc_cls_internal(cls_fd, BPF_TC_CLSACT_INGRESS);
> +       if (CHECK_FAIL(ret < 0))
> +               goto end;
> +
> +       if (CHECK_FAIL(system("tc qdisc del dev lo clsact")))
> +               goto end;
> +
> +       ret = test_tc_cls_internal(cls_fd, BPF_TC_CLSACT_EGRESS);
> +       if (CHECK_FAIL(ret < 0))
> +               goto end;
> +
> +       CHECK_FAIL(system("tc qdisc del dev lo clsact"));

please don't use CHECK_FAIL. And prefer ASSERT_xxx over CHECK().

> +
> +end:
> +       bpf_object__close(obj);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_tc_bpf_kern.c b/tools/testing/selftests/bpf/progs/test_tc_bpf_kern.c
> new file mode 100644
> index 000000000000..3dd40e21af8e
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_tc_bpf_kern.c
> @@ -0,0 +1,12 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +
> +// Dummy prog to test TC-BPF API

no C++-style comments, please (except for SPDX header, of course)
> +
> +SEC("classifier")
> +int cls(struct __sk_buff *skb)
> +{
> +       return 0;
> +}
> --
> 2.30.2
>