netdev - Re: [PATCH bpf-next v2 3/3] bpf/selftests: add test for writable bare tracepoint

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Date:   Tue, 21 Sep 2021 14:53:28 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Hou Tao <houtao1@...wei.com>
Cc:     Alexei Starovoitov <ast@...nel.org>, Yonghong Song <yhs@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH bpf-next v2 3/3] bpf/selftests: add test for writable bare tracepoint

On Fri, Sep 17, 2021 at 6:56 PM Hou Tao <houtao1@...wei.com> wrote:
>
> Add a writable bare tracepoint in bpf_testmod module, and
> trigger its calling when reading /sys/kernel/bpf_testmod
> with a specific buffer length. The reading will return
> the value in writable context if the early return flag
> is enabled in writable context.
>
> Signed-off-by: Hou Tao <houtao1@...wei.com>
> ---
>  .../bpf/bpf_testmod/bpf_testmod-events.h      | 15 ++++++++
>  .../selftests/bpf/bpf_testmod/bpf_testmod.c   | 10 ++++++
>  .../selftests/bpf/bpf_testmod/bpf_testmod.h   |  5 +++
>  .../selftests/bpf/prog_tests/module_attach.c  | 36 +++++++++++++++++++
>  .../selftests/bpf/progs/test_module_attach.c  | 14 ++++++++
>  5 files changed, 80 insertions(+)
>

[...]

> +static int trigger_module_test_writable(int *val)
> +{
> +       int fd, err;
> +       char buf[65];
> +       ssize_t rd;
> +
> +       fd = open("/sys/kernel/bpf_testmod", O_RDONLY);
> +       err = -errno;
> +       if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err))
> +               return err;
> +
> +       rd = read(fd, buf, sizeof(buf) - 1);
> +       err = rd < 0 ? -errno : -ENODATA;
> +       if (CHECK(rd <= 0, "testmod_file_rd_val", "failed: rd %zd errno %d\n",
> +                 rd, errno)) {
> +               close(fd);
> +               return err;
> +       }
> +

please use ASSERT_xxx() consistently

> +       buf[rd] = '\0';
> +       *val = strtol(buf, NULL, 0);
> +       close(fd);
> +
> +       return 0;
> +}
> +

[...]