linux-kernel - Re: [RESEND PATCH bpf-next v3 2/2] selftests/bpf: Add testcase for xdp attaching failure tracepoint

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Date:   Thu, 27 Jul 2023 09:57:25 +0800
From:   Leon Hwang <hffilwlqm@...il.com>
To:     Martin KaFai Lau <martin.lau@...ux.dev>
Cc:     ast@...nel.org, daniel@...earbox.net, john.fastabend@...il.com,
        andrii@...nel.org, song@...nel.org, yhs@...com, kpsingh@...nel.org,
        sdf@...gle.com, haoluo@...gle.com, jolsa@...nel.org,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, hawk@...nel.org, tangyeechou@...il.com,
        kernel-patches-bot@...com, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [RESEND PATCH bpf-next v3 2/2] selftests/bpf: Add testcase for
 xdp attaching failure tracepoint



On 27/7/23 05:52, Martin KaFai Lau wrote:
> On 7/20/23 8:52 AM, Leon Hwang wrote:
>> Add a test case for the tracepoint of xdp attaching failure by bpf
>> tracepoint when attach XDP to a device with invalid flags option.
>>
>> The bpf tracepoint retrieves error message from the tracepoint, and
>> then put the error message to a perf buffer. The testing code receives
>> error message from perf buffer, and then ASSERT "Invalid XDP flags for
>> BPF link attachment".
>>
>> Signed-off-by: Leon Hwang <hffilwlqm@...il.com>
>> ---
>>   .../selftests/bpf/prog_tests/xdp_attach.c     | 65 +++++++++++++++++++
>>   .../bpf/progs/test_xdp_attach_fail.c          | 52 +++++++++++++++
>>   2 files changed, 117 insertions(+)
>>   create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c
>>
>> diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_attach.c b/tools/testing/selftests/bpf/prog_tests/xdp_attach.c
>> index fa3cac5488f5d..99f8d03f3c8bd 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/xdp_attach.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/xdp_attach.c
>> @@ -1,5 +1,6 @@
>>   // SPDX-License-Identifier: GPL-2.0
>>   #include <test_progs.h>
>> +#include "test_xdp_attach_fail.skel.h"
>>     #define IFINDEX_LO 1
>>   #define XDP_FLAGS_REPLACE        (1U << 4)
>> @@ -85,10 +86,74 @@ static void test_xdp_attach(const char *file)
>>       bpf_object__close(obj1);
>>   }
>>   +struct xdp_errmsg {
>> +    char msg[64];
>> +};
>> +
>> +static void on_xdp_errmsg(void *ctx, int cpu, void *data, __u32 size)
>> +{
>> +    struct xdp_errmsg *ctx_errmg = ctx, *tp_errmsg = data;
>> +
>> +    memcpy(&ctx_errmg->msg, &tp_errmsg->msg, size);
>> +}
>> +
>> +static const char tgt_errmsg[] = "Invalid XDP flags for BPF link attachment";
>> +
>> +static void test_xdp_attach_fail(const char *file)
> 
> The test crashed: https://github.com/kernel-patches/bpf/actions/runs/5672753995/job/15373384795#step:6:8037
> 
> Please monitor the CI test result in the future.
> 

Get it. I'll fix it as soon as possible. And make sure all the CI tests are passed.

>> +{
>> +    __u32 duration = 0;
>> +    int err, fd_xdp, fd_link_xdp;
>> +    struct bpf_object *obj = NULL;
>> +    struct test_xdp_attach_fail *skel = NULL;
>> +    struct bpf_link *link = NULL;
>> +    struct perf_buffer *pb = NULL;
>> +    struct xdp_errmsg errmsg = {};
>> +
>> +    LIBBPF_OPTS(bpf_link_create_opts, opts);
>> +
>> +    skel = test_xdp_attach_fail__open_and_load();
>> +    if (!ASSERT_OK_PTR(skel, "test_xdp_attach_fail_skel"))
>> +        goto out_close;
>> +
>> +    link = bpf_program__attach_tracepoint(skel->progs.tp__xdp__bpf_xdp_link_attach_failed,
>> +                          "xdp", "bpf_xdp_link_attach_failed");
>> +    if (!ASSERT_OK_PTR(link, "attach_tp"))
>> +        goto out_close;
>> +
>> +    /* set up perf buffer */
>> +    pb = perf_buffer__new(bpf_map__fd(skel->maps.xdp_errmsg_pb), 1,
>> +                  on_xdp_errmsg, NULL, &errmsg, NULL);
>> +
>> +    err = bpf_prog_test_load(file, BPF_PROG_TYPE_XDP, &obj, &fd_xdp);
>> +    if (CHECK_FAIL(err))
>> +        goto out_close;
>> +
>> +    opts.flags = 0xFF; // invalid flags to fail to attach XDP prog
>> +    fd_link_xdp = bpf_link_create(fd_xdp, IFINDEX_LO, BPF_XDP, &opts);
>> +    if (CHECK(fd_link_xdp != -22, "bpf_link_create_failed",
> 
> Please stay with the ASSERT_* macro.
> 

Get it.


Thanks,
Leon