linux-kernel - Re: [External] Re: [PATCH bpf-next] selftests/bpf: fix some bugs in map_lookup_percpu

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Date:   Tue, 17 May 2022 15:05:42 +0800
From:   Feng Zhou <zhoufeng.zf@...edance.com>
To:     Yonghong Song <yhs@...com>, ast@...nel.org, daniel@...earbox.net,
        andrii@...nel.org, kafai@...com, songliubraving@...com,
        john.fastabend@...il.com, kpsingh@...nel.org, rostedt@...dmis.org,
        mingo@...hat.com, jolsa@...nel.org, davemarchevsky@...com,
        joannekoong@...com, geliang.tang@...e.com
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org, duanxiongchun@...edance.com,
        songmuchun@...edance.com, wangdongdong.6@...edance.com,
        cong.wang@...edance.com, zhouchengming@...edance.com,
        yosryahmed@...gle.com
Subject: Re: [External] Re: [PATCH bpf-next] selftests/bpf: fix some bugs in
 map_lookup_percpu_elem testcase

在 2022/5/17 上午11:09, Yonghong Song 写道:
>
>
> On 5/15/22 7:24 PM, Feng zhou wrote:
>> From: Feng Zhou <zhoufeng.zf@...edance.com>
>>
>> comments from Andrii Nakryiko, details in here:
>> https://lore.kernel.org/lkml/20220511093854.411-1-zhoufeng.zf@bytedance.com/T/ 
>>
>>
>> use /* */ instead of //
>> use libbpf_num_possible_cpus() instead of sysconf(_SC_NPROCESSORS_ONLN)
>> use 8 bytes for value size
>> fix memory leak
>> use ASSERT_EQ instead of ASSERT_OK
>> add bpf_loop to fetch values on each possible CPU
>>
>> Fixes: ed7c13776e20c74486b0939a3c1de984c5efb6aa ("selftests/bpf: add 
>> test case for bpf_map_lookup_percpu_elem")
>> Signed-off-by: Feng Zhou <zhoufeng.zf@...edance.com>
>
> LGTM with a few nits below.
> Acked-by: Yonghong Song <yhs@...com>
>
Ok, will do. Thanks.

>> ---
>>   .../bpf/prog_tests/map_lookup_percpu_elem.c   | 49 +++++++++------
>>   .../bpf/progs/test_map_lookup_percpu_elem.c   | 61 ++++++++++++-------
>>   2 files changed, 70 insertions(+), 40 deletions(-)
>>
>> diff --git 
>> a/tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c 
>> b/tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c
>> index 58b24c2112b0..89ca170f1c25 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c
>> @@ -1,30 +1,39 @@
>> -// SPDX-License-Identifier: GPL-2.0
>> -// Copyright (c) 2022 Bytedance
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/* Copyright (c) 2022 Bytedance */
>>     #include <test_progs.h>
>
> The above empty line is unnecessary.
>
>>   #include "test_map_lookup_percpu_elem.skel.h"
>>   -#define TEST_VALUE  1
>> -
>>   void test_map_lookup_percpu_elem(void)
>>   {
>>       struct test_map_lookup_percpu_elem *skel;
>> -    int key = 0, ret;
>> -    int nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
>> -    int *buf;
>> +    __u64 key = 0, sum;
>> +    int ret, i;
>> +    int nr_cpus = libbpf_num_possible_cpus();
>> +    __u64 *buf;
>>   -    buf = (int *)malloc(nr_cpus*sizeof(int));
>> +    buf = (__u64 *)malloc(nr_cpus*sizeof(__u64));
>>       if (!ASSERT_OK_PTR(buf, "malloc"))
>>           return;
>> -    memset(buf, 0, nr_cpus*sizeof(int));
>> -    buf[0] = TEST_VALUE;
>>   -    skel = test_map_lookup_percpu_elem__open_and_load();
>> -    if (!ASSERT_OK_PTR(skel, 
>> "test_map_lookup_percpu_elem__open_and_load"))
>> -        return;
>> +    for (i=0; i<nr_cpus; i++)
>> +        buf[i] = i;
>> +    sum = (nr_cpus-1)*nr_cpus/2;
>> +
>> +    skel = test_map_lookup_percpu_elem__open();
>> +    if (!ASSERT_OK_PTR(skel, "test_map_lookup_percpu_elem__open"))
>> +        goto exit;
>> +
>> +    skel->rodata->nr_cpus = nr_cpus;
>> +
>> +    ret = test_map_lookup_percpu_elem__load(skel);
>> +    if (!ASSERT_OK(ret, "test_map_lookup_percpu_elem__load"))
>> +        goto cleanup;
>> +
>>       ret = test_map_lookup_percpu_elem__attach(skel);
>> -    ASSERT_OK(ret, "test_map_lookup_percpu_elem__attach");
>> +    if (!ASSERT_OK(ret, "test_map_lookup_percpu_elem__attach"))
>> +        goto cleanup;
>>         ret = 
>> bpf_map_update_elem(bpf_map__fd(skel->maps.percpu_array_map), &key, 
>> buf, 0);
>>       ASSERT_OK(ret, "percpu_array_map update");
>> @@ -37,10 +46,14 @@ void test_map_lookup_percpu_elem(void)
>>         syscall(__NR_getuid);
>>   -    ret = skel->bss->percpu_array_elem_val == TEST_VALUE &&
>> -          skel->bss->percpu_hash_elem_val == TEST_VALUE &&
>> -          skel->bss->percpu_lru_hash_elem_val == TEST_VALUE;
>> -    ASSERT_OK(!ret, "bpf_map_lookup_percpu_elem success");
>> +    test_map_lookup_percpu_elem__detach(skel);
>> +
>> +    ASSERT_EQ(skel->bss->percpu_array_elem_sum, sum, "percpu_array 
>> lookup percpu elem");
>> +    ASSERT_EQ(skel->bss->percpu_hash_elem_sum, sum, "percpu_hash 
>> lookup percpu elem");
>> +    ASSERT_EQ(skel->bss->percpu_lru_hash_elem_sum, sum, 
>> "percpu_lru_hash lookup percpu elem");
>>   +cleanup:
>>       test_map_lookup_percpu_elem__destroy(skel);
>> +exit:
>> +    free(buf);
>>   }
> [...]
>> +struct read_percpu_elem_ctx {
>> +    void *map;
>> +    __u64 sum;
>> +};
>> +
>> +static int read_percpu_elem_callback(__u32 index, struct 
>> read_percpu_elem_ctx *ctx)
>> +{
>> +    __u64 key = 0;
>> +    __u64 *value;
>
> Please add an empty line here.
>
>> +    value = bpf_map_lookup_percpu_elem(ctx->map, &key, index);
>> +    if (value)
>> +        ctx->sum += *value;
>> +    return 0;
>> +}
>> +
> [...]