Messages in this thread | | | Date | Thu, 12 May 2022 11:58:38 +0800 | Subject | Re: [External] Re: [PATCH bpf-next v2 2/2] selftests/bpf: add test case for bpf_map_lookup_percpu_elem | From | Feng Zhou <> |
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在 2022/5/12 上午11:34, Andrii Nakryiko 写道: > On Wed, May 11, 2022 at 2:39 AM Feng zhou <zhoufeng.zf@bytedance.com> wrote: >> From: Feng Zhou <zhoufeng.zf@bytedance.com> >> >> test_progs: >> Tests new ebpf helpers bpf_map_lookup_percpu_elem. >> >> Signed-off-by: Feng Zhou <zhoufeng.zf@bytedance.com> >> --- >> .../bpf/prog_tests/map_lookup_percpu_elem.c | 46 ++++++++++++++++ >> .../bpf/progs/test_map_lookup_percpu_elem.c | 54 +++++++++++++++++++ >> 2 files changed, 100 insertions(+) >> create mode 100644 tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c >> create mode 100644 tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c >> >> 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 >> new file mode 100644 >> index 000000000000..58b24c2112b0 >> --- /dev/null >> +++ b/tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c >> @@ -0,0 +1,46 @@ >> +// SPDX-License-Identifier: GPL-2.0 >> +// Copyright (c) 2022 Bytedance > /* */ instead of //
Ok, I will do. Thanks.
> >> + >> +#include <test_progs.h> >> + >> +#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); > I think this is actually wrong and will break selftests on systems > with offline CPUs. Please use libbpf_num_possible_cpus() instead.
Ok, I will do. Thanks.
> >> + int *buf; >> + >> + buf = (int *)malloc(nr_cpus*sizeof(int)); >> + if (!ASSERT_OK_PTR(buf, "malloc")) >> + return; >> + memset(buf, 0, nr_cpus*sizeof(int)); > this is wrong, kernel expects to have roundup(sz, 8) per each CPU, > while you have just 4 bytes per each element > > please also have spaces around multiplication operator here and above
Ok, I will use 8 bytes for key and val. Thanks.
>> + 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; > buf leaking here
Yes, sorry for my negligence.
> >> + ret = test_map_lookup_percpu_elem__attach(skel); >> + ASSERT_OK(ret, "test_map_lookup_percpu_elem__attach"); >> + >> + ret = bpf_map_update_elem(bpf_map__fd(skel->maps.percpu_array_map), &key, buf, 0); >> + ASSERT_OK(ret, "percpu_array_map update"); >> + >> + ret = bpf_map_update_elem(bpf_map__fd(skel->maps.percpu_hash_map), &key, buf, 0); >> + ASSERT_OK(ret, "percpu_hash_map update"); >> + >> + ret = bpf_map_update_elem(bpf_map__fd(skel->maps.percpu_lru_hash_map), &key, buf, 0); >> + ASSERT_OK(ret, "percpu_lru_hash_map update"); >> + >> + 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"); > this would be better done as three separate ASSERT_EQ(), combining > into opaque true/false isn't helpful if something breaks
Good suggestion.
> >> + >> + test_map_lookup_percpu_elem__destroy(skel); >> +} >> diff --git a/tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c b/tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c >> new file mode 100644 >> index 000000000000..5d4ef86cbf48 >> --- /dev/null >> +++ b/tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c >> @@ -0,0 +1,54 @@ >> +// SPDX-License-Identifier: GPL-2.0 >> +// Copyright (c) 2022 Bytedance > /* */ instead of //
Ok, I will do. Thanks.
> >> + >> +#include "vmlinux.h" >> +#include <bpf/bpf_helpers.h> >> + >> +int percpu_array_elem_val = 0; >> +int percpu_hash_elem_val = 0; >> +int percpu_lru_hash_elem_val = 0; >> + >> +struct { >> + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); >> + __uint(max_entries, 1); >> + __type(key, __u32); >> + __type(value, __u32); >> +} percpu_array_map SEC(".maps"); >> + >> +struct { >> + __uint(type, BPF_MAP_TYPE_PERCPU_HASH); >> + __uint(max_entries, 1); >> + __type(key, __u32); >> + __type(value, __u32); >> +} percpu_hash_map SEC(".maps"); >> + >> +struct { >> + __uint(type, BPF_MAP_TYPE_LRU_PERCPU_HASH); >> + __uint(max_entries, 1); >> + __type(key, __u32); >> + __type(value, __u32); >> +} percpu_lru_hash_map SEC(".maps"); >> + >> +SEC("tp/syscalls/sys_enter_getuid") >> +int sysenter_getuid(const void *ctx) >> +{ >> + __u32 key = 0; >> + __u32 cpu = 0; >> + __u32 *value; >> + >> + value = bpf_map_lookup_percpu_elem(&percpu_array_map, &key, cpu); >> + if (value) >> + percpu_array_elem_val = *value; >> + >> + value = bpf_map_lookup_percpu_elem(&percpu_hash_map, &key, cpu); >> + if (value) >> + percpu_hash_elem_val = *value; >> + >> + value = bpf_map_lookup_percpu_elem(&percpu_lru_hash_map, &key, cpu); >> + if (value) >> + percpu_lru_hash_elem_val = *value; >> + > if the test happens to run on CPU 0 then the test doesn't really test > much. It would be more interesting to have a bpf_loop() iteration that > would fetch values on each possible CPU instead and do something with > it.
Good suggestion. I check the code and find no bpf helper function to get possible CPU nums.
I think for the test function, read cpu0 elem value correctly should be considered to be no problem.
Or is it necessary to add a new helper function to get num_possible_cpus ?
> >> + return 0; >> +} >> + >> +char _license[] SEC("license") = "GPL"; >> -- >> 2.20.1 >>
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