Date:   Fri, 8 Feb 2019 17:31:08 +0000
From:   Song Liu <songliubraving@...com>
To:     Andrii Nakryiko <andriin@...com>
CC:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Yonghong Song <yhs@...com>, Alexei Starovoitov <ast@...com>,
        Martin Lau <kafai@...com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Kernel Team <Kernel-team@...com>,
        "daniel@...earbox.net" <daniel@...earbox.net>
Subject: Re: [PATCH v3 bpf-next 4/4] tools/bpf: remove btf__get_strings
 superseded() by raw data API



> On Feb 7, 2019, at 6:55 PM, Andrii Nakryiko <andriin@...com> wrote:
> 
> Now that we have btf__get_raw_data() it's trivial for tests to iterate
> over all strings for testing purposes, which eliminates the need for
> btf__get_strings() API.
> 
> Signed-off-by: Andrii Nakryiko <andriin@...com>
> ---
> tools/lib/bpf/btf.c                    |  7 -----
> tools/lib/bpf/btf.h                    |  2 --
> tools/testing/selftests/bpf/test_btf.c | 39 +++++++++++++++++---------
> 3 files changed, 26 insertions(+), 22 deletions(-)
> 
> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index c87cc3d71b9f..a986dc28f17d 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -447,13 +447,6 @@ const void *btf__get_raw_data(const struct btf *btf, __u32 *size)
> 	return btf->data;
> }
> 
> -void btf__get_strings(const struct btf *btf, const char **strings,
> -		      __u32 *str_len)
> -{
> -	*strings = btf->strings;
> -	*str_len = btf->hdr->str_len;
> -}
> -
> const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
> {
> 	if (offset < btf->hdr->str_len)
> diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
> index ad9f648260c2..6179291f2cec 100644
> --- a/tools/lib/bpf/btf.h
> +++ b/tools/lib/bpf/btf.h
> @@ -67,8 +67,6 @@ LIBBPF_API __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
> LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);
> LIBBPF_API int btf__fd(const struct btf *btf);
> LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
> -LIBBPF_API void btf__get_strings(const struct btf *btf, const char **strings,
> -				 __u32 *str_len);

I guess we need to update libbpf.map with this? 

> LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
> LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);
> LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
> diff --git a/tools/testing/selftests/bpf/test_btf.c b/tools/testing/selftests/bpf/test_btf.c
> index 447acc34db94..bbcacba39590 100644
> --- a/tools/testing/selftests/bpf/test_btf.c
> +++ b/tools/testing/selftests/bpf/test_btf.c
> @@ -5882,15 +5882,17 @@ static void dump_btf_strings(const char *strs, __u32 len)
> static int do_test_dedup(unsigned int test_num)
> {
> 	const struct btf_dedup_test *test = &dedup_tests[test_num - 1];
> -	int err = 0, i;
> -	__u32 test_nr_types, expect_nr_types, test_str_len, expect_str_len;
> -	void *raw_btf;
> -	unsigned int raw_btf_size;
> +	__u32 test_nr_types, expect_nr_types, test_btf_size, expect_btf_size;
> +	const struct btf_header *test_hdr, *expect_hdr;
> 	struct btf *test_btf = NULL, *expect_btf = NULL;
> +	const void *test_btf_data, *expect_btf_data;
> 	const char *ret_test_next_str, *ret_expect_next_str;
> 	const char *test_strs, *expect_strs;
> 	const char *test_str_cur, *test_str_end;
> 	const char *expect_str_cur, *expect_str_end;
> +	unsigned int raw_btf_size;
> +	void *raw_btf;
> +	int err = 0, i;
> 
> 	fprintf(stderr, "BTF dedup test[%u] (%s):", test_num, test->descr);
> 
> @@ -5927,23 +5929,34 @@ static int do_test_dedup(unsigned int test_num)
> 		goto done;
> 	}
> 
> -	btf__get_strings(test_btf, &test_strs, &test_str_len);
> -	btf__get_strings(expect_btf, &expect_strs, &expect_str_len);
> -	if (CHECK(test_str_len != expect_str_len,
> -		  "test_str_len:%u != expect_str_len:%u",
> -		  test_str_len, expect_str_len)) {
> +	test_btf_data = btf__get_raw_data(test_btf, &test_btf_size);
> +	expect_btf_data = btf__get_raw_data(expect_btf, &expect_btf_size);
> +	if (CHECK(test_btf_size != expect_btf_size,
> +		  "test_btf_size:%u != expect_btf_size:%u",
> +		  test_btf_size, expect_btf_size)) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	test_hdr = test_btf_data;
> +	test_strs = test_btf_data + test_hdr->str_off;
> +	expect_hdr = expect_btf_data;
> +	expect_strs = expect_btf_data + expect_hdr->str_off;
> +	if (CHECK(test_hdr->str_len != expect_hdr->str_len,
> +		  "test_hdr->str_len:%u != expect_hdr->str_len:%u",
> +		  test_hdr->str_len, expect_hdr->str_len)) {
> 		fprintf(stderr, "\ntest strings:\n");
> -		dump_btf_strings(test_strs, test_str_len);
> +		dump_btf_strings(test_strs, test_hdr->str_len);
> 		fprintf(stderr, "\nexpected strings:\n");
> -		dump_btf_strings(expect_strs, expect_str_len);
> +		dump_btf_strings(expect_strs, expect_hdr->str_len);
> 		err = -1;
> 		goto done;
> 	}
> 
> 	test_str_cur = test_strs;
> -	test_str_end = test_strs + test_str_len;
> +	test_str_end = test_strs + test_hdr->str_len;
> 	expect_str_cur = expect_strs;
> -	expect_str_end = expect_strs + expect_str_len;
> +	expect_str_end = expect_strs + expect_hdr->str_len;
> 	while (test_str_cur < test_str_end && expect_str_cur < expect_str_end) {
> 		size_t test_len, expect_len;
> 
> -- 
> 2.17.1
> 

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