libbpf: Rename btf__get_from_id() as btf__load_from_kernel_by_id()

Rename function btf__get_from_id() as btf__load_from_kernel_by_id() to
better indicate what the function does. Change the new function so that,
instead of requiring a pointer to the pointer to update and returning
with an error code, it takes a single argument (the id of the BTF
object) and returns the corresponding pointer. This is more in line with
the existing constructors.

The other tools calling the (soon-to-be) deprecated btf__get_from_id()
function will be updated in a future commit.

References:

- https://github.com/libbpf/libbpf/issues/278
- https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#btfh-apis

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210729162028.29512-4-quentin@isovalent.com

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 7e0de560490ec95b58cba36e03437930d073239d..948c29fee4472f14da04c5d973b77c6be434c266 100644 (file)
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -1383,21 +1383,30 @@ exit_free:
        return btf;
 }
 
-int btf__get_from_id(__u32 id, struct btf **btf)
+struct btf *btf__load_from_kernel_by_id(__u32 id)
 {
-       struct btf *res;
-       int err, btf_fd;
+       struct btf *btf;
+       int btf_fd;
 
-       *btf = NULL;
        btf_fd = bpf_btf_get_fd_by_id(id);
        if (btf_fd < 0)
-               return libbpf_err(-errno);
-
-       res = btf_get_from_fd(btf_fd, NULL);
-       err = libbpf_get_error(res);
+               return libbpf_err_ptr(-errno);
 
+       btf = btf_get_from_fd(btf_fd, NULL);
        close(btf_fd);
 
+       return libbpf_ptr(btf);
+}
+
+int btf__get_from_id(__u32 id, struct btf **btf)
+{
+       struct btf *res;
+       int err;
+
+       *btf = NULL;
+       res = btf__load_from_kernel_by_id(id);
+       err = libbpf_get_error(res);
+
        if (err)
                return libbpf_err(err);
 

diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index fd8a21d936efe0244627e3a0486745a1927fc917..5d955329a1f4eb6b8a4809a5e33892781b23ad72 100644 (file)
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -44,6 +44,9 @@ LIBBPF_API struct btf *btf__parse_elf_split(const char *path, struct btf *base_b
 LIBBPF_API struct btf *btf__parse_raw(const char *path);
 LIBBPF_API struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf);
 
+LIBBPF_API struct btf *btf__load_from_kernel_by_id(__u32 id);
+LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);
+
 LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf);
 LIBBPF_API int btf__load(struct btf *btf);
 LIBBPF_API int btf__load_into_kernel(struct btf *btf);
@@ -67,7 +70,6 @@ LIBBPF_API void btf__set_fd(struct btf *btf, int fd);
 LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
 LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
 LIBBPF_API const char *btf__str_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,
                                    __u32 expected_key_size,
                                    __u32 expected_value_size,

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 9a657d6d7da3be0a1fbe8951be64a61607b16f0f..313883179919f7a5d1ca3ffe8799d8f7cbc6a54a 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8316,7 +8316,7 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
 {
        struct bpf_prog_info_linear *info_linear;
        struct bpf_prog_info *info;
-       struct btf *btf = NULL;
+       struct btf *btf;
        int err;
 
        info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0);
@@ -8333,7 +8333,8 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
                pr_warn("The target program doesn't have BTF\n");
                goto out;
        }
-       if (btf__get_from_id(info->btf_id, &btf)) {
+       btf = btf__load_from_kernel_by_id(info->btf_id);
+       if (libbpf_get_error(btf)) {
                pr_warn("Failed to get BTF of the program\n");
                goto out;
        }

diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 4d80eb8c56b05d7483fa87dfaf5c549af89160ca..3a9c6939301ebbab026fa6cb920df0eb854acf6f 100644 (file)
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -375,6 +375,7 @@ LIBBPF_0.5.0 {
                bpf_map_lookup_and_delete_elem_flags;
                bpf_program__attach_kprobe_opts;
                bpf_object__gen_loader;
+               btf__load_from_kernel_by_id;
                btf__load_into_kernel;
                btf_dump__dump_type_data;
                libbpf_set_strict_mode;