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

1 files changed, 3 insertions, 2 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 9a657d6d7da3..313883179919 100644
--- 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;
 	}