libbpf: Deprecate ambiguously-named bpf_program__size() API

mainline inclusion
from mainline-5.16-rc1
commit c4813e96
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c4813e969ac471af730902377a2656b6b1b92c4d

-------------------------------------------------

The name of the API doesn't convey clearly that this size is in number
of bytes (there needed to be a separate comment to make this clear in
libbpf.h). Further, measuring the size of BPF program in bytes is not
exactly the best fit, because BPF programs always consist of 8-byte
instructions. As such, bpf_program__insn_cnt() is a better alternative
in pretty much any imaginable case.

So schedule bpf_program__size() deprecation starting from v0.7 and it
will be removed in libbpf 1.0.
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211025224531.1088894-5-andrii@kernel.org
(cherry picked from commit c4813e96)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

tools/lib/bpf/libbpf.h

@@ -217,6 +217,7 @@ LIBBPF_API bool bpf_program__autoload(const struct bpf_program *prog);
 LIBBPF_API int bpf_program__set_autoload(struct bpf_program *prog, bool autoload);
 
 /* returns program size in bytes */
+LIBBPF_DEPRECATED_SINCE(0, 7, "use bpf_program__insn_cnt() instead")
 LIBBPF_API size_t bpf_program__size(const struct bpf_program *prog);
 
 struct bpf_insn;