Commit 36153532 authored by Andrey Ignatov's avatar Andrey Ignatov Committed by Daniel Borkmann
Browse files

libbpf: Fix compile error in libbpf_attach_type_by_name 



Arnaldo Carvalho de Melo reported build error in libbpf when clang
version 3.8.1-24 (tags/RELEASE_381/final) is used:

libbpf.c:2201:36: error: comparison of constant -22 with expression of
type 'const enum bpf_attach_type' is always false
[-Werror,-Wtautological-constant-out-of-range-compare]
                if (section_names[i].attach_type == -EINVAL)
                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^  ~~~~~~~
1 error generated.

Fix the error by keeping "is_attachable" property of a program in a
separate struct field instead of trying to use attach_type itself.

Fixes: 956b620f ("libbpf: Introduce libbpf_attach_type_by_name")
Reported-by: default avatarArnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent deee2cae

tools/lib/bpf/libbpf.c

+7 −6
Original line number Diff line number Diff line
@@ -2084,19 +2084,19 @@ void bpf_program__set_expected_attach_type(struct bpf_program *prog, 
	prog->expected_attach_type = type;

}



#define BPF_PROG_SEC_IMPL(string, ptype, eatype, atype) \

	{ string, sizeof(string) - 1, ptype, eatype, atype }

#define BPF_PROG_SEC_IMPL(string, ptype, eatype, is_attachable, atype) \

	{ string, sizeof(string) - 1, ptype, eatype, is_attachable, atype }



/* Programs that can NOT be attached. */

#define BPF_PROG_SEC(string, ptype) BPF_PROG_SEC_IMPL(string, ptype, 0, -EINVAL)

#define BPF_PROG_SEC(string, ptype) BPF_PROG_SEC_IMPL(string, ptype, 0, 0, 0)



/* Programs that can be attached. */

#define BPF_APROG_SEC(string, ptype, atype) \

	BPF_PROG_SEC_IMPL(string, ptype, 0, atype)

	BPF_PROG_SEC_IMPL(string, ptype, 0, 1, atype)



/* Programs that must specify expected attach type at load time. */

#define BPF_EAPROG_SEC(string, ptype, eatype) \

	BPF_PROG_SEC_IMPL(string, ptype, eatype, eatype)

	BPF_PROG_SEC_IMPL(string, ptype, eatype, 1, eatype)



/* Programs that can be attached but attach type can't be identified by section

 * name. Kept for backward compatibility.
@@ -2108,6 +2108,7 @@ static const struct { 
	size_t len;

	enum bpf_prog_type prog_type;

	enum bpf_attach_type expected_attach_type;

	int is_attachable;

	enum bpf_attach_type attach_type;

} section_names[] = {

	BPF_PROG_SEC("socket",			BPF_PROG_TYPE_SOCKET_FILTER),
@@ -2198,7 +2199,7 @@ int libbpf_attach_type_by_name(const char *name, 
	for (i = 0; i < ARRAY_SIZE(section_names); i++) {

		if (strncmp(name, section_names[i].sec, section_names[i].len))

			continue;

		if (section_names[i].attach_type == -EINVAL)

		if (!section_names[i].is_attachable)

			return -EINVAL;

		*attach_type = section_names[i].attach_type;

		return 0;

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