Commit 43cb8cba authored by Hao Luo's avatar Hao Luo Committed by Andrii Nakryiko
Browse files

libbpf: Allows disabling auto attach 

Adds libbpf APIs for disabling auto-attach for individual functions.
This is motivated by the use case of cgroup iter [1]. Some iter
types require their parameters to be non-zero, therefore applying
auto-attach on them will fail. With these two new APIs, users who
want to use auto-attach and these types of iters can disable
auto-attach on the program and perform manual attach.

[1] https://lore.kernel.org/bpf/CAEf4BzZ+a2uDo_t6kGBziqdz--m2gh2_EUwkGLDtMd65uwxUjA@mail.gmail.com/



Signed-off-by: default avatarHao Luo <haoluo@google.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220816234012.910255-1-haoluo@google.com
parent 807662ca

tools/lib/bpf/libbpf.c

+14 −1
Original line number Diff line number Diff line
@@ -417,6 +417,7 @@ struct bpf_program { 


	int fd;

	bool autoload;

	bool autoattach;

	bool mark_btf_static;

	enum bpf_prog_type type;

	enum bpf_attach_type expected_attach_type;
@@ -755,6 +756,8 @@ bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog, 
		prog->autoload = true;

	}



	prog->autoattach = true;



	/* inherit object's log_level */

	prog->log_level = obj->log_level;
@@ -8314,6 +8317,16 @@ int bpf_program__set_autoload(struct bpf_program *prog, bool autoload) 
	return 0;

}



bool bpf_program__autoattach(const struct bpf_program *prog)

{

	return prog->autoattach;

}



void bpf_program__set_autoattach(struct bpf_program *prog, bool autoattach)

{

	prog->autoattach = autoattach;

}



const struct bpf_insn *bpf_program__insns(const struct bpf_program *prog)

{

	return prog->insns;
@@ -12346,7 +12359,7 @@ int bpf_object__attach_skeleton(struct bpf_object_skeleton *s) 
		struct bpf_program *prog = *s->progs[i].prog;

		struct bpf_link **link = s->progs[i].link;



		if (!prog->autoload)

		if (!prog->autoload || !prog->autoattach)

			continue;



		/* auto-attaching not supported for this program */

tools/lib/bpf/libbpf.h

+2 −0
Original line number Diff line number Diff line
@@ -260,6 +260,8 @@ LIBBPF_API const char *bpf_program__name(const struct bpf_program *prog); 
LIBBPF_API const char *bpf_program__section_name(const struct bpf_program *prog);

LIBBPF_API bool bpf_program__autoload(const struct bpf_program *prog);

LIBBPF_API int bpf_program__set_autoload(struct bpf_program *prog, bool autoload);

LIBBPF_API bool bpf_program__autoattach(const struct bpf_program *prog);

LIBBPF_API void bpf_program__set_autoattach(struct bpf_program *prog, bool autoattach);



struct bpf_insn;

tools/lib/bpf/libbpf.map

+2 −0
Original line number Diff line number Diff line
@@ -358,6 +358,8 @@ LIBBPF_1.0.0 { 
		bpf_obj_get_opts;

		bpf_prog_query_opts;

		bpf_program__attach_ksyscall;

		bpf_program__autoattach;

		bpf_program__set_autoattach;

		btf__add_enum64;

		btf__add_enum64_value;

		libbpf_bpf_attach_type_str;