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Subject[PATCH bpf-next] libbpf: allow disabling auto attach
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Add 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 for them and perform manual attach.

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

Signed-off-by: Hao Luo <haoluo@google.com>
---
tools/lib/bpf/libbpf.c | 16 ++++++++++++++++
tools/lib/bpf/libbpf.h | 2 ++
2 files changed, 18 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index aa05a99b913d..25f654d25b46 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -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;
@@ -12349,6 +12362,9 @@ int bpf_object__attach_skeleton(struct bpf_object_skeleton *s)
if (!prog->autoload)
continue;

+ if (!prog->autoattach)
+ continue;
+
/* auto-attaching not supported for this program */
if (!prog->sec_def || !prog->sec_def->prog_attach_fn)
continue;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 61493c4cddac..88a1ac34b12a 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -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;

--
2.37.1.595.g718a3a8f04-goog
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