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 <[email protected]>
---
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
On Tue, Aug 16, 2022 at 3:01 PM Andrii Nakryiko
<[email protected]> wrote:
>
> On Tue, Aug 16, 2022 at 2:49 PM Hao Luo <[email protected]> wrote:
> >
> > 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 <[email protected]>
> > ---
> > 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
[...]
> > 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;
> > +
>
> nit: I'd combine as if (!prog->autoload || !prog->autoattach), they
> are very coupled in this sense
>
Sure.
> > /* 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);
>
> please add these APIs to libbpf.map as well
>
Ok. Which section? LIBBPF_1.0.0? Do the items in each section have a
particular order?
> it would be also nice to have a simple test validating that skeleton's
> auto-attach doesn't attach program (no link will be created) if
> bpf_program__set_autoattach(false) is called before. Can you please
> add that as well?
>
Ok. Will add a test and send v2.
> >
> > struct bpf_insn;
> >
> > --
> > 2.37.1.595.g718a3a8f04-goog
> >
On Tue, Aug 16, 2022 at 3:16 PM Hao Luo <[email protected]> wrote:
>
> On Tue, Aug 16, 2022 at 3:01 PM Andrii Nakryiko
> <[email protected]> wrote:
> >
> > On Tue, Aug 16, 2022 at 2:49 PM Hao Luo <[email protected]> wrote:
> > >
> > > 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 <[email protected]>
> > > ---
> > > 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
> [...]
> > > 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;
> > > +
> >
> > nit: I'd combine as if (!prog->autoload || !prog->autoattach), they
> > are very coupled in this sense
> >
>
> Sure.
>
> > > /* 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);
> >
> > please add these APIs to libbpf.map as well
> >
>
> Ok. Which section? LIBBPF_1.0.0? Do the items in each section have a
> particular order?
Yes, 1.0.0 section. All the functions are sorted alphabetically.
> > it would be also nice to have a simple test validating that skeleton's
> > auto-attach doesn't attach program (no link will be created) if
> > bpf_program__set_autoattach(false) is called before. Can you please
> > add that as well?
> >
>
> Ok. Will add a test and send v2.
>
> > >
> > > struct bpf_insn;
> > >
> > > --
> > > 2.37.1.595.g718a3a8f04-goog
> > >
On Tue, Aug 16, 2022 at 2:49 PM Hao Luo <[email protected]> wrote:
>
> 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 <[email protected]>
> ---
> 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;
> +
nit: I'd combine as if (!prog->autoload || !prog->autoattach), they
are very coupled in this sense
> /* 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);
please add these APIs to libbpf.map as well
it would be also nice to have a simple test validating that skeleton's
auto-attach doesn't attach program (no link will be created) if
bpf_program__set_autoattach(false) is called before. Can you please
add that as well?
>
> struct bpf_insn;
>
> --
> 2.37.1.595.g718a3a8f04-goog
>
On Tue, Aug 16, 2022 at 3:55 PM Andrii Nakryiko
<[email protected]> wrote:
>
> On Tue, Aug 16, 2022 at 3:16 PM Hao Luo <[email protected]> wrote:
> >
> > On Tue, Aug 16, 2022 at 3:01 PM Andrii Nakryiko
> > <[email protected]> wrote:
> > >
> > > On Tue, Aug 16, 2022 at 2:49 PM Hao Luo <[email protected]> wrote:
> > > >
> > > > 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 <[email protected]>
> > > > ---
[...]
> > > > 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);
> > >
> > > please add these APIs to libbpf.map as well
> > >
> >
> > Ok. Which section? LIBBPF_1.0.0? Do the items in each section have a
> > particular order?
>
> Yes, 1.0.0 section. All the functions are sorted alphabetically.
>
Thanks for confirming. :)