| Message ID | 20200720061741.1514673-1-irogers@google.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [v2] libbpf bpf_helpers: Use __builtin_offsetof for offsetof | expand |
On Sun, Jul 19, 2020 at 11:18 PM Ian Rogers <irogers@google.com> wrote: > > The non-builtin route for offsetof has a dependency on size_t from > stdlib.h/stdint.h that is undeclared and may break targets. > The offsetof macro in bpf_helpers may disable the same macro in other > headers that have a #ifdef offsetof guard. Rather than add additional > dependencies improve the offsetof macro declared here to use the > builtin that is available since llvm 3.7 (the first with a BPF backend). > > Signed-off-by: Ian Rogers <irogers@google.com> > --- Acked-by: Andrii Nakryiko <andriin@fb.com> > tools/lib/bpf/bpf_helpers.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h > index a510d8ed716f..bc14db706b88 100644 > --- a/tools/lib/bpf/bpf_helpers.h > +++ b/tools/lib/bpf/bpf_helpers.h > @@ -40,7 +40,7 @@ > * Helper macro to manipulate data structures > */ > #ifndef offsetof > -#define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER) > +#define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER) > #endif > #ifndef container_of > #define container_of(ptr, type, member) \ > -- > 2.28.0.rc0.105.gf9edc3c819-goog >
On Sun, Jul 19, 2020 at 11:21 PM Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > > On Sun, Jul 19, 2020 at 11:18 PM Ian Rogers <irogers@google.com> wrote: > > > > The non-builtin route for offsetof has a dependency on size_t from > > stdlib.h/stdint.h that is undeclared and may break targets. > > The offsetof macro in bpf_helpers may disable the same macro in other > > headers that have a #ifdef offsetof guard. Rather than add additional > > dependencies improve the offsetof macro declared here to use the > > builtin that is available since llvm 3.7 (the first with a BPF backend). > > > > Signed-off-by: Ian Rogers <irogers@google.com> > > --- > > Acked-by: Andrii Nakryiko <andriin@fb.com> Applied. Thanks
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h index a510d8ed716f..bc14db706b88 100644 --- a/tools/lib/bpf/bpf_helpers.h +++ b/tools/lib/bpf/bpf_helpers.h @@ -40,7 +40,7 @@ * Helper macro to manipulate data structures */ #ifndef offsetof -#define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER) +#define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER) #endif #ifndef container_of #define container_of(ptr, type, member) \
The non-builtin route for offsetof has a dependency on size_t from stdlib.h/stdint.h that is undeclared and may break targets. The offsetof macro in bpf_helpers may disable the same macro in other headers that have a #ifdef offsetof guard. Rather than add additional dependencies improve the offsetof macro declared here to use the builtin that is available since llvm 3.7 (the first with a BPF backend). Signed-off-by: Ian Rogers <irogers@google.com> --- tools/lib/bpf/bpf_helpers.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)