diff mbox series

[v1,02/13] libbpf: Make __printf define conditional

Message ID 20240310020509.647319-3-irogers@google.com (mailing list archive)
State New, archived
Headers show
Series tools header compiler.h update | expand

Commit Message

Ian Rogers March 10, 2024, 2:04 a.m. UTC
libbpf depends upon linux/err.h which has a linux/compiler.h
dependency. In the kernel includes, as opposed to the tools version,
linux/compiler.h includes linux/compiler_attributes.h which defines
__printf. As the libbpf.c __printf definition isn't guarded by an
ifndef, this leads to a duplicate definition compilation error when
trying to update the tools/include/linux/compiler.h. Fix this by
adding the missing ifndef.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/lib/bpf/libbpf.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Andrii Nakryiko March 11, 2024, 5:49 p.m. UTC | #1
On Sat, Mar 9, 2024 at 6:05 PM Ian Rogers <irogers@google.com> wrote:
>
> libbpf depends upon linux/err.h which has a linux/compiler.h
> dependency. In the kernel includes, as opposed to the tools version,
> linux/compiler.h includes linux/compiler_attributes.h which defines
> __printf. As the libbpf.c __printf definition isn't guarded by an
> ifndef, this leads to a duplicate definition compilation error when
> trying to update the tools/include/linux/compiler.h. Fix this by
> adding the missing ifndef.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/lib/bpf/libbpf.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index afd09571c482..2152360b4b18 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -66,7 +66,9 @@
>   */
>  #pragma GCC diagnostic ignored "-Wformat-nonliteral"
>
> -#define __printf(a, b) __attribute__((format(printf, a, b)))
> +#ifndef __printf
> +# define __printf(a, b)        __attribute__((format(printf, a, b)))

styling nit: don't add spaces between # and define, please

overall LGTM

Acked-by: Andrii Nakryiko <andrii@kernel.org>

Two questions, though.

1. It seems like just dropping #define __printf in libbpf.c compiles
fine (I checked both building libbpf directly, and BPF selftest, and
perf, and bpftool directly, all of them built fine). So we can
probably just drop this. I'll need to add __printf on Github, but
that's fine.

2. Logistics. Which tree should this patch go through? Can I land it
in bpf-next or it's too much inconvenience for you?


> +#endif
>
>  static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
>  static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
> --
> 2.44.0.278.ge034bb2e1d-goog
>
Ian Rogers March 11, 2024, 6:54 p.m. UTC | #2
On Mon, Mar 11, 2024 at 10:49 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Sat, Mar 9, 2024 at 6:05 PM Ian Rogers <irogers@google.com> wrote:
> >
> > libbpf depends upon linux/err.h which has a linux/compiler.h
> > dependency. In the kernel includes, as opposed to the tools version,
> > linux/compiler.h includes linux/compiler_attributes.h which defines
> > __printf. As the libbpf.c __printf definition isn't guarded by an
> > ifndef, this leads to a duplicate definition compilation error when
> > trying to update the tools/include/linux/compiler.h. Fix this by
> > adding the missing ifndef.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/lib/bpf/libbpf.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index afd09571c482..2152360b4b18 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -66,7 +66,9 @@
> >   */
> >  #pragma GCC diagnostic ignored "-Wformat-nonliteral"
> >
> > -#define __printf(a, b) __attribute__((format(printf, a, b)))
> > +#ifndef __printf
> > +# define __printf(a, b)        __attribute__((format(printf, a, b)))
>
> styling nit: don't add spaces between # and define, please
>
> overall LGTM
>
> Acked-by: Andrii Nakryiko <andrii@kernel.org>
>
> Two questions, though.
>
> 1. It seems like just dropping #define __printf in libbpf.c compiles
> fine (I checked both building libbpf directly, and BPF selftest, and
> perf, and bpftool directly, all of them built fine). So we can
> probably just drop this. I'll need to add __printf on Github, but
> that's fine.
>
> 2. Logistics. Which tree should this patch go through? Can I land it
> in bpf-next or it's too much inconvenience for you?

Thanks Andrii,

dropping the #define (1) sgtm but the current compiler.h will fail to
build libbpf.c without the later compiler.h update in this series.
This causes another logistic issue for your point 2. Presumably if
this patch goes through bpf-next, the first patch "tools bpf:
Synchronize bpf.h with kernel uapi version" should also go through the
bpf-next.

Thanks,
Ian


> > +#endif
> >
> >  static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
> >  static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
> > --
> > 2.44.0.278.ge034bb2e1d-goog
> >
Andrii Nakryiko March 11, 2024, 8:51 p.m. UTC | #3
On Mon, Mar 11, 2024 at 11:54 AM Ian Rogers <irogers@google.com> wrote:
>
> On Mon, Mar 11, 2024 at 10:49 AM Andrii Nakryiko
> <andrii.nakryiko@gmail.com> wrote:
> >
> > On Sat, Mar 9, 2024 at 6:05 PM Ian Rogers <irogers@google.com> wrote:
> > >
> > > libbpf depends upon linux/err.h which has a linux/compiler.h
> > > dependency. In the kernel includes, as opposed to the tools version,
> > > linux/compiler.h includes linux/compiler_attributes.h which defines
> > > __printf. As the libbpf.c __printf definition isn't guarded by an
> > > ifndef, this leads to a duplicate definition compilation error when
> > > trying to update the tools/include/linux/compiler.h. Fix this by
> > > adding the missing ifndef.
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > >  tools/lib/bpf/libbpf.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > > index afd09571c482..2152360b4b18 100644
> > > --- a/tools/lib/bpf/libbpf.c
> > > +++ b/tools/lib/bpf/libbpf.c
> > > @@ -66,7 +66,9 @@
> > >   */
> > >  #pragma GCC diagnostic ignored "-Wformat-nonliteral"
> > >
> > > -#define __printf(a, b) __attribute__((format(printf, a, b)))
> > > +#ifndef __printf
> > > +# define __printf(a, b)        __attribute__((format(printf, a, b)))
> >
> > styling nit: don't add spaces between # and define, please
> >
> > overall LGTM
> >
> > Acked-by: Andrii Nakryiko <andrii@kernel.org>
> >
> > Two questions, though.
> >
> > 1. It seems like just dropping #define __printf in libbpf.c compiles
> > fine (I checked both building libbpf directly, and BPF selftest, and
> > perf, and bpftool directly, all of them built fine). So we can
> > probably just drop this. I'll need to add __printf on Github, but
> > that's fine.
> >
> > 2. Logistics. Which tree should this patch go through? Can I land it
> > in bpf-next or it's too much inconvenience for you?
>
> Thanks Andrii,
>
> dropping the #define (1) sgtm but the current compiler.h will fail to
> build libbpf.c without the later compiler.h update in this series.
> This causes another logistic issue for your point 2. Presumably if
> this patch goes through bpf-next, the first patch "tools bpf:
> Synchronize bpf.h with kernel uapi version" should also go through the
> bpf-next.
>

That's what I'm saying, it seems to work without your patches already.
At least on bpf-next/master. But it's ok, let's keep it and just add
#ifndef guard, that will make my life easier when syncing to Github
later one. Then the patch can go through other trees and eventually
make it into bpf-next and then Github. So please keep my ack for
#ifndef version, thanks.

> Thanks,
> Ian
>
>
> > > +#endif
> > >
> > >  static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
> > >  static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
> > > --
> > > 2.44.0.278.ge034bb2e1d-goog
> > >
diff mbox series

Patch

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index afd09571c482..2152360b4b18 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -66,7 +66,9 @@ 
  */
 #pragma GCC diagnostic ignored "-Wformat-nonliteral"
 
-#define __printf(a, b)	__attribute__((format(printf, a, b)))
+#ifndef __printf
+# define __printf(a, b)	__attribute__((format(printf, a, b)))
+#endif
 
 static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
 static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);