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.
- 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.
- 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