netdev - Re: [PATCH] libbpf: fix samples/bpf build failure due to undefined UINT32

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Date:   Tue, 23 Apr 2019 16:26:53 -0700
From:   Y Song <ys114321@...il.com>
To:     "Daniel T. Lee" <danieltimlee@...il.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] libbpf: fix samples/bpf build failure due to undefined UINT32_MAX

On Tue, Apr 23, 2019 at 1:26 PM Daniel T. Lee <danieltimlee@...il.com> wrote:
>
> Currently, building bpf samples will cause the following error.
>
>     ./tools/lib/bpf/bpf.h:132:27: error: 'UINT32_MAX' undeclared here (not in a function) ..
>      #define BPF_LOG_BUF_SIZE (UINT32_MAX >> 8) /* verifier maximum in kernels <= 5.1 */
>                                ^
>     ./samples/bpf/bpf_load.h:31:25: note: in expansion of macro 'BPF_LOG_BUF_SIZE'
>      extern char bpf_log_buf[BPF_LOG_BUF_SIZE];
>                              ^~~~~~~~~~~~~~~~
>
> Due to commit 4519efa6f8ea ("libbpf: fix BPF_LOG_BUF_SIZE off-by-one error")
> hard-coded size of BPF_LOG_BUF_SIZE has been replaced with UINT32_MAX which is
> defined in <stdint.h> header.
>
> Even with this change, bpf selftests are running fine since these are built
> with clang and it includes header(-idirafter) from clang/6.0.0/include.
> (it has <stdint.h>)
>
>     clang -I. -I./include/uapi -I../../../include/uapi -idirafter /usr/local/include -idirafter /usr/include \
>     -idirafter /usr/lib/llvm-6.0/lib/clang/6.0.0/include -idirafter /usr/include/x86_64-linux-gnu \
>     -Wno-compare-distinct-pointer-types -O2 -target bpf -emit-llvm -c progs/test_sysctl_prog.c -o - | \
>     llc -march=bpf -mcpu=generic  -filetype=obj -o /linux/tools/testing/selftests/bpf/test_sysctl_prog.o
>
> But bpf samples are compiled with GCC, and it only searches and includes
> headers declared at the target file. As '#include <stdint.h>' hasn't been
> declared in tools/lib/bpf/bpf.h, it causes build failure of bpf samples.
>
>     gcc -Wp,-MD,./samples/bpf/.sockex3_user.o.d -Wall -Wmissing-prototypes -Wstrict-prototypes \
>     -O2 -fomit-frame-pointer -std=gnu89 -I./usr/include -I./tools/lib/ -I./tools/testing/selftests/bpf/ \
>     -I./tools/  lib/ -I./tools/include -I./tools/perf -c -o ./samples/bpf/sockex3_user.o ./samples/bpf/sockex3_user.c;
>
> This commit add declaration of '#include <stdint.h>' to tools/lib/bpf/bpf.h
> to fix this problem.
>
> Signed-off-by: Daniel T. Lee <danieltimlee@...il.com>
> ---
>  tools/lib/bpf/bpf.h | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index ff2506fe6bd2..9593fec75652 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -26,6 +26,7 @@
>  #include <linux/bpf.h>
>  #include <stdbool.h>
>  #include <stddef.h>
> +#include <stdint.h>

I my case, I have the following in /usr/include/linux/bpf.h:
  #include <linux/types.h>
  #include <linux/bpf_common.h>

The <linux/bpf.h> is included in tools/lib/bpf/bpf.h.

and at tools/include/linux/types.h, I got
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

So I don't have any issues.
Could you check your system whether any of the above files
missing or mismatched during compilation process?

>
>  #ifdef __cplusplus
>  extern "C" {
> --
> 2.17.1
>