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From:   Andrea Righi <andrea.righi@canonical.com>
To:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>
Cc:     Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>, Hao Luo <haoluo@google.com>,
        Jiri Olsa <jolsa@kernel.org>, Mykola Lysenko <mykolal@fb.com>,
        Shuah Khan <shuah@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>,
        Paolo Pisati <paolo.pisati@canonical.com>, bpf@vger.kernel.org,
        linux-kselftest@vger.kernel.org, llvm@lists.linux.dev,
        linux-kernel@vger.kernel.org
Subject: [PATCH] selftests/bpf: ignore pointer types check with clang
Date:   Wed, 12 Apr 2023 11:59:12 +0200
Message-Id: <20230412095912.188453-1-andrea.righi@canonical.com>
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Building bpf selftests with clang can trigger errors like the following:

  CLNG-BPF [test_maps] bpf_iter_netlink.bpf.o
progs/bpf_iter_netlink.c:32:4: error: incompatible pointer types assigning to 'struct sock *' from 'struct sock___17 *' [-Werror,-Wincompatible-pointer-types]
        s = &nlk->sk;
          ^ ~~~~~~~~
1 error generated.

This is due to the fact that bpftool emits duplicate data types with
different names in vmlinux.h (i.e., `struct sock` in this case) and
these types, despite having a different name, represent in fact the same
object.

Add -Wno-incompatible-pointer-types to CLANG_CLAGS to prevent these
errors.

Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
---
 tools/testing/selftests/bpf/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index b677dcd0b77a..0d9ef819a065 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -356,7 +356,8 @@ BPF_CFLAGS = -g -Werror -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN) 		\
 	     -I$(abspath $(OUTPUT)/../usr/include)
 
 CLANG_CFLAGS = $(CLANG_SYS_INCLUDES) \
-	       -Wno-compare-distinct-pointer-types
+	       -Wno-compare-distinct-pointer-types \
+	       -Wno-incompatible-pointer-types
 
 $(OUTPUT)/test_l4lb_noinline.o: BPF_CFLAGS += -fno-inline
 $(OUTPUT)/test_xdp_noinline.o: BPF_CFLAGS += -fno-inline
-- 
2.39.2