netdev - [PATCH v3 bpf] selftests/bpf: do not ignore clang failures

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Message-Id: <20190711091249.59865-1-iii@linux.ibm.com>
Date:   Thu, 11 Jul 2019 11:12:49 +0200
From:   Ilya Leoshkevich <iii@...ux.ibm.com>
To:     bpf@...r.kernel.org, netdev@...r.kernel.org
Cc:     andrii.nakryiko@...il.com, daniel@...earbox.net,
        liu.song.a23@...il.com, Ilya Leoshkevich <iii@...ux.ibm.com>
Subject: [PATCH v3 bpf] selftests/bpf: do not ignore clang failures

When compiling an eBPF prog fails, make still returns 0, because
failing clang command's output is piped to llc and therefore its
exit status is ignored.

When clang fails, pipe the string "clang failed" to llc. This will make
llc fail with an informative error message. This solution was chosen
over using pipefail, having separate targets or getting rid of llc
invocation due to its simplicity.

In addition, pull Kbuild.include in order to get .DELETE_ON_ERROR target,
which would cause partial .o files to be removed.

Signed-off-by: Ilya Leoshkevich <iii@...ux.ibm.com>
---
v1->v2: use intermediate targets instead of pipefail
v2->v3: pipe "clang failed" instead of using intermediate targets

tools/testing/selftests/bpf/Makefile | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index e36356e2377e..e375f399b7a6 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
+include ../../../../scripts/Kbuild.include
 
 LIBDIR := ../../../lib
 BPFDIR := $(LIBDIR)/bpf
@@ -185,8 +186,8 @@ $(ALU32_BUILD_DIR)/test_progs_32: prog_tests/*.c
 
 $(ALU32_BUILD_DIR)/%.o: progs/%.c $(ALU32_BUILD_DIR) \
 					$(ALU32_BUILD_DIR)/test_progs_32
-	$(CLANG) $(CLANG_FLAGS) \
-		 -O2 -target bpf -emit-llvm -c $< -o - |      \
+	($(CLANG) $(CLANG_FLAGS) -O2 -target bpf -emit-llvm -c $< -o - || \
+		echo "clang failed") | \
 	$(LLC) -march=bpf -mattr=+alu32 -mcpu=$(CPU) $(LLC_FLAGS) \
 		-filetype=obj -o $@
 ifeq ($(DWARF2BTF),y)
@@ -197,16 +198,16 @@ endif
 # Have one program compiled without "-target bpf" to test whether libbpf loads
 # it successfully
 $(OUTPUT)/test_xdp.o: progs/test_xdp.c
-	$(CLANG) $(CLANG_FLAGS) \
-		-O2 -emit-llvm -c $< -o - | \
+	($(CLANG) $(CLANG_FLAGS) -O2 -emit-llvm -c $< -o - || \
+		echo "clang failed") | \
 	$(LLC) -march=bpf -mcpu=$(CPU) $(LLC_FLAGS) -filetype=obj -o $@
 ifeq ($(DWARF2BTF),y)
 	$(BTF_PAHOLE) -J $@
 endif
 
 $(OUTPUT)/%.o: progs/%.c
-	$(CLANG) $(CLANG_FLAGS) \
-		 -O2 -target bpf -emit-llvm -c $< -o - |      \
+	($(CLANG) $(CLANG_FLAGS) -O2 -target bpf -emit-llvm -c $< -o - || \
+		echo "clang failed") | \
 	$(LLC) -march=bpf -mcpu=$(CPU) $(LLC_FLAGS) -filetype=obj -o $@
 ifeq ($(DWARF2BTF),y)
 	$(BTF_PAHOLE) -J $@
-- 
2.21.0