[PATCH 5.7 163/204] selftests/bpf: Prevent runqslower from racing on building bpftool

Greg Kroah-Hartman
2020-08-20T12:52:37Z

From: Andrii Nakryiko <andriin@fb.com>

[ Upstream commit 6bcaf41f9613278cd5897fc80ab93033bda8efaa ]

runqslower's Makefile is building/installing bpftool into
$(OUTPUT)/sbin/bpftool, which coincides with $(DEFAULT_BPFTOOL). In practice
this means that often when building selftests from scratch (after `make
clean`), selftests are racing with runqslower to simultaneously build bpftool
and one of the two processes fail due to file being busy. Prevent this race by
explicitly order-depending on $(BPFTOOL_DEFAULT).

Fixes: a2c9652f751e ("selftests: Refactor build to remove tools/lib/bpf from include path")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200805004757.2960750-1-andriin@fb.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/bpf/Makefile | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index af139d0e2e0c6..666b1b786bd29 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -138,7 +138,9 @@ VMLINUX_BTF_PATHS := $(if $(O),$(O)/vmlinux) \
/boot/vmlinux-$(shell uname -r)
VMLINUX_BTF := $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))

-$(OUTPUT)/runqslower: $(BPFOBJ)
+DEFAULT_BPFTOOL := $(SCRATCH_DIR)/sbin/bpftool
+
+$(OUTPUT)/runqslower: $(BPFOBJ) | $(DEFAULT_BPFTOOL)
$(Q)$(MAKE) $(submake_extras) -C $(TOOLSDIR)/bpf/runqslower \
OUTPUT=$(SCRATCH_DIR)/ VMLINUX_BTF=$(VMLINUX_BTF) \
BPFOBJ=$(BPFOBJ) BPF_INCLUDE=$(INCLUDE_DIR) && \
@@ -160,7 +162,6 @@ $(OUTPUT)/test_netcnt: cgroup_helpers.c
$(OUTPUT)/test_sock_fields: cgroup_helpers.c
$(OUTPUT)/test_sysctl: cgroup_helpers.c

-DEFAULT_BPFTOOL := $(SCRATCH_DIR)/sbin/bpftool
BPFTOOL ?= $(DEFAULT_BPFTOOL)
$(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) \
$(BPFOBJ) | $(BUILD_DIR)/bpftool
--
2.25.1