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From: Andrii Nakryiko <andriin@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
	<daniel@iogearbox.net>
Cc: <andrii.nakryiko@gmail.com>, <kernel-team@fb.com>,
	Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH bpf] selftests/bpf: prevent runqslower from racing on building bpftool
Date: Tue, 4 Aug 2020 17:47:57 -0700	[thread overview]
Message-ID: <20200805004757.2960750-1-andriin@fb.com> (raw)

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>
---
 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 e7a8cf83ba48..48425f9251b5 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -142,7 +142,9 @@ 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) &&	\
@@ -164,7 +166,6 @@ $(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
-- 
2.24.1


             reply	other threads:[~2020-08-05  0:48 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-05  0:47 Andrii Nakryiko [this message]
2020-08-06  6:27 ` [PATCH bpf] selftests/bpf: prevent runqslower from racing on building bpftool John Fastabend
2020-08-06 23:38   ` Alexei Starovoitov

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