tools/bpf/runqslower: Fix override option for VMLINUX_BTF (a835d38d) · Commits · 戴 / test

The runqslower tool refuses to build without a file to read vmlinux BTF from. The build fails with an error message to override the location by setting the VMLINUX_BTF variable if autodetection fails. However, the Makefile doesn't actually work with that override - the error message is still emitted. Fix this by including the value of VMLINUX_BTF in the expansion, and only emitting the error message if the *result* is empty. Also permit running 'make clean' even though no VMLINUX_BTF is set. Fixes: ("tools/bpf: Add runqslower tool to tools/bpf") Signed-off-by:

Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by:

Alexei Starovoitov <ast@kernel.org> Acked-by:

Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/157952560237.1683545.17771785178857224877.stgit@toke.dk

tools/bpf/runqslower/Makefile

+10 −9

Original line number	Diff line number	Diff line
		@@ -10,13 +10,9 @@ CFLAGS := -g -Wall

		# Try to detect best kernel BTF source
		KERNEL_REL := $(shell uname -r)
		ifneq ("$(wildcard /sys/kernel/btf/vmlinux)","")
		VMLINUX_BTF := /sys/kernel/btf/vmlinux
		else ifneq ("$(wildcard /boot/vmlinux-$(KERNEL_REL))","")
		VMLINUX_BTF := /boot/vmlinux-$(KERNEL_REL)
		else
		$(error "Can't detect kernel BTF, use VMLINUX_BTF to specify it explicitly")
		endif
		VMLINUX_BTF_PATHS := /sys/kernel/btf/vmlinux /boot/vmlinux-$(KERNEL_REL)
		VMLINUX_BTF_PATH := $(or $(VMLINUX_BTF),$(firstword \
		$(wildcard $(VMLINUX_BTF_PATHS))))

		abs_out := $(abspath $(OUTPUT))
		ifeq ($(V),1)
		@@ -67,9 +63,14 @@ $(OUTPUT):
		$(call msg,MKDIR,$@)
		$(Q)mkdir -p $(OUTPUT)

		$(OUTPUT)/vmlinux.h: $(VMLINUX_BTF) \| $(OUTPUT) $(BPFTOOL)
		$(OUTPUT)/vmlinux.h: $(VMLINUX_BTF_PATH) \| $(OUTPUT) $(BPFTOOL)
		$(call msg,GEN,$@)
		$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
		$(Q)if [ ! -e "$(VMLINUX_BTF_PATH)" ] ; then \
		echo "Couldn't find kernel BTF; set VMLINUX_BTF to" \
		"specify its location." >&2; \
		exit 1;\
		fi
		$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@

		$(OUTPUT)/libbpf.a: \| $(OUTPUT)
		$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) \

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