[PATCH 1/3] tools/tracing: Use tools/build makefiles on latency-collector

[Daniel Bristot de Oliveira <bristot@kernel.org>]

Use tools/build/ makefiles to build latency-collector, inheriting
the benefits of it. For example, having a proper way to
handle dependencies.

Inspired on perf and objtool.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
---
 tools/tracing/latency/.gitignore      |  1 +
 tools/tracing/latency/Build           |  1 +
 tools/tracing/latency/Makefile        | 48 +++++++++++++++++----------
 tools/tracing/latency/Makefile.config | 28 ++++++++++++++++
 4 files changed, 61 insertions(+), 17 deletions(-)
 create mode 100644 tools/tracing/latency/Build
 create mode 100644 tools/tracing/latency/Makefile.config

diff --git a/tools/tracing/latency/.gitignore b/tools/tracing/latency/.gitignore
index 0863960761e7..11490d9da0b3 100644
--- a/tools/tracing/latency/.gitignore
+++ b/tools/tracing/latency/.gitignore
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0
 latency-collector
+FEATURE-DUMP
diff --git a/tools/tracing/latency/Build b/tools/tracing/latency/Build
new file mode 100644
index 000000000000..0ce65ea72bf9
--- /dev/null
+++ b/tools/tracing/latency/Build
@@ -0,0 +1 @@
+latency-collector-y += latency-collector.o
diff --git a/tools/tracing/latency/Makefile b/tools/tracing/latency/Makefile
index 40c4ddaf8be1..3a2b5e8f5997 100644
--- a/tools/tracing/latency/Makefile
+++ b/tools/tracing/latency/Makefile
@@ -1,24 +1,38 @@
 # SPDX-License-Identifier: GPL-2.0
-# Makefile for vm tools
-#
-VAR_CFLAGS := $(shell pkg-config --cflags libtracefs 2>/dev/null)
-VAR_LDLIBS := $(shell pkg-config --libs libtracefs 2>/dev/null)
+export srctree := $(abspath ../../..)
+export CC      := gcc
+export LD      := ld
+export AR      := ar
+export PKG_CONFIG := pkg-config
 
-TARGETS = latency-collector
-CFLAGS = -Wall -Wextra -g -O2 $(VAR_CFLAGS)
-LDFLAGS = -lpthread $(VAR_LDLIBS)
+FEATURE_TESTS := libtraceevent
+FEATURE_TESTS += libtracefs
+FEATURE_DISPLAY := libtraceevent
+FEATURE_DISPLAY += libtracefs
 
-all: $(TARGETS)
+latency-collector:
 
-%: %.c
-	$(CC) $(CFLAGS) -o $@ $< $(LDFLAGS)
+include $(srctree)/tools/build/Makefile.include
+include $(srctree)/tools/build/Makefile.feature
+include $(srctree)/tools/scripts/Makefile.include
+include Makefile.config
 
-clean:
-	$(RM) latency-collector
+CFLAGS += $(INCLUDES) $(LIB_INCLUDES)
+
+export CFLAGS := $(CFLAGS)
+
+latency-collector: latency-collector-in.o
+	$(QUIET_LINK)$(CC) $(LDFLAGS) -o $@ $^ $(EXTLIBS)
 
-prefix ?= /usr/local
-sbindir ?= ${prefix}/sbin
+latency-collector.%: fixdep FORCE
+	make -f $(srctree)/tools/build/Makefile.build dir=. $@
+
+latency-collector-in.o: fixdep FORCE
+	make $(build)=latency-collector
+
+clean:
+	$(call QUIET_CLEAN, latency-collector)
+	@find . -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
+	@rm -f latency-collector FEATURE-DUMP
 
-install: all
-	install -d $(DESTDIR)$(sbindir)
-	install -m 755 -p $(TARGETS) $(DESTDIR)$(sbindir)
+.PHONY: FORCE clean
diff --git a/tools/tracing/latency/Makefile.config b/tools/tracing/latency/Makefile.config
new file mode 100644
index 000000000000..5100d89346ab
--- /dev/null
+++ b/tools/tracing/latency/Makefile.config
@@ -0,0 +1,28 @@
+STOP_ERROR :=
+
+define lib_setup
+  $(eval EXTLIBS += -l$(1))
+  $(eval LIB_INCLUDES += $(shell sh -c "$(PKG_CONFIG) --cflags lib$(1)"))
+endef
+
+$(call feature_check,libtraceevent)
+ifeq ($(feature-libtraceevent), 1)
+  $(call detected,CONFIG_LIBTRACEEVENT)
+  $(call lib_setup,traceevent)
+else
+  STOP_ERROR := 1
+  $(info libtraceevent is missing. Please install libtraceevent-dev/libtraceevent-devel)
+endif
+
+$(call feature_check,libtracefs)
+ifeq ($(feature-libtracefs), 1)
+  $(call detected,CONFIG_LIBTRACEFS)
+  $(call lib_setup,tracefs)
+else
+  STOP_ERROR := 1
+  $(info libtracefs is missing. Please install libtracefs-dev/libtracefs-devel)
+endif
+
+ifeq ($(STOP_ERROR),1)
+  $(error Please, check the errors above.)
+endif
-- 
2.44.0