[for-linus][PATCH 4/4] rtla: Consolidate and show all necessary libraries that failed for building

[Steven Rostedt]

From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>

When building rtla tools, if the necessary libraries are not installed
(libtraceevent and libtracefs), show the ones that are missing in one
consolidated output, and also show how to install them (at least for
Fedora).

Link: https://lore.kernel.org/all/CAHk-=wh+e1qcCnEYJ3JRDVLNCYbJ=0u+Ts5bOYZnY3mX_k-hFA@xxxxxxxxxxxxxx/
Link: https://lkml.kernel.org/r/20220810113918.5d19ce59@xxxxxxxxxxxxxxxxxx

Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
 tools/tracing/rtla/Makefile | 62 +++++++++++++++++++++----------------
 1 file changed, 36 insertions(+), 26 deletions(-)

diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile
index f392708c7a1e..22e28b76f800 100644
--- a/tools/tracing/rtla/Makefile
+++ b/tools/tracing/rtla/Makefile
@@ -61,40 +61,50 @@ endif
 LIBTRACEEVENT_MIN_VERSION = 1.5
 LIBTRACEFS_MIN_VERSION = 1.3
 
+.PHONY:	all warnings show_warnings
+all:	warnings rtla
+
 TEST_LIBTRACEEVENT = $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEEVENT_MIN_VERSION) libtraceevent > /dev/null 2>&1 || echo n")
 ifeq ("$(TEST_LIBTRACEEVENT)", "n")
-.PHONY: warning_traceevent
-warning_traceevent:
-	@echo "********************************************"
-	@echo "** NOTICE: libtraceevent version $(LIBTRACEEVENT_MIN_VERSION) or higher not found"
-	@echo "**"
-	@echo "** Consider installing the latest libtraceevent from your"
-	@echo "** distribution, e.g., 'dnf install libtraceevent' on Fedora,"
-	@echo "** or from source:"
-	@echo "**"
-	@echo "**  https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/ "
-	@echo "**"
-	@echo "********************************************"
+WARNINGS = show_warnings
+MISSING_LIBS += echo "**   libtraceevent version $(LIBTRACEEVENT_MIN_VERSION) or higher";
+MISSING_PACKAGES += "libtraceevent-devel"
+MISSING_SOURCE += echo "**  https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/ ";
 endif
 
 TEST_LIBTRACEFS = $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEFS_MIN_VERSION) libtracefs > /dev/null 2>&1 || echo n")
 ifeq ("$(TEST_LIBTRACEFS)", "n")
-.PHONY: warning_tracefs
-warning_tracefs:
-	@echo "********************************************"
-	@echo "** NOTICE: libtracefs version $(LIBTRACEFS_MIN_VERSION) or higher not found"
-	@echo "**"
-	@echo "** Consider installing the latest libtracefs from your"
-	@echo "** distribution, e.g., 'dnf install libtracefs' on Fedora,"
-	@echo "** or from source:"
-	@echo "**"
-	@echo "**  https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ "
-	@echo "**"
-	@echo "********************************************"
+WARNINGS = show_warnings
+MISSING_LIBS += echo "**   libtracefs version $(LIBTRACEFS_MIN_VERSION) or higher";
+MISSING_PACKAGES += "libtracefs-devel"
+MISSING_SOURCE += echo "**  https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ ";
 endif
 
-.PHONY:	all
-all:	rtla
+define show_dependencies
+	@echo "********************************************";				\
+	echo "** NOTICE: Failed build dependencies";					\
+	echo "**";									\
+	echo "** Required Libraries:";							\
+	$(MISSING_LIBS)									\
+	echo "**";									\
+	echo "** Consider installing the latest libtracefs from your";			\
+	echo "** distribution, e.g., 'dnf install $(MISSING_PACKAGES)' on Fedora,";	\
+	echo "** or from source:";							\
+	echo "**";									\
+	$(MISSING_SOURCE)								\
+	echo "**";									\
+	echo "********************************************"
+endef
+
+show_warnings:
+	$(call show_dependencies);
+
+ifneq ("$(WARNINGS)", "")
+ERROR_OUT = $(error Please add the necessary dependencies)
+
+warnings: $(WARNINGS)
+	$(ERROR_OUT)
+endif
 
 rtla: $(OBJ)
 	$(CC) -o rtla $(LDFLAGS) $(OBJ) $(LIBS)
-- 
2.35.1