tools/resolve_btfids: Check objects before removing

[ Upstream commit f231309 ]

We want this clean to be called from tree's root clean
and that one is silent if there's nothing to clean.

Adding check for all object to clean and display CLEAN
messages only if there are objects to remove.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210205124020.683286-3-jolsa@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

tools/bpf/resolve_btfids/Makefile

@@ -64,13 +64,20 @@ $(BINARY): $(BPFOBJ) $(SUBCMDOBJ) $(BINARY_IN)
 	$(call msg,LINK,$@)
 	$(Q)$(CC) $(BINARY_IN) $(LDFLAGS) -o $@ $(BPFOBJ) $(SUBCMDOBJ) $(LIBS)
 
+clean_objects := $(wildcard $(OUTPUT)/*.o                \
+                            $(OUTPUT)/.*.o.cmd           \
+                            $(OUTPUT)/.*.o.d             \
+                            $(OUTPUT)/libbpf             \
+                            $(OUTPUT)/libsubcmd          \
+                            $(OUTPUT)/resolve_btfids)
+
+ifneq ($(clean_objects),)
 clean: fixdep-clean
 	$(call msg,CLEAN,$(BINARY))
-	$(Q)$(RM) -f $(BINARY); \
-	$(RM) -rf $(if $(OUTPUT),$(OUTPUT),.)/feature; \
-	$(RM) -rf $(OUTPUT)/libbpf; \
-	$(RM) -rf $(OUTPUT)/libsubcmd; \
-	find $(if $(OUTPUT),$(OUTPUT),.) -name \*.o -or -name \*.o.cmd -or -name \*.o.d | xargs $(RM)
+	$(Q)$(RM) -rf $(clean_objects)
+else
+clean:
+endif
 
 tags:
 	$(call msg,GEN,,tags)