From 436b2ac603d58504f38041a0cd8adb5aeace992b Mon Sep 17 00:00:00 2001
From: Masahiro Yamada <masahiroy@kernel.org>
Date: Mon, 1 Jun 2020 14:57:12 +0900
Subject: modpost: invoke modpost only when input files are updated

Currently, the second pass of modpost is always invoked when you run
'make' or 'make modules' even if none of modules is changed.

Use if_changed to invoke it only when it is necessary.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---
 scripts/Makefile.modpost | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

(limited to 'scripts/Makefile.modpost')

diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index 896c799911c5..f29a02196b72 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -90,7 +90,7 @@ endif
 
 # modpost options for modules (both in-kernel and external)
 MODPOST += \
-	$(addprefix -i ,$(input-symdump)) \
+	$(addprefix -i ,$(wildcard $(input-symdump))) \
 	$(if $(CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS)$(KBUILD_NSDEPS),-N)
 
 # 'make -i -k' ignores compile errors, and builds as many modules as possible.
@@ -98,13 +98,18 @@ ifneq ($(findstring i,$(filter-out --%,$(MAKEFLAGS))),)
 MODPOST += -n
 endif
 
+$(input-symdump):
+	@:
+
 # Read out modules.order to pass in modpost.
 # Otherwise, allmodconfig would fail with "Argument list too long".
 quiet_cmd_modpost = MODPOST $@
-      cmd_modpost = sed 's/ko$$/o/' $(MODORDER) | $(MODPOST) -T -
+      cmd_modpost = sed 's/ko$$/o/' $< | $(MODPOST) -T -
 
-$(output-symdump): FORCE
-	$(call cmd,modpost)
+$(output-symdump): $(MODORDER) $(input-symdump) FORCE
+	$(call if_changed,modpost)
+
+targets += $(output-symdump)
 
 __modpost: $(output-symdump)
 ifneq ($(KBUILD_MODPOST_NOFINAL),1)
@@ -114,6 +119,13 @@ endif
 PHONY += FORCE
 FORCE:
 
+existing-targets := $(wildcard $(sort $(targets)))
+
+-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
+
+PHONY += FORCE
+FORCE:
+
 endif
 
 .PHONY: $(PHONY)
-- 
cgit