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>

diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index 896c799911c5fd54c384ace69187040d5132b56b..f29a02196b7261cd6b332c4d70118abcccdc74b7 100644 (file)
--- 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)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 4a2f27d97bf172509018a3db8319aaf1e1d5299f..b839c48689dff7c8e0cec94aeb38f8377c23a06a 100644 (file)
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2375,6 +2375,25 @@ static void add_srcversion(struct buffer *b, struct module *mod)
        }
 }
 
+static void write_buf(struct buffer *b, const char *fname)
+{
+       FILE *file;
+
+       file = fopen(fname, "w");
+       if (!file) {
+               perror(fname);
+               exit(1);
+       }
+       if (fwrite(b->p, 1, b->pos, file) != b->pos) {
+               perror(fname);
+               exit(1);
+       }
+       if (fclose(file) != 0) {
+               perror(fname);
+               exit(1);
+       }
+}
+
 static void write_if_changed(struct buffer *b, const char *fname)
 {
        char *tmp;
@@ -2407,16 +2426,7 @@ static void write_if_changed(struct buffer *b, const char *fname)
  close_write:
        fclose(file);
  write:
-       file = fopen(fname, "w");
-       if (!file) {
-               perror(fname);
-               exit(1);
-       }
-       if (fwrite(b->p, 1, b->pos, file) != b->pos) {
-               perror(fname);
-               exit(1);
-       }
-       fclose(file);
+       write_buf(b, fname);
 }
 
 /* parse Module.symvers file. line format:
@@ -2508,7 +2518,7 @@ static void write_dump(const char *fname)
                        symbol = symbol->next;
                }
        }
-       write_if_changed(&buf, fname);
+       write_buf(&buf, fname);
        free(buf.p);
 }