selftests: kallsyms: fix double build stupidity

The current arrangement will have the test modules rebuilt on
any make without having the script or code actually change.
Take Masahiro Yamada's suggested fix and cleanups on the Makefile
to fix this.

Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: 84b4a51fce4ccc66 ("selftests: add new kallsyms selftests")
Closes: https://lore.kernel.org/all/CAK7LNATRDODmfz1tE=inV-DQqPA4G9vKH+38zMbaGdpTuFWZFw@mail.gmail.com/T/#me6c8f98e82acbee6e75a31b34bbb543eb4940b15
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

diff --git a/lib/tests/module/Makefile b/lib/tests/module/Makefile
index af5c27b996cb15d2f48218755b3ea3d81ffd7280..2f3e1a772c2c4a4205a10825a408eb98227e989d 100644 (file)
--- a/lib/tests/module/Makefile
+++ b/lib/tests/module/Makefile
@@ -3,13 +3,12 @@ obj-$(CONFIG_TEST_KALLSYMS_B) += test_kallsyms_b.o
 obj-$(CONFIG_TEST_KALLSYMS_C) += test_kallsyms_c.o
 obj-$(CONFIG_TEST_KALLSYMS_D) += test_kallsyms_d.o
 
-$(obj)/%.c: FORCE
-       @$(kecho) "  GEN     $@"
-       $(Q)$(srctree)/lib/tests/module/gen_test_kallsyms.sh $@\
-               $(CONFIG_TEST_KALLSYMS_NUMSYMS) \
-               $(CONFIG_TEST_KALLSYMS_SCALE_FACTOR)
+quiet_cmd_gen_test_kallsyms = GEN     $@
+       cmd_gen_test_kallsyms = $< $@ \
+       $(CONFIG_TEST_KALLSYMS_NUMSYMS) \
+       $(CONFIG_TEST_KALLSYMS_SCALE_FACTOR)
 
-clean-files += test_kallsyms_a.c
-clean-files += test_kallsyms_b.c
-clean-files += test_kallsyms_c.c
-clean-files += test_kallsyms_d.c
+$(obj)/%.c: $(src)/gen_test_kallsyms.sh FORCE
+       $(call if_changed,gen_test_kallsyms)
+
+targets += $(foreach x, a b c d, test_kallsyms_$(x).c)