4.19-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 9390dff66a52d1a60c6e517d8fa6cdbdffc83cb1 ]
If include/config/auto.conf.cmd is lost for some reasons, it is not self-healing, so the top Makefile misses to run syncconfig. Move include/config/auto.conf.cmd to the target side.
I used a pattern rule instead of a normal rule here although it is a bit gross.
If the rule were written with a normal rule like this,
include/config/auto.conf \ include/config/auto.conf.cmd \ include/config/tristate.conf: $(KCONFIG_CONFIG) $(Q)$(MAKE) -f $(srctree)/Makefile syncconfig
... syncconfig would be executed per target.
Using a pattern rule makes sure that syncconfig is executed just once because Make assumes the recipe will create all of the targets.
Here is a quote from the GNU Make manual [1]:
"Pattern rules may have more than one target. Unlike normal rules, this does not act as many different rules with the same prerequisites and recipe. If a pattern rule has multiple targets, make knows that the rule's recipe is responsible for making all of the targets. The recipe is executed only once to make all the targets. When searching for a pattern rule to match a target, the target patterns of a rule other than the one that matches the target in need of a rule are incidental: make worries only about giving a recipe and prerequisites to the file presently in question. However, when this file's recipe is run, the other targets are marked as having been updated themselves."
[1]: https://www.gnu.org/software/make/manual/html_node/Pattern-Intro.html
Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com Signed-off-by: Sasha Levin sashal@kernel.org --- Makefile | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/Makefile b/Makefile index 8de5fab711d8..f1a5d7deaf5f 100644 --- a/Makefile +++ b/Makefile @@ -626,12 +626,15 @@ ifeq ($(may-sync-config),1) -include include/config/auto.conf.cmd
# To avoid any implicit rule to kick in, define an empty command -$(KCONFIG_CONFIG) include/config/auto.conf.cmd: ; +$(KCONFIG_CONFIG): ;
# The actual configuration files used during the build are stored in # include/generated/ and include/config/. Update them if .config is newer than # include/config/auto.conf (which mirrors .config). -include/config/%.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd +# +# This exploits the 'multi-target pattern rule' trick. +# The syncconfig should be executed only once to make all the targets. +%/auto.conf %/auto.conf.cmd %/tristate.conf: $(KCONFIG_CONFIG) $(Q)$(MAKE) -f $(srctree)/Makefile syncconfig else # External modules and some install targets need include/generated/autoconf.h