On Sat, 18 May 2019, Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> wrote: > On Fri, May 17, 2019 at 4:48 AM Jani Nikula <jani.nikula@xxxxxxxxx> wrote: >> >> Sometimes it's useful to be able to explicitly ensure certain headers >> remain self-contained, i.e. that they are compilable as standalone >> units, by including and/or forward declaring everything they depend on. >> >> Add special target header-test-y where individual Makefiles can add >> headers to be tested if CONFIG_HEADER_TEST is enabled. This will >> generate a dummy C file per header that gets built as part of extra-y. >> >> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> >> Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> >> Cc: Michal Marek <michal.lkml@xxxxxxxxxxx> >> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> >> --- >> Documentation/kbuild/makefiles.txt | 7 +++++++ >> init/Kconfig | 9 +++++++++ >> scripts/Makefile.build | 10 ++++++++++ >> scripts/Makefile.lib | 3 +++ >> 4 files changed, 29 insertions(+) >> >> diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt >> index 03c065855eaf..73df58e5ea0c 100644 >> --- a/Documentation/kbuild/makefiles.txt >> +++ b/Documentation/kbuild/makefiles.txt >> @@ -1036,6 +1036,13 @@ When kbuild executes, the following steps are followed (roughly): >> In this example, extra-y is used to list object files that >> shall be built, but shall not be linked as part of built-in.a. >> >> + header-test-y >> + >> + header-test-y specifies headers (*.h) in the current directory that >> + should be compile tested to ensure they are self-contained, >> + i.e. compilable as standalone units. If CONFIG_HEADER_TEST is enabled, >> + this autogenerates dummy sources to include the headers, and builds them >> + as part of extra-y. >> >> --- 6.7 Commands useful for building a boot image >> >> diff --git a/init/Kconfig b/init/Kconfig >> index 4592bf7997c0..d91b157201b1 100644 >> --- a/init/Kconfig >> +++ b/init/Kconfig >> @@ -95,6 +95,15 @@ config COMPILE_TEST >> here. If you are a user/distributor, say N here to exclude useless >> drivers to be distributed. >> >> +config HEADER_TEST >> + bool "Compile test headers that should be standalone compilable" >> + help >> + Compile test headers listed in header-test-y target to ensure they are >> + self-contained, i.e. compilable as standalone units. >> + >> + If you are a developer or tester and want to ensure the requested >> + headers are self-contained, say Y here. Otherwise, choose N. >> + >> config LOCALVERSION >> string "Local version - append to kernel release" >> help >> diff --git a/scripts/Makefile.build b/scripts/Makefile.build >> index 76ca30cc4791..4d4bf698467a 100644 >> --- a/scripts/Makefile.build >> +++ b/scripts/Makefile.build >> @@ -291,6 +291,16 @@ quiet_cmd_cc_lst_c = MKLST $@ >> $(obj)/%.lst: $(src)/%.c FORCE >> $(call if_changed_dep,cc_lst_c) >> >> +# Dummy C sources for header test (header-test-y target) >> +# --------------------------------------------------------------------------- >> + >> +quiet_cmd_header_test = HDRTEST $@ >> + cmd_header_test = echo "\#include \"$(<F)\"" > $@ >> + >> +# FIXME: would be nice to be able to limit this implicit rule to header-test-y >> +$(obj)/%.header_test.c: $(src)/%.h FORCE >> + $(call if_changed,header_test) >> + >> # Compile assembler sources (.S) >> # --------------------------------------------------------------------------- >> >> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib >> index 8a1f64f17740..c2839de06485 100644 >> --- a/scripts/Makefile.lib >> +++ b/scripts/Makefile.lib >> @@ -66,6 +66,9 @@ extra-y += $(patsubst %.dtb,%.dt.yaml, $(dtb-y)) >> extra-$(CONFIG_OF_ALL_DTBS) += $(patsubst %.dtb,%.dt.yaml, $(dtb-)) >> endif >> >> +# Test self-contained headers >> +extra-$(CONFIG_HEADER_TEST) += $(patsubst %.h,%.header_test.o,$(header-test-y)) >> + >> # Add subdir path >> >> extra-y := $(addprefix $(obj)/,$(extra-y)) >> -- >> 2.20.1 >> > > > Thanks, probably we should do this. > > At least, this check will be useful > for uapi headers since the kernel does not > test the self-containedness of > exported headers, (then turned out be problematic > later in user-space). > > I will take a little time to considier > how far we can extend the idea about > "headers should be self-contained". Thanks! Please let me know if/when you need further action from me, I won't post new versions until then. BR, Jani. -- Jani Nikula, Intel Open Source Graphics Center
