Some UAPI headers included <stdlib.h>, like this: #ifndef __KERNEL__ #include <stdlib.h> #endif As it turned out, they just included it for no good reason. After some fixes, now I can compile-test UAPI headers (CONFIG_UAPI_HEADER_TEST=y) without including <stdlib.h> from the system header search paths. To avoid somebody getting it back again, this commit adds the dummy header, usr/dummy-include/stdlib.h I added $(srctree)/usr/dummy-include to the header search paths. Because it is searched before the system directories, if someone tries to include <stdlib.h>, they will see the error message. While I am here, I also replaced $(objtree)/usr/include with $(obj), but it has no functional change. If we can make kernel headers self-contained (that is, none of exported kernel headers includes system headers), we will be able to add the -nostdinc flag, but that is much far from where we stand now. As a realistic solution, we can ban header inclusion individually by putting a dummy header into usr/dummy-include/. Currently, no header include <stdbool.h>. I put it as well before somebody attempts to use it. Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- usr/dummy-include/stdbool.h | 7 +++++++ usr/dummy-include/stdlib.h | 7 +++++++ usr/include/Makefile | 2 +- 3 files changed, 15 insertions(+), 1 deletion(-) create mode 100644 usr/dummy-include/stdbool.h create mode 100644 usr/dummy-include/stdlib.h diff --git a/usr/dummy-include/stdbool.h b/usr/dummy-include/stdbool.h new file mode 100644 index 000000000000..54ff9e9c90ac --- /dev/null +++ b/usr/dummy-include/stdbool.h @@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef _STDBOOL_H +#define _STDBOOL_H + +#error "Please do not include <stdbool.h> from exported headers" + +#endif /* _STDBOOL_H */ diff --git a/usr/dummy-include/stdlib.h b/usr/dummy-include/stdlib.h new file mode 100644 index 000000000000..e8c21888e371 --- /dev/null +++ b/usr/dummy-include/stdlib.h @@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef _STDLIB_H +#define _STDLIB_H + +#error "Please do not include <stdlib.h> from exported headers" + +#endif /* _STDLIB_H */ diff --git a/usr/include/Makefile b/usr/include/Makefile index fa9819e022b7..7740777b49f8 100644 --- a/usr/include/Makefile +++ b/usr/include/Makefile @@ -15,7 +15,7 @@ UAPI_CFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS)) # USERCFLAGS might contain sysroot location for CC. UAPI_CFLAGS += $(USERCFLAGS) -override c_flags = $(UAPI_CFLAGS) -Wp,-MMD,$(depfile) -I$(objtree)/usr/include +override c_flags = $(UAPI_CFLAGS) -Wp,-MMD,$(depfile) -I $(obj) -I $(srctree)/usr/dummy-include # The following are excluded for now because they fail to build. # -- 2.32.0
