| Message ID | 20220328172130.197319-2-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] agpgart.h: do not include <stdlib.h> from exported header | expand |
On Tue, Mar 29, 2022 at 02:21:30AM +0900, Masahiro Yamada wrote: > 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 <stdlib.h> included. > > 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 is just a small refactoring. > > If we achieve the situation where none of system headers is included > from exported kernel headers (i.e. kernel headers become self-contained), > we might be able to add -nostdinc, but that is much far from where we > stand now. (see many no-header-test lines in usr/include/Makefile) > > As a realistic solution, you can forbid 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@kernel.org> Nice work! Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
On Tue, Mar 29, 2022 at 3:04 PM Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > On Tue, Mar 29, 2022 at 02:21:30AM +0900, Masahiro Yamada wrote: > > 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 <stdlib.h> included. > > > > 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 is just a small refactoring. > > > > If we achieve the situation where none of system headers is included > > from exported kernel headers (i.e. kernel headers become self-contained), > > we might be able to add -nostdinc, but that is much far from where we > > stand now. (see many no-header-test lines in usr/include/Makefile) > > > > As a realistic solution, you can forbid 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@kernel.org> > > Nice work! > > Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> I made a mistake in the patch subject. The correct title should be: kbuild: forbid exported headers from including <stdlib.h>, <stdbool.h> I will fix it in v2. We cannot ban <stdint.h> for now because there are still some users. A fix-up patch exists, but the fuse maintainer was opposed to it. https://lore.kernel.org/lkml/20220318171405.2728855-1-cmllamas@google.com/
On Tue, Mar 29, 2022 at 04:16:02PM +0900, Masahiro Yamada wrote: > On Tue, Mar 29, 2022 at 3:04 PM Greg Kroah-Hartman > <gregkh@linuxfoundation.org> wrote: > > > > On Tue, Mar 29, 2022 at 02:21:30AM +0900, Masahiro Yamada wrote: > > > 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 <stdlib.h> included. > > > > > > 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 is just a small refactoring. > > > > > > If we achieve the situation where none of system headers is included > > > from exported kernel headers (i.e. kernel headers become self-contained), > > > we might be able to add -nostdinc, but that is much far from where we > > > stand now. (see many no-header-test lines in usr/include/Makefile) > > > > > > As a realistic solution, you can forbid 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@kernel.org> > > > > Nice work! > > > > Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > I made a mistake in the patch subject. > > The correct title should be: > > kbuild: forbid exported headers from including <stdlib.h>, <stdbool.h> > > I will fix it in v2. Ah, missed that, yes. > We cannot ban <stdint.h> for now because there are still some users. > > A fix-up patch exists, but the fuse maintainer was opposed to it. > https://lore.kernel.org/lkml/20220318171405.2728855-1-cmllamas@google.com/ It's not ok for one lone file to break the rules that all other uapi header files follow. I think that needs to be fixed, there is NOTHING special about that one subsystem to justify this. Uniformity is good, and should be followed, and I strongly think that change needs to be accepted. thanks, greg k-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. #
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 <stdlib.h> included. 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 is just a small refactoring. If we achieve the situation where none of system headers is included from exported kernel headers (i.e. kernel headers become self-contained), we might be able to add -nostdinc, but that is much far from where we stand now. (see many no-header-test lines in usr/include/Makefile) As a realistic solution, you can forbid 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@kernel.org> --- 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