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authorMasahiro Yamada <masahiroy@kernel.org>2022-04-04 15:19:42 +0900
committerArnd Bergmann <arnd@arndb.de>2022-05-13 10:56:10 +0200
commit02a6e4be2ff44344f58b078c18dc3ab3877fcfe5 (patch)
tree386a0581ce2dd8e4b1d456666f9007f54c90638f /usr/dummy-include/stdlib.h
parent783eb354fb3dcd598e8e7e8a2ed88c0fb6ce5d2f (diff)
kbuild: prevent exported headers from including <stdlib.h>, <stdbool.h>
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@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'usr/dummy-include/stdlib.h')
-rw-r--r--usr/dummy-include/stdlib.h7
1 files changed, 7 insertions, 0 deletions
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 */