Re: [PATCH] asm-generic/ioctl.h: use BUILD_BUG_ON_ZERO() for type check
From: Arnd Bergmann
Date: Wed Feb 24 2021 - 03:44:12 EST
On Wed, Feb 24, 2021 at 2:57 AM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
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On Wed, Feb 24, 2021 at 5:04 AM Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
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> On Tue, Feb 23, 2021 at 11:06 AM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
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My intention is to improve the UAPI/KAPI decoupling
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to decrease the task of scripts/headers_install.sh
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Ideally, we could export UAPI headers with
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almost no modification.
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It is true that scripts/unifdef can remove #ifndef __KERNEL__
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blocks, but having the kernel-space code in UAPI headers
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does not make sense. Otherwise, our initial motivation
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"separate them by directory structure" would be lost.
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So, I believe redefining _IOC_TYPECHECK is the right direction.
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I can add comments if this is not clear.
Maybe using '#ifndef _IOC_TYPECHECK' would help here?
Another alternative might be to find a way to rewrite the typecheck
macro to make it safe to be used in user space as well, and not
have two different versions.
Arnd