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From: Al Viro <viro@zeniv.linux.org.uk>
To: tanzirh@google.com
Cc: Kees Cook <keescook@chromium.org>,
	Andy Shevchenko <andy@kernel.org>,
	linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
	Nick DeSaulniers <nnn@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	llvm@lists.linux.dev
Subject: Re: [PATCH] lib/string: shrink lib/string.i via IWYU
Date: Tue, 5 Dec 2023 21:57:29 +0000	[thread overview]
Message-ID: <20231205215729.GG1674809@ZenIV> (raw)
In-Reply-To: <20231205213807.GE1674809@ZenIV>

On Tue, Dec 05, 2023 at 09:38:07PM +0000, Al Viro wrote:

> It also breeds includes of asm/*.h, by the look of the output, which is
> not a good thing in general ;-/  E.g. #include <asm/uaccess.h> *anywhere*
> outside of linux/uaccess.h is a bad idea.

Let me elaborate a bit:

Consider e.g. a situation when we have linux/foo.h pulling asm/foo.h;
among the things declared there is foo_bar(), which is identical in
18 instances of asm/foo.h (out of current 21).

At some point we notice that; the obvious approach would be to have
3 unusual architectures have their asm/foo.h define _ARCH_HAS_ODD_FOO_BAR
and put the common variant in linux/foo.h under ifndef _ARCH_HAS_ODD_FOO_BAR.

Except that any file that pulls asm/foo.h will get broken by that.
And something like your tool might convert the users of linux/foo.h to
asm/foo.h - all it takes is using only the primitives that currently
happen to be in asm/foo.h on all architectures.

This is not an artifical example, BTW - look at the history of uaccess.h and
checksum.h...

  parent reply	other threads:[~2023-12-05 21:57 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-05 20:58 [PATCH] lib/string: shrink lib/string.i via IWYU tanzirh
2023-12-05 21:04 ` Andrew Morton
2023-12-05 21:14   ` Nick Desaulniers
2023-12-05 21:24     ` Andrew Morton
2023-12-05 21:39       ` Nick Desaulniers
2023-12-05 21:43         ` Al Viro
2023-12-05 21:57           ` Nick Desaulniers
2023-12-11 20:47           ` Nick Desaulniers
2023-12-11 20:50             ` Andy Shevchenko
2023-12-05 21:53         ` Andy Shevchenko
2023-12-05 22:05           ` Nick Desaulniers
2023-12-07  6:25         ` Christoph Hellwig
2023-12-05 21:38 ` Al Viro
2023-12-05 21:51   ` Nick Desaulniers
2023-12-05 21:59     ` Greg KH
2023-12-05 22:14       ` Nick Desaulniers
2023-12-05 23:46         ` Greg KH
2023-12-06  0:55           ` Al Viro
2023-12-06  3:00             ` Al Viro
2023-12-06  3:09               ` Greg KH
2023-12-14 21:04                 ` Al Viro
2023-12-15 21:03                   ` Al Viro
2023-12-07 12:50         ` Andy Shevchenko
2023-12-05 22:01     ` Andy Shevchenko
2023-12-05 22:10       ` Randy Dunlap
2023-12-05 22:25         ` Nick Desaulniers
2023-12-05 22:15       ` Al Viro
2023-12-05 22:20         ` Nick Desaulniers
2023-12-05 22:32         ` Al Viro
2023-12-07 12:52         ` Andy Shevchenko
2023-12-05 21:57   ` Al Viro [this message]
2023-12-05 21:50 ` Andy Shevchenko
2023-12-05 22:05 ` Andy Shevchenko
2023-12-06  7:10 ` kernel test robot
2023-12-07 12:55   ` Andy Shevchenko

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