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Date:   Sun, 22 Apr 2018 21:41:50 -1000
From:   Joey Pabalinas <joeypabalinas@gmail.com>
To:     Luciano Coelho <luciano.coelho@intel.com>
Cc:     Kalle Valo <kvalo@codeaurora.org>,
        Joey Pabalinas <joeypabalinas@gmail.com>,
        Kees Cook <keescook@chromium.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org
Subject: Re: New sparse warning from min_t(): expression using sizeof(void)
Message-ID: <20180423074150.cc4nrr4ogfql43fx@gmail.com>
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On Mon, Apr 23, 2018 at 09:20:14AM +0300, Luciano Coelho wrote:
> Thanks, this solves the problem for me, but I'm still getting a lot of
> this:
>=20
> ./include/linux/mm.h:533:24: warning: constant 0xffffc90000000000 is so b=
ig it is unsigned long
>=20
> Is there a patch in sparse to solve this one as well? Or is this an
> actual error that must be fixed in mm.h?

This is definitely a valid warning in the general case (integer promotion
rules can cause *incredibly* difficult to find bugs if you overlook them,
so it's very useful to get a warning when a promotion occurs implicitly to
integer constants).

In this case though, you are comparing it against `unsigned long addr`
which is exactly the same type, so there's no bug.

It could possibly be argued that in:

> arch/x86/include/asm/pgtable_64_types.h:122: # define VMALLOC_START __VMA=
LLOC_BASE_L4
> arch/x86/include/asm/pgtable_64_types.h:108: #define __VMALLOC_BASE_L4 0x=
ffffc90000000000

__VMALLOC_BASE_L4 would be better written as 0xffffc90000000000UL, which wo=
uld
indeed shut up sparse.

--=20
Cheers,
Joey Pabalinas

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