linux-kernel - Re: [PATCH v6 2/2] lib: make a test module with set/clear bit

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Date:   Wed, 15 Apr 2020 17:46:23 +0300
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     Jesse Brandeburg <jesse.brandeburg@...el.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux@...musvillemoes.dk,
        dan.j.williams@...el.com, peterz@...radead.org
Subject: Re: [PATCH v6 2/2] lib: make a test module with set/clear bit

On Tue, Mar 10, 2020 at 03:17:47PM -0700, Jesse Brandeburg wrote:
> Test some bit clears/sets to make sure assembly doesn't change, and
> that the set_bit and clear_bit functions work and don't cause sparse
> warnings.
> 
> Instruct Kbuild to build this file with extra warning level -Wextra,
> to catch new issues, and also doesn't hurt to build with C=1.
> 
> This was used to test changes to arch/x86/include/asm/bitops.h.
> 
> In particular, sparse (C=1) was very concerned when the last bit
> before a natural boundary, like 7, or 31, was being tested, as this
> causes sign extension (0xffffff7f) for instance when clearing bit 7.
> 
> Recommended usage:
> make defconfig
> scripts/config -m CONFIG_TEST_BITOPS
> make modules_prepare
> make C=1 W=1 lib/test_bitops.ko
> objdump -S -d lib/test_bitops.ko
> insmod lib/test_bitops.ko
> rmmod lib/test_bitops.ko
> <check dmesg>, there should be no compiler/sparse warnings and no
> error messages in log.

Seems this didn't make the kernel. Perhaps you need to send it to Andrew Morton.

-- 
With Best Regards,
Andy Shevchenko