[linux-next:master 775/10756] drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: chip_good.isra.11() falls through to next function put_chip.isra.15()

[linux-next:master 775/10756] drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: chip_good.isra.11() falls through to next function put_chip.isra.15()

[kbuild test robot]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   41539ebf9bacf9a9102322ad944990f5a38f5538
commit: e75a6795ed132f26f69d08dea958630d5993056d [775/10756] locking/atomics, kcsan: Add KCSAN instrumentation
config: x86_64-randconfig-s2-20200124 (attached as .config)
compiler: gcc-4.9 (Debian 4.9.2-10+deb8u1) 4.9.2
reproduce:
        git checkout e75a6795ed132f26f69d08dea958630d5993056d
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: chip_ready.isra.10() falls through to next function cfi_amdstd_panic_wait()
>> drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: chip_good.isra.11() falls through to next function put_chip.isra.15()

---
0-DAY kernel test infrastructure                 Open Source Technology Center
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org Intel Corporation

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Re: [linux-next:master 775/10756] drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: chip_good.isra.11() falls through to next function put_chip.isra.15()

[Marco Elver]

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On Fri, 24 Jan 2020 at 08:21, kbuild test robot <lkp@intel.com> wrote:
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   41539ebf9bacf9a9102322ad944990f5a38f5538
> commit: e75a6795ed132f26f69d08dea958630d5993056d [775/10756] locking/atomics, kcsan: Add KCSAN instrumentation
> config: x86_64-randconfig-s2-20200124 (attached as .config)
> compiler: gcc-4.9 (Debian 4.9.2-10+deb8u1) 4.9.2
> reproduce:
>         git checkout e75a6795ed132f26f69d08dea958630d5993056d
>         # save the attached .config to linux build tree
>         make ARCH=x86_64
>
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@intel.com>
>
> All warnings (new ones prefixed by >>):
>
>    drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: chip_ready.isra.10() falls through to next function cfi_amdstd_panic_wait()
> >> drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: chip_good.isra.11() falls through to next function put_chip.isra.15()

It seems there are similar warnings here, and this is just due to GCC
generating different code. So I believe this should be fixed by the
author of this driver.

What may have happened is that the change to introduce KCSAN
instrumentation for atomics causes GCC to generate different code
here, thus the new warning. (We have a change to atomic-instrumented.h
in the pipeline which switches inline to __always_inline, which might
change codegen again.)

Thanks,
-- Marco