Re: include/linux/atomic/atomic-arch-fallback.h:60:32: error: implicit declaration of function 'arch_cmpxchg64'; did you mean 'arch_cmpxchg'?

[Chen, Rong A <rong.a.chen@intel.com>]

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On 9/13/2021 4:57 PM, Mark Rutland wrote:
> On Sun, Sep 12, 2021 at 04:24:21AM +0800, kernel test robot wrote:
>> Hi Mark,
>>
>> FYI, the error/warning still remains.
> 
> As pointed out previously [1,2], this is an existing bug (in that arc
> does not have an implementation of cmpxchg64(), but it's possible to
> select code which uses it in test configurations). My changes to the
> core atomic headers only change the way in which the error manifests,
> and have nothing to do with the underlying problem.
> 
> I thought we were going to stop reporting this [3]?

Hi Mark,

Thanks for the feedback, we only ignored the below one:

   include/linux/atomic-arch-fallback.h:60:32: error: implicit 
declaration of function 'arch_cmpxchg64'; did you mean 'arch_cmpxchg'? 
[-Werror=implicit-function-declaration]

we'll update the pattern to ignore all.

Best Regards,
Rong Chen

> 
> If we want to "fix" this kernel side, then we either need to:
> 
> * Implement cmpxchg64() for arc
> 
> * Add an ARCH_HAS_CMPXCHG64, and dependencies in kconfig where it is used
> 
> Thanks,
> Mark.
> 
> [1] https://lore.kernel.org/lkml/a38e3284-62ee-4894-0475-2668733c5903(a)infradead.org/
> [2] https://lore.kernel.org/lkml/20210712143151.GB94622(a)C02TD0UTHF1T.local/
> [3] https://lore.kernel.org/lkml/717d9f89-078b-1698-46fb-9b3393ecddc4(a)intel.com/
> 
>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>> head:   c605c39677b9842b0566013e0cf30bc13e90bdbc
>> commit: e3d18cee258b898017b298b5b93f8134dd62aee3 locking/atomic: centralize generated headers
>> date:   8 weeks ago
>> config: arc-allyesconfig (attached as .config)
>> compiler: arceb-elf-gcc (GCC) 11.2.0
>> reproduce (this is a W=1 build):
>>          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>>          chmod +x ~/bin/make.cross
>>          # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e3d18cee258b898017b298b5b93f8134dd62aee3
>>          git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>>          git fetch --no-tags linus master
>>          git checkout e3d18cee258b898017b298b5b93f8134dd62aee3
>>          # save the attached .config to linux build tree
>>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=arc
>>
>> If you fix the issue, kindly add following tag as appropriate
>> Reported-by: kernel test robot <lkp@intel.com>
>>
>> All errors (new ones prefixed by >>):
>>
>>     In file included from include/linux/atomic.h:80,
>>                      from drivers/iommu/io-pgtable-arm.c:12:
>>     drivers/iommu/io-pgtable-arm.c: In function 'arm_lpae_install_table':
>>>> include/linux/atomic/atomic-arch-fallback.h:60:32: error: implicit declaration of function 'arch_cmpxchg64'; did you mean 'arch_cmpxchg'? [-Werror=implicit-function-declaration]
>>        60 | #define arch_cmpxchg64_relaxed arch_cmpxchg64
>>           |                                ^~~~~~~~~~~~~~
>>     include/linux/atomic/atomic-instrumented.h:1261:9: note: in expansion of macro 'arch_cmpxchg64_relaxed'
>>      1261 |         arch_cmpxchg64_relaxed(__ai_ptr, __VA_ARGS__); \
>>           |         ^~~~~~~~~~~~~~~~~~~~~~
>>     drivers/iommu/io-pgtable-arm.c:320:15: note: in expansion of macro 'cmpxchg64_relaxed'
>>       320 |         old = cmpxchg64_relaxed(ptep, curr, new);
>>           |               ^~~~~~~~~~~~~~~~~
>>     cc1: some warnings being treated as errors
>>
>>
>> vim +60 include/linux/atomic/atomic-arch-fallback.h
>>
>> 37f8173dd84936 include/linux/atomic-arch-fallback.h Peter Zijlstra 2020-01-24  56
>> 37f8173dd84936 include/linux/atomic-arch-fallback.h Peter Zijlstra 2020-01-24  57  #ifndef arch_cmpxchg64_relaxed
>> 37f8173dd84936 include/linux/atomic-arch-fallback.h Peter Zijlstra 2020-01-24  58  #define arch_cmpxchg64_acquire arch_cmpxchg64
>> 37f8173dd84936 include/linux/atomic-arch-fallback.h Peter Zijlstra 2020-01-24  59  #define arch_cmpxchg64_release arch_cmpxchg64
>> 29f006fdefe6f8 include/linux/atomic-arch-fallback.h Peter Zijlstra 2020-08-29 @60  #define arch_cmpxchg64_relaxed arch_cmpxchg64
>> 37f8173dd84936 include/linux/atomic-arch-fallback.h Peter Zijlstra 2020-01-24  61  #else /* arch_cmpxchg64_relaxed */
>> 37f8173dd84936 include/linux/atomic-arch-fallback.h Peter Zijlstra 2020-01-24  62
>>
>> :::::: The code at line 60 was first introduced by commit
>> :::::: 29f006fdefe6f88abde973a0b0f20d2704e93fd4 asm-generic/atomic: Add try_cmpxchg() fallbacks
>>
>> :::::: TO: Peter Zijlstra <peterz@infradead.org>
>> :::::: CC: Ingo Molnar <mingo@kernel.org>
>>
>> ---
>> 0-DAY CI Kernel Test Service, Intel Corporation
>> https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org
> 
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