Re: [paulmckrcu:cmpxchg2.2026.09.22a 25/28] arch/arc/include/asm/cmpxchg.h:46:58: error: pointer type mismatch in conditional expression

[Vineet Gupta <vineet.gupta@linux.dev>]

On 9/24/26 13:58, Bradley Morgan wrote:
> On 24 September 2026 21:52:55 BST, Vineet Gupta <vgupta@kernel.org> wrote:
>> On 9/24/26 00:51, kernel test robot wrote:
>>> tree:   https://github.com/paulmckrcu/linux cmpxchg2.2026.09.22a
>>> head:   54c282c15475ebfae4712fe3ab637c9d19c723d6
>>> commit: b6d4f6af38f85e7948fd64f9bf09cbb858b4dade [25/28] ARC: Emulate
>> two-byte cmpxchg
>>> config: arc-allyesconfig
>> (https://download.01.org/0day-ci/archive/20260924/202609241517.SSV1Goz3-lkp@intel.com/config)
>>> compiler: arc-linux-gcc (GCC) 16.1.0
>>> reproduce (this is a W=1 build):
>> (https://download.01.org/0day-ci/archive/20260924/202609241517.SSV1Goz3-lkp@intel.com/reproduce)
>>> If you fix the issue in a separate patch/commit (i.e. not just a new
>> version of
>>> the same patch/commit), kindly add following tags
>>> | Reported-by: kernel test robot <lkp@intel.com>
>>> | Closes:
>> https://lore.kernel.org/oe-kbuild-all/202609241517.SSV1Goz3-lkp@intel.com/
>>> All errors (new ones prefixed by >>):
>>>
>>>      In file included from arch/arc/include/asm/atomic.h:13,
>>>                       from include/linux/atomic.h:7,
>>>                       from include/asm-generic/bitops/lock.h:5,
>>>                       from arch/arc/include/asm/bitops.h:190,
>>>                       from include/linux/bitops.h:67,
>>>                       from include/linux/log2.h:12,
>>>                       from include/asm-generic/div64.h:55,
>>>                       from ./arch/arc/include/generated/asm/div64.h:1,
>>>                       from include/linux/math.h:6,
>>>                       from include/linux/math64.h:6,
>>>                       from include/linux/time.h:6,
>>>                       from include/linux/stat.h:19,
>>>                       from include/linux/fs_dirent.h:5,
>>>                       from include/linux/fs/super_types.h:5,
>>>                       from include/linux/fs/super.h:5,
>>>                       from include/linux/fs.h:5,
>>>                       from include/linux/fscrypt.h:16,
>>>                       from fs/crypto/fscrypt_private.h:15,
>>>                       from fs/crypto/hooks.c:10:
>>>      fs/crypto/hooks.c: In function 'fscrypt_get_symlink':
>>>>> arch/arc/include/asm/cmpxchg.h:46:58: error: pointer type mismatch in
>> conditional expression [-Wincompatible-pointer-types]
>>>         46 |         unsigned long _new_ = (unsigned long)(0 ? *(_p_) :
>> (new));              \
>>
>> Issue is in  fs/crypto/hooks.c doing cmpxchg_release(&inode->i_link, NULL,
>> pstr.name)
>> where i_link is char * and pstr.name is unsigned char *),
>>
>> The problem is when pointer types are incompatible and that's exactly the
>> W toggle above.
>>
>> So Bradley's patch needs this fixup
>>
>> diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
>> index 4596edfefa95..9053098bb152 100644
>> --- a/arch/arc/include/asm/cmpxchg.h
>> +++ b/arch/arc/include/asm/cmpxchg.h
>> @@ -42,8 +42,10 @@
>>   #define arch_cmpxchg_relaxed(ptr, old, new)     \
>>   ({    \
>>          __typeof__(ptr) _p_ = (ptr);     \
>> -       unsigned long _old_ = (unsigned long)(0 ? *(_p_) : (old));             \
>> -       unsigned long _new_ = (unsigned long)(0 ? *(_p_) : (new));             \
>> +       __typeof__(*(ptr)) _o_ = (old);    \
>> +       __typeof__(*(ptr)) _n_ = (new);    \
>> +       unsigned long _old_ = (unsigned long)_o_;            \
>> +       unsigned long _new_ = (unsigned long)_n_;            \
>>
>> P.S: For arch changes shouldn't the submitter be required to at least test
>> the building, specially when this involves the macro maze. Its really easy
>> with crosstool hosting all the cross-compilers [1] - just download and
>> untar.
>>
>> [1]
>> https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_64/16.2.0/
> Well thanks but I didn't have a proper server till yesterday.

A relatively decent laptop works for me.

> I'll post all arch patches when Paul tells me how he wants it

Please do a minimal compile build - it will save you the re-spins.

> Like if he wants u16 in first then arch changes sent.

Sure !

Cheers,
-Vineet

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