Re: [PATCH] hexagon: fix using plain integer as NULL pointer warning in cmpxchg

["Maíra Canal" <mcanal@igalia.com>]

Hi Brian,

Do you have an estimate for when this patch will be picked? We are 
getting build reports from Hexagon in the V3D GPU driver [1].

[1] 
https://lore.kernel.org/oe-kbuild-all/202501031246.AD8Jjze0-lkp@intel.com/

Best Regards,
- Maíra

On 07/01/25 07:17, Christian Gmeiner wrote:
> Hi Willem,
> 
>>
>> From: Willem de Bruijn <willemb@google.com>
>>
>> Sparse reports
>>
>>      net/ipv4/inet_diag.c:1511:17: sparse: sparse: Using plain integer as NULL pointer
>>
>> Due to this code calling cmpxchg on a non-integer type
>> struct inet_diag_handler *
>>
>>      return !cmpxchg((const struct inet_diag_handler**)&inet_diag_table[type],
>>                      NULL, h) ? 0 : -EEXIST;
>>
>> While hexagon's cmpxchg assigns an integer value to a variable of this
>> type.
>>
>>      __typeof__(*(ptr)) __oldval = 0;
>>
>> Update this assignment to cast 0 to the correct type.
>>
>> The original issue is easily reproduced at head with the below block,
>> and is absent after this change.
>>
>>      make LLVM=1 ARCH=hexagon defconfig
>>      make C=1 LLVM=1 ARCH=hexagon net/ipv4/inet_diag.o
>>
>> Fixes: 99a70aa051d2 ("Hexagon: Add processor and system headers")
>> Reported-by: kernel test robot <lkp@intel.com>
>> Closes: https://lore.kernel.org/oe-kbuild-all/202411091538.PGSTqUBi-lkp@intel.com/
>> Signed-off-by: Willem de Bruijn <willemb@google.com>
> 
> Closes: https://lore.kernel.org/oe-kbuild-all/202501031246.AD8Jjze0-lkp@intel.com/
> Tested-by: Christian Gmeiner <cgmeiner@igalia.com>
> 
>> ---
>>   arch/hexagon/include/asm/cmpxchg.h | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/hexagon/include/asm/cmpxchg.h b/arch/hexagon/include/asm/cmpxchg.h
>> index bf6cf5579cf4..9c58fb81f7fd 100644
>> --- a/arch/hexagon/include/asm/cmpxchg.h
>> +++ b/arch/hexagon/include/asm/cmpxchg.h
>> @@ -56,7 +56,7 @@ __arch_xchg(unsigned long x, volatile void *ptr, int size)
>>          __typeof__(ptr) __ptr = (ptr);                          \
>>          __typeof__(*(ptr)) __old = (old);                       \
>>          __typeof__(*(ptr)) __new = (new);                       \
>> -       __typeof__(*(ptr)) __oldval = 0;                        \
>> +       __typeof__(*(ptr)) __oldval = (__typeof__(*(ptr))) 0;   \
>>                                                                  \
>>          asm volatile(                                           \
>>                  "1:     %0 = memw_locked(%1);\n"                \
>> --
>> 2.47.0.338.g60cca15819-goog
>>
>>
> 
>