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

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Message-ID: <b0504158-e9e2-4f00-8a9a-a653a6a0e313@igalia.com>
Date: Sun, 26 Jan 2025 19:59:00 -0300
From: Maíra Canal <mcanal@...lia.com>
To: Christian Gmeiner <christian.gmeiner@...il.com>,
 Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: linux-hexagon@...r.kernel.org, bcain@...cinc.com,
 linux-kernel@...r.kernel.org, dhowells@...hat.com, edumazet@...gle.com,
 Willem de Bruijn <willemb@...gle.com>, kernel test robot <lkp@...el.com>,
 mcanal@...lia.com
Subject: Re: [PATCH] hexagon: fix using plain integer as NULL pointer warning
 in cmpxchg

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@...gle.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@...el.com>
>> Closes: https://lore.kernel.org/oe-kbuild-all/202411091538.PGSTqUBi-lkp@intel.com/
>> Signed-off-by: Willem de Bruijn <willemb@...gle.com>
> 
> Closes: https://lore.kernel.org/oe-kbuild-all/202501031246.AD8Jjze0-lkp@intel.com/
> Tested-by: Christian Gmeiner <cgmeiner@...lia.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
>>
>>
> 
>