Re: [PATCH v2] maple_tree: Use correct variable type in sizeof

[Peng Zhang <zhangpeng.00@bytedance.com>]

在 2023/4/11 11:42, Matthew Wilcox 写道:
> On Mon, Apr 10, 2023 at 08:29:35PM -0700, Andrew Morton wrote:
>> On Tue, 11 Apr 2023 10:35:13 +0800 Peng Zhang <zhangpeng.00@bytedance.com> wrote:
>>
>>> The type of variable pointed to by pivs is unsigned long, but the type
>>> used in sizeof is a pointer type. Change it to unsigned long.
>> Thanks, but there's nothing in this changelog which explains why a
>> -stable backport is being proposed.  When fixing a bug, please always
>> describe the user-visible effects of that bug.
> There is no user-visible effect of this bug as the assembly code
> generated will be identical.

Therefore, if this has always been the case, cc stable
is also unnecessary.

>
>>> --- a/lib/maple_tree.c
>>> +++ b/lib/maple_tree.c
>>> @@ -3255,7 +3255,7 @@ static inline void mas_destroy_rebalance(struct ma_state *mas, unsigned char end
>>>   
>>>   		if (tmp < max_p)
>>>   			memset(pivs + tmp, 0,
>>> -			       sizeof(unsigned long *) * (max_p - tmp));
>>> +			       sizeof(unsigned long) * (max_p - tmp));
>>>   
>>>   		if (tmp < mt_slots[mt])
>>>   			memset(slots + tmp, 0, sizeof(void *) * (max_s - tmp));
>> Is there any situation in which
>> sizeof(unsigned long *) != sizeof(unsigned long)?
> Windows 64-bit (pointer 64-bit, unsigned long is 32 bit) is the only
> one I know.  Linux is all ILP32 or LP64.  There may be some embedded
> environments which are different, but I have no idea what they might be.
>