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Subject: Re: [PATCH] drm/drm_vblank.c: avoid unsigned int to signed int cast
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To:     Sui Jingfeng <15330273260@189.cn>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        David Laight <David.Laight@ACULAB.COM>,
        Li Yi <liyi@loongson.cn>
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Hi,

On 2023/5/23 12:26, Sui Jingfeng wrote:
> Hi,
>
> On 2023/5/22 19:29, Jani Nikula wrote:
>> In general, do not use unsigned types in arithmethic to avoid negative
>> values, because most people will be tripped over by integer promotion
>> rules, and you'll get negative values anyway.
>
>
> Here I'm sure about this,
>
Here, I'm NOT sure about this


> but there are plenty unsigned types arithmetic in the kernel.
>
> take kmalloc_array() function as an example in 
> /tools/virto/linux/kernel.h
>
>
> static inline void *kmalloc_array(unsigned n, size_t s, gfp_t gfp)
> {
>     return kmalloc(n * s, gfp);
> }
>
>
> NOTE that *size_t* is an unsigned integral data type.