linux-kernel - Re: [PATCH v4 1/6] devres: provide devm_krealloc

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Message-ID: <fb513ce8-3c2a-6b67-7abe-1d5671b682d0@traphandler.com>
Date:   Fri, 14 Oct 2022 11:17:06 +0200
From:   Jean-Jacques Hiblot <jjhiblot@...phandler.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Bartosz Golaszewski <brgl@...ev.pl>
CC:     <lee.jones@...aro.org>, <pavel@....cz>, <robh+dt@...nel.org>,
        <sven.schwermer@...ruptive-technologies.com>,
        <krzysztof.kozlowski+dt@...aro.org>, <johan+linaro@...nel.org>,
        <marijn.suijten@...ainline.org>, <bjorn.andersson@...aro.org>,
        <jacek.anaszewski@...il.com>, <linux-leds@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/6] devres: provide devm_krealloc_array()


On 07/10/2022 18:18, Andy Shevchenko wrote:
>>   {
>>          return devm_kmalloc_array(dev, n, size, flags | __GFP_ZERO);
>>   }
> Missed blank line?

There is no blank line after the definitions of devm_kzalloc(), 
devm_kmalloc_array() and devm_kcalloc() defined just above.

>
>> +static inline void *devm_krealloc_array(struct device *dev,
>> +                                       void *p,
>> +                                       size_t new_n,
>> +                                       size_t new_size,
>> +                                       gfp_t flags)
>> +{
>> +       size_t bytes;
>> +
>> +       if (unlikely(check_mul_overflow(new_n, new_size, &bytes)))
>> +               return NULL;
> I'm not sure it is what we want, but I have read the man realloc and found this:
>
>        ... reallocarray() fails safely in the case where the multiplication
>        would overflow.  If such an overflow occurs, reallocarray() returns NULL,
>        sets  errno  to  ENOMEM,  and leaves the original block of memory
>        unchanged.
>
> So, perhaps you can add that this behaviour mimics reallocarray()?

except for the errno part, that is what is does. I don't think we should 
use ERR_PTR in this case as the other allocation functions don't use it.

>
>> +       return devm_krealloc(dev, p, bytes, flags);
>> +}
> ...
>
> All comments are minor, feel free to add
> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
>