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Date:   Wed, 13 Dec 2023 13:56:02 -0800
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v3 09/29] selftests/resctrl: Create cache_portion_size()
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To:     =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>,
        <linux-kselftest@vger.kernel.org>, Shuah Khan <shuah@kernel.org>,
        "Shaopeng Tan" <tan.shaopeng@jp.fujitsu.com>,
        =?UTF-8?Q?Maciej_Wiecz=C3=B3r-Retman?= 
        <maciej.wieczor-retman@intel.com>,
        Fenghua Yu <fenghua.yu@intel.com>
CC:     <linux-kernel@vger.kernel.org>
References: <20231211121826.14392-1-ilpo.jarvinen@linux.intel.com>
 <20231211121826.14392-10-ilpo.jarvinen@linux.intel.com>
From:   Reinette Chatre <reinette.chatre@intel.com>
In-Reply-To: <20231211121826.14392-10-ilpo.jarvinen@linux.intel.com>
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Hi Ilpo,

On 12/11/2023 4:18 AM, Ilpo Järvinen wrote:
> +/*
> + * cache_portion_size - Calculate the size of a cache portion
> + * @cache_size:		Total cache size in bytes
> + * @portion_mask:	Cache portion mask
> + * @full_cache_mask:	Full Cache Bit Mask (CBM) for the cache
> + *
> + * Return: The size of the cache portion in bytes.
> + */
> +static inline int cache_portion_size(unsigned long cache_size,
> +				     unsigned long portion_mask,
> +				     unsigned long full_cache_mask)
> +{
> +	return cache_size * count_bits(portion_mask) / count_bits(full_cache_mask);
> +}
> +

Even after you added the new zero check the static checker I tried
was not able to recognize that this is safe. Could you please add a check
to ensure that there will be no divide-by-zero here?

Reinette