linux-kernel - Re: [PATCH] mmc: sdhci-cadence: use struct

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Message-ID: <994dec08-a6fb-56b1-c931-9a034e9a5f8d@intel.com>
Date:   Mon, 12 Aug 2019 11:23:07 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mmc: sdhci-cadence: use struct_size() helper

On 8/08/19 7:53 PM, Gustavo A. R. Silva wrote:
> One of the more common cases of allocation size calculations is finding
> the size of a structure that has a zero-sized array at the end, along
> with memory for some number of elements for that array. For example:
> 
> struct sdhci_cdns_priv {
> 	...
>         struct sdhci_cdns_phy_param phy_params[0];
> };
> 
> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes.
> 
> So, replace the following form:
> 
> sizeof(*priv) + sizeof(priv->phy_params[0]) * nr_phy_params
> 
> with:
> 
> struct_size(priv, phy_params, nr_phy_params)
> 
> Also, notice that, in this case, variable priv_size is not necessary,
> hence it is removed.
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

Acked-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
>  drivers/mmc/host/sdhci-cadence.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
> index 163d1cf4367e..1768a13f89be 100644
> --- a/drivers/mmc/host/sdhci-cadence.c
> +++ b/drivers/mmc/host/sdhci-cadence.c
> @@ -337,7 +337,6 @@ static int sdhci_cdns_probe(struct platform_device *pdev)
>  	struct sdhci_pltfm_host *pltfm_host;
>  	struct sdhci_cdns_priv *priv;
>  	struct clk *clk;
> -	size_t priv_size;
>  	unsigned int nr_phy_params;
>  	int ret;
>  	struct device *dev = &pdev->dev;
> @@ -351,8 +350,8 @@ static int sdhci_cdns_probe(struct platform_device *pdev)
>  		return ret;
>  
>  	nr_phy_params = sdhci_cdns_phy_param_count(dev->of_node);
> -	priv_size = sizeof(*priv) + sizeof(priv->phy_params[0]) * nr_phy_params;
> -	host = sdhci_pltfm_init(pdev, &sdhci_cdns_pltfm_data, priv_size);
> +	host = sdhci_pltfm_init(pdev, &sdhci_cdns_pltfm_data,
> +				struct_size(priv, phy_params, nr_phy_params));
>  	if (IS_ERR(host)) {
>  		ret = PTR_ERR(host);
>  		goto disable_clk;
>