Re: [PATCH 1/3] soc: ti: pruss: do device_node auto cleanup

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Fri, 10 May 2024 12:43:22 +0530
Kousik Sanagavarapu <five231003@gmail.com> wrote:

> Use scope based cleanup instead of manual of_node_put() calls, hence
> simplifying the handling of error paths at various places.
> 
> Suggested-by: Julia Lawall <julia.lawall@inria.fr>
> Signed-off-by: Kousik Sanagavarapu <five231003@gmail.com>
> ---
>  drivers/soc/ti/pruss.c | 48 ++++++++++++++----------------------------
>  1 file changed, 16 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/soc/ti/pruss.c b/drivers/soc/ti/pruss.c
> index 24a42e0b645c..8f238d59eca9 100644
> --- a/drivers/soc/ti/pruss.c
> +++ b/drivers/soc/ti/pruss.c
> @@ -381,13 +381,13 @@ static int pruss_clk_mux_setup(struct pruss *pruss, struct clk *clk_mux,
>  static int pruss_clk_init(struct pruss *pruss, struct device_node *cfg_node)
>  {
>  	const struct pruss_private_data *data;
> -	struct device_node *clks_np;
>  	struct device *dev = pruss->dev;
>  	int ret = 0;
>  
>  	data = of_device_get_match_data(dev);
>  
> -	clks_np = of_get_child_by_name(cfg_node, "clocks");
> +	struct device_node *clks_np __free(device_node) =
> +			of_get_child_by_name(cfg_node, "clocks");
>  	if (!clks_np) {
>  		dev_err(dev, "%pOF is missing its 'clocks' node\n", cfg_node);
>  		return -ENODEV;
> @@ -398,7 +398,7 @@ static int pruss_clk_init(struct pruss *pruss, struct device_node *cfg_node)
>  					  "coreclk-mux", clks_np);
>  		if (ret) {
>  			dev_err(dev, "failed to setup coreclk-mux\n");
> -			goto put_clks_node;
> +			return ret;

This driver would also benefit from use of dev_err_probe() for all cases
like this that are called only from the probe() callback.
			return dev_err_probe(dev, ret, "failed to setup coreclk-mux\n2);

Handles any deferred cases nicely, but in general simplifies code by
making these printer error message and return cases a single line.


>  		}
>  	}
>  
> @@ -406,13 +406,10 @@ static int pruss_clk_init(struct pruss *pruss, struct device_node *cfg_node)
>  				  clks_np);
>  	if (ret) {
>  		dev_err(dev, "failed to setup iepclk-mux\n");
> -		goto put_clks_node;
> +		return ret;
>  	}
>  
> -put_clks_node:
> -	of_node_put(clks_np);
> -
> -	return ret;
> +	return 0;
>  }
>  
>  static struct regmap_config regmap_conf = {
> @@ -424,26 +421,22 @@ static struct regmap_config regmap_conf = {
>  static int pruss_cfg_of_init(struct device *dev, struct pruss *pruss)
>  {
>  	struct device_node *np = dev_of_node(dev);
> -	struct device_node *child;
> +	struct device_node *child __free(device_node) =
> +			of_get_child_by_name(np, "cfg");
>  	struct resource res;
>  	int ret;
>  
> -	child = of_get_child_by_name(np, "cfg");
>  	if (!child) {
>  		dev_err(dev, "%pOF is missing its 'cfg' node\n", child);
>  		return -ENODEV;
>  	}
>  
> -	if (of_address_to_resource(child, 0, &res)) {
> -		ret = -ENOMEM;
> -		goto node_put;
> -	}
> +	if (of_address_to_resource(child, 0, &res))
> +		return -ENOMEM;
>  
>  	pruss->cfg_base = devm_ioremap(dev, res.start, resource_size(&res));
> -	if (!pruss->cfg_base) {
> -		ret = -ENOMEM;
> -		goto node_put;
> -	}
> +	if (!pruss->cfg_base)
> +		return -ENOMEM;
>  
>  	regmap_conf.name = kasprintf(GFP_KERNEL, "%pOFn@%llx", child,
>  				     (u64)res.start);
> @@ -455,16 +448,13 @@ static int pruss_cfg_of_init(struct device *dev, struct pruss *pruss)
>  	if (IS_ERR(pruss->cfg_regmap)) {
>  		dev_err(dev, "regmap_init_mmio failed for cfg, ret = %ld\n",
>  			PTR_ERR(pruss->cfg_regmap));
> -		ret = PTR_ERR(pruss->cfg_regmap);
> -		goto node_put;
> +		return PTR_ERR(pruss->cfg_regmap);
>  	}
>  
>  	ret = pruss_clk_init(pruss, child);
>  	if (ret)
>  		dev_err(dev, "pruss_clk_init failed, ret = %d\n", ret);
>  
> -node_put:
> -	of_node_put(child);
>  	return ret;
>  }
>  
> @@ -472,7 +462,6 @@ static int pruss_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
>  	struct device_node *np = dev_of_node(dev);
> -	struct device_node *child;
>  	struct pruss *pruss;
>  	struct resource res;
>  	int ret, i, index;
> @@ -494,7 +483,8 @@ static int pruss_probe(struct platform_device *pdev)
>  	pruss->dev = dev;
>  	mutex_init(&pruss->lock);
>  
> -	child = of_get_child_by_name(np, "memories");
> +	struct device_node *child __free(device_node) =
> +			of_get_child_by_name(np, "memories");

In this case, the scope of the device_node being held is increased quite
a bit.  Whilst that shouldn't be a problem, it is a bit ugly.

Perhaps factor this code out into another function similar to the ones above?

Jonathan


>  	if (!child) {
>  		dev_err(dev, "%pOF is missing its 'memories' node\n", child);
>  		return -ENODEV;
> @@ -510,22 +500,17 @@ static int pruss_probe(struct platform_device *pdev)
>  
>  		index = of_property_match_string(child, "reg-names",
>  						 mem_names[i]);
> -		if (index < 0) {
> -			of_node_put(child);
> +		if (index < 0)
>  			return index;
> -		}
>  
> -		if (of_address_to_resource(child, index, &res)) {
> -			of_node_put(child);
> +		if (of_address_to_resource(child, index, &res))
>  			return -EINVAL;
> -		}
>  
>  		pruss->mem_regions[i].va = devm_ioremap(dev, res.start,
>  							resource_size(&res));
>  		if (!pruss->mem_regions[i].va) {
>  			dev_err(dev, "failed to parse and map memory resource %d %s\n",
>  				i, mem_names[i]);
> -			of_node_put(child);
>  			return -ENOMEM;
>  		}
>  		pruss->mem_regions[i].pa = res.start;
> @@ -535,7 +520,6 @@ static int pruss_probe(struct platform_device *pdev)
>  			mem_names[i], &pruss->mem_regions[i].pa,
>  			pruss->mem_regions[i].size, pruss->mem_regions[i].va);
>  	}
> -	of_node_put(child);
>  
>  	platform_set_drvdata(pdev, pruss);
>  


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