linux-kernel - Re: [PATCH v3 2/6] irqchip: Add interrupt controller support for Realtek DHC SoCs

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Message-ID: <d94c79bf-04c4-4e87-bd7e-a8755508ac89@suswa.mountain>
Date:   Wed, 29 Nov 2023 11:21:06 +0300
From:   Dan Carpenter <dan.carpenter@...aro.org>
To:     James Tai <james.tai@...ltek.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        kernel test robot <lkp@...el.com>,
        Dan Carpenter <error27@...il.com>
Subject: Re: [PATCH v3 2/6] irqchip: Add interrupt controller support for
 Realtek DHC SoCs

On Wed, Nov 29, 2023 at 01:43:35PM +0800, James Tai wrote:
> +static int realtek_intc_subset(struct device_node *node, struct realtek_intc_data *data, int index)
> +{
> +	struct realtek_intc_subset_data *subset_data = &data->subset_data[index];
> +	const struct realtek_intc_subset_cfg *cfg = &data->info->cfg[index];
> +	int irq;
> +
> +	irq = irq_of_parse_and_map(node, index);
> +	if (irq <= 0)
> +		return irq;

I don't think irq_of_parse_and_map() can return negatives.  Only zero
on error.  Returning zero on error is a historical artifact with IRQ
functions and a constant source of bugs.  But here returning zero is
success.  See my blog for more details:
https://staticthinking.wordpress.com/2023/08/07/writing-a-check-for-zero-irq-error-codes/

So this should probably be:

	irq = irq_of_parse_and_map(node, index);
	if (!irq)
		return -ENODEV;

I should create a static checker warning for this...  Possibly I should
create a static checker warning any time someone does:

	if (foo <= 0)
		return foo;

> +
> +	subset_data->common = data;
> +	subset_data->cfg = cfg;
> +	subset_data->parent_irq = irq;
> +	irq_set_chained_handler_and_data(irq, realtek_intc_handler, subset_data);
> +
> +	return 0;
> +}
> +
> +int realtek_intc_probe(struct platform_device *pdev, const struct realtek_intc_info *info)
> +{
> +	struct realtek_intc_data *data;
> +	struct device *dev = &pdev->dev;
> +	struct device_node *node = dev->of_node;
> +	int ret, i;
> +
> +	data = devm_kzalloc(dev, struct_size(data, subset_data, info->cfg_num), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->base = of_iomap(node, 0);
> +	if (!data->base) {
> +		ret = -ENOMEM;
> +		goto out_cleanup;

devm_ allocations are cleaned up automatically so there is no need to
call devm_kfree() before returning.

regards,
dan carpenter

> +	}
> +
> +	data->info = info;
> +
> +	raw_spin_lock_init(&data->lock);
> +
> +	data->domain = irq_domain_add_linear(node, 32, &realtek_intc_domain_ops, data);
> +	if (!data->domain) {
> +		ret = -ENOMEM;
> +		goto out_cleanup;
> +	}
> +
> +	data->subset_data_num = info->cfg_num;
> +	for (i = 0; i < info->cfg_num; i++) {
> +		ret = realtek_intc_subset(node, data, i);
> +		if (ret) {
> +			WARN(ret, "failed to init subset %d: %d", i, ret);
> +			ret = -ENOMEM;
> +			goto out_cleanup;
> +		}
> +	}
> +
> +	platform_set_drvdata(pdev, data);
> +
> +	return 0;
> +
> +out_cleanup:
> +
> +	if (data->base)
> +		iounmap(data->base);
> +
> +	devm_kfree(dev, data);
> +
> +	return ret;
> +}