Re: [PATCH] irqchip/sifive-plic: Panic if initialization fails

[Radu Rendec]

On Fri, 2026-09-11 at 16:50 +0200, Nam Cao wrote:
> If PLIC initialization fails, the driver unwinds and returns an error.
> However, that is futile because the system cannot function without the
> PLIC: all device interrupts are routed through it.
> 
> Instead of the unnecessary cleanups, panic when PLIC initialization fails.
> 
> Signed-off-by: Nam Cao <namcao@xxxxxxxxxxxxx>
> ---
>  drivers/irqchip/irq-sifive-plic.c | 56 +++++++++----------------------
>  1 file changed, 15 insertions(+), 41 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index a7cddadddf40..70a7478373e4 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -643,13 +643,11 @@ static int plic_probe(struct fwnode_handle *fwnode)
>  
>  	error = plic_parse_nr_irqs_and_contexts(fwnode, &nr_irqs, &nr_contexts, &gsi_base, &id);
>  	if (error)
> -		goto fail_free_regs;
> +		return error;
>  
>  	priv = kzalloc_obj(*priv);
> -	if (!priv) {
> -		error = -ENOMEM;
> -		goto fail_free_regs;
> -	}
> +	if (!priv)
> +		return -ENOMEM;
>  
>  	priv->fwnode = fwnode;
>  	priv->plic_quirks = plic_quirks;
> @@ -668,10 +666,8 @@ static int plic_probe(struct fwnode_handle *fwnode)
>  	priv->acpi_plic_id = id;
>  
>  	priv->prio_save = bitmap_zalloc(nr_irqs, GFP_KERNEL);
> -	if (!priv->prio_save) {
> -		error = -ENOMEM;
> -		goto fail_free_priv;
> -	}
> +	if (!priv->prio_save)
> +		return -ENOMEM;
>  
>  	for (i = 0; i < nr_contexts; i++) {
>  		error = plic_parse_context_parent(fwnode, i, &parent_hwirq, &cpu,
> @@ -735,10 +731,8 @@ static int plic_probe(struct fwnode_handle *fwnode)
>  
>  		handler->enable_save = kcalloc(priv->irq_groups, sizeof(*handler->enable_save),
>  					       GFP_KERNEL);
> -		if (!handler->enable_save) {
> -			error = -ENOMEM;
> -			goto fail_cleanup_contexts;
> -		}
> +		if (!handler->enable_save)
> +			return -ENOMEM;
>  done:
>  		for_each_device_irq(hwirq, priv) {
>  			plic_toggle(handler, hwirq, 0);
> @@ -748,10 +742,8 @@ static int plic_probe(struct fwnode_handle *fwnode)
>  	}
>  
>  	priv->irqdomain = irq_domain_create_linear(fwnode, nr_irqs, &plic_irqdomain_ops, priv);
> -	if (WARN_ON(!priv->irqdomain)) {
> -		error = -ENOMEM;
> -		goto fail_cleanup_contexts;
> -	}
> +	if (!priv->irqdomain)
> +		return -ENOMEM;
>  
>  	/*
>  	 * We can have multiple PLIC instances so setup global state
> @@ -799,33 +791,13 @@ static int plic_probe(struct fwnode_handle *fwnode)
>  	pr_info("%pfwP: mapped %d interrupts with %d handlers for %d contexts.\n",
>  		fwnode, nr_irqs, nr_handlers, nr_contexts);
>  	return 0;
> -
> -fail_cleanup_contexts:
> -	for (i = 0; i < nr_contexts; i++) {
> -		if (plic_parse_context_parent(fwnode, i, &parent_hwirq, &cpu, priv->acpi_plic_id))
> -			continue;
> -		if (parent_hwirq != RV_IRQ_EXT || cpu < 0)
> -			continue;
> -
> -		handler = per_cpu_ptr(&plic_handlers, cpu);
> -		handler->present = false;
> -		handler->hart_base = NULL;
> -		handler->enable_base = NULL;
> -		kfree(handler->enable_save);
> -		handler->enable_save = NULL;
> -		handler->priv = NULL;
> -	}
> -	bitmap_free(priv->prio_save);
> -fail_free_priv:
> -	kfree(priv);
> -fail_free_regs:
> -	iounmap(regs);
> -	return error;
>  }
>  
>  static int plic_platform_probe(struct platform_device *pdev)
>  {
> -	return plic_probe(pdev->dev.fwnode);
> +	if (plic_probe(pdev->dev.fwnode))
> +		panic("%pfwP: Failed to initialize\n", pdev->dev.fwnode);
> +	return 0;
>  }
>  
>  static struct platform_driver plic_driver = {
> @@ -842,7 +814,9 @@ builtin_platform_driver(plic_driver);
>  static int __init plic_early_probe(struct device_node *node,
>  				   struct device_node *parent)
>  {
> -	return plic_probe(&node->fwnode);
> +	if (plic_probe(&node->fwnode))
> +		panic("%pfwP: Failed to initialize\n", &node->fwnode);
> +	return 0;
>  }
>  
>  IRQCHIP_DECLARE(riscv, "allwinner,sun20i-d1-plic", plic_early_probe);

Reviewed-by: Radu Rendec <radu@xxxxxxxxxx>