linux-kernel - Re: [PATCH v2] PCI: mediatek-gen3: Fix refcount leak in mtk_pcie_init_irq

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Message-ID: <20220531181316.24452-1-miles.chen@mediatek.com>
Date:   Wed, 1 Jun 2022 02:13:16 +0800
From:   Miles Chen <miles.chen@...iatek.com>
To:     <linmq006@...il.com>
CC:     <bhelgaas@...gle.com>, <jianjun.wang@...iatek.com>, <kw@...ux.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <linux-pci@...r.kernel.org>,
        <lorenzo.pieralisi@....com>, <matthias.bgg@...il.com>,
        <maz@...nel.org>, <robh@...nel.org>, <ryder.lee@...iatek.com>
Subject: Re: [PATCH v2] PCI: mediatek-gen3: Fix refcount leak in mtk_pcie_init_irq_domains

Hi Miaoqian,

>of_get_child_by_name() returns a node pointer with refcount
>incremented, we should use of_node_put() on it when not need anymore.
>Add missing of_node_put() to avoid refcount leak.
>
>Fixes: 814cceebba9b ("PCI: mediatek-gen3: Add INTx support")
>Signed-off-by: Miaoqian Lin <linmq006@...il.com>
>---
>changes in v2:
>- move of_node_put(intc_node) right after irq_domain_add_linear to cover
>normal path and error paths.
>
>v1 link: https://lore.kernel.org/all/20220526110246.53502-1-linmq006@gmail.com/
>---
> drivers/pci/controller/pcie-mediatek-gen3.c | 1 +
> 1 file changed, 1 insertion(+)
>
>diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
>index 3e8d70bfabc6..19a01daad304 100644
>--- a/drivers/pci/controller/pcie-mediatek-gen3.c
>+++ b/drivers/pci/controller/pcie-mediatek-gen3.c
>@@ -598,6 +598,7 @@ static int mtk_pcie_init_irq_domains(struct mtk_gen3_pcie *pcie)
> 
> 	pcie->intx_domain = irq_domain_add_linear(intc_node, PCI_NUM_INTX,
> 						  &intx_domain_ops, pcie);
>+	of_node_put(intc_node);
> 	if (!pcie->intx_domain) {
> 		dev_err(dev, "failed to create INTx IRQ domain\n");
> 		return -ENODEV;
>
> 		

Thanks for this v2 patch. I think we can do similar things like
rtl8365mb_irq_setup() in drivers/net/dsa/realtek/rtl8365mb.c.

When I read the error path, I will go back and see if everything is
released, so I think it is clearer to put of_node_put() in the error
path and before return 0.

How do you think?

i.g.,

static int mtk_pcie_init_irq_domains(struct mtk_gen3_pcie *pcie)
{
	struct device *dev = pcie->dev;
	struct device_node *intc_node, *node = dev->of_node;
	int ret;

	raw_spin_lock_init(&pcie->irq_lock);

	/* Setup INTx */
	intc_node = of_get_child_by_name(node, "interrupt-controller");
	if (!intc_node) {
		dev_err(dev, "missing interrupt-controller node\n");
		return -ENODEV;
	}

	pcie->intx_domain = irq_domain_add_linear(intc_node, PCI_NUM_INTX,
						  &intx_domain_ops, pcie);
	if (!pcie->intx_domain) {
		dev_err(dev, "failed to create INTx IRQ domain\n");
		ret = -ENODEV;
		goto out_put_node;
	}

	/* Setup MSI */
	mutex_init(&pcie->lock);

	pcie->msi_bottom_domain = irq_domain_add_linear(node, PCIE_MSI_IRQS_NUM,
				  &mtk_msi_bottom_domain_ops, pcie);
	if (!pcie->msi_bottom_domain) {
		dev_err(dev, "failed to create MSI bottom domain\n");
		ret = -ENODEV;
		goto err_msi_bottom_domain;
	}

	pcie->msi_domain = pci_msi_create_irq_domain(dev->fwnode,
						     &mtk_msi_domain_info,
						     pcie->msi_bottom_domain);
	if (!pcie->msi_domain) {
		dev_err(dev, "failed to create MSI domain\n");
		ret = -ENODEV;
		goto err_msi_domain;
	}

	of_node_put(intc);
	return 0;

err_msi_domain:
	irq_domain_remove(pcie->msi_bottom_domain);
err_msi_bottom_domain:
	irq_domain_remove(pcie->intx_domain);
out_put_node:
	of_node_put(intc);

	return ret;
}

thanks,
Miles