[PATCH v2 3/3] PCI: rzg3s: Fix IRQ domain initialization error handling

[Prabhakar]

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>

rzg3s_pcie_init_irqdomain() installs chained handlers for the INTx
parent interrupts before creating the INTx irqdomain and initializing
MSI support.

If any subsequent step fails, such as obtaining an INTx IRQ,
creating the irqdomain, or initializing MSI, the error path returns
without removing any chained handlers that were already installed.
This leaves stale handler and data pointers attached to the parent
interrupts.

Fix the error path by unwinding the chained handler registration before
returning. Also clear the chained handlers during
rzg3s_pcie_teardown_irqdomain() so that teardown fully mirrors the
initialization sequence.

Fixes: 7ef502fb35b28 ("PCI: Add Renesas RZ/G3S host controller driver")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
---
v1->v2:
- Restricted the code to max 80 columns.
- Moved calling irq_domain_remove() under err_cleanup_intx label.
---
 drivers/pci/controller/pcie-rzg3s-host.c | 49 +++++++++++++++++-------
 1 file changed, 36 insertions(+), 13 deletions(-)

diff --git a/drivers/pci/controller/pcie-rzg3s-host.c b/drivers/pci/controller/pcie-rzg3s-host.c
index f51b5d7c1998..70f1faf7e422 100644
--- a/drivers/pci/controller/pcie-rzg3s-host.c
+++ b/drivers/pci/controller/pcie-rzg3s-host.c
@@ -1006,22 +1006,35 @@ static const struct irq_domain_ops rzg3s_pcie_intx_domain_ops = {
 	.xlate = irq_domain_xlate_onetwocell,
 };
 
+static void rzg3s_pcie_clear_intx_handlers(struct rzg3s_pcie_host *host,
+					   int count)
+{
+	while (--count >= 0) {
+		irq_set_chained_handler_and_data(host->intx_irqs[count], NULL,
+						 NULL);
+	}
+}
+
 static int rzg3s_pcie_init_irqdomain(struct rzg3s_pcie_host *host)
 {
 	struct device *dev = host->dev;
 	struct platform_device *pdev = to_platform_device(dev);
+	int i, ret;
 
-	for (int i = 0; i < PCI_NUM_INTX; i++) {
+	for (i = 0; i < PCI_NUM_INTX; i++) {
 		char irq_name[5] = {0};
 		int irq;
 
 		scnprintf(irq_name, ARRAY_SIZE(irq_name), "int%c", 'a' + i);
 
 		irq = platform_get_irq_byname(pdev, irq_name);
-		if (irq < 0)
-			return dev_err_probe(dev, irq,
-					     "Failed to parse and map INT%c IRQ\n",
-					     'A' + i);
+		if (irq < 0) {
+			ret = irq;
+			dev_err_probe(dev, ret,
+				      "Failed to parse and map INT%c IRQ\n",
+				      'A' + i);
+			goto err_cleanup_intx;
+		}
 
 		host->intx_irqs[i] = irq;
 		irq_set_chained_handler_and_data(irq,
@@ -1033,21 +1046,29 @@ static int rzg3s_pcie_init_irqdomain(struct rzg3s_pcie_host *host)
 						     PCI_NUM_INTX,
 						     &rzg3s_pcie_intx_domain_ops,
 						     host);
-	if (!host->intx_domain)
-		return dev_err_probe(dev, -EINVAL,
-				     "Failed to add irq domain for INTx IRQs\n");
+	if (!host->intx_domain) {
+		ret = -EINVAL;
+		dev_err_probe(dev, ret,
+			      "Failed to add irq domain for INTx IRQs\n");
+		goto err_cleanup_intx;
+	}
 	irq_domain_update_bus_token(host->intx_domain, DOMAIN_BUS_WIRED);
 
 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
-		int ret = rzg3s_pcie_init_msi(host);
+		ret = rzg3s_pcie_init_msi(host);
 
-		if (ret) {
-			irq_domain_remove(host->intx_domain);
-			return ret;
-		}
+		if (ret)
+			goto err_cleanup_intx;
 	}
 
 	return 0;
+
+err_cleanup_intx:
+	if (host->intx_domain)
+		irq_domain_remove(host->intx_domain);
+	rzg3s_pcie_clear_intx_handlers(host, i);
+
+	return ret;
 }
 
 static void rzg3s_pcie_teardown_irqdomain(struct rzg3s_pcie_host *host)
@@ -1055,6 +1076,8 @@ static void rzg3s_pcie_teardown_irqdomain(struct rzg3s_pcie_host *host)
 	if (IS_ENABLED(CONFIG_PCI_MSI))
 		rzg3s_pcie_teardown_msi(host);
 
+	rzg3s_pcie_clear_intx_handlers(host, PCI_NUM_INTX);
+
 	irq_domain_remove(host->intx_domain);
 }
 
-- 
2.54.0