linux-kernel - [PATCH] PCI: rcar-host: Use proper IRQ domain

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Message-ID: <20250809144447.3939284-1-claudiu.beznea.uj@bp.renesas.com>
Date: Sat,  9 Aug 2025 17:44:47 +0300
From: Claudiu <claudiu.beznea@...on.dev>
To: marek.vasut+renesas@...il.com,
	yoshihiro.shimoda.uh@...esas.com,
	lpieralisi@...nel.org,
	kwilczynski@...nel.org,
	mani@...nel.org,
	robh@...nel.org,
	bhelgaas@...gle.com,
	geert+renesas@...der.be,
	magnus.damm@...il.com,
	namcao@...utronix.de,
	tglx@...utronix.de
Cc: claudiu.beznea@...on.dev,
	linux-pci@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: [PATCH] PCI: rcar-host: Use proper IRQ domain

From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>

Starting with commit dd26c1a23fd5 ("PCI: rcar-host: Switch to
msi_create_parent_irq_domain()"), the MSI parent IRQ domain is NULL because
the object of type struct irq_domain_info passed to:

msi_create_parent_irq_domain() ->
  irq_domain_instantiate()() ->
    __irq_domain_instantiate()

has no reference to the parent IRQ domain. Using msi->domain->parent as an
argument for generic_handle_domain_irq() leads to a "Unable to handle
kernel NULL pointer dereference at virtual address" error.

This error was identified while switching the upcoming RZ/G3S PCIe host
controller driver to msi_create_parent_irq_domain() (which was using a
similar pattern to handle MSIs (see link section)), but it was not tested
on hardware using the pcie-rcar-host controller driver due to lack of
hardware.

Link: https://lore.kernel.org/all/20250704161410.3931884-6-claudiu.beznea.uj@bp.renesas.com/
Fixes: dd26c1a23fd5 ("PCI: rcar-host: Switch to msi_create_parent_irq_domain()")
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
---
 drivers/pci/controller/pcie-rcar-host.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pcie-rcar-host.c b/drivers/pci/controller/pcie-rcar-host.c
index fe288fd770c4..4780e0109e58 100644
--- a/drivers/pci/controller/pcie-rcar-host.c
+++ b/drivers/pci/controller/pcie-rcar-host.c
@@ -584,7 +584,7 @@ static irqreturn_t rcar_pcie_msi_irq(int irq, void *data)
 		unsigned int index = find_first_bit(&reg, 32);
 		int ret;
 
-		ret = generic_handle_domain_irq(msi->domain->parent, index);
+		ret = generic_handle_domain_irq(msi->domain, index);
 		if (ret) {
 			/* Unknown MSI, just clear it */
 			dev_dbg(dev, "unexpected MSI\n");
-- 
2.43.0