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Message-ID: <87zfc8h6c6.fsf@yellow.woof>
Date: Sat, 09 Aug 2025 17:18:01 +0200
From: Nam Cao <namcao@...utronix.de>
To: Claudiu <claudiu.beznea@...on.dev>, 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,
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: Re: [PATCH] PCI: rcar-host: Use proper IRQ domain
Claudiu <claudiu.beznea@...on.dev> writes:
> 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.
Right. Before that commit, msi->domain is the domain of the children PCI
devices, and msi->domain->parent is the domain of this device.
That commit changed msi->domain to be the domain of this
device. msi->domain->parent does not exist anymore.
drivers/pci/controller/pcie-xilinx.c has the same issue, let me send a
patch..
> 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>
Reviewed-by: Nam Cao <namcao@...utronix.de>
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