[PATCH] irqchip/riscv-aplic: Fix crash when MSI domain is missing

[Anup Patel]

On Fri, Nov 15, 2024 at 1:31 AM Samuel Holland
<samuel.holland at sifive.com> wrote:
>
> If the APLIC driver is probed before the IMSIC driver, the parent MSI
> domain will be missing, which causes a NULL pointer dereference in
> msi_create_device_irq_domain(). Avoid this by deferring probe until the
> parent MSI domain is available. Use dev_err_probe() to avoid printing an
> error message when returning -EPROBE_DEFER.

The -EPROBE_DEFER is not needed because we expect that platforms to
use "msi-parent" DT property in APLIC DT node which in-turn allows Linux
DD framework to re-order probing based on fw_devlink dependencies. The
APLIC DT bindings mandates that any of "interrupt-extended" or "msi-parent"
DT properties MUST be present.

Can you elaborate a bit more on how you are hitting this issue ?

Regards,
Anup

>
> Fixes: ca8df97fe679 ("irqchip/riscv-aplic: Add support for MSI-mode")
> Signed-off-by: Samuel Holland <samuel.holland at sifive.com>
> ---
>
>  drivers/irqchip/irq-riscv-aplic-main.c | 3 ++-
>  drivers/irqchip/irq-riscv-aplic-msi.c  | 3 +++
>  2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/irqchip/irq-riscv-aplic-main.c b/drivers/irqchip/irq-riscv-aplic-main.c
> index 900e72541db9..93e7c51f944a 100644
> --- a/drivers/irqchip/irq-riscv-aplic-main.c
> +++ b/drivers/irqchip/irq-riscv-aplic-main.c
> @@ -207,7 +207,8 @@ static int aplic_probe(struct platform_device *pdev)
>         else
>                 rc = aplic_direct_setup(dev, regs);
>         if (rc)
> -               dev_err(dev, "failed to setup APLIC in %s mode\n", msi_mode ? "MSI" : "direct");
> +               dev_err_probe(dev, rc, "failed to setup APLIC in %s mode\n",
> +                             msi_mode ? "MSI" : "direct");
>
>  #ifdef CONFIG_ACPI
>         if (!acpi_disabled)
> diff --git a/drivers/irqchip/irq-riscv-aplic-msi.c b/drivers/irqchip/irq-riscv-aplic-msi.c
> index 945bff28265c..fb8d1838609f 100644
> --- a/drivers/irqchip/irq-riscv-aplic-msi.c
> +++ b/drivers/irqchip/irq-riscv-aplic-msi.c
> @@ -266,6 +266,9 @@ int aplic_msi_setup(struct device *dev, void __iomem *regs)
>                         if (msi_domain)
>                                 dev_set_msi_domain(dev, msi_domain);
>                 }
> +
> +               if (!dev_get_msi_domain(dev))
> +                       return -EPROBE_DEFER;
>         }
>
>         if (!msi_create_device_irq_domain(dev, MSI_DEFAULT_DOMAIN, &aplic_msi_template,
> --
> 2.45.1
>
>
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