Re: [PATCH v2 3/3] PCI: ultrarisc: allow DP1000 driver to build as module

[Jia Wang <wangjia@ultrarisc.com>]

On 2026-07-06 10:07 +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [High] Missing `.remove` callback leaves the PCI root bus registered, causing a use-after-free on module unload.
> --
> 
> commit 14ef8e08324f6393567996c3e1dc0b2cadbcfc0a
> Author: Jia Wang <wangjia@ultrarisc.com>
> 
> PCI: ultrarisc: allow DP1000 driver to build as module
> 
> This commit changes the driver registration from builtin_platform_driver()
> to module_platform_driver(). This allows the driver to be built and
> dynamically loaded or unloaded as a kernel module.
> 
> > diff --git a/drivers/pci/controller/dwc/pcie-ultrarisc.c b/drivers/pci/controller/dwc/pcie-ultrarisc.c
> > --- a/drivers/pci/controller/dwc/pcie-ultrarisc.c
> > +++ b/drivers/pci/controller/dwc/pcie-ultrarisc.c
> > @@ -225,7 +225,7 @@ static struct platform_driver ultrarisc_pcie_driver = {
> >  	},
> >  	.probe = ultrarisc_pcie_probe,
> >  };
> > -builtin_platform_driver(ultrarisc_pcie_driver);
> > +module_platform_driver(ultrarisc_pcie_driver);
> 
> [Severity: High]
> By switching to module_platform_driver(), this driver can now be unloaded
> dynamically. However, since ultrarisc_pcie_driver lacks a .remove callback,
> will unloading the module leave the active PCI root bus, IRQ domains, and
> child devices registered?
> 
> If devres automatically frees the struct ultrarisc_pcie memory and unmaps
> MMIO registers on module unload while the PCI subsystem still retains
> pointers to them, could this result in a use-after-free and kernel panic
> during subsequent PCI config space accesses?
>

Thanks for pointing this out.

The driver does support `CONFIG_PCIE_ULTRARISC=m`, so it should provide a
proper teardown path for module unload. I'll add a `.remove()` callback in
the next version to clean up the PCI host resources accordingly.
 
> >  
> >  MODULE_DESCRIPTION("UltraRISC DP1000 DWC PCIe host controller");
> >  MODULE_LICENSE("GPL");
> 
> -- 
> Sashiko AI review · https://sashiko.dev/#/patchset/20260706-ultrarisc-pci-clk-v2-0-2f3fb6fba66b@ultrarisc.com?part=3
> 

Best regards,
Jia Wang