Re: [PATCH 1/2] PCI/VMD: Detach resources after stopping root bus

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Mon, Oct 15, 2018 at 06:48:07PM -0600, Jon Derrick wrote:
> The VMD removal path calls pci_stop_root_bus, which tears down the pcie
> tree, including detaching all of the attached drivers. During driver
> detachment, devices may use pci_release_region to release resources.
> This path relies on the resource being accessible in resource tree.
> 
> By detaching the child domain from the parent resource domain prior to
> stopping the bus, we are preventing the list traversal from finding the
> resource to be freed. If we instead detach the resource after stopping
> the bus, we will have properly freed the resource and detaching is
> simply accounting at that point.
> 
> Without this order, the resource is never freed and is orphaned on VMD
> removal, leading to warning:
> [  181.940162] Trying to free nonexistent resource <e5a10000-e5a13fff>
> 
> Fixes 2c2c5c5cd213aea38c850bb6edc9b7f77f29802f:
> "x86/PCI: VMD: Attach VMD resources to parent domain's resource tree"
> Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
> ---
>  drivers/pci/controller/vmd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

I have applied this patch to pci/vmd for v4.20, thanks.

Lorenzo

> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index fd2dbd7..46ed80f 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -813,12 +813,12 @@ static void vmd_remove(struct pci_dev *dev)
>  {
>  	struct vmd_dev *vmd = pci_get_drvdata(dev);
>  
> -	vmd_detach_resources(vmd);
>  	sysfs_remove_link(&vmd->dev->dev.kobj, "domain");
>  	pci_stop_root_bus(vmd->bus);
>  	pci_remove_root_bus(vmd->bus);
>  	vmd_cleanup_srcu(vmd);
>  	vmd_teardown_dma_ops(vmd);
> +	vmd_detach_resources(vmd);
>  	irq_domain_remove(vmd->irq_domain);
>  }
>  
> -- 
> 1.8.3.1
>