Re: [PATCH v11 05/15] arm64: PCI: Manage controller-specific data on per-controller basis

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

On Mon, Dec 05, 2016 at 05:25:57PM -0600, Bjorn Helgaas wrote:
> From: Tomasz Nowicki <tn@semihalf.com>
> 
> Currently we use one shared global acpi_pci_root_ops structure to keep
> controller-specific ops. We pass its pointer to acpi_pci_root_create() and
> associate it with a host bridge instance for good.  Such a design implies
> serious drawback. Any potential manipulation on the single system-wide
> acpi_pci_root_ops leads to kernel crash. The structure content is not
> really changing even across multiple host bridges creation; thus it was not
> an issue so far.
> 
> In preparation for adding ECAM quirks mechanism (where controller-specific
> PCI ops may be different for each host bridge) allocate new
> acpi_pci_root_ops and fill in with data for each bridge. Now it is safe to
> have different controller-specific info. As a consequence free
> acpi_pci_root_ops when host bridge is released.
> 
> No functional changes in this patch.
> 
> Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
>  arch/arm64/kernel/pci.c |   17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
> index 7909f59..1eb42ba 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -169,33 +169,36 @@ static void pci_acpi_generic_release_info(struct acpi_pci_root_info *ci)
>  
>  	ri = container_of(ci, struct acpi_pci_generic_root_info, common);
>  	pci_ecam_free(ri->cfg);
> +	kfree(ci->ops);
>  	kfree(ri);
>  }
>  
> -static struct acpi_pci_root_ops acpi_pci_root_ops = {
> -	.release_info = pci_acpi_generic_release_info,
> -};
> -
>  /* Interface called from ACPI code to setup PCI host controller */
>  struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>  {
>  	int node = acpi_get_node(root->device->handle);
>  	struct acpi_pci_generic_root_info *ri;
>  	struct pci_bus *bus, *child;
> +	struct acpi_pci_root_ops *root_ops;
>  
>  	ri = kzalloc_node(sizeof(*ri), GFP_KERNEL, node);
>  	if (!ri)
>  		return NULL;
>  
> +	root_ops = kzalloc_node(sizeof(*root_ops), GFP_KERNEL, node);
> +	if (!root_ops)
> +		return NULL;
> +
>  	ri->cfg = pci_acpi_setup_ecam_mapping(root);
>  	if (!ri->cfg) {
>  		kfree(ri);
> +		kfree(root_ops);
>  		return NULL;
>  	}
>  
> -	acpi_pci_root_ops.pci_ops = &ri->cfg->ops->pci_ops;
> -	bus = acpi_pci_root_create(root, &acpi_pci_root_ops, &ri->common,
> -				   ri->cfg);
> +	root_ops->release_info = pci_acpi_generic_release_info;
> +	root_ops->pci_ops = &ri->cfg->ops->pci_ops;
> +	bus = acpi_pci_root_create(root, root_ops, &ri->common, ri->cfg);
>  	if (!bus)
>  		return NULL;
>  
>