On Mon, Jul 10, 2017 at 01:34:09PM +0100, Lorenzo Pieralisi wrote:
> If pci_scan_root_bus() fails (ie returns NULL) pcibios_scan_bus() must
> return immediately since the struct pci_bus pointer it returns is not
> valid and cannot be used.
>
> Move code checking the pci_scan_root_bus() return value to reinstate
> proper pcibios_scanbus() error path behaviour.
>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> Cc: Paul Burton <paul.burton@xxxxxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
I agree this is certainly broken. In fact, I think I broke it with
9e808eb6a768 ("PCI: Cleanup control flow") in 2015. So probably v4.14
material?
> ---
> arch/mips/pci/pci-legacy.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/arch/mips/pci/pci-legacy.c b/arch/mips/pci/pci-legacy.c
> index 174575a..71d62f8 100644
> --- a/arch/mips/pci/pci-legacy.c
> +++ b/arch/mips/pci/pci-legacy.c
> @@ -89,16 +89,16 @@ static void pcibios_scanbus(struct pci_controller *hose)
> pci_add_resource(&resources, hose->busn_resource);
> bus = pci_scan_root_bus(NULL, next_busno, hose->pci_ops, hose,
> &resources);
> - hose->bus = bus;
> -
> - need_domain_info = need_domain_info || pci_domain_nr(bus);
> - set_pci_need_domain_info(hose, need_domain_info);
> -
> if (!bus) {
> pci_free_resource_list(&resources);
> return;
> }
>
> + hose->bus = bus;
> +
> + need_domain_info = need_domain_info || pci_domain_nr(bus);
> + set_pci_need_domain_info(hose, need_domain_info);
> +
> next_busno = bus->busn_res.end + 1;
> /* Don't allow 8-bit bus number overflow inside the hose -
> reserve some space for bridges. */
> --
> 2.10.0
>
