Hi Bjorn,
On Fri, Mar 24, 2017 at 09:25:41AM -0500, Bjorn Helgaas wrote:
> On Thu, Mar 09, 2017 at 06:46:15PM -0800, Brian Norris wrote:
> > Currently, if we try to unbind the platform device, the remove will
> > succeed, but the removal won't undo most of the registration, leaving
> > partially-configured PCI devices in the system.
> >
> > This allows, for example, a simple 'lspci' to crash the system, as it
> > will try to touch the freed (via devm_*) driver structures.
> >
> > So let's implement device remove().
>
> How exactly do you reproduce this problem?
On RK3399:
# echo f8000000.pcie > /sys/bus/platform/drivers/rockchip-pcie/unbind
# lspci
> There are several other drivers that are superficially similar, e.g.,
> they define a struct platform_driver without a .remove method. Do
> they all have this problem? Some of them do set .suppress_bind_attrs
> = true; is that relevant to this scenario?
Yes, I think .suppress_bind_attrs would be enough to prevent this,
according to my reading of the code and comments:
* @suppress_bind_attrs: Disables bind/unbind via sysfs.
> In fact, the only other callers of pci_remove_root_bus() are
> iproc_pcie_remove(), hv_pci_remove(), and vmd_remove().
Then iProc would suffer from the same memory leak in
of_pci_get_host_bridge_resources() [1]. It *would* suffer from the same
domain allocation issues in of_pci_bus_find_domain_nr() ->
pci_get_new_domain_nr() [2], except that all iProc device trees (in
mainline at least) use the 'linux,pci-domain' property to avoid it.
HyperV and VMD drivers use ACPI, which uses neither
pci_get_new_domain_nr() nor of_pci_get_host_bridge_resources().
> These don't have .remove:
>
> imx6_pcie_driver
> ls_pcie_driver
> armada8k_pcie_driver
> artpec6_pcie_driver
> dw_plat_pcie_driver
> hisi_pcie_driver
> hisi_pcie_almost_ecam_driver
> spear13xx_pcie_driver
> gen_pci_driver
I think these are all technically broken.
> These don't have .remove but do set .suppress_bind_attrs = true:
>
> dra7xx_pcie_driver
> qcom_pcie_driver
> advk_pcie_driver
> mvebu_pcie_driver
> rcar_pci_driver
> rcar_pcie_driver
> tegra_pcie_driver
> altera_pcie_driver
> nwl_pcie_driver
> xilinx_pcie_driver
Those are fine then, I suppose.
Brian
[1] PCI: return resource_entry in pci_add_resource helpers
https://patchwork.kernel.org/patch/9642229/
of/pci: Fix memory leak in of_pci_get_host_bridge_resources
https://patchwork.kernel.org/patch/9642231/
[2] PCI: use IDA to manage domain number if not getting it from DT
https://patchwork.kernel.org/patch/9638353/
