On Thu, Aug 9, 2012 at 11:12 PM, Taku Izumi <izumi.taku@xxxxxxxxxxxxxx> wrote:
> From: Jiang Liu <jiang.liu@xxxxxxxxxx>
>
> Correctly clean up pci root buses in function pci_remove_bus()
>
> The function pci_create_root_bus() allocates the pci bus structure,
> registers the bus device and creates the legacy files for a pci root
> bus, but returns without setting the is_added flag. The is_added flag
> for a pci root bus will be set by function pci_scan_child_bus().
> If a pci root bus is destroyed before calling pci_scan_child_bus(),
> the is_added flag will not be set.
What's the scenario where this happens? Most of the
pci_scan_child_bus() calls look like this:
bus = pci_create_root_bus();
pci_scan_child_bus(bus);
In those cases, there's no opportunity to destroy the root bus before
calling pci_scan_child_bus().
I don't like to add additional tests as you're doing here because it's
telling us that we have more special cases to think about. Apparently
bus->is_added is telling us that we've created legacy files and
registered the bus device. EXCEPT for root buses. Why is it
different for root buses? Why don't we set root_bus->is_added at the
same time we create the legacy files and register the root bus's
device?
> So teach function pci_remove_bus()
> to detect such a case and correctly clean up pci root buses.
>
> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
> Signed-off-by: Taku Izumi <izumi.taku@xxxxxxxxxxxxxx>
> ---
> drivers/pci/remove.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> Index: Bjorn-next-0808/drivers/pci/remove.c
> ===================================================================
> --- Bjorn-next-0808.orig/drivers/pci/remove.c
> +++ Bjorn-next-0808/drivers/pci/remove.c
> @@ -70,11 +70,10 @@ void pci_remove_bus(struct pci_bus *pci_
> list_del(&pci_bus->node);
> pci_bus_release_busn_res(pci_bus);
> up_write(&pci_bus_sem);
> - if (!pci_bus->is_added)
> - return;
> -
> - pci_remove_legacy_files(pci_bus);
> - device_unregister(&pci_bus->dev);
> + if (pci_bus->is_added || pci_is_root_bus(pci_bus)) {
> + pci_remove_legacy_files(pci_bus);
> + device_unregister(&pci_bus->dev);
> + }
> }
> EXPORT_SYMBOL(pci_remove_bus);
>
>
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