Re: [Qemu-devel] [PATCH v3] pci: clean all funcs when hot-removing multifunc device

[Michael S. Tsirkin]

On Fri, May 11, 2012 at 01:09:13AM +0800, Jiang Liu wrote:
> On 05/10/2012 11:44 PM, Amos Kong wrote:
> 
> > diff --git a/drivers/pci/hotplug/acpiphp_glue.c 
> > b/drivers/pci/hotplug/acpiphp_glue.c
> > index 806c44f..a7442d9 100644
> > --- a/drivers/pci/hotplug/acpiphp_glue.c
> > +++ b/drivers/pci/hotplug/acpiphp_glue.c
> > @@ -885,7 +885,7 @@ static void disable_bridges(struct pci_bus *bus)
> >  static int disable_device(struct acpiphp_slot *slot)
> >  {
> >     struct acpiphp_func *func;
> > -   struct pci_dev *pdev;
> > +   struct pci_dev *pdev, *tmp;
> >     struct pci_bus *bus = slot->bridge->pci_bus;
> >  
> >     /* The slot will be enabled when func 0 is added, so check
> > @@ -902,9 +902,10 @@ static int disable_device(struct acpiphp_slot *slot)
> >                     func->bridge = NULL;
> >             }
> >  
> > -           pdev = pci_get_slot(slot->bridge->pci_bus,
> > -                               PCI_DEVFN(slot->device, func->function));
> > -           if (pdev) {
> > +           list_for_each_entry_safe(pdev, tmp, &bus->devices, bus_list) {
> > +                   if (PCI_SLOT(pdev->devfn) != slot->device)
> > +                           continue;
> > +
> The pci_bus_sem lock should be acquired when walking the bus->devices list.
> Otherwise it may cause invalid memory access if another thread is modifying
> the bus->devices list concurrently.
> 
> BTW, what's the relationship with "[PATCH v3] hotplug: add device per func
> in ACPI DSDT tables"? Seems they are both solving the same issue.

That's a bios patch. It's needed if you want broken linux to work.  This
makes linux behave properly on the original bios.

> >                     pci_stop_bus_device(pdev);
> >                     if (pdev->subordinate) {
> >                             disable_bridges(pdev->subordinate);
> > 
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