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

[Jiang Liu]

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.

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