On Thu, Mar 23, 2017 at 02:58:10PM -0700, Long Li wrote:
> From: Long Li <lon...@microsoft.com>
> 
> hv_pci_devices_present is called in hv_pci_remove when we remove a PCI
> device from host (e.g. by disabling SRIOV on a device). In hv_pci_remove,
> the bus is already removed before the call, so we don't need to rescan the
> bus in the workqueue scheduled from hv_pci_devices_present.
> 
> By introducing status hv_pcibus_removed, we can avoid this situation.
> 
> Signed-off-by: Long Li <lon...@microsoft.com>
> Reported-by: Xiaofeng Wang <xiaof...@redhat.com>
> Acked-by: K. Y. Srinivasan <k...@microsoft.com>

Applied both patches to pci/host-hv for v4.12, thanks!  They both applied
perfectly :)

> ---
>  drivers/pci/host/pci-hyperv.c | 20 +++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
> index ada9856..39fafda 100644
> --- a/drivers/pci/host/pci-hyperv.c
> +++ b/drivers/pci/host/pci-hyperv.c
> @@ -350,6 +350,7 @@ enum hv_pcibus_state {
>       hv_pcibus_init = 0,
>       hv_pcibus_probed,
>       hv_pcibus_installed,
> +     hv_pcibus_removed,
>       hv_pcibus_maximum
>  };
>  
> @@ -1504,13 +1505,24 @@ static void pci_devices_present_work(struct 
> work_struct *work)
>               put_pcichild(hpdev, hv_pcidev_ref_initial);
>       }
>  
> -     /* Tell the core to rescan bus because there may have been changes. */
> -     if (hbus->state == hv_pcibus_installed) {
> +     switch(hbus->state) {
> +     case hv_pcibus_installed:
> +             /*
> +             * Tell the core to rescan bus
> +             * because there may have been changes.
> +             */
>               pci_lock_rescan_remove();
>               pci_scan_child_bus(hbus->pci_bus);
>               pci_unlock_rescan_remove();
> -     } else {
> +             break;
> +
> +     case hv_pcibus_init:
> +     case hv_pcibus_probed:
>               survey_child_resources(hbus);
> +             break;
> +
> +     default:
> +             break;
>       }
>  
>       up(&hbus->enum_sem);
> @@ -2185,6 +2197,7 @@ static int hv_pci_probe(struct hv_device *hdev,
>       hbus = kzalloc(sizeof(*hbus), GFP_KERNEL);
>       if (!hbus)
>               return -ENOMEM;
> +     hbus->state = hv_pcibus_init;
>  
>       /*
>        * The PCI bus "domain" is what is called "segment" in ACPI and
> @@ -2348,6 +2361,7 @@ static int hv_pci_remove(struct hv_device *hdev)
>               pci_stop_root_bus(hbus->pci_bus);
>               pci_remove_root_bus(hbus->pci_bus);
>               pci_unlock_rescan_remove();
> +             hbus->state = hv_pcibus_removed;
>       }
>  
>       hv_pci_bus_exit(hdev);
> -- 
> 2.7.4
> 
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