RE: [PATCH 1/2 v3] pci-hyperv: properly handle pci bus remove

[KY Srinivasan]

> -----Original Message-----
> From: Bjorn Helgaas [mailto:helgaas@xxxxxxxxxx]
> Sent: Friday, November 11, 2016 1:04 PM
> To: Long Li <longli@xxxxxxxxxxxxx>
> Cc: KY Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang Zhang
> <haiyangz@xxxxxxxxxxxxx>; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>;
> devel@xxxxxxxxxxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Long Li <longli@xxxxxxxxxxxxx>
> Subject: Re: [PATCH 1/2 v3] pci-hyperv: properly handle pci bus remove
> 
> On Mon, Oct 03, 2016 at 11:42:47PM -0700, Long Li wrote:
> > From: Long Li <longli@xxxxxxxxxxxxx>
> >
> > 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 <longli@xxxxxxxxxxxxx>
> > Tested-by: Cathy Avery <cavery@xxxxxxxxxx>
> > Reported-by: Xiaofeng Wang <xiaofwan@xxxxxxxxxx>

Acked-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>


> 
> I need an ack from the Hyper-V maintainers.  I see acks for previous
> versions, but I don't know whether you've changed things that would
> invalidate those acks.  If the acks still apply, please include them
> and repost these patches.
> 
> Also, please run "git log --oneline drivers/pci/host/pci-hyperv.c" and make
> your subject line match the previous ones.
> 
> > ---
> >  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 a8deeca..4a37598 100644
> > --- a/drivers/pci/host/pci-hyperv.c
> > +++ b/drivers/pci/host/pci-hyperv.c
> > @@ -348,6 +348,7 @@ enum hv_pcibus_state {
> >  	hv_pcibus_init = 0,
> >  	hv_pcibus_probed,
> >  	hv_pcibus_installed,
> > +	hv_pcibus_removed,
> >  	hv_pcibus_maximum
> >  };
> >
> > @@ -1481,13 +1482,24 @@ 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);
> > @@ -2163,6 +2175,7 @@ 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
> > @@ -2305,6 +2318,7 @@ 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;
> >  	}
> >
> >  	ret = hv_send_resources_released(hdev);
> > --
> > 1.8.5.6
> >
> > --
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