Re: PCI hotplug problem

[Rafal Wojtczuk <rafal@invisiblethingslab.com>]

On Mon, Sep 27, 2010 at 01:07:05PM -0400, Konrad Rzeszutek Wilk wrote:

> > The idea of using PCI hotplug is nice, however, PCI hotplug does not seem to
> > work with the used setup (xen-3.4.3, all 64bit). Hot-unplug works, however the 
> > following hotplug makes the driver domain kernel spit out the following:
[cut]
> > Sep 24 09:46:15 localhost kernel: [  126.846523] iwlagn 0000:00:01.0: device
> > not available (can't reserve [mem 0xf8000000-0xf8001fff 64bit])
[cut]
> > Others seem to experience similar problems (e.g.
> > http://permalink.gmane.org/gmane.comp.emulators.xen.devel/80766). Does
> > anyone know the solution ?
> 
> I had an off-mailing list conversation with that fellow and I spun out
> a bunch of patches to fix his issue.
> 
> You need these patches:
> Konrad Rzeszutek Wilk (3):
>       xen-pcifront: Enforce scanning of device functions on initial execution.
>       xen-pcifront: Claim PCI resources before going live.
>       xen-pcifront: Don't race with udev when discovering new devices.
> 
> I think they are in Jeremy's upstream tree.. ah, right you guys aren't using
> Jeremy's tree.
> 
> Get them from: git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git
> 
> pv/pcifront-2.6.34

Indeed these patches help, thank you.
There is one more problem with the linux-2.6.18-xen.hg pcifront (that affect
derived code, e.g. OpenSUSE kernel, too). unbind_from_irqhandler() is
mistakenly passed evtchn, instead of irq. Compare line 68 of
http://xenbits.xensource.com/linux-2.6.18-xen.hg?file/a66a7c64b1d0/drivers/xen/pcifront/xenbus.c
with pvops equivalent
http://git.kernel.org/?p=linux/kernel/git/jeremy/xen.git;a=blob;f=drivers/pci/xen-pcifront.c;h=10868aeae818d69980b8519f8a77b38d6ab58a4c;hb=HEAD#l758

The following patch helps.
Regards,
Rafal Wojtczuk


unbind_from_irqhandler takes irq, not evtchn, as its first argument.

Signed-off-by: Rafal Wojtczuk <rafal@invisiblethingslab.com>
--- linux-2.6.34.1/drivers/xen/pcifront/xenbus.c.orig   2010-09-29 16:47:39.961674359 +0200
+++ linux-2.6.34.1/drivers/xen/pcifront/xenbus.c        2010-09-29 16:47:49.458675391 +0200
@@ -61,7 +61,7 @@ static void free_pdev(struct pcifront_de

        /*For PCIE_AER error handling job*/
        flush_scheduled_work();
-       unbind_from_irqhandler(pdev->evtchn, pdev);
+       unbind_from_irqhandler(irq_from_evtchn(pdev->evtchn), pdev);

        if (pdev->evtchn != INVALID_EVTCHN)
                xenbus_free_evtchn(pdev->xdev, pdev->evtchn);