> -----Original Message-----
> From: Jan Beulich <jbeul...@suse.com>
> Sent: 05 December 2019 08:44
> To: Durrant, Paul <pdurr...@amazon.com>
> Cc: Sander Eikelenboom <li...@eikelenboom.it>; xen-
> de...@lists.xenproject.org; Igor Druzhinin <igor.druzhi...@citrix.com>;
> Paul Durrant <p...@xen.org>
> Subject: Re: xen-unstable (4.14 to be): Assertion '!preempt_count()'
> failed at preempt.c:36
>
> On 05.12.2019 09:35, Durrant, Paul wrote:
> > --- a/xen/drivers/passthrough/pci.c
> > +++ b/xen/drivers/passthrough/pci.c
> > @@ -1696,16 +1696,12 @@ int iommu_do_pci_domctl(
> >
> > pcidevs_lock();
> > ret = device_assigned(seg, bus, devfn);
> > - if ( domctl->cmd == XEN_DOMCTL_test_assign_device )
> > + if ( ret && domctl->cmd == XEN_DOMCTL_test_assign_device )
> > {
> > - if ( ret )
> > - {
> > - printk(XENLOG_G_INFO
> > - "%04x:%02x:%02x.%u already assigned, or non-
> existent\n",
> > - seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
> > - ret = -EINVAL;
> > - }
> > - break;
> > + printk(XENLOG_G_INFO
> > + "%04x:%02x:%02x.%u already assigned, or non-
> existent\n",
> > + seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
> > + ret = -EINVAL;
> > }
>
> But this seems wrong - you'd end up calling assign_device() even
> for the XEN_DOMCTL_test_assign_device case, when ret is 0. All we
> want is to delete the break statement afaict.
>
Ah, yes; that logic is quite confusing. The patch should indeed be:
---8<---
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index ced0c28e4f..c07a63981a 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -1705,7 +1705,6 @@ int iommu_do_pci_domctl(
seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
ret = -EINVAL;
}
- break;
}
else if ( !ret )
ret = assign_device(d, seg, bus, devfn, flags);
---8<---
> Jan
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