powerpc/pseries/vio: Dispose of virq mapping on vdevice unregister

commit b8f89fea599d91e674497aad572613eb63181f31 upstream.

When a vdevice is DLPAR removed from the system the vio subsystem
doesn't bother unmapping the virq from the irq_domain. As a result we
have a virq mapped to a hardware irq that is no longer valid for the
irq_domain. A side effect is that we are left with /proc/irq/<irq#>
affinity entries, and attempts to modify the smp_affinity of the irq
will fail.

In the following observed example the kernel log is spammed by
ics_rtas_set_affinity errors after the removal of a VSCSI adapter.
This is a result of irqbalance trying to adjust the affinity every 10
seconds.

  rpadlpar_io: slot U8408.E8E.10A7ACV-V5-C25 removed
  ics_rtas_set_affinity: ibm,set-xive irq=655385 returns -3
  ics_rtas_set_affinity: ibm,set-xive irq=655385 returns -3

This patch fixes the issue by calling irq_dispose_mapping() on the
virq of the viodev on unregister.

Fixes: f2ab6219969f ("powerpc/pseries: Add PFO support to the VIO bus")
Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/powerpc/kernel/vio.c b/arch/powerpc/kernel/vio.c
index 904c66128faeb7d31a8463532929d187254da7ed..f30807e7697b5ac08e501a3e4570acac3f6eb4b7 100644 (file)
--- a/arch/powerpc/kernel/vio.c
+++ b/arch/powerpc/kernel/vio.c
@@ -1572,6 +1572,8 @@ static struct device_attribute vio_dev_attrs[] = {
 void vio_unregister_device(struct vio_dev *viodev)
 {
        device_unregister(&viodev->dev);
+       if (viodev->family == VDEVICE)
+               irq_dispose_mapping(viodev->irq);
 }
 EXPORT_SYMBOL(vio_unregister_device);