[libvirt] [PATCH] qemu: Do not free the device from activePciHostdevs if it's in use

[Osier Yang]

* src/qemu/qemu_hostdev.c (qemuDomainReAttachHostdevDevices):
pciDeviceListFree(pcidevs) at the end free()s the device even if
it's in use by other domain, this is complete wrong, and will
cause race. E.g.

# sh test1.sh
Device pci_0000_00_19_0 dettached

Domain test started

Device attached successfully

error: Failed to start domain test2
error: Requested operation is not valid: PCI device 0000:00:19.0 is in use by domain test

[ -- 1th time --]
Device pci_0000_00_19_0 re-attached

[ -- 2th time --]
Device pci_0000_00_19_0 re-attached

[ -- 3th time --]
Device pci_0000_00_19_0 re-attached

[ -- 4th time --]
Device pci_0000_00_19_0 re-attached

[ -- 5th time --]
Device pci_0000_00_19_0 re-attached

clean up
Domain test destroyed

Device pci_0000_00_19_0 re-attached

[root at Osier libvirt]# sh test1.sh
Device pci_0000_00_19_0 dettached

Domain test started

Device attached successfully

error: Failed to start domain test2
error: Requested operation is not valid: PCI device 0000:00:19.0 is in use by domain test

[ -- 1th time --]
Device pci_0000_00_19_0 re-attached

[ -- 2th time --]
Device pci_0000_00_19_0 re-attached

[ -- 3th time --]
Device pci_0000_00_19_0 re-attached

[ -- 4th time --]
Device pci_0000_00_19_0 re-attached

[ -- 5th time --]
Device pci_0000_00_19_0 re-attached

clean up
Domain test destroyed

Device pci_0000_00_19_0 re-attached

[root at Osier libvirt]# sh test1.sh
Device pci_0000_00_19_0 dettached

Domain test started

Device attached successfully

error: Failed to start domain test2
error: Requested operation is not valid: PCI device 0000:00:19.0 is in use by domain test

[ -- 1th time --]
Device pci_0000_00_19_0 re-attached

[ -- 2th time --]
Device pci_0000_00_19_0 re-attached

[ -- 3th time --]
Device pci_0000_00_19_0 re-attached

[ -- 4th time --]
Device pci_0000_00_19_0 re-attached

[ -- 5th time --]
Device pci_0000_00_19_0 re-attached

clean up
Domain test destroyed

Device pci_0000_00_19_0 re-attached

[root at Osier libvirt]# sh test1.sh
Device pci_0000_00_19_0 dettached

Domain test started

Device attached successfully

error: Failed to start domain test2
error: Requested operation is not valid: PCI device 0000:00:19.0 is in use by domain test

[ -- 1th time --]
error: Failed to re-attach device pci_0000_00_19_0
error: internal error Not reattaching active device 0000:00:19.0

[ -- 2th time --]
Device pci_0000_00_19_0 re-attached

[ -- 3th time --]
Device pci_0000_00_19_0 re-attached

[ -- 4th time --]
Device pci_0000_00_19_0 re-attached

[ -- 5th time --]
Device pci_0000_00_19_0 re-attached

clean up
Domain test destroyed

Device pci_0000_00_19_0 re-attached


The patch also fixes another problem alongside, there won't
be error like "qemuDomainReAttachHostdevDevices: Not reattaching active
device 0000:00:19.0" in daemon log if some device is in active.
As pciResetDevice and pciReattachDevice won't be called for
the device anymore. This is sensiable as we already reported
error when preparing the device if it's active. Blindly trying
to pciResetDevice & pciReattachDevice on the device and getting
an error is just redundant.
---
 src/qemu/qemu_hostdev.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/src/qemu/qemu_hostdev.c b/src/qemu/qemu_hostdev.c
index 1fb373e..7efbab0 100644
--- a/src/qemu/qemu_hostdev.c
+++ b/src/qemu/qemu_hostdev.c
@@ -369,8 +369,10 @@ void qemuDomainReAttachHostdevDevices(struct qemud_driver *driver,
          */
         activeDev = pciDeviceListFind(driver->activePciHostdevs, dev);
         if (activeDev &&
-            STRNEQ_NULLABLE(name, pciDeviceGetUsedBy(activeDev)))
+            STRNEQ_NULLABLE(name, pciDeviceGetUsedBy(activeDev))) {
+            pciDeviceListSteal(pcidevs, dev);
             continue;
+        }
 
         /* pciDeviceListFree() will take care of freeing the dev. */
         pciDeviceListSteal(driver->activePciHostdevs, dev);
-- 
1.7.6