When loadvm'ing a *running* snapshot qemu crashes due to an invalid
free. It's fortunately caught early by glibc heap memory corruption
protection and qemu gets killed with SIGABRT.

Steps to reproduce:

1) Create VM (e.g w/ virsh define)
2) Start the VM and take a snapshot while it's running and having a
   PCI bridge attached
3) Destroy the VM and revert the running snapshot.

This commit fixes the issue.

Signed-off-by: Matthias Weckbecker <matthias@weckbecker.name>
---
 hw/pci/pci_bridge.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
index ee9dff2d3a..b9143ac88b 100644
--- a/hw/pci/pci_bridge.c
+++ b/hw/pci/pci_bridge.c
@@ -241,9 +241,9 @@ void pci_bridge_update_mappings(PCIBridge *br)
      * while another accesses an unaffected region. */
     memory_region_transaction_begin();
     pci_bridge_region_del(br, br->windows);
+    pci_bridge_region_cleanup(br, w);
     br->windows = pci_bridge_region_init(br);
     memory_region_transaction_commit();
-    pci_bridge_region_cleanup(br, w);
 }
 
 /* default write_config function for PCI-to-PCI bridge */
-- 
2.16.3