qdev: Check if unplug handler exists before calling it

A bus may have hotplugging enabled but not have the 'unplug'
callback defined, which would lead to a crash on trying to
unplug a device on the bus.

Fix by introducing an assert to check if the callback is valid.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/hw/qdev.c b/hw/qdev.c
index c7884d0..d19d531 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -258,6 +258,8 @@ int qdev_unplug(DeviceState *dev)
                    dev->parent_bus->name);
         return -1;
     }
+    assert(dev->info->unplug != NULL);
+
     return dev->info->unplug(dev);
 }