From: David Woodhouse <dwmw@amazon.co.uk>
If xen_backend_device_create() fails to instantiate a device, the XenBus
code will just keep trying over and over again each time the bus is
re-enumerated, as long as the backend appears online and in
XenbusStateInitialising.
The only thing which prevents the XenBus code from recreating duplicates
of devices which already exist, is the fact that xen_device_realize()
sets the backend state to XenbusStateInitWait. If the attempt to create
the device doesn't get *that* far, that's when it will keep getting
retried.
My first thought was to handle errors by setting the backend state to
XenbusStateClosed, but that doesn't work for XenConsole which wants to
*ignore* any device of type != "ioemu" completely.
So, make xen_backend_device_create() *keep* the XenBackendInstance for a
failed device, and provide a new xen_backend_exists() function to allow
xen_bus_type_enumerate() to check whether one already exists before
creating a new one.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
hw/xen/xen-backend.c | 27 +++++++++++++++++++++------
hw/xen/xen-bus.c | 3 ++-
include/hw/xen/xen-backend.h | 1 +
3 files changed, 24 insertions(+), 7 deletions(-)