diff options
author | Paul Durrant <paul.durrant@citrix.com> | 2019-09-13 09:21:58 +0100 |
---|---|---|
committer | Anthony PERARD <anthony.perard@citrix.com> | 2019-09-24 12:18:47 +0100 |
commit | 3809f7583ba463b9877755e6ca5f5f036430fdda (patch) | |
tree | 3d413d8f344d3f7f5c6a002168333b8ecab1e217 /include | |
parent | d198b711f9ff9032d7270d78d5b5b17abf740e75 (diff) |
xen: perform XenDevice clean-up in XenBus watch handler
Cleaning up offline XenDevice objects directly in
xen_device_backend_changed() is dangerous as xen_device_unrealize() will
modify the watch list that is being walked. Even the QLIST_FOREACH_SAFE()
used in notifier_list_notify() is insufficient as *two* notifiers (for
the frontend and backend watches) are removed, thus potentially rendering
the 'next' pointer unsafe.
The solution is to use the XenBus backend_watch handler to do the clean-up
instead, as it is invoked whilst walking a separate watch list.
This patch therefore adds a new 'inactive_devices' list to XenBus, to which
offline devices are added by xen_device_backend_changed(). The XenBus
backend_watch registration is also changed to not only invoke
xen_bus_enumerate() but also a new xen_bus_cleanup() function, which will
walk 'inactive_devices' and perform the necessary actions.
For safety an extra 'online' check is also added to xen_bus_type_enumerate()
to make sure that no attempt is made to create a new XenDevice object for a
backend that is offline.
NOTE: This patch also includes some cosmetic changes:
- substitute the local variable name 'backend_state'
in xen_bus_type_enumerate() with 'state', since there
is no ambiguity with any other state in that context.
- change xen_device_state_is_active() to
xen_device_frontend_is_active() (and pass a XenDevice directly)
since the state tests contained therein only apply to a frontend.
- use 'state' rather then 'xendev->backend_state' in
xen_device_backend_changed() to shorten the code.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20190913082159.31338-4-paul.durrant@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Diffstat (limited to 'include')
-rw-r--r-- | include/hw/xen/xen-bus.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/hw/xen/xen-bus.h b/include/hw/xen/xen-bus.h index 0d198148f6..3d5532258d 100644 --- a/include/hw/xen/xen-bus.h +++ b/include/hw/xen/xen-bus.h @@ -32,7 +32,9 @@ typedef struct XenDevice { XenWatch *backend_online_watch; xengnttab_handle *xgth; bool feature_grant_copy; + bool inactive; QLIST_HEAD(, XenEventChannel) event_channels; + QLIST_ENTRY(XenDevice) list; } XenDevice; typedef char *(*XenDeviceGetName)(XenDevice *xendev, Error **errp); @@ -68,6 +70,7 @@ typedef struct XenBus { struct xs_handle *xsh; XenWatchList *watch_list; XenWatch *backend_watch; + QLIST_HEAD(, XenDevice) inactive_devices; } XenBus; typedef struct XenBusClass { |