3809f7583b
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>
143 lines
4.8 KiB
C
143 lines
4.8 KiB
C
/*
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* Copyright (c) 2018 Citrix Systems Inc.
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#ifndef HW_XEN_BUS_H
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#define HW_XEN_BUS_H
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#include "hw/xen/xen_common.h"
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#include "hw/sysbus.h"
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#include "qemu/notify.h"
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typedef void (*XenWatchHandler)(void *opaque);
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typedef struct XenWatchList XenWatchList;
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typedef struct XenWatch XenWatch;
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typedef struct XenEventChannel XenEventChannel;
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typedef struct XenDevice {
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DeviceState qdev;
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domid_t frontend_id;
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char *name;
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struct xs_handle *xsh;
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XenWatchList *watch_list;
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char *backend_path, *frontend_path;
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enum xenbus_state backend_state, frontend_state;
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Notifier exit;
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XenWatch *backend_state_watch, *frontend_state_watch;
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bool backend_online;
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XenWatch *backend_online_watch;
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xengnttab_handle *xgth;
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bool feature_grant_copy;
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bool inactive;
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QLIST_HEAD(, XenEventChannel) event_channels;
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QLIST_ENTRY(XenDevice) list;
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} XenDevice;
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typedef char *(*XenDeviceGetName)(XenDevice *xendev, Error **errp);
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typedef void (*XenDeviceRealize)(XenDevice *xendev, Error **errp);
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typedef void (*XenDeviceFrontendChanged)(XenDevice *xendev,
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enum xenbus_state frontend_state,
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Error **errp);
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typedef void (*XenDeviceUnrealize)(XenDevice *xendev, Error **errp);
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typedef struct XenDeviceClass {
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/*< private >*/
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DeviceClass parent_class;
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/*< public >*/
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const char *backend;
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const char *device;
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XenDeviceGetName get_name;
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XenDeviceRealize realize;
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XenDeviceFrontendChanged frontend_changed;
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XenDeviceUnrealize unrealize;
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} XenDeviceClass;
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#define TYPE_XEN_DEVICE "xen-device"
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#define XEN_DEVICE(obj) \
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OBJECT_CHECK(XenDevice, (obj), TYPE_XEN_DEVICE)
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#define XEN_DEVICE_CLASS(class) \
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OBJECT_CLASS_CHECK(XenDeviceClass, (class), TYPE_XEN_DEVICE)
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#define XEN_DEVICE_GET_CLASS(obj) \
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OBJECT_GET_CLASS(XenDeviceClass, (obj), TYPE_XEN_DEVICE)
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typedef struct XenBus {
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BusState qbus;
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domid_t backend_id;
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struct xs_handle *xsh;
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XenWatchList *watch_list;
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XenWatch *backend_watch;
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QLIST_HEAD(, XenDevice) inactive_devices;
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} XenBus;
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typedef struct XenBusClass {
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/*< private >*/
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BusClass parent_class;
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} XenBusClass;
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#define TYPE_XEN_BUS "xen-bus"
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#define XEN_BUS(obj) \
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OBJECT_CHECK(XenBus, (obj), TYPE_XEN_BUS)
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#define XEN_BUS_CLASS(class) \
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OBJECT_CLASS_CHECK(XenBusClass, (class), TYPE_XEN_BUS)
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#define XEN_BUS_GET_CLASS(obj) \
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OBJECT_GET_CLASS(XenBusClass, (obj), TYPE_XEN_BUS)
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void xen_bus_init(void);
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void xen_device_backend_set_state(XenDevice *xendev,
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enum xenbus_state state);
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enum xenbus_state xen_device_backend_get_state(XenDevice *xendev);
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void xen_device_backend_printf(XenDevice *xendev, const char *key,
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const char *fmt, ...)
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GCC_FMT_ATTR(3, 4);
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void xen_device_frontend_printf(XenDevice *xendev, const char *key,
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const char *fmt, ...)
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GCC_FMT_ATTR(3, 4);
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int xen_device_frontend_scanf(XenDevice *xendev, const char *key,
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const char *fmt, ...);
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void xen_device_set_max_grant_refs(XenDevice *xendev, unsigned int nr_refs,
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Error **errp);
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void *xen_device_map_grant_refs(XenDevice *xendev, uint32_t *refs,
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unsigned int nr_refs, int prot,
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Error **errp);
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void xen_device_unmap_grant_refs(XenDevice *xendev, void *map,
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unsigned int nr_refs, Error **errp);
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typedef struct XenDeviceGrantCopySegment {
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union {
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void *virt;
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struct {
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uint32_t ref;
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off_t offset;
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} foreign;
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} source, dest;
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size_t len;
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} XenDeviceGrantCopySegment;
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void xen_device_copy_grant_refs(XenDevice *xendev, bool to_domain,
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XenDeviceGrantCopySegment segs[],
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unsigned int nr_segs, Error **errp);
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typedef bool (*XenEventHandler)(void *opaque);
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XenEventChannel *xen_device_bind_event_channel(XenDevice *xendev,
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AioContext *ctx,
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unsigned int port,
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XenEventHandler handler,
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void *opaque, Error **errp);
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void xen_device_notify_event_channel(XenDevice *xendev,
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XenEventChannel *channel,
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Error **errp);
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void xen_device_unbind_event_channel(XenDevice *xendev,
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XenEventChannel *channel,
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Error **errp);
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#endif /* HW_XEN_BUS_H */
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