Devices may have component devices and buses. Device realization may fail. Realization is recursive: a device's realize() method realizes its components, and device_set_realized() realizes its buses (which should in turn realize the devices on that bus, except bus_set_realized() doesn't implement that, yet). When realization of a component or bus fails, we need to roll back: unrealize everything we realized so far. If any of these unrealizes failed, the device would be left in an inconsistent state. Must not happen. device_set_realized() lets it happen: it ignores errors in the roll back code starting at label child_realize_fail. Since realization is recursive, unrealization must be recursive, too. But how could a partly failed unrealize be rolled back? We'd have to re-realize, which can fail. This design is fundamentally broken. device_set_realized() does not roll back at all. Instead, it keeps unrealizing, ignoring further errors. It can screw up even for a device with no buses: if the lone dc->unrealize() fails, it still unregisters vmstate, and calls listeners' unrealize() callback. bus_set_realized() does not roll back either. Instead, it stops unrealizing. Fortunately, no unrealize method can fail, as we'll see below. To fix the design error, drop parameter @errp from all the unrealize methods. Any unrealize method that uses @errp now needs an update. This leads us to unrealize() methods that can fail. Merely passing it to another unrealize method cannot cause failure, though. Here are the ones that do other things with @errp: * virtio_serial_device_unrealize() Fails when qbus_set_hotplug_handler() fails, but still does all the other work. On failure, the device would stay realized with its resources completely gone. Oops. Can't happen, because qbus_set_hotplug_handler() can't actually fail here. Pass &error_abort to qbus_set_hotplug_handler() instead. * hw/ppc/spapr_drc.c's unrealize() Fails when object_property_del() fails, but all the other work is already done. On failure, the device would stay realized with its vmstate registration gone. Oops. Can't happen, because object_property_del() can't actually fail here. Pass &error_abort to object_property_del() instead. * spapr_phb_unrealize() Fails and bails out when remove_drcs() fails, but other work is already done. On failure, the device would stay realized with some of its resources gone. Oops. remove_drcs() fails only when chassis_from_bus()'s object_property_get_uint() fails, and it can't here. Pass &error_abort to remove_drcs() instead. Therefore, no unrealize method can fail before this patch. device_set_realized()'s recursive unrealization via bus uses object_property_set_bool(). Can't drop @errp there, so pass &error_abort. We similarly unrealize with object_property_set_bool() elsewhere, always ignoring errors. Pass &error_abort instead. Several unrealize methods no longer handle errors from other unrealize methods: virtio_9p_device_unrealize(), virtio_input_device_unrealize(), scsi_qdev_unrealize(), ... Much of the deleted error handling looks wrong anyway. One unrealize methods no longer ignore such errors: usb_ehci_pci_exit(). Several realize methods no longer ignore errors when rolling back: v9fs_device_realize_common(), pci_qdev_unrealize(), spapr_phb_realize(), usb_qdev_realize(), vfio_ccw_realize(), virtio_device_realize(). Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20200505152926.18877-17-armbru@redhat.com>
95 lines
2.4 KiB
C
95 lines
2.4 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_BLOCK_H
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#define HW_XEN_BLOCK_H
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#include "hw/xen/xen-bus.h"
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#include "hw/block/block.h"
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#include "hw/block/dataplane/xen-block.h"
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#include "sysemu/iothread.h"
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typedef enum XenBlockVdevType {
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XEN_BLOCK_VDEV_TYPE_INVALID,
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XEN_BLOCK_VDEV_TYPE_DP,
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XEN_BLOCK_VDEV_TYPE_XVD,
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XEN_BLOCK_VDEV_TYPE_HD,
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XEN_BLOCK_VDEV_TYPE_SD,
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XEN_BLOCK_VDEV_TYPE__MAX
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} XenBlockVdevType;
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typedef struct XenBlockVdev {
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XenBlockVdevType type;
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unsigned long disk;
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unsigned long partition;
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unsigned long number;
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} XenBlockVdev;
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typedef struct XenBlockProperties {
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XenBlockVdev vdev;
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BlockConf conf;
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unsigned int max_ring_page_order;
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IOThread *iothread;
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} XenBlockProperties;
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typedef struct XenBlockDrive {
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char *id;
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char *node_name;
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} XenBlockDrive;
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typedef struct XenBlockIOThread {
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char *id;
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} XenBlockIOThread;
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typedef struct XenBlockDevice {
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XenDevice xendev;
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XenBlockProperties props;
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const char *device_type;
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unsigned int info;
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XenBlockDataPlane *dataplane;
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XenBlockDrive *drive;
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XenBlockIOThread *iothread;
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} XenBlockDevice;
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typedef void (*XenBlockDeviceRealize)(XenBlockDevice *blockdev, Error **errp);
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typedef void (*XenBlockDeviceUnrealize)(XenBlockDevice *blockdev);
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typedef struct XenBlockDeviceClass {
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/*< private >*/
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XenDeviceClass parent_class;
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/*< public >*/
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XenBlockDeviceRealize realize;
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XenBlockDeviceUnrealize unrealize;
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} XenBlockDeviceClass;
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#define TYPE_XEN_BLOCK_DEVICE "xen-block"
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#define XEN_BLOCK_DEVICE(obj) \
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OBJECT_CHECK(XenBlockDevice, (obj), TYPE_XEN_BLOCK_DEVICE)
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#define XEN_BLOCK_DEVICE_CLASS(class) \
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OBJECT_CLASS_CHECK(XenBlockDeviceClass, (class), TYPE_XEN_BLOCK_DEVICE)
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#define XEN_BLOCK_DEVICE_GET_CLASS(obj) \
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OBJECT_GET_CLASS(XenBlockDeviceClass, (obj), TYPE_XEN_BLOCK_DEVICE)
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typedef struct XenDiskDevice {
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XenBlockDevice blockdev;
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} XenDiskDevice;
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#define TYPE_XEN_DISK_DEVICE "xen-disk"
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#define XEN_DISK_DEVICE(obj) \
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OBJECT_CHECK(XenDiskDevice, (obj), TYPE_XEN_DISK_DEVICE)
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typedef struct XenCDRomDevice {
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XenBlockDevice blockdev;
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} XenCDRomDevice;
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#define TYPE_XEN_CDROM_DEVICE "xen-cdrom"
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#define XEN_CDROM_DEVICE(obj) \
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OBJECT_CHECK(XenCDRomDevice, (obj), TYPE_XEN_CDROM_DEVICE)
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#endif /* HW_XEN_BLOCK_H */
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