qemu-e2k/include/sysemu/blockdev.h
Markus Armbruster 3ae59580a0 block: Keep DriveInfo alive until BlockDriverState dies
If the BDS's refcnt > 0, drive_del() destroys the DriveInfo, but not
the BDS.  This can happen in three places:

* Device model destruction during unplug: blockdev_auto_del()

* Xen IDE unplug: pci_piix3_xen_ide_unplug()

* drive_del command when no device model is attached: do_drive_del()

The other callers of drive_del are on error paths where refcnt == 1.

If the user somehow manages to plug in a device model using a BDS that
has gone through drive_del(), the legacy configuration passed in
DriveInfo doesn't reach the device model, and automatic deletion on
unplug doesn't work.  Worse, some device models such as scsi-disk
crash when DriveInfo doesn't exist.

This is theoretical; I didn't research an actual reproducer. The problem
was introduced when we replaced DriveInfo reference counting by BDS
reference counting in commit a94a3fa..fa510eb.

Fix by keeping DriveInfo alive until its BDS dies.

This affects qemu_drive_opts: now you can't reuse the same ID for new
drive options until the BDS dies.  Before, you could, but since the
code always attempts to create a BDS with the same ID next, the
enclosing operation "create a new drive" failed anyway.  Different
error path, same result.

Unfortunately, the fix involves use of blockdev.c stuff from block.c,
which is a layering violation.  Fortunately, my forthcoming
BlockBackend work will get rid of it again.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Benoît Canet <benoit.canet@nodalink.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-09-25 15:24:14 +02:00

70 lines
2.1 KiB
C

/*
* QEMU host block devices
*
* Copyright (c) 2003-2008 Fabrice Bellard
*
* This work is licensed under the terms of the GNU GPL, version 2 or
* later. See the COPYING file in the top-level directory.
*/
#ifndef BLOCKDEV_H
#define BLOCKDEV_H
#include "block/block.h"
#include "qapi/error.h"
#include "qemu/queue.h"
void blockdev_mark_auto_del(BlockDriverState *bs);
void blockdev_auto_del(BlockDriverState *bs);
typedef enum {
IF_DEFAULT = -1, /* for use with drive_add() only */
/*
* IF_IDE must be zero, because we want QEMUMachine member
* block_default_type to default-initialize to IF_IDE
*/
IF_IDE = 0,
IF_NONE,
IF_SCSI, IF_FLOPPY, IF_PFLASH, IF_MTD, IF_SD, IF_VIRTIO, IF_XEN,
IF_COUNT
} BlockInterfaceType;
struct DriveInfo {
BlockDriverState *bdrv;
char *id;
const char *devaddr;
BlockInterfaceType type;
int bus;
int unit;
int auto_del; /* see blockdev_mark_auto_del() */
bool enable_auto_del; /* Only for legacy drive_new() */
int media_cd;
int cyls, heads, secs, trans;
QemuOpts *opts;
char *serial;
QTAILQ_ENTRY(DriveInfo) next;
};
DriveInfo *drive_get(BlockInterfaceType type, int bus, int unit);
DriveInfo *drive_get_by_index(BlockInterfaceType type, int index);
int drive_get_max_bus(BlockInterfaceType type);
DriveInfo *drive_get_next(BlockInterfaceType type);
DriveInfo *drive_get_by_blockdev(BlockDriverState *bs);
QemuOpts *drive_def(const char *optstr);
QemuOpts *drive_add(BlockInterfaceType type, int index, const char *file,
const char *optstr);
DriveInfo *drive_new(QemuOpts *arg, BlockInterfaceType block_default_type);
void drive_del(DriveInfo *dinfo);
void drive_info_del(DriveInfo *dinfo);
/* device-hotplug */
DriveInfo *add_init_drive(const char *opts);
void qmp_change_blockdev(const char *device, const char *filename,
const char *format, Error **errp);
void do_commit(Monitor *mon, const QDict *qdict);
int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data);
#endif