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scsi/scsi-bus: scsi_device_find: don't return unrealized devices 

The device core first places a device on the bus and then realizes it.
Make scsi_device_find avoid returing such devices to avoid
races in drivers that use an iothread (currently virtio-scsi)

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1812399

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200913160259.32145-7-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20201006123904.610658-11-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2020-10-06 15:39:01 +03:00
parent a23151e8cc
commit 8ddf958e8d
1 changed files with 53 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

83
hw/scsi/scsi-bus.c
View File

@ -24,6 +24,55 @@ static void scsi_target_free_buf(SCSIRequest *req);
static int next_scsi_bus;
static SCSIDevice *do_scsi_device_find(SCSIBus *bus,
int channel, int id, int lun,
bool include_unrealized)
{
BusChild *kid;
SCSIDevice *retval = NULL;
QTAILQ_FOREACH_RCU(kid, &bus->qbus.children, sibling) {
DeviceState *qdev = kid->child;
SCSIDevice *dev = SCSI_DEVICE(qdev);
if (dev->channel == channel && dev->id == id) {
if (dev->lun == lun) {
retval = dev;
break;
}
/*
* If we don't find exact match (channel/bus/lun),
* we will return the first device which matches channel/bus
*/
if (!retval) {
retval = dev;
}
}
}
/*
* This function might run on the IO thread and we might race against
* main thread hot-plugging the device.
* We assume that as soon as .realized is set to true we can let
* the user access the device.
*/
if (retval && !include_unrealized &&
!qatomic_load_acquire(&retval->qdev.realized)) {
retval = NULL;
}
return retval;
}
SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun)
{
RCU_READ_LOCK_GUARD();
return do_scsi_device_find(bus, channel, id, lun, false);
}
static void scsi_device_realize(SCSIDevice *s, Error **errp)
{
SCSIDeviceClass *sc = SCSI_DEVICE_GET_CLASS(s);
@ -137,7 +186,10 @@ static bool scsi_bus_is_address_free(SCSIBus *bus,
int channel, int target, int lun,
SCSIDevice **p_dev)
{
SCSIDevice *d = scsi_device_find(bus, channel, target, lun);
SCSIDevice *d;
RCU_READ_LOCK_GUARD();
d = do_scsi_device_find(bus, channel, target, lun, true);
if (d && d->lun == lun) {
if (p_dev) {
*p_dev = d;
@ -1570,35 +1622,6 @@ static char *scsibus_get_fw_dev_path(DeviceState *dev)
qdev_fw_name(dev), d->id, d->lun);
}
SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun)
{
BusChild *kid;
SCSIDevice *target_dev = NULL;
RCU_READ_LOCK_GUARD();
QTAILQ_FOREACH_RCU(kid, &bus->qbus.children, sibling) {
DeviceState *qdev = kid->child;
SCSIDevice *dev = SCSI_DEVICE(qdev);
if (dev->channel == channel && dev->id == id) {
if (dev->lun == lun) {
return dev;
}
/*
* If we don't find exact match (channel/bus/lun),
* we will return the first device which matches channel/bus
*/
if (!target_dev) {
target_dev = dev;
}
}
}
return target_dev;
}
/* SCSI request list. For simplicity, pv points to the whole device */
static int put_scsi_requests(QEMUFile *f, void *pv, size_t size,