Am 04.01.2023 um 20:56 hat Stefan Hajnoczi geschrieben: > scsi_device_purge_requests() is called from I/O code by virtio-scsi TMF > emulation code. It must not call Global State APIs like blk_drain() > because that results in an assertion failure. > > blk_drain() is a Global State API because it uses bdrv_unref(). Actually > ref/unref is unnecessary in device emulation code because the drive= > qdev property holds the reference.
Just for the record: We came to the conclusion that this isn't true. We're not doing blk_ref/unref here, but bdrv_ref/unref. The function calls bdrv_drained_end(bs), so the node must still exist at that point and the ref/unref is required to ensure this. The root node of the BlockBackend can change, so without the ref/unref pair the last reference to the node can go away even if the BlockBackend still exists. So we'll need a different solution. Kevin
