Re: [PATCH v1] vhost-scsi: do not validate vrings during endpoint teardown

[Mike Christie <michael.christie@oracle.com>]

On 11/5/26 11:48 PM, Yuho Choi wrote:
> vhost_scsi_clear_endpoint() checks every virtqueue with vhost_vq_access_ok() before disabling the backends and waiting for in-flight SCSI commands. If that check fails, endpoint teardown is skipped. vhost_scsi_release() ignores the error and
> 
> 
> vhost_scsi_clear_endpoint() checks every virtqueue with
> vhost_vq_access_ok() before disabling the backends and waiting for
> in-flight SCSI commands.  If that check fails, endpoint teardown is
> skipped.
> 
> vhost_scsi_release() ignores the error and frees the vhost-scsi state.
> vhost_dev_stop() drains vhost work, but it does not wait for commands
> owned by the target core.  A later command or TMF completion can therefore
> dereference its saved virtqueue pointer after the virtqueue has been freed.
> 
> Vring access is not a prerequisite for tearing an endpoint down.  Remove
> the check so teardown always disables the backends and waits for in-flight
> commands before releasing their state.
> 
Can you describe the bug a little more?

If we have done vhost_scsi_set_endpoint successfully, are you saying a later
call to vhost_scsi_clear_endpoint could fail the vhost_vq_access_ok check
and not teardown the endpoint?

Or are you saying that even if we never did vhost_scsi_set_endpoint then
when vhost_scsi_release is called, a command could be running in the
vhost-scsi driver and so we need to do something? Is the something a
"vhost_vq_set_backend(vq, NULL)" and vhost_scsi_flush(vs)?