On Wed, Mar 02, 2022 at 12:19:20PM +0100, Cornelia Huck wrote: > > +/* > > + * vfio_mig_get_next_state - Compute the next step in the FSM > > + * @cur_fsm - The current state the device is in > > + * @new_fsm - The target state to reach > > + * @next_fsm - Pointer to the next step to get to new_fsm > > + * > > + * Return 0 upon success, otherwise -errno > > + * Upon success the next step in the state progression between cur_fsm and > > + * new_fsm will be set in next_fsm. > > What about non-success? Can the caller make any assumption about > next_fsm in that case? Because... I checked both mlx5 and acc, both properly ignore the next_fsm value on error. This oddness aros when Alex asked to return an errno instead of the state value. > > + * any -> ERROR > > + * ERROR cannot be specified as a device state, however any transition request > > + * can be failed with an errno return and may then move the device_state into > > + * ERROR. In this case the device was unable to execute the requested arc and > > + * was also unable to restore the device to any valid device_state. > > + * To recover from ERROR VFIO_DEVICE_RESET must be used to return the > > + * device_state back to RUNNING. > > ...this seems to indicate that not moving into STATE_ERROR is an > option anyway. Yes, but it is never done by vfio_mig_get_next_state() it is only directly triggered inside the driver. > Do we need any extra guidance in the description for > vfio_mig_get_next_state()? I think no, it is typical in linux that function failure means output arguments are not valid Jason
