Re: [PATCH V4 mlx5-next 11/13] vfio/mlx5: Implement vfio_pci driver for mlx5 devices

Jason Gunthorpe
2021-10-26T23:46:24Z

On Tue, Oct 26, 2021 at 04:42:28PM -0600, Alex Williamson wrote:

> > + /* Saving switches on and not running */
> > + if ((flipped_bits &
> > + (VFIO_DEVICE_STATE_RUNNING | VFIO_DEVICE_STATE_SAVING)) &&
> > + ((state & (VFIO_DEVICE_STATE_RUNNING |
> > + VFIO_DEVICE_STATE_SAVING)) == VFIO_DEVICE_STATE_SAVING)) {
>
> Can't this be reduced to:
>
> if ((flipped_bits & ~VFIO_DEVICE_STATE_RESUMING) &&
> (state == VFIO_DEVICE_STATE_SAVING)) {
>
> Maybe there's an argument for the original to be more invariant of TBD
> device_state bits?

I definitely prefer to see it explicit for this reason.

The shorter version relies on too much implicit stuff - eg that
SAVING|RESUMING is rejected at the top and seeing RESUMING as part of
a stanza that is only about SAVING|RUNNING is less reasable.

Jason