Re: [Qemu-devel] [PATCH v2 2/5] vfio-ccw: concurrent I/O handling

[Halil Pasic]

On Mon, 21 Jan 2019 12:03:51 +0100
Cornelia Huck <address@hidden> wrote:

> --- a/drivers/s390/cio/vfio_ccw_private.h
> +++ b/drivers/s390/cio/vfio_ccw_private.h
> @@ -28,6 +28,7 @@
>   * @mdev: pointer to the mediated device
>   * @nb: notifier for vfio events
>   * @io_region: MMIO region to input/output I/O arguments/results
> + * @io_mutex: protect against concurrent update of I/O structures

We could be a bit more specific about what does this mutex guard.
Is it only io_region, or cp, irb and the new regions a well? ->state does
not seem to be covered, but should need some sort of synchronisation
too, or?

>   * @cp: channel program for the current I/O operation
>   * @irb: irb info received from interrupt
>   * @scsw: scsw info
> @@ -42,6 +43,7 @@ struct vfio_ccw_private {
>       struct mdev_device      *mdev;
>       struct notifier_block   nb;
>       struct ccw_io_region    *io_region;
> +     struct mutex            io_mutex;
>  
>       struct channel_program  cp;
>       struct irb              irb;
> --