On Wed, May 18 2022, Jason Wang <jasowang@xxxxxxxxxx> wrote:
> This patch allows the new introduced __virtio_break_device() to
> unbreak the virtqueue.
>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
> Cc: Marc Zyngier <maz@xxxxxxxxxx>
> Cc: Halil Pasic <pasic@xxxxxxxxxxxxx>
> Cc: Cornelia Huck <cohuck@xxxxxxxxxx>
> Cc: Vineeth Vijayan <vneethv@xxxxxxxxxxxxx>
> Cc: Peter Oberparleiter <oberpar@xxxxxxxxxxxxx>
> Cc: linux-s390@xxxxxxxxxxxxxxx
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> drivers/virtio/virtio_ring.c | 21 +++++++++++++++++++++
> include/linux/virtio.h | 1 +
> 2 files changed, 22 insertions(+)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index cfb028ca238e..5b7df7c455f0 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -2397,6 +2397,27 @@ void virtio_break_device(struct virtio_device *dev)
> }
> EXPORT_SYMBOL_GPL(virtio_break_device);
>
> +/*
> + * This should allow the device to be used by the driver. You may
> + * need to grab appropriate locks to flush. This should only be used
Hm, to flush what?
> + * in some specific case e.g (probing and restoring). Driver should
> + * not call this directly.
Maybe "This function should only be called by the core, not directly by
the driver."?
> + */
> +void __virtio_unbreak_device(struct virtio_device *dev)
> +{
> + struct virtqueue *_vq;
> +
> + spin_lock(&dev->vqs_list_lock);
> + list_for_each_entry(_vq, &dev->vqs, list) {
> + struct vring_virtqueue *vq = to_vvq(_vq);
> +
> + /* Pairs with READ_ONCE() in virtqueue_is_broken(). */
> + WRITE_ONCE(vq->broken, false);
> + }
> + spin_unlock(&dev->vqs_list_lock);
> +}
> +EXPORT_SYMBOL_GPL(__virtio_unbreak_device);
> +
> dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
> {
> struct vring_virtqueue *vq = to_vvq(_vq);
