Re: [PATCH 8/9] rpmsg: virtio: use rpmsg_ns driver to manage ns announcement

Mathieu Poirier
2020-08-25T16:54:43Z

Hi Arnaud,

On Fri, Jul 31, 2020 at 01:47:31PM +0200, Arnaud Pouliquen wrote:
> Use the new rpmsg_ns API to send the name service announcements if
> the VIRTIO_RPMSG_F_NS is set, else just not implement the ops.
>
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
> ---
> drivers/rpmsg/virtio_rpmsg_bus.c | 94 +++++---------------------------
> 1 file changed, 13 insertions(+), 81 deletions(-)
>
> diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
> index f771fdae150e..3c771a6392be 100644
> --- a/drivers/rpmsg/virtio_rpmsg_bus.c
> +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
> @@ -91,35 +91,6 @@ struct rpmsg_hdr {
> u8 data[];
> } __packed;
>
> -/**
> - * struct rpmsg_ns_msg - dynamic name service announcement message
> - * @name: name of remote service that is published
> - * @addr: address of remote service that is published
> - * @flags: indicates whether service is created or destroyed
> - *
> - * This message is sent across to publish a new service, or announce
> - * about its removal. When we receive these messages, an appropriate
> - * rpmsg channel (i.e device) is created/destroyed. In turn, the ->probe()
> - * or ->remove() handler of the appropriate rpmsg driver will be invoked
> - * (if/as-soon-as one is registered).
> - */
> -struct rpmsg_ns_msg {
> - char name[RPMSG_NAME_SIZE];
> - __virtio32 addr;
> - __virtio32 flags;
> -} __packed;
> -
> -/**
> - * enum rpmsg_ns_flags - dynamic name service announcement flags
> - *
> - * @RPMSG_NS_CREATE: a new remote service was just created
> - * @RPMSG_NS_DESTROY: a known remote service was just destroyed
> - */
> -enum rpmsg_ns_flags {
> - RPMSG_NS_CREATE = 0,
> - RPMSG_NS_DESTROY = 1,
> -};
> -
> /**
> * @vrp: the remote processor this channel belongs to
> */
> @@ -324,60 +295,18 @@ static void virtio_rpmsg_destroy_ept(struct rpmsg_endpoint *ept)
> __rpmsg_destroy_ept(vch->vrp, ept);
> }
>
> -static int virtio_rpmsg_announce_create(struct rpmsg_device *rpdev)
> -{
> - struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
> - struct virtproc_info *vrp = vch->vrp;
> - struct device *dev = &rpdev->dev;
> - int err = 0;
> -
> - /* need to tell remote processor's name service about this channel ? */
> - if (rpdev->announce && rpdev->ept &&
> - virtio_has_feature(vrp->vdev, VIRTIO_RPMSG_F_NS)) {
> - struct rpmsg_ns_msg nsm;
> -
> - strncpy(nsm.name, rpdev->id.name, RPMSG_NAME_SIZE);
> - nsm.addr = cpu_to_virtio32(vrp->vdev, rpdev->ept->addr);
> - nsm.flags = cpu_to_virtio32(vrp->vdev, RPMSG_NS_CREATE);
> -
> - err = rpmsg_sendto(rpdev->ept, &nsm, sizeof(nsm), RPMSG_NS_ADDR);
> - if (err)
> - dev_err(dev, "failed to announce service %d\n", err);
> - }
> -
> - return err;
> -}
> -
> -static int virtio_rpmsg_announce_destroy(struct rpmsg_device *rpdev)
> -{
> - struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
> - struct virtproc_info *vrp = vch->vrp;
> - struct device *dev = &rpdev->dev;
> - int err = 0;
> -
> - /* tell remote processor's name service we're removing this channel */
> - if (rpdev->announce && rpdev->ept &&
> - virtio_has_feature(vrp->vdev, VIRTIO_RPMSG_F_NS)) {
> - struct rpmsg_ns_msg nsm;
> -
> - strncpy(nsm.name, rpdev->id.name, RPMSG_NAME_SIZE);
> - nsm.addr = cpu_to_virtio32(vrp->vdev, rpdev->ept->addr);
> - nsm.flags = cpu_to_virtio32(vrp->vdev, RPMSG_NS_DESTROY);
> -
> - err = rpmsg_sendto(rpdev->ept, &nsm, sizeof(nsm), RPMSG_NS_ADDR);
> - if (err)
> - dev_err(dev, "failed to announce service %d\n", err);
> - }
> -
> - return err;
> -}
> -
> static const struct rpmsg_device_ops virtio_rpmsg_ops = {
> .create_channel = virtio_rpmsg_create_channel,
> .release_channel = virtio_rpmsg_release_channel,
> .create_ept = virtio_rpmsg_create_ept,
> - .announce_create = virtio_rpmsg_announce_create,
> - .announce_destroy = virtio_rpmsg_announce_destroy,
> +};
> +
> +static const struct rpmsg_device_ops virtio_rpmsg_w_nsa_ops = {
> + .create_channel = virtio_rpmsg_create_channel,
> + .release_channel = virtio_rpmsg_release_channel,
> + .create_ept = virtio_rpmsg_create_ept,
> + .announce_create = rpmsg_ns_announce_create,
> + .announce_destroy = rpmsg_ns_announce_destroy,
> };
>
> static void virtio_rpmsg_release_device(struct device *dev)
> @@ -423,7 +352,10 @@ __rpmsg_create_channel(struct virtproc_info *vrp,
> rpdev = &vch->rpdev;
> rpdev->src = chinfo->src;
> rpdev->dst = chinfo->dst;
> - rpdev->ops = &virtio_rpmsg_ops;
> + if (virtio_has_feature(vrp->vdev, VIRTIO_RPMSG_F_NS))
> + rpdev->ops = &virtio_rpmsg_w_nsa_ops;
> + else
> + rpdev->ops = &virtio_rpmsg_ops;

Yesterday I struggled with this part and I still do this morning. Function
__rpmsg_create_channel() can only be called if VIRTIO_RPMSG_F_NS is set so there
is no need to check it again. I would also have expected this patch to be a
simple replace of the .announce_create/destroy functions. Adding an ops that
doesn't have the .announce_create/destroy functions looks like a feature to me,
and one that I don't quite get.

Do you think you could expand on the motivation behind this patch?

Thanks,
Mathieu

>
> /*
> * rpmsg server channels has predefined local address (for now),
> @@ -933,7 +865,7 @@ static int rpmsg_probe(struct virtio_device *vdev)
>
> /* Assign public information to the rpmsg_device */
> rpdev_ns = &vch->rpdev;
> - rpdev_ns->ops = &virtio_rpmsg_ops;
> + rpdev_ns->ops = &virtio_rpmsg_w_nsa_ops;
>
> rpdev_ns->dev.parent = &vrp->vdev->dev;
> rpdev_ns->dev.release = virtio_rpmsg_release_device;
> --
> 2.17.1
>