Re: [PATCH v1 06/13] xen/pvcalls: implement listen command

[Juergen Gross]

On 22/07/17 02:11, Stefano Stabellini wrote:
> Send PVCALLS_LISTEN to the backend.
> 
> Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
> CC: boris.ostrovsky@xxxxxxxxxx
> CC: jgross@xxxxxxxx
> ---
>  drivers/xen/pvcalls-front.c | 49 +++++++++++++++++++++++++++++++++++++++++++++
>  drivers/xen/pvcalls-front.h |  1 +
>  2 files changed, 50 insertions(+)
> 
> diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
> index 71619bc..80fd5fb 100644
> --- a/drivers/xen/pvcalls-front.c
> +++ b/drivers/xen/pvcalls-front.c
> @@ -361,6 +361,55 @@ int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
>  	return 0;
>  }
>  
> +int pvcalls_front_listen(struct socket *sock, int backlog)
> +{
> +	struct pvcalls_bedata *bedata;
> +	struct sock_mapping *map;
> +	struct xen_pvcalls_request *req;
> +	int notify, req_id, ret;
> +
> +	if (!pvcalls_front_dev)
> +		return -ENOTCONN;
> +	bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
> +
> +	map = (struct sock_mapping *) READ_ONCE(sock->sk->sk_send_head);
> +	if (!map)
> +		return -ENOTSOCK;
> +
> +	if (map->passive.status != PVCALLS_STATUS_BIND)
> +		return -EOPNOTSUPP;
> +
> +	spin_lock(&bedata->pvcallss_lock);
> +	req_id = bedata->ring.req_prod_pvt & (RING_SIZE(&bedata->ring) - 1);
> +	BUG_ON(req_id >= PVCALLS_NR_REQ_PER_RING);

BUG_ON() again!


Juergen

> +	if (RING_FULL(&bedata->ring) ||
> +	    bedata->rsp[req_id].req_id != PVCALLS_INVALID_ID) {
> +		spin_unlock(&bedata->pvcallss_lock);
> +		return -EAGAIN;
> +	}
> +	req = RING_GET_REQUEST(&bedata->ring, req_id);
> +	req->req_id = req_id;
> +	req->cmd = PVCALLS_LISTEN;
> +	req->u.listen.id = (uint64_t) sock;
> +	req->u.listen.backlog = backlog;
> +
> +	bedata->ring.req_prod_pvt++;
> +	RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
> +	spin_unlock(&bedata->pvcallss_lock);
> +	if (notify)
> +		notify_remote_via_irq(bedata->irq);
> +
> +	wait_event(bedata->inflight_req,
> +		   READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
> +
> +	map->passive.status = PVCALLS_STATUS_LISTEN;
> +	ret = bedata->rsp[req_id].ret;
> +	/* read ret, then set this rsp slot to be reused */
> +	smp_mb();
> +	WRITE_ONCE(bedata->rsp[req_id].req_id, PVCALLS_INVALID_ID);
> +	return ret;
> +}
> +
>  static const struct xenbus_device_id pvcalls_front_ids[] = {
>  	{ "pvcalls" },
>  	{ "" }
> diff --git a/drivers/xen/pvcalls-front.h b/drivers/xen/pvcalls-front.h
> index 8b0a274..aa8fe10 100644
> --- a/drivers/xen/pvcalls-front.h
> +++ b/drivers/xen/pvcalls-front.h
> @@ -9,5 +9,6 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
>  int pvcalls_front_bind(struct socket *sock,
>  		       struct sockaddr *addr,
>  		       int addr_len);
> +int pvcalls_front_listen(struct socket *sock, int backlog);
>  
>  #endif
>