Re: [PATCH v2 07/18] xen/pvcalls: implement socket command

[Boris Ostrovsky]

On 05/19/2017 07:22 PM, Stefano Stabellini wrote:
> Just reply with success to the other end for now. Delay the allocation
> of the actual socket to bind and/or connect.
>
> Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
> CC: boris.ostrovsky@xxxxxxxxxx
> CC: jgross@xxxxxxxx
> ---
>  drivers/xen/pvcalls-back.c | 29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> index 9dc8a28..fed54bf 100644
> --- a/drivers/xen/pvcalls-back.c
> +++ b/drivers/xen/pvcalls-back.c
> @@ -12,12 +12,17 @@
>   * GNU General Public License for more details.
>   */
>  
> +#include <linux/inet.h>
>  #include <linux/kthread.h>
>  #include <linux/list.h>
>  #include <linux/radix-tree.h>
>  #include <linux/module.h>
>  #include <linux/semaphore.h>
>  #include <linux/wait.h>
> +#include <net/sock.h>
> +#include <net/inet_common.h>
> +#include <net/inet_connection_sock.h>
> +#include <net/request_sock.h>
>  
>  #include <xen/events.h>
>  #include <xen/grant_table.h>
> @@ -55,7 +60,29 @@ struct pvcalls_back_priv {
>  static int pvcalls_back_socket(struct xenbus_device *dev,
>  		struct xen_pvcalls_request *req)
>  {
> -	return 0;
> +	struct pvcalls_back_priv *priv;
> +	int ret;
> +	struct xen_pvcalls_response *rsp;
> +
> +	priv = dev_get_drvdata(&dev->dev);
> +
> +	if (req->u.socket.domain != AF_INET ||
> +	    req->u.socket.type != SOCK_STREAM ||
> +	    (req->u.socket.protocol != 0 &&
> +	     req->u.socket.protocol != AF_INET))
> +		ret = -EAFNOSUPPORT;
> +	else
> +		ret = 0;
> +
> +	/* leave the actual socket allocation for later */

Why is this allocation deferred (to connect and bind)? Doesn't it in
some way violate semantics of socket call?


-boris

> +
> +	rsp = RING_GET_RESPONSE(&priv->ring, priv->ring.rsp_prod_pvt++);
> +	rsp->req_id = req->req_id;
> +	rsp->cmd = req->cmd;
> +	rsp->u.socket.id = req->u.socket.id;
> +	rsp->ret = ret;
> +
> +	return ret;
>  }
>  
>  static int pvcalls_back_connect(struct xenbus_device *dev,